Inkjet ink and inkjet recording method

Abstract

To provide an inkjet ink capable of yielding an image recording material that offers superior invisibility and exhibits prolonged infrared absorption performance compared to the conventional art, as well as applications thereof.SOLUTION: An inkjet ink comprises a dye compound represented by the formula 1, a dispersant, a water-soluble organic solvent, and water, where the dispersant is a polymer containing an acidic functional group and an ethylene oxide chain. In the formula 1, the details of T1, T2, R1, R2, X1, and n are not provided.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to an inkjet ink and an inkjet recording method. [Background technology]

[0002] In recent years, various applications utilizing the properties of near-infrared absorbing dyes have been proposed. For example, near-infrared absorbing dyes are used in a wide variety of applications, such as optical film applications, such as infrared cut films and heat shielding films for plasma display panels or CCDs (imaging devices); light-to-heat conversion materials for write-once optical disks or flash melt fixing materials; information display materials, such as security inks and invisible barcode inks; and medical materials, such as diagnostic markers and drugs for photodynamic therapy. The characteristic performance of these near-infrared absorbing dyes requires that they have strong absorption in the near-infrared or infrared region, and that they have as little absorption as possible in the visible light region (invisibility). They are also required to maintain their infrared absorbing ability for a long time.

[0003] For example, Patent Document 1 describes an ink for ink-jet recording that contains a specific cyanine dye and a medium. Patent Document 2 describes a near infrared absorbing composition containing a squarylium dye, a resin, a dispersant, and at least one member selected from the group consisting of an organic solvent and water. Patent Document 3 describes an ultraviolet-curable non-aqueous inkjet ink that contains a monomer solvent containing a donor monomer and an acceptor monomer, a pigment, and a polymer dispersant, but does not contain water, and that undergoes polymerization due to the charge density difference between the donor monomer and the acceptor monomer, in which the polymer dispersant has a comb structure having a main chain and a side chain bonded to the main chain, and the difference between the SP value of the polymer dispersant and the SP value of the monomer solvent is 1.6 or less. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2022 / 049862 [Patent Document 2] JP 2019-001983 A [Patent Document 3] JP 2013-129746 A Summary of the Invention [Problem to be solved by the invention]

[0005] Near-infrared absorbing dyes are required to have excellent invisibility and to maintain their infrared absorbing ability for a longer period than ever before.

[0006] The present disclosure has been made in consideration of the above circumstances, and an object of one embodiment of the present invention is to provide an inkjet ink and an inkjet recording method that are capable of obtaining an image recording that is excellent in invisibility and maintains infrared absorbing ability for a longer period than conventional methods. [Means for solving the problem]

[0007] The present disclosure includes the following aspects. <1> The composition includes a dye compound represented by the following formula 1, a dispersant, a water-soluble organic solvent, and water, An ink-jet ink, wherein the dispersant is a polymer containing acidic functional groups and ethylene oxide chains. [ka] In formula 1, L 1 R represents a methine chain consisting of an odd number of methine groups. 1 and R 2 Each independently represents an aliphatic group or an aromatic group. 1 and T 2 each independently represents a non-metallic atomic group forming an optionally condensed 5- or 6-membered nitrogen-containing heterocycle; Cy is an anion moiety; X 1represents an organic cation represented by the following formula 2-1, 2-2, or 2-3, or an organic cation having a structure represented by formula 2-4, where n is not 0 and represents a number necessary to neutralize the charge.

[0008] [ka]

[0009] [ka]

[0010] [ka]

[0011] [ka]

