Aqueous solution of additive for ink composition, aqueous solution of colorant for ink composition, ink composition, ink composition for inkjet recording, and inkjet recording method

Abstract

Provided are an aqueous additive solution for ink compositions, an aqueous colorant solution for ink compositions, and an ink composition which have excellent storage stability, an ink composition for ink-jet recording which comprises said ink composition, and an ink-jet recording method in which the ink composition for ink-jet recording is used. These are: an aqueous additive solution for ink compositions which comprises a compound represented by the general formula (A) given in the description, a compound represented by the general formula (II), and water; an aqueous colorant solution for ink compositions; an ink composition; an ink composition for ink-jet recording which comprises said ink composition; and an ink-jet recording method in which the ink composition for ink-jet recording is used.

Description

[Technical Field]

[0001] The present invention relates to an aqueous additive solution for an ink composition, an aqueous colorant solution for an ink composition, an ink composition, an ink composition for inkjet recording, and an inkjet recording method. [Background technology]

[0002] The ink jet recording method has rapidly become widespread and is continuing to develop because of its low material costs, high speed recording, low noise during recording, and ease of color recording. Compositions containing various colorants (dyes) have been proposed as ink compositions used in inkjet recording methods. Compounds (additives) to be added to ink compositions have also been investigated to improve various performances. For example, Patent Documents 1 to 3 describe compounds with high planarity as additives that can be used in ink compositions containing dyes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent No. 4686151 [Patent Document 2] Japanese Patent Application Publication No. 2020-76048 [Patent Document 3] International Publication No. 2021 / 039651 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, inkjet printers equipped with large-capacity ink tanks with a capacity of 50 mL or more have been developed, and inkjet printers equipped with large-capacity ink tanks are said to be superior in terms of printing costs, etc., because they reduce the frequency of ink cartridge replacement. However, in a large-capacity ink tank, the ink composition will remain in the ink tank for a long period of time, and therefore the ink composition is required to have a level of storage stability not previously available. Furthermore, storage stability is also required for the aqueous additive solutions used to prepare ink compositions.

[0005] Patent Document 1 does not consider the above point of view. Patent Documents 2 and 3 discuss the storage stability of ink compositions, but there is room for further improvement. Furthermore, they do not discuss the storage stability of aqueous additive solutions.

[0006] In particular, if the pH values ​​of the aqueous additive solution and aqueous colorant solution used in preparing the ink composition are high (for example, pH value greater than 9.0), it may become practically difficult to adjust the pH value of the ink composition for inkjet recording (for example, pH value = 8.5). Furthermore, if the pH values ​​of the aqueous additive solution, aqueous colorant solution, and ink composition are high, decomposition of the colorant and additives may occur. If the pH value of the additive aqueous solution and the colorant aqueous solution becomes low (for example, the pH value becomes lower than 6.0), there is a high risk of precipitation of the colorant (for example, acid dye) and the additive. If the pH value of the ink composition is low (for example, if the pH value is lower than 6.0), the risk of corrosion of the ink head of the inkjet printer increases, and the risk of precipitation of the colorant (for example, acid dye) and additives as well as the additive aqueous solution and colorant aqueous solution also increases. Therefore, fluctuations in pH value are also linked to variations in optimized liquid properties (solubility stability, absorbance, viscosity, surface tension, etc.), raising concerns about the impact on delicate ink head characteristics (for example, there is a risk of reducing ink ejection stability (clogging) and continuous ejection stability (reliability)).

[0007] An object of the present invention is to provide an aqueous solution of an additive for an ink composition, an aqueous solution of a colorant for an ink composition, and an ink composition that have excellent storage stability (excellent antiseptic properties, and when stored for a long period of time, there is little precipitation of insoluble matter, little change in absorbance, viscosity, and surface tension, and little change in pH value), an ink composition for inkjet recording that contains the ink composition, and an inkjet recording method that uses the ink composition for inkjet recording. [Means for solving the problem]

[0008] The present inventors have found that the above object can be achieved by the following configuration.

[0009] <1> An aqueous solution of an additive for an ink composition, comprising a compound represented by the following general formula (A), a compound represented by the following general formula (II), and water.

[0010] [ka]

[0011] In general formula (A), T 1 , T 2 , and T 3 are each independently: *-NH-(CH2) n -Rt, *-NH-(CH2) n -OH, *-N-{(CH2) n -OH}2, *-NH-CH2CH(OH)CH2-Rt, *-OM, a halogen atom, or a substituted or unsubstituted arylamino group. 1 , T 2 , and T 3 At least one of the following is -NH-(CH2) n -Rt, *-NH-(CH2) n -OH, *-N-{(CH2) n-OH}2, or *-NH-CH2CH(OH)CH2-Rt. * represents a bonding site to the triazine ring, n represents an integer of 1 to 5, and Rt represents CO2M, SO3M, or PO(OM)2. M represents a hydrogen atom or a counter cation. When multiple n's are present, the multiple n's may be the same or different. When multiple M's are present, the multiple M's may be the same or different.

[0012] [ka]

[0013] In general formula (II), Ar 20 represents a benzene ring or a naphthalene ring. 21 ~R 28 R each independently represents a hydrogen atom or a substituent. 21 and R 22 may be bonded to form a ring. 23 and R 24 may be bonded to form a ring. 25 and R 26 may be bonded to form a ring. 27 and R 28 may be bonded to form a ring. 29 represents a substituent. 20 represents a benzene ring, k represents an integer of 0 to 4. 20 When R represents a naphthalene ring, k represents an integer of 0 to 6. 29 If there are multiple R 29 may be the same or different. 29 If there are multiple R 29 may be bonded to form a ring, provided that the compound represented by general formula (II) has at least one hydrophilic group. <2> The compound represented by the general formula (A) is at least one compound selected from the following compound group (a): <1> 2. An aqueous solution of the additive for an ink composition according to claim 1.

[0014] [ka]

[0015] In the compounds of the compound group (a), M represents a hydrogen atom or a counter cation. When a compound contains a plurality of Ms, the plurality of Ms may be the same or different. <3> R in the above general formula (II) 21 ~R 29 At least one of the above has an ionic hydrophilic group. <1> or <2> 2. An aqueous solution of the additive for an ink composition according to claim 1. <4> The content of the compound represented by the general formula (II) is 5.0 to 20.0% by mass based on the total mass of the aqueous ink composition additive solution. <1> ~ <3> 10. The aqueous solution of an additive for an ink composition according to claim 9. <5> The content of the compound represented by the general formula (A) is 0.01 to 1.0% by mass based on the total mass of the aqueous ink composition additive solution. <1> ~ <4> 10. The aqueous solution of an additive for an ink composition according to claim 9. <6> Further, a chelating agent is contained, <1> ~ <5> 10. The aqueous solution of an additive for an ink composition according to claim 9. <7> The content of the chelating agent is 0.001 to 1.0% by mass based on the total mass of the aqueous ink composition additive solution. <6> 2. An aqueous solution of the additive for an ink composition according to claim 1. <8> Furthermore, it contains preservatives, <1> ~ <7> 10. The aqueous solution of an additive for an ink composition according to claim 9. <9> The content of the preservative is 0.01 to 1.0 mass % based on the total mass of the aqueous ink composition additive solution. <8> 2. An aqueous solution of the additive for an ink composition according to claim 1. <10> Further, containing a buffering agent, <1> ~ <9> 10. The aqueous solution of an additive for an ink composition according to claim 9. <11> pH value at 25°C is 6.5 to 9.0. <1> ~ <10> 10. The aqueous solution of an additive for an ink composition according to claim 9. <12> An aqueous colorant solution for an ink composition, comprising a compound represented by the following general formula (A), a compound represented by the following general formula (II), water, and a colorant:

[0016] [ka]

[0017] In general formula (A), T 1 , T 2 , and T 3 are each independently: *-NH-(CH2) n -Rt, *-NH-(CH2) n -OH, *-N-{(CH2) n -OH}2, *-NH-CH2CH(OH)CH2-Rt, *-OM, a halogen atom, or a substituted or unsubstituted arylamino group. 1 , T 2 , and T 3 At least one of the following is -NH-(CH2) n -Rt, *-NH-(CH2) n -OH, *-N-{(CH2) n -OH}2, or *-NH-CH2CH(OH)CH2-Rt. * represents a bonding site to the triazine ring, n represents an integer of 1 to 5, and Rt represents CO2M, SO3M, or PO(OM)2. M represents a hydrogen atom or a counter cation. When multiple n's are present, the multiple n's may be the same or different. When multiple M's are present, the multiple M's may be the same or different.

[0018] [ka]

[0019] In general formula (II), Ar 20 represents a benzene ring or a naphthalene ring. 21 ~R 28R each independently represents a hydrogen atom or a substituent. 21 and R 22 may be bonded to form a ring. 23 and R 24 may be bonded to form a ring. 25 and R 26 may be bonded to form a ring. 27 and R 28 may be bonded to form a ring. 29 represents a substituent. 20 represents a benzene ring, k represents an integer of 0 to 4. 20 When R represents a naphthalene ring, k represents an integer of 0 to 6. 29 If there are multiple R 29 may be the same or different. 29 If there are multiple R 29 may be bonded to form a ring, provided that the compound represented by general formula (II) has at least one hydrophilic group. <13> The compound represented by the general formula (A) is at least one compound selected from the following compound group (a): <12> 2. An aqueous colorant solution for an ink composition according to claim 1.

[0020] [ka]

[0021] In the compounds of the compound group (a), M represents a hydrogen atom or a counter cation. When a compound contains a plurality of Ms, the plurality of Ms may be the same or different. <14> the content of the colorant is 5.0 to 20.0 mass % based on the total mass of the aqueous colorant solution for the ink composition; <12> or <13> 2. An aqueous colorant solution for an ink composition according to claim 1. <15> The colorant is a water-soluble dye. <12> ~ <14> 10. The aqueous colorant solution for an ink composition according to claim 9, wherein the aqueous colorant solution for an ink composition according to claim 9 is an aqueous colorant solution for an ink composition according to any one of claims 1 to 9. <16> the content of the compound represented by the general formula (II) is 0.5 to 8.0% by mass based on the total mass of the aqueous colorant solution for the ink composition; <12> ~ <15> 10. The aqueous colorant solution for an ink composition according to claim 9, wherein the aqueous colorant solution for an ink composition according to claim 9 is an aqueous colorant solution for an ink composition according to any one of claims 1 to 9. <17> the content of the compound represented by the general formula (A) is 0.001 to 0.3 mass % based on the total mass of the aqueous colorant solution for the ink composition; <12> ~ <16> 10. The aqueous colorant solution for an ink composition according to claim 9, wherein the aqueous colorant solution for an ink composition according to claim 9 is an aqueous colorant solution for an ink composition according to any one of claims 1 to 9. <18> Further, a chelating agent is contained, <12> ~ <17> 10. The aqueous colorant solution for an ink composition according to claim 9, wherein the aqueous colorant solution for an ink composition according to claim 9 is an aqueous colorant solution for an ink composition according to any one of claims 1 to 9. <19> The content of the chelating agent is 0.001 to 1.0% by mass based on the total mass of the aqueous ink composition additive solution. <18> 2. An aqueous colorant solution for an ink composition according to claim 1. <20> Furthermore, it contains preservatives, <12> ~ <19> 10. The aqueous colorant solution for an ink composition according to claim 9, wherein the aqueous colorant solution for an ink composition according to claim 9 is an aqueous colorant solution for an ink composition according to any one of claims 1 to 9. <21> The content of the preservative is 0.01 to 1.0 mass % based on the total mass of the aqueous ink composition additive solution. <20> 2. An aqueous colorant solution for an ink composition according to claim 1. <22> Further, containing a buffering agent, <12> ~ <21> 10. The aqueous colorant solution for an ink composition according to claim 9, wherein the aqueous colorant solution for an ink composition according to claim 9 is an aqueous colorant solution for an ink composition according to any one of claims 1 to 9. <23> pH value at 25°C is 6.5 to 9.0. <12> ~ <22> 10. The aqueous colorant solution for an ink composition according to claim 9, wherein the aqueous colorant solution for an ink composition according to claim 9 is an aqueous colorant solution for an ink composition according to any one of claims 1 to 9. <24> An ink composition comprising a compound represented by the following general formula (A), a compound represented by the following general formula (II), water, and a colorant.

[0022] [ka]

[0023] In general formula (A), T 1 , T 2, and T 3 are each independently: *-NH-(CH2) n -Rt, *-NH-(CH2) n -OH, *-N-{(CH2) n -OH}2, *-NH-CH2CH(OH)CH2-Rt, *-OM, a halogen atom, or a substituted or unsubstituted arylamino group. 1 , T 2 , and T 3 At least one of the following is -NH-(CH2) n -Rt, *-NH-(CH2) n -OH, *-N-{(CH2) n -OH}2, or *-NH-CH2CH(OH)CH2-Rt. * represents a bonding site to the triazine ring, n represents an integer of 1 to 5, and Rt represents CO2M, SO3M, or PO(OM)2. M represents a hydrogen atom or a counter cation. When multiple n's are present, the multiple n's may be the same or different. When multiple M's are present, the multiple M's may be the same or different.

[0024] [ka]

[0025] In general formula (II), Ar 20 represents a benzene ring or a naphthalene ring. 21 ~R 28 R each independently represents a hydrogen atom or a substituent. 21 and R 22 may be bonded to form a ring. 23 and R 24 may be bonded to form a ring. 25 and R 26 may be bonded to form a ring. 27 and R 28 may be bonded to form a ring. 29 represents a substituent. 20 represents a benzene ring, k represents an integer of 0 to 4. 20 When R represents a naphthalene ring, k represents an integer of 0 to 6. 29If there are multiple R 29 may be the same or different. 29 If there are multiple R 29 may be bonded to form a ring, provided that the compound represented by general formula (II) has at least one hydrophilic group. <25> The compound represented by the general formula (A) is at least one compound selected from the following compound group (a): <24> The ink composition according to claim 1.

[0026] [ka]

[0027] In the compounds of the compound group (a), M represents a hydrogen atom or a counter cation. When a compound contains a plurality of Ms, the plurality of Ms may be the same or different. <26> The content of the colorant is 0.1 to 10.0% by mass based on the total mass of the ink composition. <24> or <25> The ink composition according to claim 1. <27> Further, a chelating agent is contained, <24> ~ <26> 10. The ink composition according to any one of claims 1 to 9. <28> The content of the chelating agent is 0.001 to 1.0% by mass based on the total mass of the ink composition. <27> The ink composition according to claim 1. <29> Furthermore, it contains preservatives, <24> ~ <28> 10. The ink composition according to any one of claims 1 to 9. <30> The content of the preservative is 0.001 to 0.5% by mass based on the total mass of the ink composition. <29> The ink composition according to claim 1. <31> Further, containing a buffering agent, <24> ~ <30> 10. The ink composition according to any one of claims 1 to 9. <32> pH value at 25°C is 6.5 to 9.0. <24> ~ <31> 10. The ink composition according to any one of claims 1 to 9. <33> <24> ~ <32> 10. An ink composition for ink jet recording, comprising the ink composition according to any one of claims 1 to 9. <34> Using an inkjet recording head <33> 10. An ink jet recording method comprising a step of ejecting the ink composition for ink jet recording according to claim 1. [Effects of the Invention]

[0028] According to the present invention, it is possible to provide an aqueous solution of an additive for an ink composition, an aqueous colorant solution for an ink composition, and an ink composition, which have excellent storage stability (excellent antiseptic properties, and when stored for a long period of time, there is little precipitation of insoluble matter, little change in absorbance, viscosity, and surface tension, and little change in pH value), an ink composition for inkjet recording containing the above ink composition, and an inkjet recording method using the above ink composition for inkjet recording. DETAILED DESCRIPTION OF THE INVENTION

[0029] The present invention will be described in more detail below with reference to preferred embodiments.