[0012] In formula 2-1, A 11 and A 12 Each independently represents a nitrogen atom or a phosphorus atom. 11 R each independently represents a divalent linking group. 1a , R 1b , R 1c , R 1d , E 11 , and E 12 Each independently represents an aliphatic group or an aromatic group. 1a , R 1b , R 1c , and R 1d may be bonded to each other to form a ring. m1 is an integer of 1 or more. In formula 2-2, A 21 , A 22 , and A 23 Each independently represents a nitrogen atom or a phosphorus atom. 21 and B. 22 R each independently represents a divalent linking group. 2a and R 2bEach independently represents an aliphatic group or an aromatic group. m2 is an integer of 0 or more. G 21 A 21 It represents a group of non-metallic atoms forming an aromatic ring containing G 22 A 23 represents a group of non-metallic atoms forming an aromatic ring containing In formula 2-3, A 31 and A 32 Each independently represents a nitrogen atom or a phosphorus atom. 31 R represents a divalent linking group. 3a and R 3b Each independently represents an aliphatic group or an aromatic group. 31 A 31 It represents a group of non-metallic atoms forming an aromatic ring containing G 32 A 32 represents a group of non-metallic atoms forming an aromatic ring containing In formula 2-4, A 41 Each independently represents a nitrogen atom or a phosphorus atom. 41 R each independently represents a single bond or a divalent linking group. 4a , R 4b and R 4c Each independently represents an aliphatic group or an aromatic group. 41 and E 42 R each independently represents a single bond or an aliphatic group. 4a , R 4b and R 4c One of them is E 41 Or E 42 may be bonded to form a ring. m4 is an integer of 2 or more. <2> The dispersant further comprises a structural unit derived from at least one selected from the group consisting of styrene and styrene derivatives. <1> 2. The ink-jet ink according to claim 1 . <3> The content of the structural unit derived from at least one selected from the group consisting of styrene and styrene derivatives is 1 mol % to 60 mol % based on the total amount of the dispersant. <1> or <2> 2. The ink-jet ink according to claim 1 . <4> a mass ratio of the content of the dispersant to the content of the colorant compound represented by formula 1 is 0.1 to 3; <1> ~ <3> 13. The ink-jet ink according to any one of claims 1 to 12. <5> The SP value of the mixed solvent consisting of water and a water-soluble organic solvent is 40.0MPa. 1 / 2 That's all. <1> ~ <4> 13. The ink-jet ink according to any one of claims 1 to 12. <6> The SP value of water-soluble organic solvent is A [MPa 1 / 2 ]year, When the ratio of the water-soluble organic solvent to the total content of water and the water-soluble organic solvent is B mass%, A and B satisfy the following formula T1: <1> ~ <5> 13. The ink-jet ink according to any one of claims 1 to 12. 10≦B≦1.6×A-7 …(T1) <7> A and B satisfy the following formula T2: <6> 2. The ink-jet ink according to claim 1 . 10≦B≦1.6×A-12 …(T2) <8> The ratio of the water-soluble organic solvent to the total content of water and the water-soluble organic solvent is 15% by mass to 35% by mass. <1> ~ <7> 13. The ink-jet ink according to any one of claims 1 to 12. <9> In formula 1, Cy is represented by the following formula 4: <1> ~ <8> 13. The ink-jet ink according to any one of claims 1 to 12. [ka] In equation 4, Y 1 and Y 2 are each independently 3 R 4 -, -O-, -S-, -Se-, or -NR 5 - stands for R 3 , R 4 , and R 5 R each independently represents a hydrogen atom, an aliphatic group, or an aromatic ring group. 3 and R 4 may be bonded to each other to form a ring. 1 and A2 each independently represents a nonmetallic atomic group forming an aromatic ring or an aromatic heterocycle. 2 each independently represents a methine chain consisting of 1, 2, or 3 methine groups; L 2 R has no substituents. 6 and R 7 R each independently represents a hydrogen atom or an aliphatic group. 6 and R 7 may be linked together to form a ring. 8 is expressed by the following formula A. -S A -T A Formula A In formula A, S A is a single bond, an alkylene group, an alkenylene group, an alkynylene group, -O-, -S-, -NR L1 -, -C(=O)-, -C(=O)O-, -C(=O)NR L1 -, -S(=O)2-, -OR L2 - or a group formed by combining at least two of these, R L1 each independently represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, or a monovalent heterocyclic group; R L2 represents an alkylene group, an arylene group, or a divalent heterocyclic group; T A represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, a monovalent heterocyclic group, a cyano group, a hydroxyl group, a formyl group, a carboxy group, an amino group, a thiol group, a sulfo group, a phosphoryl group, a boryl group, a vinyl group, an ethynyl group, a trialkylsilyl group, or a trialkoxysilyl group. <10> On the substrate, <1> ~ <9> 2. An inkjet recording method comprising the step of applying the inkjet ink according to any one of the above items by an inkjet recording system. Effect of the Invention

[0013] According to the present disclosure, there are provided an inkjet ink and an inkjet recording method that can obtain an image recorded with excellent invisibility and in which infrared absorbing ability is maintained for a longer period than before. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The inkjet ink and the inkjet recording method of the present disclosure will be described in detail below.

[0015] In this specification, a numerical range indicated using "to" means a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in this specification, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in a certain numerical range. In addition, in the numerical ranges described in this specification, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples.

[0016] In this specification, the amount of each component in a composition means the total amount of the multiple substances present in the composition when multiple substances corresponding to each component are present in the composition, unless otherwise specified. As used herein, a combination of two or more preferred embodiments is a more preferred embodiment. In this specification, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved.

[0017] In this specification, the term "(meth)acrylate" is a concept that encompasses both acrylate and methacrylate, and the term "(meth)acrylic" is a concept that encompasses both acrylic and methacrylic. In this specification, a monovalent heterocyclic group refers to a group obtained by removing one hydrogen atom from a heterocyclic compound, and a divalent heterocyclic group refers to a group obtained by removing two hydrogen atoms from a heterocyclic compound.

[0018] <<Inkjet ink>> The inkjet ink of the present disclosure contains a dye compound represented by Formula 1 described below, a dispersant, a water-soluble organic solvent, and water, and the dispersant is a polymer containing an acidic functional group and an ethylene oxide chain.

[0019] The dye compound represented by formula 1 has excellent infrared absorbing ability and has little absorption in the visible range, and therefore has excellent invisibility. Furthermore, the dye compound represented by formula 1 can maintain its infrared absorbing ability for a longer period than conventional dye compounds.

[0020] The dye compound represented by formula 1 is a cyanine dye, and the cyanine dye is likely to form an aggregate. When the cyanine dye forms an aggregate, it absorbs light of long wavelengths, and is therefore excellent in invisibility and durability such as light resistance and wet heat resistance. As described below, the dye compound represented by formula 1 has a cyanine dye structure and an organic cation represented by formula 2-1, formula 2-2, or formula 2-3, or an organic cation having a structure represented by formula 2-4. Since these organic cations have a flexible molecular structure, it is presumed that they are highly effective in binding cyanine dyes together at positions where they can appropriately form an aggregate. Since the dye compound represented by formula 1 has a high ability to form an aggregate, it is believed that an inkjet ink containing the dye compound represented by formula 1 can maintain infrared absorption ability for a longer period of time than before.

[0021] The present inventors have found that the formation of an aggregate of a cyanine dye is easily affected by the polarity and acid-base properties of the medium in which the cyanine dye is dispersed, and have found that by adding a specific dispersant to the inkjet ink, the aggregate formed can be further stabilized and the infrared absorbing ability can be maintained for a longer period of time.

[0022] In the present disclosure, the mechanism by which the above-mentioned effects are obtained is not clear, but is presumed to be as follows.

[0023] First, since the dispersant contains an ethylene oxide chain, the wettability of the dye compound represented by formula 1 to a dispersion medium (water and water-soluble organic solvent) is improved due to hydrophobic interaction between the ethylene oxide chain and the dye compound represented by formula 1. It is believed that the dispersant contains an acidic functional group, and thus cations dissociated from the dispersant contribute to the formation of associations. Furthermore, it is believed that since the dispersant contains an ethylene oxide chain, the formed aggregate is stabilized by hydrophobic interaction between the ethylene oxide chain and the dye compound represented by formula 1. By stabilizing the aggregates, the infrared absorbing ability can be maintained for a longer period of time.

[0024] In contrast, Patent Document 1 does not include any description focusing on the dispersant. Furthermore, Patent Document 2 and Patent Document 3 do not include any description of the dye compound represented by Formula 1. None of Patent Documents 1 to 3 includes any description of the contribution of the dispersant contained in the inkjet ink of the present disclosure to the formation of aggregates.

[0025] Hereinafter, each component contained in the ink-jet ink (hereinafter, simply referred to as "ink") of the present disclosure will be described.

[0026] <Dye compound represented by formula 1> The inks of the present disclosure include a dye compound represented by Formula 1.