[0030] <Aqueous solution of additives for ink composition> The aqueous additive solution for an ink composition of the present invention (also simply referred to as "aqueous additive solution") contains a compound represented by the following general formula (A), a compound represented by the following general formula (II), and water.

[0031] [ka]

[0032] In general formula (A), T 1 , T 2 , and T 3 are each independently: *-NH-(CH2) n -Rt, *-NH-(CH2) n-OH, *-N-{(CH2) n -OH}2, *-NH-CH2CH(OH)CH2-Rt, *-OM, a halogen atom, or a substituted or unsubstituted arylamino group. 1 , T 2 , and T 3 At least one of the following is -NH-(CH2) n -Rt, *-NH-(CH2) n -OH, *-N-{(CH2) n -OH}2, or *-NH-CH2CH(OH)CH2-Rt. * represents a bonding site to the triazine ring, n represents an integer of 1 to 5, and Rt represents CO2M, SO3M, or PO(OM)2. M represents a hydrogen atom or a counter cation. When multiple n's are present, the multiple n's may be the same or different. When multiple M's are present, the multiple M's may be the same or different.

[0033] [ka]

[0034] In general formula (II), Ar 20 represents a benzene ring or a naphthalene ring. 21 ~R 28 R each independently represents a hydrogen atom or a substituent. 21 and R 22 may be bonded to form a ring. 23 and R 24 may be bonded to form a ring. 25 and R 26 may be bonded to form a ring. 27 and R 28 may be bonded to form a ring. 29 represents a substituent. 20 represents a benzene ring, k represents an integer of 0 to 4. 20 When R represents a naphthalene ring, k represents an integer of 0 to 6. 29 If there are multiple R 29 may be the same or different. 29 If there are multiple R29 may be bonded to form a ring, provided that the compound represented by general formula (II) has at least one hydrophilic group.

[0035] The compound represented by the general formula (A) above and the compound represented by the general formula (II) above can be used as an additive in an ink composition. The aqueous additive solution of the present invention can be used to prepare an ink composition, and is particularly preferably used to prepare an ink composition for ink jet recording. The aqueous additive solution of the present invention and the ink composition prepared using the aqueous additive solution of the present invention have excellent storage stability. Although the detailed mechanism is not completely clear, it is believed that the combined use of the compound represented by general formula (A) above and the compound represented by general formula (II) above as additives results in the formation of strong intermolecular interactions, increasing compatibility and improving water solubility and dissolution stability, thereby improving storage stability.

[0036] (Compound represented by general formula (A)) The compound represented by general formula (A) will be explained below. The compound represented by general formula (A) is also called "compound (A)".

[0037] [ka]

[0038] In general formula (A), T 1 , T 2 , and T 3 are each independently: *-NH-(CH2) n -Rt, *-NH-(CH2) n -OH, *-N-{(CH2) n -OH}2, *-NH-CH2CH(OH)CH2-Rt, *-OM, a halogen atom, or a substituted or unsubstituted arylamino group. 1 , T 2 , and T 3 At least one of the following is -NH-(CH2) n -Rt, *-NH-(CH2)n -OH, *-N-{(CH2) n -OH}2, or *-NH-CH2CH(OH)CH2-Rt. * represents a bonding site to the triazine ring, n represents an integer of 1 to 5, and Rt represents CO2M, SO3M, or PO(OM)2. M represents a hydrogen atom or a counter cation. When multiple n's are present, the multiple n's may be the same or different. When multiple M's are present, the multiple M's may be the same or different.

[0039] In general formula (A), T 1 , T 2 , and T 3 are each independently: *-NH-(CH2) n -Rt, *-NH-(CH2) n -OH, *-N-{(CH2) n -OH}2, *-NH-CH2CH(OH)CH2-Rt, *-OM, a halogen atom, or a substituted or unsubstituted arylamino group. The halogen atom is preferably a chlorine atom. The arylamino group is preferably an arylamino group having 6 to 20 carbon atoms, more preferably an arylamino group having 6 to 10 carbon atoms, and even more preferably a phenylamino group. The arylamino group may have a substituent, and the substituent is not particularly limited, but is preferably an amino group. However, T 1 , T 2 , and T 3 At least one of the following is -NH-(CH2) n -Rt, *-NH-(CH2) n -OH, *-N-{(CH2) n -OH)}2, or *-NH-CH2CH(OH)CH2-Rt. T 1 , T 2 , and T 3 One of them is *-NH-(CH2) n -Rt, *-NH-(CH2) n -OH, *-N-{(CH2) n -OH)}2, or *-NH-CH2CH(OH)CH2-Rt, or T 1 , T 2, and T 3 Two of them are *-NH-(CH2) n -Rt, *-NH-(CH2) n -OH, *-N-{(CH2) n -OH)}2, or *-NH-CH2CH(OH)CH2-Rt, or T 1 , T 2 , and T 3 All of the above are -NH-(CH2) n -Rt, *-NH-(CH2) n -OH, *-N-((CH2) n -OH)2, or *-NH-CH2CH(OH)CH2-Rt.

[0040] n represents an integer of 1 to 5, and from the viewpoints of inexpensive availability of raw materials for the compound represented by general formula (A), water solubility, and storage stability in the ink composition for inkjet recording, n more preferably represents an integer of 2 to 4, even more preferably represents 2 or 3, and most preferably represents 2.

[0041] M represents a hydrogen atom or a counter cation. M may be a single type or a mixture of multiple types. When multiple Ms are present in one type of compound (A), the multiple Ms may be the same or different.

[0042] Compound (A) can also be in the form of an internal salt.

[0043] M represents a hydrogen atom or a counter cation. The counter cation is not particularly limited, and examples thereof include alkali metal ions, ammonium ions, and organic cations (such as tetramethylammonium, guanidinium, and pyridinium). M is preferably a hydrogen atom, an alkali metal ion, or an ammonium ion, more preferably an alkali metal ion or an ammonium ion, further preferably a lithium ion, a sodium ion, or a potassium ion, particularly preferably a lithium ion or a sodium ion, and most preferably a lithium ion.

[0044] When M represents a specific cation (e.g., lithium ion), all M do not have to be lithium ions, but it is preferable that the counter cation with the highest abundance ratio is substantially lithium ion. Under such abundance ratio conditions, M can contain hydrogen atoms, alkali metal ions (e.g., sodium ions, potassium ions), ammonium ions, etc. The amount of lithium ions is preferably 50% or more, more preferably 60% or more, even more preferably 80% or more, and particularly preferably 90% or more, with the upper limit being preferably 100%.

[0045] When the specific cation is a cation other than a lithium ion (for example, a sodium ion), the same applies as in the case of a lithium ion.

[0046] Since compound (A) is intended for use as an aqueous solution, it is preferable that the compound have an ionic hydrophilic group that enhances water solubility. Examples of the ionic hydrophilic group include a sulfo group (-SO3M), a carboxy group (-CO2M), a phosphate group (-PO(OM)2), and a hydroxyl group (-OM). Examples of the ionic hydrophilic group include a sulfo group (-SO3M), a carboxy group (-CO2M), and a hydroxyl group (-OM), more preferably a sulfo group (-SO3M) and a hydroxyl group (-OM), and most preferably a sulfo group (-SO3M). M is as described above. In particular, the lithium salt of the sulfo group (-SO3Li) is preferable because it enhances the water solubility of the compound and improves solution stability. As described above, the ionic hydrophilic group may be in the form of a free acid, a salt, or a mixture of a free acid and a salt.

[0047] In the present invention, when the compound is a salt, the salt is dissolved in water in a completely dissociated state into ions. When the compound has an ionic hydrophilic group with a high acid dissociation constant (pKa), most of the salt may be dissociated and some of the salt may be dissolved in water in a non-dissociated state.

[0048] The compound represented by general formula (A) is preferably at least one compound selected from the following compound group (a):

[0049] When compound (A) is in the form of an intramolecular salt, the charge positions of the cation and anion are exemplified by localized chemical structural formulas, but may include all limiting chemical structures that can be assumed within the scope of common sense in organic chemistry.

[0050] [ka]

[0051] In the compounds of the compound group (a), M represents a hydrogen atom or a counter cation. When a compound contains a plurality of Ms, the plurality of Ms may be the same or different. M is as described above.

[0052] Preferred specific examples of the compound (A) are shown below, but the compound (A) is not limited to these.

[0053] [ka]

[0054] [ka]

[0055] Compound (A) can be easily synthesized, isolated, and purified by using known methods (e.g., the methods described in Japanese Patent No. 4686151, etc.) alone or in combination, and, if necessary, further applying a reverse osmosis membrane purification method, a gel filtration chromatography purification method, or a preparative high performance liquid chromatography purification method. Representative examples of the synthesis scheme for compound (A) are shown below, but the invention is not limited thereto. Using cyanuric chloride as a starting material, compounds having an s-triazine ring can be easily synthesized by a single method or a combination of several known methods. The three types of substituents on the s-triazine ring can be introduced with good selectivity by known methods (e.g., by adjusting the pH value of the reaction system, the nucleophilicity of the introduced substituents, and the order of introducing the substituents) depending on the reactivity of the three chlorine atoms of cyanuric chloride and the type of substituents to be introduced.

[0056] [ka]

[0057] [ka]

[0058] [ka]

[0059] The above R1, R2, R3, R4, R5, and R6 each independently represent a hydrogen atom or a corresponding substituent in compound (A). M has the same meaning as in compound (A).

[0060] The aforementioned compound (a)-2 corresponds to the compound represented by (c) above, and can be synthesized by the above synthesis scheme. The above-mentioned compounds (a)-1, (a)-3, (a)-7 to (a)-20, (a)-22, and (a)-23 correspond to the compound represented by (d) above, and can be synthesized by the above synthesis scheme. The aforementioned compound (a)-4 corresponds to the compound represented by (f) above, and can be synthesized by the above synthesis scheme. The aforementioned compound (a)-21 corresponds to the compound represented by (g) above, and can be synthesized by the above synthesis scheme. The above-mentioned compounds (a)-5 and (a)-6 correspond to the compounds represented by (i) above, and can be synthesized by the above synthesis scheme.

[0061] The content of compound (A) in the aqueous additive solution of the present invention (when two or more types of compound (A) are contained, the total amount of compound (A)) is preferably 0.01 to 1.0 mass%, more preferably 0.05 to 1.0 mass%, and particularly preferably 0.1 to 1.0 mass%, based on the total mass of the aqueous additive solution.

[0062] When the content of compound (A) in the aqueous additive solution is 0.01% by mass or more, the intermolecular interaction with the compound represented by general formula (II) in the aqueous additive solution is strengthened (compatibility is increased), and the effect of the long-term aqueous solution solubility stability of the compound represented by general formula (II) is more easily exhibited. On the other hand, when the content of compound (A) in the aqueous additive solution is 1.0% by mass or less, the solids concentration in the aqueous additive solution does not increase, the range of fluctuation over time in the liquid properties during storage of the aqueous additive solution is reduced, and the continuous ejection stability (reliability) of the ink composition for inkjet recording prepared using the aqueous additive solution is improved.

[0063] (Compound represented by general formula (II)) The compound represented by general formula (II) (also referred to as "compound (II)") contained in the aqueous additive solution of the present invention will be described below.

[0064] [ka]

[0065] In general formula (II), Ar 20 represents a benzene ring or a naphthalene ring. 21 ~R 28R each independently represents a hydrogen atom or a substituent. 21 and R 22 may be bonded to form a ring. 23 and R 24 may be bonded to form a ring. 25 and R 26 may be bonded to form a ring. 27 and R 28 may be bonded to form a ring. 29 represents a substituent. 20 represents a benzene ring, k represents an integer of 0 to 4. 20 When R represents a naphthalene ring, k represents an integer of 0 to 6. 29 If there are multiple R 29 may be the same or different. 29 If there are multiple R 29 may be bonded to form a ring, provided that the compound represented by general formula (II) has at least one hydrophilic group.

[0066] The compound represented by general formula (II) is preferably a colorless, water-soluble planar compound having more than 10 delocalized π electrons in one molecule.

[0067] As the number of π electrons constituting the delocalized π electron system increases and the π electron system expands, absorption often occurs in the visible range. In the present invention, "colorless" also includes a state in which the image is very slightly colored, but the color does not affect the image. The water-soluble compound represented by general formula (II) may be a fluorescent compound, but is preferably a non-fluorescent compound, and more preferably a compound with a longest absorption peak wavelength (λmax) of 350 nm or less, more preferably 320 nm or less, and a molar extinction coefficient of 10,000 or less.

[0068] There is no particular upper limit to the number of delocalized π electrons in one molecule of the compound represented by general formula (II), but it is preferably 80 or less, more preferably 50 or less, and particularly preferably 30 or less. In addition, more than 10 π electrons may form one large delocalized system, or two or more delocalized systems.

[0069] The compound represented by general formula (II) is preferably water-soluble, and is preferably a compound that dissolves at least 1 g in 100 g of water at 20° C. More preferably, it is a compound that dissolves at least 5 g, and most preferably, it is a compound that dissolves at least 10 g.

[0070] The compound represented by general formula (II) has at least one hydrophilic group in one molecule, and preferably has at least two hydrophilic groups in one molecule. Examples of hydrophilic groups include, but are not limited to, sulfo (-SO3M), carboxy (-CO2M), hydroxy (-OM), phosphate (-PO(OM)2), carbonamido, sulfonamido, and quaternary ammonium groups. Preferred hydrophilic groups are ionic hydrophilic groups, with sulfo (-SO3M) and carboxy (-CO2M) groups being more preferred, and sulfo (-SO3M) being most preferred.

[0071] M represents a hydrogen atom or a counter cation. The counter cation is not particularly limited, and examples thereof include alkali metal ions, ammonium ions, and organic cations (e.g., tetramethylammonium, guanidinium, pyridinium, etc.). M is preferably a hydrogen atom, an ammonium ion, or an alkali metal ion, more preferably an alkali metal ion, further preferably a lithium ion, a sodium ion, or a potassium ion, and particularly preferably a lithium ion or a sodium ion. The counter cation may be a single salt or a mixed salt.

[0072] The compound represented by general formula (II) preferably has 1 to 10 hydrophilic groups, and more preferably has 2 to 8 hydrophilic groups, in one molecule. The compound represented by general formula (II) preferably has 2 to 6 ionic hydrophilic groups, and more preferably 2 to 4 ionic hydrophilic groups, in one molecule. R in general formula (II)21 ~R 29 Preferably, at least one of R has an ionic hydrophilic group, more preferably -SO3M, and R 21 ~R 29 It is more preferable that 2 to 6 of R 21 ~R 29 It is particularly preferable that two to four of these have -SO3M.

[0073] In general formula (II), R 21 ~R 28 each independently represents a hydrogen atom or a substituent, and examples of the substituent include an alkyl group, an aryl group, an aralkyl group, a heterocyclic group, an alkoxy group, an aryloxy group, an amino group (including an anilino group and a heterocyclic amino group), an acyl group, an acylamino group, a ureido group, a halogen atom, a sulfamoyl group, a carbamoyl group, a sulfonamido group, a sulfonyl group, a sulfenyl group, a sulfinyl group, the aforementioned hydrophilic groups, etc. Furthermore, when these substituents can further have one or more substituents, groups having a substituent selected from the above-mentioned substituents as the further substituent are also included in the examples of the above-mentioned substituents. R 21 ~R 28 and each independently preferably represent a hydrogen atom or an alkyl group. The alkyl group is preferably an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms, and most preferably an alkyl group having 1 to 6 carbon atoms. From the viewpoint of storage stability, the alkyl group preferably has the aforementioned hydrophilic group as a substituent.

[0074] R 21 and R 22 , R 23 and R 24 , R 25 and R 26 , R 27 and R 28 may be bonded to each other to form a ring. The ring is not particularly limited, but may be an aromatic ring or a non-aromatic ring, and is preferably a 5-membered or 6-membered ring. In addition, the ring may be formed by bonding R 21 ~R 28may contain heteroatoms (for example, oxygen atoms, nitrogen atoms, sulfur atoms) in addition to the nitrogen atom to which is bonded.

[0075] R 29 represents a substituent, and examples of the substituent include an alkyl group, an aryl group, an aralkyl group, a heterocyclic group, an alkoxy group, an aryloxy group, an amino group (including an anilino group and a heterocyclic amino group), an acyl group, an acylamino group, a ureido group, a halogen atom, a sulfamoyl group, a carbamoyl group, a sulfonamido group, a sulfonyl group, a sulfenyl group, a sulfinyl group, the aforementioned hydrophilic groups, etc. Furthermore, when these substituents can further have one or more substituents, groups having a substituent selected from the above-mentioned substituents as the further substituent are also included in the examples of the above-mentioned substituents. R 29 If there are multiple R 29 may be the same or different. 29 If there are multiple R 29 may be bonded to form a ring. The ring is not particularly limited, but may be an aromatic ring or a non-aromatic ring, and is preferably a 5- or 6-membered ring. The ring may also contain a heteroatom (e.g., oxygen atom, nitrogen atom, sulfur atom).

[0076] In general formula (II), Ar 20 represents a benzene ring or a naphthalene ring, and preferably represents a benzene ring. Ar 20 represents a benzene ring, k represents an integer of 0 to 4, preferably an integer of 0 to 2, and more preferably 0 or 1. Ar 20 represents a naphthalene ring, k represents an integer of 0 to 6, preferably an integer of 0 to 4, more preferably an integer of 0 to 2, and further preferably 0 or 1.

[0077] The content of compound (II) in the aqueous additive solution of the present invention (when two or more types of compound (II) are contained, the total amount of compound (II)) is preferably 5.0 to 20.0 mass%, more preferably 10.0 to 20.0 mass%, and most preferably 12.0 to 18.0 mass%, based on the total mass of the aqueous additive solution.

[0078] Although the detailed mechanism of action is still in the realm of speculation, it is believed that when the content of compound (II) in the aqueous additive solution is 5.0% by mass or more, the intermolecular interaction between compound (A) and compound (II) in the aqueous additive solution becomes stronger, resulting in high compatibility and an optimum range of interaction, making it easier for the aqueous additive solution containing compound (II) to exhibit its long-term dissolution stability effect. On the other hand, when the content of compound (II) in the aqueous additive solution is 20.0 mass % or less, the solids concentration in the aqueous additive solution does not increase, and the range of fluctuation over time in the liquid properties when the aqueous additive solution is stored becomes extremely small, which is thought to improve the continuous ejection stability (reliability) of the ink composition for inkjet recording prepared using the aqueous additive solution.

[0079] Compound (II) can be easily synthesized, isolated, and purified by using known methods (e.g., the methods described in Japanese Patent No. 4686151, etc.) alone or in combination, and, if necessary, further applying a reverse osmosis membrane purification method, a gel filtration chromatography purification method, or a preparative high performance liquid chromatography purification method.

[0080] Specific examples of compound (II) are shown below, but are not limited to these.

[0081] [ka]

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[0088] (chelating agent) The aqueous additive solution of the present invention may contain a chelating agent. Chelating agents (also called "chelating agents") are compounds that bind to inorganic or metal cations, particularly preferably multivalent cations, to form chelate compounds. In the present invention, the chelating agent has the function of preventing the formation and growth of insoluble precipitates in the aqueous additive solution and ink composition derived from inorganic or metal cations (particularly polyvalent cations) (i.e., it functions as a solubilizing agent).

[0033] By containing a chelating agent, the aqueous additive solution of the present invention can suppress the occurrence of precipitated foreign matter during long-term storage of the aqueous additive solution and the ink composition using the aqueous additive solution, and when an ink composition for inkjet recording using the aqueous additive solution and the ink composition after long-term storage is used for printing with an inkjet printer, ink clogging in nozzles etc. is less likely to occur, making it possible to obtain high-quality printed matter. There are no particular limitations on the chelating agent that can be used in the present invention, and various agents can be used.

[0089] As the chelating agent, any solubilizing agent that has the effect of forming a complex with cations present in the additive aqueous solution and the ink composition through a chelating action, thereby suppressing the occurrence and growth of precipitates in the additive aqueous solution and the ink composition, can be used alone or in combination, but a water-soluble compound is preferred.

[0090] Examples of chelating agents include ethylenediaminetetraacetic acid (EDTA) or a salt thereof (e.g., EDTA-tetrasodium (tetrasodium salt), EDTA-tetralithium (tetralithium salt), etc.), picolinic acid or a salt thereof (e.g., sodium picolinate), quinolinic acid or a salt thereof (e.g., sodium quinolinate), 1,10-phenanthroline, 8-hydroxyquinoline, 3-hydroxy-2,2'-iminodisuccinic acid tetrasodium, methylglycine diacetate (MGDA) or a salt thereof, L-glutamic acid diacetate (GLDA) or a salt thereof, L-aspartic acid diacetate (ASDA) or a salt thereof, hydroxyethyliminodiacetic acid (HIDA) or a salt thereof, 3-hydroxy-2,2'-iminodisuccinic acid (HIDS) or a salt thereof, dicarboxymethylglutamic acid (CMGA) or a salt thereof, and (S,S)-ethylenediaminedisuccinic acid (EDDS) or a salt thereof. Among the salts of the chelating agents, preferred are, for example, monovalent metal salts such as sodium, potassium, and lithium, as well as ammonium and amine salts. Among the chelating agents, these salts exhibit even smaller attenuation of their chelating action in response to pH changes in the aqueous additive solution and ink composition. Therefore, the chelating action is exerted over a wider range of pH, further improving the adaptability of the aqueous additive solution and ink composition to pH changes, such as changes over time.

[0091] The content of the chelating agent is preferably 0.001 to 1.0 mass %, more preferably 0.01 to 0.5 mass %, and particularly preferably 0.01 to 0.1 mass %, based on the total mass of the aqueous additive solution.

[0092] When the content of the chelating agent is 0.001% by mass or more, the chelating effect can be effectively exhibited, and when the content is 1.0% by mass or less, the addition of the chelating agent can be prevented from excessively increasing the viscosity of the additive aqueous solution or the pH.

[0093] (water) The aqueous additive solution of the present invention can be prepared using water as a medium, and if necessary, can also be prepared by dissolving or dispersing compound (A) and compound (II) in a lipophilic medium or an aqueous medium. Examples of water contained in the aqueous additive solution of the present invention include pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, and ultrapure water.

[0094] The content of water in the aqueous additive solution of the present invention is not particularly limited, but from the viewpoint of storage stability, it is preferably 50 to 95 mass %, more preferably 60 to 95 mass %, even more preferably 70 to 95 mass %, and particularly preferably 80 to 95 mass %, based on the total mass of the aqueous additive solution.

[0095] (Water-miscible organic solvent) The aqueous additive solution of the present invention may contain, in addition to water, other solvents, preferably water-miscible organic solvents. Examples of water-miscible organic solvents include alcohols (e.g., methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, t-butanol, pentanol, hexanol, cyclohexanol, benzyl alcohol), polyhydric alcohols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol), glycol derivatives (e.g., ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether, di ... propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol Examples of suitable water-miscible organic solvents include methyl ether, triethylene glycol monomethyl ether, ethylene glycol diacetate, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, and ethylene glycol monophenyl ether; amines (e.g., ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenetriamine, triethylenetetramine, polyethyleneimine, and tetramethylpropylenediamine); and other polar solvents (e.g., formamide, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, sulfolane, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, acetonitrile, and acetone). Two or more water-miscible organic solvents may be used in combination.

[0096] When the aqueous additive solution of the present invention contains a water-miscible organic solvent, the content of the water-miscible organic solvent is preferably 0.01 to 50 mass %, more preferably 0.01 to 30 mass %, and even more preferably 0.01 to 20 mass %, based on the total mass of the aqueous additive solution.

[0097] (preservatives) Explain preservatives. In the present invention, the term "preservative" refers to a substance that has the function of preventing the occurrence and growth of microorganisms, particularly bacteria and fungi (molds). The term "preservative" also includes antifungal agents. The aqueous additive solution of the present invention may contain a preservative. By using a preservative in the aqueous additive solution of the present invention, it is possible to suppress the generation and proliferation of bacteria and mold even when the aqueous additive solution is stored for a long period of time. When an ink composition for inkjet recording using the aqueous additive solution after long-term storage is used to print with an inkjet printer, ink clogging in nozzles and the like is less likely to occur, making it possible to obtain high-quality printed matter. In the present invention, various preservatives can be used.

[0098] Examples of preservatives include inorganic preservatives containing heavy metal ions (such as silver ion-containing substances) and salts. Organic preservatives include quaternary ammonium salts (such as tetrabutylammonium chloride, cetylpyridinium chloride, and benzyltrimethylammonium chloride), phenol derivatives (such as phenol, cresol, butylphenol, xylenol, and bisphenol), phenoxy ether derivatives (such as phenoxyethanol), heterocyclic compounds (such as benzotriazole, Proxel, and 1,2-benzisothiazolin-3-one), alkanediols (such as pentylene glycol (1,2-pentanediol), isopentyldiol (3-methyl-1,3-butanediol), and hexanediol (1,2-hexanediol). ), caprylyl glycol (1,2-octanediol), acid amides, carbamic acid, carbamates, amidines and guanidines, pyridines (sodium pyridinethione-1-oxide, etc.), diazines, triazines, pyrroles and imidazoles, oxazoles and oxazines, thiazoles and thiadiazines, thioureas, thiosemicarbazides, dithiocarbamates, sulfides, sulfoxides, sulfones, sulfamides, antibiotics (penicillin, tetracycline, etc.), sodium dehydroacetate, sodium benzoate, p-hydroxybenzoic acid ethyl ester, and various salts thereof can be used. As the preservative, it is preferable to use at least one preservative selected from the group consisting of heterocyclic compounds, phenol derivatives, phenoxy ether derivatives, and alkanediols. Furthermore, preservatives that can be used include those described in "Anti-bacterial and Anti-fungal Handbook" (Gihodo: 1986) and "Anti-bacterial and Anti-fungal Agent Dictionary" (edited by the Japanese Society of Anti-bacterial and Anti-fungal Agent Dictionary Editorial Committee).

[0099] These compounds may be of various types, such as oil-soluble or water-soluble structures, but water-soluble compounds are preferred. The aqueous additive solution of the present invention may contain two or more preservatives. The use of two or more preservatives in combination improves the storage stability, particularly the hue stability, of the recorded image formed using the aqueous additive solution and the ink composition for inkjet recording using the aqueous additive solution, and also significantly improves the ink ejection stability when printing with an inkjet printer using the ink composition for inkjet recording using the aqueous additive solution after long-term storage, thereby further enhancing the effects of the present invention. This is thought to be because the development of resistance of bacteria and mold to each preservative is suppressed when bacteria and mold come into contact with two or more preservatives. When two or more kinds of preservatives are combined, it is preferable that these preservatives have skeletons with different chemical structures.In addition, when two or more kinds of preservatives are contained, it is preferable that at least one kind of preservative is a heterocyclic compound, a phenol derivative, a phenoxy ether derivative, or an alkanediol, and among them, it is preferable that it is a heterocyclic compound.For example, it is preferable to mention a combination of a heterocyclic compound and a phenoxy ether derivative, a combination of a heterocyclic compound and a phenol derivative, or a combination of a heterocyclic compound and an alkanediol.

[0100] Furthermore, the heterocyclic compound is preferably a thiazole-based compound or a benzotriazole-based compound. Thiazole compounds, among other preservatives, particularly function as antifungal agents. Examples of thiazole compounds include benzisothiazoline, isothiazolin, 1,2-benzisothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, 2-(thiocyanomethylthio)benzthiazole, 2-mercaptobenzthiazole, and 3-allyloxy-1,2-benzisothiazole-1,1-oxide. Furthermore, the PROXEL (registered trademark) series (BDN, BD20, GXL, LV, XL2, XL2(s), Ultra10, etc.) manufactured and sold by LONZA Corporation can also be used as thiazole antifungal agents.

[0101] Benzotriazole compounds also function as rust inhibitors, and can prevent rusting of metal materials (especially 42 alloy (nickel-iron alloy containing 42% nickel)) constituting inkjet heads, which is caused in part by contact with an aqueous additive solution and an ink composition. Examples of benzotriazole compounds include 1H-benzotriazole, 4-methyl-1H-benzotriazole, 5-methyl-1H-benzotriazole, and their sodium or potassium salts.

[0102] When two or more preservatives are combined, the content ratio is not particularly limited, but the content of each preservative is preferably 1% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, of the total preservative content. Furthermore, the content of each preservative is preferably 99% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less, of the total preservative content. By setting the content within the above range, the effects of each preservative can be efficiently obtained, and a synergistic effect between the preservatives can be easily achieved. Furthermore, while maintaining the effectiveness of the preservatives, the possibility of rashes and the like occurring in people who come into contact with the additive aqueous solution or the ink composition, especially those who are sensitive to preservatives, can be reduced.