[0027] [ka]

[0028] In formula 1, L 1 R represents a methine chain consisting of an odd number of methine groups. 1 and R 2 Each independently represents an aliphatic group or an aromatic group. 1 and T 2 each independently represents a non-metallic atomic group forming an optionally condensed 5- or 6-membered nitrogen-containing heterocycle; Cy is an anion moiety; X 1represents an organic cation represented by the following formula 2-1, 2-2, or 2-3, or an organic cation having a structure represented by formula 2-4, where n is not 0 and represents a number necessary to neutralize the charge.

[0029] [L 1 ] In formula 1, L 1 represents a methine chain consisting of an odd number of methine groups. 1 preferably represents a methine chain consisting of 5, 7, or 9 methine groups, and more preferably represents a methine chain consisting of 5 or 7 methine groups.

[0030] The methine group at the center of the methine chain preferably has a substituent represented by formula A. A and T A More on this later. *-S A -T A Formula A

[0031] The methine groups other than the central methine group of the methine chain may have a substituent, but preferably have no substituent.

[0032] The methine chain may have a crosslinked structure at any position. For example, the methine chain may form a ring structure by bonding carbon atoms constituting the methine chain. The ring structure is not particularly limited, but is preferably an aliphatic ring, more preferably a 5-membered aliphatic ring or a 6-membered aliphatic ring.

[0033] Specifically, L 1 is preferably a group represented by the following formula L1-1, L1-2, L2-1 or L2-2, and more preferably a group represented by the following formula L1-2 or L2-2.

[0034] [ka]

[0035] In formula L1-1, formula L1-2, formula L2-1, and formula L2-2, A represents a substituent represented by the above formula A, and each wavy line portion independently represents L in formula 1. 1 It indicates the bonding position with structures other than the above.

[0036] In formula L2-1 and formula L2-2, Y L represents a non-metallic atomic group forming an aliphatic ring or a heterocycle, and preferably represents a non-metallic atomic group forming an aliphatic ring. L is preferably an alkylene group, and examples of the alkylene group include -CH2CH2- and -CH2C(Z)2-CH2-. The aliphatic ring is preferably a 5-membered aliphatic ring or a 6-membered aliphatic ring. Each Z independently represents a hydrogen atom or an alkyl group. Z is preferably a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and more preferably a hydrogen atom or a methyl group. Two Zs may be bonded to form a ring structure.

[0037] The group represented by the above formula L2-1 or L2-2 is preferably a group represented by the following formulas L3-1 to L3-4.

[0038] [ka]

[0039] In formula L3-3 and formula L3-4, each Z independently represents a hydrogen atom or an alkyl group. Z is preferably a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and more preferably a hydrogen atom or a methyl group. Two Zs may be bonded to form a ring structure.

[0040] In formulas L3-1 to L3-4, A represents a substituent represented by the above formula A, and each wavy line portion independently represents L in formula 1. 1 It indicates the bonding position with structures other than the above.

[0041] In formula A, S A is a single bond, an alkylene group, an alkenylene group, an alkynylene group, -O-, -S-, -NR L1-, -C(=O)-, -C(=O)O-, -C(=O)NR L1 -, -S(=O)2-, -OR L2 From the viewpoint of invisibility, S A is preferably a single bond, an alkylene group, an alkenylene group or an alkynylene group, and more preferably a single bond.

[0042] The alkylene group is preferably an alkylene group having 1 to 10 carbon atoms, more preferably an alkylene group having 1 to 4 carbon atoms, and further preferably a methylene group or an ethylene group.

[0043] The alkenylene group is preferably an alkenylene group having 2 to 10 carbon atoms, more preferably an alkenylene group having 2 to 4 carbon atoms, and even more preferably an alkenylene group having 2 or 3 carbon atoms.

[0044] The alkynylene group is preferably an alkynylene group having 2 to 10 carbon atoms, more preferably an alkynylene group having 2 to 4 carbon atoms, and even more preferably an alkynylene group having 2 or 3 carbon atoms.

[0045] The alkylene group, alkenylene group, and alkynylene group may be linear or branched, and some or all of the carbon atoms contained in each group may form a cyclic structure.

[0046] Hereinafter, the same applies to the descriptions of alkylene groups, alkenylene groups, and alkynylene groups in the present disclosure, unless otherwise specified.