[0103] When the aqueous additive solution of the present invention contains a preservative, the content of the preservative (the total content when two or more preservatives are contained) is not particularly limited, but is preferably 0.001 to 1.0 mass% based on the total amount of the aqueous additive solution, more preferably 0.005 to 1.0 mass%, even more preferably 0.01 to 1.0 mass%, particularly preferably 0.01 to 0.5 mass%, and most preferably 0.01 to 0.4 mass%. By setting the content within the above range, the effect of the preservative can be obtained more efficiently and the putrefaction of the water and the formation of precipitates can be suppressed.

[0104] In the aqueous additive solution of the present invention, the mass ratio of the preservative to the total amount of compound (A) and compound (II) (compound (A) + compound (II)) / preservative is preferably 90 / 10 to 99 / 1. By setting the content within the above range, compound (A) and compound (II) can be stably dissolved in the aqueous additive solution of the present invention, and at the same time, the effect of preventing the occurrence and growth of bacteria and fungi (mold) can be achieved.

[0105] (buffering agent) The aqueous additive solution of the present invention may contain a buffer (pH value stabilizer). From the viewpoint of improving the storage stability of the aqueous additive solution of the present invention and the storage stability of an ink composition using the aqueous additive solution, the aqueous additive solution of the present invention is preferably weakly acidic to neutral to basic, more preferably neutral to basic, even more preferably neutral to weakly basic, and most preferably weakly basic. For example, the pH value of the aqueous additive solution at 25°C is preferably 6.5 to 9.0, more preferably 6.8 to 9.0, and most preferably 7.0 to 9.0.

[0106] If the pH value of the aqueous additive solution at 25°C is 6.5 or higher, the dissolution stability is improved and the occurrence of precipitates is suppressed when the aqueous additive solution and the ink composition are prepared. On the other hand, if the pH value of the aqueous additive solution at 25°C is 9.0 or lower, the possibility of partial decomposition of the aqueous colorant solution for an ink composition containing a colorant in the aqueous additive solution and the colorant used in the ink composition is reduced, and the storage stability and reliability of the aqueous colorant solution for an ink composition and the ink composition are improved.

[0107] The buffer (pH stabilizer) is not particularly limited as long as it is a buffer that suppresses fluctuations in the pH value of the aqueous additive solution. Preferred examples of the buffer include lithium carbonate, lithium bicarbonate, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, an acetic acid / triethylamine mixture, and a phosphoric acid / triethylamine mixture. As the buffering agent, lithium carbonate, lithium bicarbonate, sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate are preferred, sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate are more preferred, and sodium bicarbonate is most preferred.

[0108] (Other additives) The aqueous additive solution of the present invention may contain other additives as needed, provided that the effects of the present invention are not impaired.

[0109] Examples of other additives include known additives such as drying inhibitors (wetting agents), discoloration inhibitors, emulsion stabilizers, penetration enhancers, ultraviolet absorbers, surface tension adjusters, antifoaming agents, viscosity adjusters, dispersants, dispersion stabilizers, rust inhibitors, and pH adjusters (described in JP-A-2003-306623).

[0110] The additive aqueous solution of the present invention is usually a colorless aqueous solution when it does not contain a colorant. The additive aqueous solution of the present invention can be used to prepare ink compositions of various colored and colored tones. For example, it can be used to prepare ink compositions of yellow, orange, magenta, cyan, gray, black, brown, red, green, blue, and metallic colors.

[0111] <Aqueous colorant solution for ink composition> The additive aqueous solution of the present invention can be used not only as a colorless additive aqueous solution but also as an aqueous colorant solution for the purpose of improving the storage stability of the colorant. The aqueous colorant solution for an ink composition of the present invention (also simply referred to as "aqueous colorant solution") is prepared by adding the aqueous additive solution of the present invention to an aqueous colorant solution. That is, the aqueous colorant solution of the present invention contains the compound represented by the general formula (A) above, the compound represented by the general formula (II) above, water, and a colorant. The compound (A), the compound (II), and the water contained in the aqueous colorant solution of the present invention are the same as those described in the explanation of the aqueous additive solution. The aqueous colorant solution of the present invention may further contain a water-miscible organic solvent, a chelating agent, a preservative, and a buffering agent, which are the same as those described in the description of the aqueous additive solution. The aqueous colorant solution of the present invention may further contain other additives. The other additives that may be contained in the aqueous colorant solution of the present invention are the same as those described in the description of the aqueous additive solution. The preferred ranges of the contents of water, water-miscible organic solvent, chelating agent, and preservative in the aqueous colorant solution are the same as the preferred ranges of the contents of each component (addition ratio) in the aqueous additive solution. The pH value of the aqueous colorant solution at 25° C. is preferably 6.5 to 9.0, more preferably 6.8 to 9.0, and most preferably 7.0 to 9.0.

[0112] The content of the compound (A) in the aqueous colorant solution of the present invention (when two or more types of compound (A) are contained, the total amount of the compounds (A)) is preferably 0.001 to 0.3 mass %, more preferably 0.005 to 0.1 mass %, and particularly preferably 0.01 to 0.05 mass %, based on the total mass of the aqueous colorant solution.

[0113] Although the detailed mechanism of action is still at the level of speculation, it is believed that when the content of compound (A) in the aqueous colorant solution is 0.001% by mass or more, intermolecular interactions become stronger not only between compound (A) and compound (II) but also between compound (A) and the colorant, and between compound (II) and the colorant (a synergistic effect further enhances compatibility), and the effect of long-term dissolution stability of the aqueous colorant solution containing the compound represented by general formula (II) and the colorant is more likely to be exhibited. On the other hand, when the content of compound (A) in the aqueous colorant solution is 0.3 mass % or less, the solids concentration in the aqueous colorant solution does not increase, the range of temporal fluctuation in the liquid properties during storage of the aqueous colorant solution is reduced, and it is believed that this improves the continuous ejection stability (reliability) of the ink composition for inkjet recording prepared using the aqueous colorant solution.

[0114] The content of compound (II) in the aqueous colorant solution of the present invention (when two or more types of compound (II) are contained, the total amount of compound (II)) is preferably 0.5 to 8.0 mass %, more preferably 0.9 to 7.5 mass %, and most preferably 0.95 to 3.0 mass %, based on the total mass of the aqueous colorant solution.

[0115] Although the detailed mechanism of action remains a matter of speculation, it is believed that when the content of compound (II) in the aqueous colorant solution is 0.5% by mass or more, the intermolecular interactions in the aqueous colorant solution are further strengthened not only between compound (A) and compound (II), but also between compound (A) and the colorant, and between compound (II) and the colorant, resulting in high compatibility and an optimum range of interaction, making it easier for the aqueous colorant solution containing compound (II) and the colorant to exhibit its long-term dissolution stability. On the other hand, by setting the content of compound (II) in the aqueous colorant solution to 8.0 mass % or less, the solids concentration in the aqueous colorant solution does not increase, and the range of fluctuation over time in the liquid properties during storage of the aqueous colorant solution becomes extremely small, which is thought to improve the continuous ejection stability (reliability) of the ink composition for inkjet recording prepared using the aqueous colorant solution.

[0116] The colorant used in the aqueous colorant solution is preferably a dye, more preferably a water-soluble dye. The content of the colorant in the aqueous colorant solution of the present invention is preferably 5.0 to 20.0% by mass based on the total mass of the aqueous colorant solution.

[0117] Although the detailed mechanism of action remains a matter of speculation, it is believed that when the content of the colorant in the aqueous colorant solution is 5.0% by mass or more, the intermolecular interactions in the aqueous colorant solution become stronger not only between compound (A) and compound (II), but also between compound (A) and the colorant, and between compound (II) and the colorant (a synergistic effect results in particularly high compatibility), and the effect of long-term dissolution stability of the aqueous colorant solution containing compound (II) and the colorant is more likely to be exhibited. On the other hand, by ensuring that the content of the colorant in the aqueous colorant solution is 20.0 mass % or less, the solids concentration in the aqueous colorant solution does not increase, the range of fluctuation over time in the liquid properties during storage of the aqueous colorant solution is reduced, and it is believed that this improves the continuous ejection stability (reliability) of the ink composition for inkjet recording prepared using the aqueous colorant solution.

[0118] The aqueous colorant solution of the present invention can be an aqueous colorant solution of various colors, but is particularly suitable as an aqueous colorant solution for a cyan ink composition, a gray ink composition, or a black ink composition in terms of the interaction with the colorant to be combined.

[0119] (coloring agent) When the aqueous colorant solution of the present invention is an aqueous colorant solution for a cyan ink composition, an aqueous colorant solution for a gray ink composition, or an aqueous colorant solution for a black ink composition, preferred colorants will be described below.

[0120] The colorant is preferably a dye, more preferably a water-soluble dye, and most preferably a dye having at least one hydrophilic group per dye molecule, from the viewpoints of ease of preparation of an aqueous colorant solution and long-term storage stability of the aqueous colorant solution. Examples of hydrophilic groups include, but are not limited to, sulfo (-SO3M), carboxy (-CO2M), hydroxy (-OM), phosphate (-PO(OM)2), carbonamido, sulfonamido, and quaternary ammonium groups. Preferred hydrophilic groups are ionic hydrophilic groups, with sulfo (-SO3M) and carboxy (-CO2M) groups being more preferred, and sulfo (-SO3M) being most preferred.

[0121] M represents a hydrogen atom or a counter cation. The counter cation is not particularly limited, and examples thereof include alkali metal ions, ammonium ions, and organic cations (e.g., tetramethylammonium, guanidinium, pyridinium, etc.). M is preferably a hydrogen atom, an ammonium ion, or an alkali metal ion, more preferably an alkali metal ion, further preferably a lithium ion, a sodium ion, or a potassium ion, and particularly preferably a lithium ion or a sodium ion. The counter cation may be a single salt or a mixed salt.

[0122] The colorant preferably has 1 to 10 hydrophilic groups, more preferably 2 to 5 hydrophilic groups, in one molecule of the water-soluble dye.

[0123] [Aqueous colorant solution for cyan ink composition] When the colorant aqueous solution of the present invention is an aqueous colorant solution for a cyan-toned ink composition, the colorant is preferably a cyan dye described in, for example, Japanese Patent No. 3949385, Japanese Patent No. 4145153, or WO 2021 / 039651.

[0124] Specific examples of preferred cyan dyes are listed below, but are not limited thereto. The specific examples below are mixtures containing positional isomers of a specific substituent R (see (2A) to (2D) below), and therefore the position at which the substituent is introduced is not specified and they are treated as identical. In the specific examples below, the substituent R substitutes for any hydrogen atom at the β-position, but does not substitute for the portion marked with "H" in each structural formula.

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[0147] When the colorant aqueous solution of the present invention is an aqueous colorant solution for a cyan ink composition, the content of the colorant is preferably 5.0 to 20.0 mass %, more preferably 5.0 to 15.0 mass %, even more preferably 5.0 to 12.0 mass %, and particularly preferably 5.0 to 10.0 mass %, based on the total mass of the aqueous colorant solution. By setting the colorant content within the above range, the intermolecular interaction between the colorant, compound (A), and compound (II) in the aqueous colorant solution becomes good, and the long-term storage stability of the aqueous colorant solution is improved.

[0148] When the content of the colorant in the aqueous colorant solution for a cyan ink composition is 5.0% by mass or more, it is thought that not only is it easy to prepare ink compositions with light or dark cyan colors, but also the effect of long-term dissolution stability of the aqueous colorant solution is more easily exhibited. On the other hand, when the content of the colorant in the aqueous colorant solution for a cyan ink composition is 20.0 mass % or less, the solids concentration in the aqueous colorant solution does not increase, and the range of fluctuation over time in the liquid properties when the aqueous colorant solution is stored (particularly, dissolution stability, change in absorbance, increase / decrease in viscosity, and change in pH value) is reduced, which is believed to improve the continuous ejection stability (reliability) of the ink composition for inkjet recording prepared using the aqueous colorant solution.

[0149] When the aqueous colorant solution is for a pale cyan ink composition, the content of the colorant is preferably 5.0 to 20.0 mass %, more preferably 5.0 to 15.0 mass %, even more preferably 8.0 to 12.0 mass %, and particularly preferably 8.0 to 10.0 mass %, based on the total mass of the aqueous colorant solution. By setting the content of the colorant within the above range, the intermolecular interaction between the colorant, compound (A), and compound (II) in the aqueous colorant solution becomes favorable, and the storage stability of the aqueous colorant solution is improved.

[0150] When the aqueous colorant solution is for a deep cyan ink composition, the content of the colorant is preferably 5.0 to 20.0 mass %, more preferably 8.0 to 15.0 mass %, even more preferably 10.0 to 15.0 mass %, and particularly preferably 10.0 to 12.0 mass %, based on the total mass of the aqueous colorant solution. By setting the content of the colorant within the above range, the intermolecular interaction between the colorant, compound (A), and compound (II) in the aqueous colorant solution becomes favorable, and the storage stability of the aqueous colorant solution is improved.

[0151] [Aqueous colorant solution for gray and black ink compositions] When the colorant aqueous solution of the present invention is a colorant aqueous solution for a gray ink composition or a colorant aqueous solution for a black ink composition (these are also collectively referred to as "aqueous colorant solution for a gray-black ink composition"), the colorant is preferably, for example, a colorant (gray dye or black dye) represented by general formula (I) described in JP-A-2020-76048.

[0152] Specific examples of preferred gray dyes or black dyes are listed below, but the present invention is not limited to these.

[0153] [ka]

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[0165] When the colorant aqueous solution of the present invention is a colorant aqueous solution for a gray-black ink composition, the colorant content is preferably 5.0 to 20.0 mass %, more preferably 5.0 to 15.0 mass %, even more preferably 5.0 to 12.0 mass %, and particularly preferably 5.0 to 10.0 mass %, based on the total mass of the colorant aqueous solution. By keeping the colorant content within this range, the intermolecular interactions between the colorant, compound (A), and compound (II) in the colorant aqueous solution become favorable, and the storage stability of the colorant aqueous solution is improved.

[0166] When the content of the colorant in the aqueous colorant solution for a gray / black ink composition is 5.0% by mass or more, it is thought that not only will it be easier to prepare the gray / black ink composition, but the effect of the long-term dissolution stability of the aqueous colorant solution will also be more easily achieved. On the other hand, if the content of the colorant in the aqueous colorant solution for a gray / black ink composition is 20.0 mass % or less, the solids concentration in the aqueous colorant solution will not increase, and the range of fluctuation over time in the liquid properties when the aqueous colorant solution is stored (particularly, solubility stability, change in absorbance, increase / decrease in viscosity, and change in pH value) will be small, and it is believed that this will improve the continuous ejection stability (reliability) of the ink composition for inkjet recording prepared using the aqueous colorant solution.

[0167] When the colorant aqueous solution is for a gray ink composition, the content of the colorant is preferably 5.0 to 20.0 mass %, more preferably 5.0 to 15.0 mass %, even more preferably 7.0 to 12.0 mass %, and particularly preferably 7.5 to 10.0 mass %, based on the total mass of the colorant aqueous solution. By setting the colorant content within the above range, the intermolecular interaction between the colorant, compound (A), and compound (II) in the colorant aqueous solution becomes good, and the storage stability of the colorant aqueous solution is improved.

[0168] When the colorant aqueous solution is for a black ink composition, the colorant content is preferably 5.0 to 20.0 mass %, more preferably 5.0 to 15.0 mass %, even more preferably 5.3 to 15.0 mass %, and particularly preferably 10.0 to 12.0 mass %, based on the total mass of the colorant aqueous solution. By setting the colorant content within the above range, the intermolecular interaction between the colorant, compound (A), and compound (II) in the colorant aqueous solution becomes good, and the storage stability of the colorant aqueous solution is improved.

[0169] (toning agent) The colorant aqueous solution of the present invention may further contain a toning agent in addition to the colorant described above. In particular, when the colorant aqueous solution is an aqueous colorant solution for a gray-black ink composition, it is preferable that the aqueous colorant solution contains a toning agent.

[0170] Examples of toning agents that can be used when the colorant aqueous solution of the present invention is an aqueous colorant solution for a gray-black ink composition include the toning agent represented by general formula (III) in JP-A-2020-76048. Specific examples of preferred toning agents are listed below, but are not limited to these.

[0171] [ka]

[0172] When the colorant aqueous solution of the present invention is a colorant aqueous solution for a gray ink composition, the content of the toning agent is preferably 0.1 to 2.0 mass %, more preferably 0.3 to 2.0 mass %, even more preferably 0.5 to 1.5 mass %, particularly preferably 0.5 to 1.3 mass %, and most preferably 0.8 to 1.2 mass %, based on the total mass of the colorant aqueous solution. The above range is preferable from the viewpoint of hue adjustment with the colorant coexisting in the colorant aqueous solution (neutral gray toning).

[0173] When the colorant aqueous solution of the present invention is an aqueous colorant solution for a black-toned ink composition, the content of the toning agent is preferably 0.1 to 5.0 mass %, more preferably 0.3 to 3.5 mass %, even more preferably 0.5 to 3.0 mass %, particularly preferably 1.0 to 3.0 mass %, and most preferably 1.5 to 2.5 mass %, based on the total mass of the aqueous colorant solution. The above ranges are preferable from the viewpoints of hue adjustment (black toning) with the colorants coexisting in the aqueous colorant solution and print density.

[0174] (magenta dye) The colorant aqueous solution of the present invention may contain another toning agent instead of or in addition to the aforementioned toning agent. In particular, when the colorant aqueous solution of the present invention is a colorant aqueous solution for a gray-black ink composition, it is preferable to contain a magenta dye as a second toning agent to improve the gray to black color tone. Examples of magenta dyes as second toning agents include the magenta dyes described in JP 2020-76048 A. Specific examples of second toning agents are listed below, but are not limited to these. In the following structural formula, Me represents a methyl group, Et represents an ethyl group, (i)Pr and Pr(i) represent isopropyl groups, t-Bu represents a tert-butyl group, and (n)CH 11 and C5H 11 (n) represents an n-pentyl group. M represents a hydrogen atom or a counter cation. M is the same as M in the compounds of the compound group (a) described above.

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[0184] When the aqueous colorant solution of the present invention contains a magenta dye as a second toning agent, the content of the magenta dye varies depending on the color value (coloring power per unit mass) of the dye used, but is preferably 0.1 to 5.0 mass %, and more preferably 0.5 to 3.0 mass %, based on the total mass of the aqueous colorant solution.

[0185] When the colorant aqueous solution of the present invention is an aqueous colorant solution for a gray ink composition, the content of the magenta dye is preferably 0.1 to 5.0 mass %, more preferably 0.3 to 3.5 mass %, even more preferably 0.5 to 3.0 mass %, particularly preferably 0.5 to 2.0 mass %, and most preferably 0.8 to 1.2 mass %, based on the total mass of the aqueous colorant solution. The above range is preferable from the viewpoint of hue adjustment (neutral gray toning) with the colorants coexisting in the aqueous colorant solution.

[0186] When the colorant aqueous solution of the present invention is an aqueous colorant solution for a black-toned ink composition, the content of the magenta dye is preferably 0.1 to 5.0 mass %, more preferably 0.3 to 3.5 mass %, even more preferably 0.5 to 3.0 mass %, particularly preferably 1.0 to 3.0 mass %, and most preferably 1.5 to 2.5 mass %, based on the total mass of the aqueous colorant solution. The above ranges are preferable from the viewpoints of hue adjustment (black toning) with the colorants coexisting in the aqueous colorant solution and print density.

[0187] (Other toning agents) The colorant aqueous solution of the present invention may contain another toning agent (third toning agent) instead of or in addition to the above-mentioned toning agent. Specific examples of the third toning agent are listed below, but the present invention is not limited to these.

[0188] [ka]

[0189] [ka]

[0190] In addition to the above-mentioned toning dyes 1 to 6, other toning dyes that can be contained in the colorant aqueous solution of the present invention are exemplified below, but are not limited to these. Note that "CI" is an abbreviation for "Color Index." CI Direct Yellow 9, 11, 28, 29, 35, 39, 41, 53, 59, 68, 87, 93, 95, 96, 106, 108, 109, 122, 130, 142, 144, 161, 163, etc. CI Acid Yellow 19, 39, 49, 50, 61, 64, 79, 110, 127, 135, 143, 151, 159, 169, 174, 190, 195, 196, 197, 199, 218, 219, 222, 227, etc. CI Reactive Yellow 2, 3, 13, 14, 15, 17, 18, 23, 24, 25, 26, 27, 29, 35, 37, 41, 42, etc. CI Basic Yellow 1, 2, 4, 11, 13, 14, 15, 19, 21, 23, 24, 25, 28, 29, 32, 36, 39, 40, etc.

[0191] When the aqueous colorant solution of the present invention contains other toning agents, the content of the other toning agents in the aqueous colorant solution (total amount when multiple types of other toning agents are used) varies depending on the color value (coloring power per unit mass) of the dye used, but is preferably 0.1 to 3.0 mass %, and more preferably 0.3 to 1.2 mass %, based on the total mass of the aqueous colorant solution.

[0192] When the colorant aqueous solution of the present invention is a colorant aqueous solution for a gray ink composition, the content of the other toning agent is preferably 0.1 to 3.0 mass %, more preferably 0.1 to 2.0 mass %, even more preferably 0.1 to 1.0 mass %, particularly preferably 0.3 to 1.0 mass %, and most preferably 0.3 to 0.5 mass %, based on the total mass of the colorant aqueous solution. The above range is preferable from the viewpoint of hue adjustment with the colorant coexisting in the colorant aqueous solution (neutral gray toning).

[0193] When the colorant aqueous solution of the present invention is a colorant aqueous solution for a black-toned ink composition, the content of the other toning agent is preferably 0.1 to 3.0 mass %, more preferably 0.1 to 2.0 mass %, even more preferably 0.1 to 1.5 mass %, particularly preferably 0.3 to 1.5 mass %, and most preferably 0.3 to 1.2 mass %, based on the total mass of the colorant aqueous solution. The above range is preferable from the viewpoints of hue adjustment (black toning) with the colorant coexisting in the colorant aqueous solution and print density.

[0194] The additive aqueous solution and colorant aqueous solution of the present invention described above are used to prepare an ink composition. Examples of the ink composition include ink compositions as image recording materials for forming images, and specific examples include inkjet recording materials, heat-sensitive recording materials, pressure-sensitive recording materials, recording materials using electrophotography, transfer-type silver halide photosensitive materials, printing inks, recording pens, etc., and inkjet recording materials, heat-sensitive recording materials, and recording materials using electrophotography are preferred, and inkjet recording materials are more preferred.

[0195] <Ink composition> The ink composition of the present invention is an ink composition containing compound (A), a compound represented by general formula (II), water, and a colorant. The ink composition of the present invention can be prepared, for example, using the above-described aqueous colorant solution of the present invention. More specifically, the ink composition can be prepared, for example, by adding a water-miscible organic solvent, other additives (e.g., a pH adjuster, a surface tension adjuster, etc.), water, etc. to the aqueous colorant solution of the present invention. The ink composition of the present invention preferably further contains a chelating agent. The ink composition of the present invention preferably further contains a preservative. The ink composition of the present invention preferably further contains a buffering agent. The compound (A), the compound (II), the water, the colorant, the water-miscible organic solvent, the chelating agent, the preservative, and the buffer are the same as those described in the description of the additive aqueous solution and the colorant aqueous solution. In addition, other components that may be contained in the ink composition of the present invention are the same as those described in the description of the additive aqueous solution and the colorant aqueous solution.

[0196] The pH value of the ink composition of the present invention at 25° C. is preferably 6.5 to 9.0, more preferably 6.8 to 9.0, and most preferably 7.0 to 9.0.

[0197] The content of the preservative in the ink composition of the present invention is preferably 0.001 to 1.0 mass%, more preferably 0.001 to 0.5 mass%, even more preferably 0.005 to 0.5 mass%, particularly preferably 0.01 to 0.5 mass%, and most preferably 0.01 to 0.4 mass%, based on the total mass of the ink composition.

[0198] The content of the chelating agent in the ink composition of the present invention is preferably 0.001 to 1.0 mass %, more preferably 0.01 to 0.5 mass %, and particularly preferably 0.01 to 0.1 mass %, based on the total mass of the ink composition.

[0199] In the ink composition of the present invention, the ratio of the chelating agent to the colorant (here, "colorant" refers to all colorants including the colorant, the toning agent, the magenta dye as the second toning agent, the third toning agent, and other colorants that may be used in combination) (the content of the chelating agent by mass: the content of the colorant by mass) is preferably in the range of 0.0001:1 to 0.15:1, more preferably in the range of 0.0001:1 to 0.05:1, and even more preferably in the range of 0.0002:1 to 0.005:1.

[0200] Metal salts can be formed by metals that are mixed in during the colorant (dye) manufacturing process or that are contained in the ink container of the ink composition and that can dissolve into the ink composition, but the above ratio can effectively prevent the generation of foreign matter that can cause clogging of the inkjet head.In addition, the chelating effect can be effectively exerted, preventing excessive increases in the viscosity and pH of the ink composition.

[0201] The ink composition of the present invention can also be used in color filters for recording and reproducing color images used in solid-state imaging devices such as CCDs (Charge-Coupled Devices) and displays such as LCDs (Liquid Crystal Displays) and PDPs (Plasma Display Panels), and in dye solutions for dyeing various fibers. The ink composition of the present invention can be used in recording methods such as printing, copying, marking, writing, drawing, stamping, etc., and is particularly suitable for use in ink jet recording methods. The ink composition of the present invention is particularly preferably used as an ink composition for ink jet recording.

[0202] The content of the colorant in the ink composition of the present invention is preferably 0.1 to 10.0% by mass based on the total mass of the ink composition.

[0203] When the ink composition of the present invention contains a cyan dye as a colorant, the ink composition of the present invention can be used as a cyan-toned ink composition for inkjet recording (also simply referred to as a "cyan ink"), and can be used as both a dark cyan ink and a light cyan ink. The dark cyan ink is particularly suitable for photo and document applications. On the other hand, the light cyan ink is particularly suitable for forming light cyan images and mixed light color images (blue, green, gray, etc.).

[0204] In the case of dark cyan ink, the content of the colorant (cyan dye) in the cyan ink is preferably 2.5 to 10.0 mass %, more preferably 3.0 to 8.0 mass %, even more preferably 3.5 to 6.0 mass %, and particularly preferably 3.5 to 5.5 mass %, based on the total mass of the cyan ink. In the case of light cyan ink, the content of the colorant (cyan dye) in the cyan ink is preferably 0.1 to 5.0 mass %, more preferably 0.5 to 3.0 mass %, even more preferably 1.0 to 2.5 mass %, and particularly preferably 1.0 to 2.0 mass %, based on the total mass of the cyan ink. By keeping the content of colorant (cyan dye) in the dark and light cyan ink within the above range, the ink has excellent storage stability, print density on various types of receiving paper (inkjet paper and plain paper), and image fastness.

[0205] When the ink composition of the present invention contains a gray dye or a black dye as a colorant, the ink composition of the present invention can be used as a gray ink composition for inkjet recording (also simply referred to as a "gray ink") or a black ink composition for inkjet recording (also simply referred to as a "black ink"). Black ink is particularly suitable for photo and document applications. Gray inks are particularly suitable for light gray imaging applications.

[0206] When the ink composition of the present invention is used as a gray ink, the content of the colorant is preferably 0.1 to 10.0 mass%, more preferably 0.2 to 7.0 mass%, even more preferably 0.3 to 5.0 mass%, particularly preferably 0.3 to 3.0 mass%, and most preferably 0.5 to 2.0 mass%, based on the total mass of the ink composition.

[0207] By setting the content of the colorant in the gray ink within the above range, it is possible to enhance the intermolecular interaction between the compound (A) and the compound (II), and also to achieve good gray hue adjustment (neutral gray toning) with the gray toning agent.

[0208] When the ink composition of the present invention is used as a black ink, the content of the colorant is preferably 0.1 to 10.0 mass %, more preferably 0.5 to 7.0 mass %, even more preferably 1.0 to 6.0 mass %, particularly preferably 3.0 to 6.0 mass %, and most preferably 3.5 to 5.5 mass %, based on the total mass of the ink composition.

[0209] By setting the content of the colorant in the black ink within the above range, it is possible to enhance the intermolecular interaction between compound (A) and compound (II), and also to improve black hue adjustment with a toning agent for black hue.

[0210] When the ink composition of the present invention contains the above-described toning agent, the content of the toning agent is preferably 0.1 to 10.0 mass %, and more preferably 0.5 to 6.0 mass %, based on the total mass of the ink composition.

[0211] In the ink composition of the present invention, the blending ratio of the content of the colorant, the total content of compound (A) and compound (II), and the content of the toning agent, based on the total mass of the ink composition, is preferably colorant / {compound (A)+compound (II)} / toning agent, 0.01 to 10.0% by mass / 0.01 to 10.0% by mass / 0.00 to 10.0% by mass, and more preferably 0.05 to 5.0% by mass / 0.05 to 5.0% by mass / 0.01 to 5.0% by mass.

[0212] When the ink composition of the present invention is a dark cyan ink, the blending ratio of the content of the colorant, the total content of compound (A) and compound (II), and the content of the toning agent, based on the total mass of the ink composition, is preferably 2.5 to 10.0 mass% / 0.25 to 3.0 mass% / 0.00 to 1.0 mass%, more preferably 3.0 to 8.0 mass% / 0.30 to 2.0 mass% / 0.00 to 0.5 mass%, even more preferably 3.5 to 6.0 mass% / 0.35 to 2.0 mass% / 0.00 to 0.10 mass%, and most preferably 3.5 to 5.5 mass% / 0.35 to 1.0 mass% / 0.00 to 0.10 mass%.

[0213] When the ink composition of the present invention is a light cyan ink, the blending ratio of the content of the colorant, the total content of compound (A) and compound (II), and the content of the toning agent, based on the total mass of the ink composition, is preferably 0.1 to 5.0 mass% / 0.01 to 2.5 mass% / 0.00 to 1.0 mass%, more preferably 0.5 to 3.0 mass% / 0.05 to 1.5 mass% / 0.00 to 0.5 mass%, even more preferably 1.0 to 2.5 mass% / 0.10 to 1.25 mass% / 0.00 to 0.10 mass%, and most preferably 1.0 to 2.0 mass% / 0.10 to 1.0 mass% / 0.00 to 0.05 mass%.

[0214] When the ink composition of the present invention is a gray ink, the blending ratio of the content of the colorant, the total content of compound (A) and compound (II), and the content of the toning agent, based on the total mass of the ink composition, is preferably 0.10 to 5.0 mass% / 0.30 to 5.0 mass% / 0.01 to 2.5 mass%, more preferably 0.30 to 3.0 mass% / 0.30 to 3.0 mass% / 0.03 to 1.5 mass%, and even more preferably 0.50 to 2.0 mass% / 0.50 to 1.5 mass% / 0.05 to 1.0 mass%.

[0215] When the ink composition of the present invention is a black ink, the ratio of the content of the colorant, the total content of compound (A) and compound (II), and the content of the toning agent, based on the total mass of the ink composition, is preferably 1.0 to 6.0 mass% / 0.1 to 3.0 mass% / 1.0 to 4.0 mass%, more preferably 3.0 to 5.5 mass% / 0.3 to 3.0 mass% / 1.0 to 3.0 mass%, and even more preferably 3.5 to 5.0 mass% / 0.3 to 2.0 mass% / 1.5 to 2.0 mass%.

[0216] When the ink composition of the present invention is a gray ink, the content of the magenta dye is preferably 0.01 to 2.0 mass%, more preferably 0.03 to 1.0 mass%, even more preferably 0.05 to 2.0 mass%, particularly preferably 0.05 to 1.0 mass%, and most preferably 0.05 to 0.50 mass%, based on the total mass of the ink composition. By keeping the content of the magenta dye within this range, hue adjustment with the colorant coexisting in the ink composition (neutral gray toning) becomes good.

[0217] When the ink composition of the present invention is a black ink, the content of the magenta dye is preferably 0.10 to 5.0 mass%, more preferably 0.50 to 3.0 mass%, even more preferably 0.5 to 3.0 mass%, particularly preferably 0.5 to 2.5 mass%, and most preferably 1.0 to 2.0 mass%, based on the total mass of the ink composition, from the viewpoint of hue adjustment with a colorant coexisting in the ink composition (black toning).

[0218] When the ink composition of the present invention contains a water-miscible organic solvent, the content of the water-miscible organic solvent is preferably 20 to 50 mass % based on the total mass of the ink composition, and more preferably 30 to 50 mass %. In particular, in the case of an ink composition for inkjet recording, the content is particularly preferably 30 to 40 mass % in terms of suitability for piezo heads and thermal heads.

[0219] <Ink composition for inkjet recording> The ink composition for ink jet recording of the present invention includes the ink composition of the present invention described above. The ink composition of the present invention described above can also be used as an ink composition for ink jet recording as it is. The reason why the ink composition for ink jet recording of the present invention has excellent color tone from gray to black or cyan and excellent storage stability is not completely clear, but the present inventors presume it as follows. By preparing an inkjet recording ink composition using an aqueous solution containing a compound (A) containing an s-triazine ring group and a compound (II) together with a colorant, it is possible to form an image with excellent gray to black or cyan color tone by an inkjet method. It is believed that the colorant forms a relatively stable aggregated state in the image immediately after it is formed. On the other hand, when the humidity of the surrounding environment increases, it is believed that highly water-soluble colorants (dyes) use moisture as a driving force to progress to a more stable aggregated state (a change in the state of existence, such as the H-aggregate of the dye), which is presumed to result in a change in the color tone of the image (a shift to shorter wavelengths due to the H-aggregate). Therefore, in the present invention, by adding compound (II), a highly planar compound, the relatively stable association state of gray to black or cyan colorants in an image immediately after inkjet printing can be stabilized by the intermolecular interaction between the colorant and compound (II), or a more stable association state can be formed immediately after image formation by the intermolecular interaction between the colorant and compound (II). As a result, it is believed that changes in the color tone of the image can be suppressed without causing changes in the association state of the colorant due to changes in the surrounding environment (humidity, light, active gases). Furthermore, by using compound (A) in combination, the interaction and compatibility between the colorant and compounds (II) and (A) are improved, which dramatically improves the storage stability and antiseptic properties of the ink composition, and it is believed that it is possible to minimize fluctuations in pH, absorbance, viscosity, and surface tension even after long-term storage of the ink composition.

[0220] <Inkjet recording method> The ink jet recording method of the present invention comprises a step of ejecting the ink composition for ink jet recording of the present invention described above using an ink jet recording head. In the inkjet recording method of the present invention, energy is applied to the ink composition for inkjet recording of the present invention to form an image on a known image-receiving material, i.e., plain paper, resin-coated paper, paper exclusively for inkjet printing, film, paper commonly used for electrophotography, fabric, glass, metal, ceramics, etc., as described in, for example, JP-A Nos. 8-169172, 8-27693, 2-276670, 7-276789, 9-323475, 62-238783, 10-153989, 10-217473, 10-235995, 10-337947, 10-217597, and 10-337947.

[0221] When forming an image, a polymer particle dispersion (also called a polymer latex) may be used in combination to impart gloss, water resistance, or weather resistance. The polymer latex may be applied to the image-receiving material before, after, or simultaneously with the application of a colorant. Therefore, it may be added to the image-receiving paper or the ink, or the polymer latex may be used alone as a liquid. Specifically, the methods described in Japanese Patent Application Nos. 2000-363090, 2000-315231, 2000-354380, 2000-343944, 2000-268952, 2000-299465, and 2000-297365 are preferably used.

[0222] The inkjet recording method of the present invention is not limited to any particular recording method, and may employ any known method, such as a charge control method that utilizes electrostatic attraction to eject ink, a drop-on-demand method (pressure pulse method) that utilizes the vibration pressure of a piezoelectric element, an acoustic inkjet method in which an electric signal is converted into an acoustic beam and irradiated onto the ink, thereby ejecting the ink using radiation pressure, and a thermal inkjet method in which the ink is heated to form bubbles and the resulting pressure is utilized. Inkjet recording methods include a method in which a large number of low-density inks known as photo inks are ejected in a small volume, a method in which multiple inks of substantially the same hue but different densities are used to improve image quality, and a method in which colorless and transparent ink is used. [Example]

[0223] EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited thereto.

[0224] Example 1 (Preparation of additive aqueous solution 1) 0.36 g of compound (a)-1, 0.072 g of compound (a)-2, 0.146 g of compound (a)-3, 14.423 g of compound (P-3), 0.065 g of chelating agent (EDTA), 0.100 g of preservative (PROXEL (registered trademark) XL2 (s) manufactured by LONZA Corporation), and 0.100 g of buffer (NaHCO3) were dissolved in 60.00 g of deionized water, and the pH was adjusted to 8.5 with a pH adjuster (10 mol / L aqueous sodium hydroxide solution). The solution was filtered under reduced pressure through a microfilter with an average pore size of 0.20 μm, washed with an appropriate amount of deionized water, and then carefully added with deionized water while checking the total mass. Additive aqueous solution 1 (100 g) was prepared. EDTA manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. was used. The same applies to the following examples and comparative examples.

[0225] Examples 2 to 16 Aqueous additive solutions 2 to 16 (100 g each) were prepared in the same manner as in Example 1, except that the types and amounts of each component were changed to those shown in Tables 1 to 4 below.

[0226] Examples 17 to 20 Additive aqueous solutions 17 to 20 (100 g each) were prepared in the same manner as in Example 1, except that the types and amounts of each component were changed to those shown in Table 4 below and the pH was adjusted to 8.5 using a pH adjuster (10 mol / L aqueous lithium hydroxide solution).

[0227] Example 21 100 g of an aqueous additive solution 21 was prepared in the same manner as in Example 1, except that the same components as in Example 2 were used and the pH was changed to 9.0.

[0228] Example 22 100 g of an aqueous additive solution 22 was prepared in the same manner as in Example 1, except that the same components as in Example 2 were used and the pH was changed to 8.0.

[0229] Example 23 100 g of an aqueous additive solution 23 was prepared in the same manner as in Example 1, except that the same components as in Example 2 were used and the pH was changed to 7.5.

[0230] Example 24 100 g of an aqueous additive solution 24 was prepared in the same manner as in Example 1, except that the same components as in Example 2 were used and the pH was changed to 7.0.

[0231] Example 25 100 g of an aqueous additive solution 25 was prepared in the same manner as in Example 1, except that the same components as in Example 2 were used and the pH was changed to 6.5.

[0232] Examples 26 to 32 Aqueous additive solutions 26 to 32 (100 g each) were prepared in the same manner as in Example 1, except that the types and amounts of each component were changed to those shown in Tables 5 and 6 below.

[0233] Comparative Examples 1 to 12 Comparative additive aqueous solutions 1 to 12 (100 g each) were prepared in the same manner as in Example 1, except that the types and amounts of each component were changed to those shown in Tables 7 to 9 below.

[0234] Comparative Examples 13 to 16 Aqueous additive solutions 13 to 16 (100 g each) were prepared in the same manner as in Example 1, except that the types and amounts of each component were changed to those shown in Table 9 below and the pH was adjusted to 8.5 using a pH adjuster (10 mol / L aqueous lithium hydroxide solution).

[0235] [Table 1]

[0236] [Table 2]

[0237] [Table 3]

[0238] [Table 4]

[0239] [Table 5]

[0240] [Table 6]

[0241] [Table 7]

[0242] [Table 8]

[0243] [Table 9]

[0244] <Storage stability of aqueous additive solution> ·Preservative The caps were removed from Nissui Pharmaceutical Co., Ltd.'s bacterial testing food stamps (for viable count and fungi), and a sufficient amount of additive solution was applied to the agar medium surface. The stamps were left uncapped for 10 hours to encourage bacterial adhesion. The caps were then replaced, and the viable count food stamps were cultured in a 36°C incubator for 2 days, and the fungi food stamps were cultured in a 23°C incubator for 5 days. Evaluation was performed visually using the following three-point scale based on the following criteria. A. No mold growth B: Slight mold growth is observed, but no tendency to grow is observed. C: Mold has developed and is showing signs of proliferation.

[0245] The aqueous additive solutions 1 to 32 and the comparative aqueous additive solutions 1 to 16 prepared in Examples 1 to 32 and Comparative Examples 1 to 16 were subjected to forced tests in which they were stored at 60°C and a relative humidity of 50% for 4 weeks, at 60°C and a relative humidity of 50% for 10 weeks, at 60°C and a relative humidity of 50% for 15 weeks, and at 60°C and a relative humidity of 50% for 20 weeks, and then evaluated for the following evaluation items.

[0246] Presence or absence of insoluble matter (precipitates) (filtration residue) The aqueous additive solution was filtered through a filter with a pore size of 0.2 μm, and then visually inspected. The solution was evaluated on a two-level scale: A if it remained dissolved, and C if foreign matter precipitated or separated.

[0247] Changes in liquid properties The additive solutions were evaluated on a three-point scale: A was assigned to solutions that maintained the same physical properties (absorbance, viscosity, and surface tension) as the respective aqueous solutions immediately after preparation, B was assigned to solutions that had changed by ±3% or more in one property after the forced test, and C was assigned to solutions that had changed by ±3% or more in two or more properties after the forced test. The absorbance, viscosity, and surface tension values ​​were measured using the following methods.

[0248] (absorbance) Using a Shimadzu UV-Vis spectrography (UV-1800), 200 mg of the additive solution was weighed out and diluted to 50 mL with deionized water. 2 mL of the diluted solution was then used to dilute to 100 mL with deionized water. The diluted solution was then poured into a 1 cm x 1 cm quartz cell and the absorbance was measured in the range of 250 nm to 400 nm at 25°C and 50% relative humidity. After confirming the absorbance at λmax in the ultraviolet range (250 to 300 nm), the change before and after the forced test was calculated.

[0249] (viscosity) Using a viscometer (RE85) manufactured by Toki Sangyo Co., Ltd., 1.5 mL of the additive aqueous solution was weighed out, and the measurement was carried out in an environment of 25°C and a relative humidity of 50 to 70%, for a measurement time of 2 minutes.

[0250] (surface tension) Using a surface tensiometer (DY-200) manufactured by Kyowa Interface Science Co., Ltd., 5 mL of the additive aqueous solution was weighed out, and then measurement was carried out using a platinum plate in an environment of 25°C and a relative humidity of 30%.

[0251] pH value change The additive solutions were evaluated on a three-point scale: A was used to evaluate solutions that maintained the same pH value as the respective solutions immediately after preparation, B was used to evaluate solutions whose pH value changed by ±0.3 or more after the forced test, and C was used to evaluate solutions whose pH value changed by ±0.5 or more after the forced test. The pH values ​​were measured using the following methods. Using a pH meter (HM-25G) manufactured by DKK-TOA Corporation, 5 mL of the additive aqueous solution was weighed out, and the measurement was carried out in an environment of 25°C and a relative humidity of 50 to 70%, for a measurement time of 2 minutes.

[0252] The results are shown in Tables 10 to 13 below. Regarding antiseptic properties, the food stamp for viable count was cultured in a constant temperature bath at 36°C for two days, and the results are shown in the "Exposure time 2 days" column. The food stamp for fungi was cultured in a constant temperature bath at 23°C for five days, and the results are shown in the "Exposure time 5 days" column. For the forced test, the results after 4 weeks of storage at 60°C and 50% relative humidity are shown in the "4 weeks" column, the results after 10 weeks of storage at 60°C and 50% relative humidity are shown in the "10 weeks" column, the results after 15 weeks of storage at 60°C and 50% relative humidity are shown in the "15 weeks" column, and the results after 20 weeks of storage at 50% relative humidity are shown in the "20 weeks" column.

[0253] [Table 10]

[0254] [Table 11]

[0255] [Table 12]

[0256] [Table 13]

[0257] The above results demonstrate that the aqueous additive solutions of the examples of the present invention have excellent storage stability even when containing high concentrations of additives. In particular, when the content of compound (A) was 0.01 to 1.00 mass% and the content of compound (II) was 5.00 to 20.00 mass%, the liquid properties did not change even after 10 weeks of forced testing, demonstrating extremely high storage stability of the aqueous additive solution. Furthermore, when a chelating agent, preservative, or buffer (pH stabilizer) was used in combination, the liquid properties and pH did not change even after 15 to 20 weeks of forced testing, demonstrating extremely high storage stability of the aqueous additive solution.

[0258] Example 33 (Preparation of Colorant Aqueous Solution 33) 0.33 parts by mass of compound (a)-1, 9.67 parts by mass of compound (P-3), 31.6 parts by mass of cyan dye (C-12), 42.2 parts by mass of cyan dye (C-26), 21.1 parts by mass of cyan dye (C-47 and C-48), 4.7 parts by mass of cyan dye (C-62), 0.4 parts by mass of cyan dye (C-73), 1.50 parts by mass of a chelating agent (EDTA), and a preservative (PROXEL (registered trademark) XL2 (s manufactured by LONZA Corporation). )) and 1.00 parts by mass of a buffer (NaHCO3) were dissolved in 200.00 parts by mass of deionized water, and the solution was adjusted to pH 8.5 with a pH adjuster (10 mol / L aqueous sodium hydroxide solution). The solution was filtered under reduced pressure through a microfilter with an average pore size of 0.20 μm, washed with an appropriate amount of deionized water, and then water was added carefully with deionized water while checking the total mass, to prepare a colorant aqueous solution (cyan dye aqueous solution) 33 (1,000 parts by mass).

[0259] Example 34 (Preparation of Colorant Aqueous Solution 34) 0.33 parts by mass of compound (a)-1, 9.67 parts by mass of compound (P-3), 6.25 parts by mass of cyan dye (C-12), 25.00 parts by mass of cyan dye (C-26), 37.50 parts by mass of cyan dye (C-47 and C-48), 25.00 parts by mass of cyan dye (C-62), 6.25 parts by mass of cyan dye (C-73), 1.50 parts by mass of a chelating agent (EDTA), and a preservative (PROXEL (registered trademark) XL2 manufactured by LONZA Corporation). After dissolving 1.00 parts by mass of (s)) and 1.00 parts by mass of a buffer (NaHCO3) in 200.00 parts by mass of deionized water, the solution was adjusted to pH 8.5 with a pH adjuster (10 mol / L aqueous sodium hydroxide solution), filtered under reduced pressure through a microfilter with an average pore size of 0.20 μm, washed with an appropriate amount of deionized water, and then water was added carefully with deionized water while checking the total mass, to prepare a colorant aqueous solution (cyan dye aqueous solution) 34 (1,000 parts by mass).

[0260] Example 35 (Preparation of Colorant Aqueous Solution 35) 0.33 parts by mass of compound (a)-1, 9.67 parts by mass of compound (P-3), 6.06 parts by mass of cyan dye (C-12), 0.19 parts by mass of cyan dye (C-14), 24.25 parts by mass of cyan dye (C-26), 0.75 parts by mass of cyan dye (C-28), 36.38 parts by mass of cyan dyes (C-47 and C-48), 1.12 parts by mass of cyan dye (C-59 and C-60), 24.25 parts by mass of cyan dye (C-62), 0.75 parts by mass of cyan dye (C-69), 6.25 parts by mass of cyan dye (C-73), chelating agent ( 1.5 parts by mass of EDTA, 1.00 parts by mass of a preservative (PROXEL (registered trademark) XL2(s) manufactured by LONZA Corporation), and 1.00 parts by mass of a buffer (NaHCO3) were dissolved in 200.00 parts by mass of deionized water, and the solution was adjusted to pH 8.5 with a pH adjuster (10 mol / L aqueous sodium hydroxide solution). The solution was filtered under reduced pressure through a microfilter with an average pore size of 0.20 μm, washed with an appropriate amount of deionized water, and then water was added carefully with deionized water while checking the total mass, to prepare a colorant aqueous solution (cyan dye aqueous solution) 35 (1,000 parts by mass).

[0261] Example 36 (Preparation of Ink Composition 36)

[0112] 48.0 parts by mass of the colorant aqueous solution 34 prepared in Example 34, 9.70 parts by mass of glycerin, 3.40 parts by mass of triethylene glycol, 9.90 parts by mass of triethylene glycol monobutyl ether, 2.5 parts by mass of 2-pyrrolidone, 1.30 parts by mass of 1,2-hexanediol, and 1.0 part by mass of Surfynol (registered trademark) 465 (manufactured by Nissin Chemical Industry Co., Ltd.) were dissolved in 20.0 parts by mass of deionized water, and the pH was adjusted to 8.5 with a pH adjuster (a 10 mol / L aqueous sodium hydroxide solution). The solution was filtered under reduced pressure using a microfilter having an average pore size of 0.20 µm, washed with an appropriate amount of deionized water, and then water was added while carefully checking the total mass with deionized water, thereby preparing ink composition (cyan dye ink composition) 36 (100 parts by mass).

[0262] Example 37 (Preparation of Ink Composition 37)

[0112] 48.0 parts by mass of the colorant aqueous solution 35 prepared in Example 35, 9.70 parts by mass of glycerin, 3.40 parts by mass of triethylene glycol, 9.90 parts by mass of triethylene glycol monobutyl ether, 2.5 parts by mass of 2-pyrrolidone, 1.30 parts by mass of 1,2-hexanediol, and 1.0 part by mass of Surfynol (registered trademark) 465 (manufactured by Nissin Chemical Industry Co., Ltd.) were dissolved in 20.0 parts by mass of deionized water, and the solution was adjusted to pH 8.5 with a pH adjuster (a 10 mol / L aqueous sodium hydroxide solution). The solution was filtered under reduced pressure using a microfilter having an average pore size of 0.20 µm, washed with an appropriate amount of deionized water, and then water was added while carefully checking the total mass with deionized water to prepare ink composition (cyan dye ink composition) 37 (100 parts by mass).

[0263] Example 38 (Preparation of Colorant Aqueous Solution 38) 2.6 parts by mass of compound (a)-1, 74.4 parts by mass of compound (P-3), 53.8 parts by mass of black dye (exemplified compound I-1), 23.1 parts by mass of toning agent (exemplified compound III-1), 23.1 parts by mass of magenta dye (M dye 14 M = Na salt) as a second toning agent, 0.33 parts by mass of chelating agent (EDTA), 1.00 parts by mass of preservative (PROXEL (registered trademark) XL2(s) manufactured by LONZA Corporation) After dissolving 1.00 parts by mass of buffer (NaHCO3) in 200.00 parts by mass of deionized water, the solution was adjusted to pH 8.5 with a pH adjuster (10 mol / L aqueous lithium hydroxide solution), filtered under reduced pressure through a microfilter with an average pore size of 0.20 μm, washed with an appropriate amount of deionized water, and then water was added while carefully checking the total mass with deionized water to prepare a colorant aqueous solution (black dye aqueous solution) 38 (1,000 parts by mass).

[0264] Example 39 (Preparation of Colorant Aqueous Solution 39) 2.6 parts by mass of compound (a)-1, 74.4 parts by mass of compound (P-3), 53.8 parts by mass of black dye (exemplified compound I-3), 23.1 parts by mass of toning agent (exemplified compound III-1), 23.1 parts by mass of magenta dye (M dye 14 M = Na salt) as a second toning agent, 0.33 parts by mass of chelating agent (EDTA), 1.00 parts by mass of preservative (PROXEL (registered trademark) XL2(s) manufactured by LONZA Corporation) After dissolving 1.00 parts by mass of buffer (NaHCO3) in 200.00 parts by mass of deionized water, the solution was adjusted to pH 8.5 with a pH adjuster (10 mol / L aqueous lithium hydroxide solution), filtered under reduced pressure through a microfilter with an average pore size of 0.20 μm, washed with an appropriate amount of deionized water, and then water was added while carefully checking the total mass with deionized water to prepare a colorant aqueous solution (black dye aqueous solution) 39 (1,000 parts by mass).

[0265] Example 40 (Preparation of Colorant Aqueous Solution 40) 0.38 parts by mass of compound (a)-1, 10.98 parts by mass of compound (P-3), 79.5 parts by mass of gray dye (exemplified compound I-1), 11.4 parts by mass of toning agent (exemplified compound III-1), 9.1 parts by mass of magenta dye (M dye 14 M = Na salt) as a second toning agent, 0.50 parts by mass of chelating agent (EDTA), 1.00 parts by mass of preservative (PROXEL (registered trademark) XL2(s) manufactured by LONZA Corporation) 1.00 parts by mass of a buffer (NaHCO3) was dissolved in 200.00 parts by mass of deionized water, and the solution was adjusted to pH 8.5 with a pH adjuster (10 mol / L aqueous lithium hydroxide solution). The solution was filtered under reduced pressure through a microfilter with an average pore size of 0.20 μm, washed with an appropriate amount of deionized water, and then water was added while carefully checking the total mass with deionized water to prepare a colorant aqueous solution (gray dye aqueous solution) 40 (1,000 parts by mass).

[0266] Example 41 (Preparation of Colorant Aqueous Solution 41) A colorant aqueous solution (black dye aqueous solution) 41 (1000 parts by mass) was prepared in the same manner as in Example 38, except that no buffer (NaHCO3) was added.

[0267] Example 42 (Preparation of Colorant Aqueous Solution 42) A colorant aqueous solution (black dye aqueous solution) 42 (1000 parts by mass) was prepared in the same manner as in Example 38, except that no preservative (PROXEL (registered trademark) XL2(s) manufactured by LONZA Corporation) was added.

[0268] Example 43 (Preparation of Colorant Aqueous Solution 43) A colorant aqueous solution (black dye aqueous solution) 43 (1000 parts by mass) was prepared in the same manner as in Example 38, except that the chelating agent (EDTA) was not added.

[0269] Example 44 (Preparation of Ink Composition 44)

[0111] 65.0 parts by mass of the colorant aqueous solution 38 prepared in Example 38, 10.0 parts by mass of glycerin, 2.0 parts by mass of triethylene glycol, 10.0 parts by mass of triethylene glycol monobutyl ether, 2.0 parts by mass of 2-pyrrolidone, and 1.0 part by mass of Surfynol (registered trademark) 465 (manufactured by Nissin Chemical Industry Co., Ltd.) were dissolved in 20.0 parts by mass of deionized water, and the pH was adjusted to 8.5 with a pH adjuster (10 mol / L aqueous sodium hydroxide solution). The solution was filtered under reduced pressure using a microfilter having an average pore size of 0.20 μm, washed with an appropriate amount of deionized water, and then water was added while carefully checking the total mass with deionized water, thereby preparing ink composition (black dye ink composition) 44 (100 parts by mass).

[0270] Example 45 (Preparation of Ink Composition 45)

[0111] 65.0 parts by mass of the colorant aqueous solution 39 prepared in Example 39, 10.0 parts by mass of glycerin, 2.0 parts by mass of triethylene glycol, 10.0 parts by mass of triethylene glycol monobutyl ether, 2.0 parts by mass of 2-pyrrolidone, and 1.0 part by mass of Surfynol (registered trademark) 465 (manufactured by Nissin Chemical Industry Co., Ltd.) were dissolved in 20.0 parts by mass of deionized water, and the pH was adjusted to 8.5 with a pH adjuster (a 10 mol / L aqueous sodium hydroxide solution). The solution was filtered under reduced pressure using a microfilter having an average pore size of 0.20 µm, washed with an appropriate amount of deionized water, and then water was added while carefully checking the total mass with deionized water, thereby preparing ink composition (black dye ink composition) 45 (100 parts by mass).

[0271] Example 46 (Preparation of Ink Composition 46) 8.8 parts by mass of the colorant aqueous solution 40 prepared in Example 40, 7.3 parts by mass of glycerin, 8.0 parts by mass of triethylene glycol, 7.6 parts by mass of triethylene glycol monobutyl ether, 2.9 parts by mass of 2-pyrrolidone, and 0.3 parts by mass of propylene glycol were dissolved in 20.0 parts by mass of deionized water, and the pH was adjusted to 8.5 with a pH adjuster (10 mol / L aqueous sodium hydroxide solution). The solution was filtered under reduced pressure using a microfilter with an average pore size of 0.20 μm, washed with an appropriate amount of deionized water, and then water was added with deionized water while carefully checking the total mass, thereby preparing ink composition (gray dye ink composition) 46 (100 parts by mass).

[0272] Example 47 (Preparation of Ink Composition 47) Ink composition (black dye ink composition) 47 (100 parts by mass) was prepared by dissolving 65.0 parts by mass of the colorant aqueous solution 38 prepared in Example 38, 6.5 parts by mass of glycerin, 2.3 parts by mass of triethylene glycol, 2.9 parts by mass of 1,5-pentanediol, 3.7 parts by mass of 2-pyrrolidone, and 0.5 parts by mass of Surfynol (registered trademark) 465 (manufactured by Nissin Chemical Industry Co., Ltd.) in 20.0 parts by mass of deionized water, and then adjusting the pH to 8.5 with a pH adjuster (10 mol / L aqueous sodium hydroxide solution). The solution was filtered under reduced pressure using a microfilter having an average pore size of 0.20 μm, washed with an appropriate amount of deionized water, and then water was added while carefully checking the total mass with deionized water, thereby preparing ink composition (black dye ink composition) 47 (100 parts by mass).

[0273] Example 48 (Preparation of Ink Composition 48) Ink composition (black dye ink composition) 48 (100 parts by mass) was prepared by dissolving 65.0 parts by mass of the colorant aqueous solution 39 prepared in Example 39, 6.5 parts by mass of glycerin, 2.3 parts by mass of triethylene glycol, 2.9 parts by mass of 1,5-pentanediol, 3.7 parts by mass of 2-pyrrolidone, and 0.5 parts by mass of Surfynol (registered trademark) 465 (manufactured by Nissin Chemical Industry Co., Ltd.) in 20.0 parts by mass of deionized water, and then adjusting the pH to 8.5 with a pH adjuster (10 mol / L aqueous sodium hydroxide solution). The solution was filtered under reduced pressure using a microfilter having an average pore size of 0.20 μm, washed with an appropriate amount of deionized water, and then water was added while carefully checking the total mass with deionized water, thereby preparing ink composition (black dye ink composition) 48 (100 parts by mass).

[0274] Example 49 (Preparation of Ink Composition 49) 8.8 parts by mass of the colorant aqueous solution 40 prepared in Example 40, 6.5 parts by mass of glycerin, 2.3 parts by mass of triethylene glycol, 2.9 parts by mass of 1,5-pentanediol, 3.7 parts by mass of 2-pyrrolidone, and 0.5 parts by mass of Surfynol (registered trademark) 465 (manufactured by Nissin Chemical Industry Co., Ltd.) were dissolved in 20.0 parts by mass of deionized water, and the pH was adjusted to 8.5 with a pH adjuster (a 10 mol / L aqueous sodium hydroxide solution). The solution was filtered under reduced pressure through a microfilter having an average pore size of 0.20 μm, washed with an appropriate amount of deionized water, and then water was added with deionized water while carefully checking the total mass, thereby preparing ink composition (gray dye ink composition) 49 (100 parts by mass).

[0275] Comparative Example 17 (Preparation of Comparative Colorant Aqueous Solution 17) Comparative colorant aqueous solution (comparative black dye aqueous solution) 17 (1000 parts by mass) was prepared in the same manner as in Example 38, except that compound (a)-1 was not added.

[0276] Comparative Example 18 (Preparation of Comparative Colorant Aqueous Solution 18) Comparative colorant aqueous solution (comparative black dye aqueous solution) 18 (1000 parts by mass) was prepared in the same manner as in Example 38, except that compound (P-3) and buffer (NaHCO3) were not added.

[0277] Comparative Example 19 (Preparation of Comparative Colorant Aqueous Solution 19) A comparative colorant aqueous solution (comparative black dye aqueous solution) 19 (1,000 parts by mass) was prepared in the same manner as in Example 38, except that compound (P-3) and preservative (PROXEL (registered trademark) XL2(s) manufactured by LONZA Corporation) were not added.

[0278] Comparative Example 20 (Preparation of Comparative Colorant Aqueous Solution 20) Comparative colorant aqueous solution (comparative black dye aqueous solution) 20 (1000 parts by mass) was prepared in the same manner as in Example 38, except that compound (P-3) and chelating agent (EDTA) were not added.

[0279] <Storage Stability of Aqueous Colorant Solution and Ink Composition> As a forced test, the colorant aqueous solutions 33 to 35, 38 to 43, ink compositions 36 to 37, and 44 to 49 prepared in Examples 33 to 49, and the comparative colorant aqueous solutions 17 to 20 prepared in Comparative Examples 17 to 20 were stored at 60°C and 50% relative humidity for 4 weeks, 10 weeks, 15 weeks, and 20 weeks at 60°C and 50% relative humidity, and then the storage stability was evaluated. The antiseptic properties, the presence or absence of insoluble matter (precipitates) (filtration residue), changes in liquid properties (absorbance, viscosity, and surface tension), and changes in pH value were evaluated using the same methods and evaluation criteria as in Examples 1 to 32 and Comparative Examples 1 to 16. However, only the absorbance measurement method was calculated under the following conditions.

[0280] (absorbance) For the aqueous colorant solution, 450 mg (0.45 g) of the aqueous colorant solution was weighed out and diluted with deionized water to 50 ml. This was then diluted with 2 ml of diluent to 100 ml with deionized water. The diluted solution was poured into a 1 cm x 1 cm quartz cell and the absorbance was measured in the range of 250 nm to 900 nm at 25°C and 50% relative humidity. After confirming the absorbance at λmax in the ultraviolet to visible range (250 to 700 nm), the change before and after the forced test was calculated. For the ink composition, 200 mg (0.2 g) of the ink composition was weighed and diluted with deionized water to 50 ml. This was then diluted with 2 ml of diluent to 100 ml with deionized water. The diluted solution was poured into a 1 cm x 1 cm quartz cell and the absorbance was measured in the range of 250 nm to 400 nm at 25°C and 50% relative humidity. After confirming the absorbance at λmax in the ultraviolet range (250 to 300 nm), the change before and after the forced test was calculated.

[0281] The results of Examples 33 to 49 and Comparative Examples 17 to 20 are shown in Tables 14 and 15 below.

[0282] [Table 14]

[0283] [Table 15]

[0284] The above results demonstrate that the aqueous colorant solution and ink composition of the present invention exhibit excellent storage stability even when containing a high concentration of colorant. In particular, when the content of compound (A) in the aqueous colorant solution was 0.001 to 0.3% by mass and the content of compound (II) was 0.5 to 8.0% by mass, the liquid properties remained unchanged even after 10 weeks of forced testing, demonstrating extremely high storage stability. Furthermore, when a chelating agent, preservative, or buffer (pH stabilizer) was used in combination, the liquid properties and pH remained unchanged even after 15 to 20 weeks of forced testing, demonstrating extremely high storage stability. [Industrial Applicability]

[0285] According to the present invention, it is possible to provide an aqueous solution of an additive for an ink composition, an aqueous colorant solution for an ink composition, and an ink composition, which have excellent storage stability (excellent antiseptic properties, and when stored for a long period of time, there is little precipitation of insoluble matter, little change in absorbance, viscosity, and surface tension, and little change in pH value), an ink composition for inkjet recording containing the above ink composition, and an inkjet recording method using the above ink composition for inkjet recording.

[0286] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on a Japanese patent application (Patent Application No. 2021-058541) filed on March 30, 2021, the contents of which are incorporated herein by reference.

Claims

1. An aqueous solution of an additive for an ink composition comprising a compound represented by the following general formula (A), a compound represented by the following general formula (II), and water. 【Chemistry 1】 In general formula (A), T １ , T ２ , and T ３ are each independently *-NH-(CH ２ ) ｎ -Rt, *-NH-(CH ２ ) ｎ -OH, *-N-{(CH ２ ) ｎ -OH} ２ , *-NH-CH ２ CH(OH)CH ２ represents —Rt, *—OM, a halogen atom, or a substituted or unsubstituted arylamino group. １ , T ２ , and T ３ At least one of the following is *-NH-(CH ２ ) ｎ -Rt, *-NH-(CH ２ ) ｎ -OH, *-N-{(CH ２ ) ｎ -OH} ２ , or *-NH-CH ２ CH(OH)CH ２ * represents a bonding site to the triazine ring, n represents an integer of 1 to 5, and Rt is CO ２ M.S.O. ３ M, or PO (OM) ２ M represents a hydrogen atom or a counter cation. When multiple n's are present, the multiple n's may be the same or different. When a plurality of M's are present, the plurality of M's may be the same or different. 【Chemistry 2】 In general formula (II), Ar ２０ represents a benzene ring or a naphthalene ring. ２１ ~R ２８ R each independently represents a hydrogen atom or a substituent. ２１ and R ２２ may be bonded to form a ring. ２３ and R ２４ may be bonded to form a ring. ２５ and R ２６ may be bonded to form a ring. ２７ and R ２８ may be bonded to form a ring. ２９ represents a substituent. ２０ represents a benzene ring, k represents an integer of 0 to 4. ２０ represents a naphthalene ring, k represents an integer of 0 to 6. ２９ If there are multiple R ２９ may be the same or different. ２９ If there are multiple R ２９ may be bonded to form a ring, provided that the compound represented by general formula (II) has at least one hydrophilic group.

2. The aqueous ink composition additive solution according to claim 1, wherein the compound represented by general formula (A) is at least one compound selected from the following compound group (a): 【Transformation 3】 In the compounds of the compound group (a), M represents a hydrogen atom or a counter cation. When a compound contains a plurality of Ms, the plurality of Ms may be the same or different.

3. R in the general formula (II) ２１ ~R ２９ 3. The aqueous solution of an additive for an ink composition according to claim 1, wherein at least one of the above has an ionic hydrophilic group.

4. 4. The aqueous ink composition additive solution according to claim 1, wherein the content of the compound represented by general formula (II) is 5.0 to 20.0 mass % based on the total mass of the aqueous ink composition additive solution.

5. 5. The aqueous ink composition additive solution according to claim 1, wherein the content of the compound represented by general formula (A) is 0.01 to 1.0 mass % based on the total mass of the aqueous ink composition additive solution.

6. The aqueous ink composition additive solution according to any one of claims 1 to 5, further comprising a chelating agent.

7. 7. The aqueous ink composition additive solution according to claim 6, wherein the content of the chelating agent is 0.001 to 1.0% by mass based on the total mass of the aqueous ink composition additive solution.

8. The aqueous ink composition additive solution according to any one of claims 1 to 7, further comprising a preservative.

9. 9. The aqueous ink composition additive solution according to claim 8, wherein the content of the preservative is 0.01 to 1.0% by mass based on the total mass of the aqueous ink composition additive solution.

10. The aqueous ink composition additive solution according to any one of claims 1 to 9, further comprising a buffering agent.

11. The aqueous ink composition additive solution according to any one of claims 1 to 10, wherein the pH value at 25°C is 6.5 to 9.

0.

12. An aqueous colorant solution for an ink composition, comprising a compound represented by the following general formula (A), a compound represented by the following general formula (II), water, and a colorant: 【Chemistry 4】 In general formula (A), T １ , T ２ , and T ３ are each independently *-NH-(CH ２ ) ｎ -Rt, *-NH-(CH ２ ) ｎ -OH, *-N-{(CH ２ ) ｎ -OH} ２ , *-NH-CH ２ CH(OH)CH ２ represents —Rt, *—OM, a halogen atom, or a substituted or unsubstituted arylamino group. １ , T ２ , and T ３ At least one of the following is *-NH-(CH ２ ) ｎ -Rt, *-NH-(CH ２ ) ｎ -OH, *-N-{(CH ２ ) ｎ -OH} ２ , or *-NH-CH ２ CH(OH)CH ２ * represents a bonding site to the triazine ring, n represents an integer of 1 to 5, and Rt is CO ２ M.S.O. ３ M, or PO (OM) ２ M represents a hydrogen atom or a counter cation. When multiple n's are present, the multiple n's may be the same or different. When a plurality of M's are present, the plurality of M's may be the same or different. 【Transformation 5】 In general formula (II), Ar ２０ represents a benzene ring or a naphthalene ring. ２１ ~R ２８ R each independently represents a hydrogen atom or a substituent. ２１ and R ２２ may be bonded to form a ring. ２３ and R ２４ may be bonded to form a ring. ２５ and R ２６ may be bonded to form a ring. ２７ and R ２８ may be bonded to form a ring. ２９ represents a substituent. ２０ represents a benzene ring, k represents an integer of 0 to 4. ２０ represents a naphthalene ring, k represents an integer of 0 to 6. ２９ If there are multiple R ２９ may be the same or different. ２９ If there are multiple R ２９ may be bonded to form a ring, provided that the compound represented by general formula (II) has at least one hydrophilic group.

13. The aqueous colorant solution for an ink composition according to claim 12, wherein the compound represented by general formula (A) is at least one compound selected from the following compound group (a): 【Transformation 6】 In the compounds of the compound group (a), M represents a hydrogen atom or a counter cation. When a compound contains a plurality of Ms, the plurality of Ms may be the same or different.

14. 14. The aqueous colorant solution for an ink composition according to claim 12, wherein the content of the colorant is 5.0 to 20.0 mass % based on the total mass of the aqueous colorant solution for an ink composition.

15. The aqueous colorant solution for an ink composition according to any one of claims 12 to 14, wherein the colorant is a water-soluble dye.

16. 16. The aqueous colorant solution for an ink composition according to claim 12, wherein the content of the compound represented by general formula (II) is 0.5 to 8.0 mass % based on the total mass of the aqueous colorant solution for an ink composition.

17. 17. The aqueous colorant solution for an ink composition according to claim 12, wherein the content of the compound represented by general formula (A) is 0.001 to 0.3 mass % based on the total mass of the aqueous colorant solution for an ink composition.

18. The aqueous colorant solution for an ink composition according to any one of claims 12 to 17, further comprising a chelating agent.

19. 19. The aqueous colorant solution for an ink composition according to claim 18, wherein the content of the chelating agent is 0.001 to 1.0% by mass based on the total mass of the aqueous additive solution for an ink composition.

20. The aqueous colorant solution for an ink composition according to any one of claims 12 to 19, further comprising a preservative.

21. 21. The aqueous colorant solution for an ink composition according to claim 20, wherein the content of the preservative is 0.01 to 1.0% by mass based on the total mass of the aqueous additive solution for an ink composition.

22. The aqueous colorant solution for an ink composition according to any one of claims 12 to 21, further comprising a buffering agent.

23. The aqueous colorant solution for an ink composition according to any one of claims 12 to 22, which has a pH value at 25°C of 6.5 to 9.

0.

24. An ink composition comprising a compound represented by the following general formula (A), a compound represented by the following general formula (II), water, and a colorant. 【Transformation 7】 In general formula (A), T １ , T ２ , and T ３ are each independently *-NH-(CH ２ ) ｎ -Rt, *-NH-(CH ２ ) ｎ -OH, *-N-{(CH ２ ) ｎ -OH} ２ , *-NH-CH ２ CH(OH)CH ２ represents —Rt, *—OM, a halogen atom, or a substituted or unsubstituted arylamino group. １ , T ２ , and T ３ At least one of the following is *-NH-(CH ２ ) ｎ -Rt, *-NH-(CH ２ ) ｎ -OH, *-N-{(CH ２ ) ｎ -OH} ２ , or *-NH-CH ２ CH(OH)CH ２ * represents a bonding site to the triazine ring, n represents an integer of 1 to 5, and Rt is CO ２ M.S.O. ３ M, or PO (OM) ２ M represents a hydrogen atom or a counter cation. When multiple n's are present, the multiple n's may be the same or different. When a plurality of M's are present, the plurality of M's may be the same or different. 【Transformation 8】 In general formula (II), Ar ２０ represents a benzene ring or a naphthalene ring. ２１ ~R ２８ R each independently represents a hydrogen atom or a substituent. ２１ and R ２２ may be bonded to form a ring. ２３ and R ２４ may be bonded to form a ring. ２５ and R ２６ may be bonded to form a ring. ２７ and R ２８ may be bonded to form a ring. ２９ represents a substituent. ２０ represents a benzene ring, k represents an integer of 0 to 4. ２０ represents a naphthalene ring, k represents an integer of 0 to 6. ２９ If there are multiple R ２９ may be the same or different. ２９ If there are multiple R ２９ may be bonded to form a ring, provided that the compound represented by general formula (II) has at least one hydrophilic group.

25. The ink composition according to claim 24, wherein the compound represented by formula (A) is at least one compound selected from the following compound group (a): 【Chemistry 9】 In the compounds of the compound group (a), M represents a hydrogen atom or a counter cation. When a compound contains a plurality of Ms, the plurality of Ms may be the same or different.

26. 26. The ink composition according to claim 24, wherein the content of the colorant is 0.1 to 10.0% by mass based on the total mass of the ink composition.

27. The ink composition according to any one of claims 24 to 26, further comprising a chelating agent.

28. 28. The ink composition according to claim 27, wherein the content of the chelating agent is 0.001 to 1.0% by mass based on the total mass of the ink composition.

29. The ink composition according to any one of claims 24 to 28, further comprising a preservative.

30. 30. The ink composition according to claim 29, wherein the content of the preservative is 0.001 to 0.5% by mass based on the total mass of the ink composition.

31. The ink composition according to any one of claims 24 to 30, further comprising a buffering agent.

32. The ink composition according to any one of claims 24 to 31, having a pH value at 25°C of 6.5 to 9.

0.

33. An ink composition for ink jet recording, comprising the ink composition according to any one of claims 24 to 32.

34. 34. An ink jet recording method comprising a step of ejecting the ink composition for ink jet recording according to claim 33 using an ink jet recording head.

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