[0047] -C(=O)O- means that the carbon atom is L 1 and the oxygen atom is T A The oxygen atom may be bonded to L 1 and the carbon atom is T A It may be bonded to.

[0048] -C(=O)NRL1 - is the carbon atom L 1 and the nitrogen atom is T A The nitrogen atom may be bonded to L 1 and the carbon atom is T A It may be bonded to.

[0049] In formula A, S A Ga-NR L1 - or -C(=O)NR L1 -If R L1 represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, or a monovalent heterocyclic group, preferably a hydrogen atom, an alkyl group, or an aryl group, and more preferably a hydrogen atom.

[0050] Examples of the halogen atom include a fluorine atom (F atom), a chlorine atom (Cl atom), a bromine atom (Br atom) and an iodine atom (I atom). Among them, the halogen atom is preferably a Cl atom or a Br atom, and more preferably a Cl atom.

[0051] The alkyl group is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and further preferably an alkyl group having 1 or 2 carbon atoms.

[0052] The aryl group is preferably an aryl group having 6 to 20 carbon atoms, more preferably a phenyl group or a naphthyl group.

[0053] The heterocycle in the monovalent heterocyclic group is preferably a 5-membered or 6-membered ring. The heterocycle may form a condensed ring with an aliphatic ring, an aromatic ring, or another heterocycle. The heteroatom in the heterocycle includes N atom, O atom, and S atom, and N atom is preferred.

[0054] Examples of the heterocycle include a pyridine ring, a piperidine ring, a furan ring, a furfuran ring, a thiophene ring, a pyrrole ring, a quinoline ring, a morpholine ring, an indole ring, an imidazole ring, a pyrazole ring, a carbazole ring, a phenothiazine ring, a phenoxazine ring, an indoline ring, a pyrrolidone ring, a thiazole ring, a pyrazine ring, a thiadiazine ring, a benzoquinoline ring, and a thiadiazole ring.

[0055] In formula A, S A -OR L2 -If R L2 represents an alkylene group, an arylene group or a divalent heterocyclic group, and is preferably an alkylene group.

[0056] The alkylene group is preferably an alkylene group having 1 to 10 carbon atoms, more preferably an alkylene group having 1 to 4 carbon atoms, and even more preferably an alkylene group having 1 or 2 carbon atoms.

[0057] The arylene group is preferably an arylene group having 6 to 20 carbon atoms, more preferably a phenylene group or naphthylene group, and further preferably a phenylene group.

[0058] The divalent heterocyclic group is R L1 It is preferable that the heterocyclic group has a structure in which one hydrogen atom has been further removed from the monovalent heterocyclic group represented by the formula:

[0059] In formula A, T A represents a halogen atom, an alkyl group, an aryl group, a monovalent heterocyclic group, a cyano group, a hydroxy group, a formyl group, a carboxy group, an amino group, a thiol group, a sulfo group, a phosphoryl group, a boryl group, a vinyl group, an ethynyl group, a trialkylsilyl group, or a trialkoxysilyl group. A is preferably an aryl group, a monovalent heterocyclic group, or a trialkylsilyl group.

[0060] Examples of the halogen atom include a fluorine atom (F atom), a chlorine atom (Cl atom), a bromine atom (Br atom) and an iodine atom (I atom). Among them, the halogen atom is preferably a Cl atom or a Br atom, and more preferably a Cl atom. The alkyl group is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and further preferably an alkyl group having 1 or 2 carbon atoms.

[0061] In formula A, T A When represents an alkyl group, T A may form a ring structure together with other carbon atoms in the methine chain. The ring structure is preferably a 5-membered or 6-membered ring.

[0062] The aryl group is preferably an aryl group having 6 to 20 carbon atoms, more preferably a phenyl group or a naphthyl group, and even more preferably a phenyl group.

[0063] The heterocycle in the monovalent heterocyclic group is preferably a 5- or 6-membered ring. The heterocycle may form a condensed ring with an aliphatic ring, an aromatic ring, or another heterocycle.

[0064] Examples of the heteroatom in the hetero ring include a N atom, an O atom, and a S atom, and a N atom is preferred.

[0065] Examples of the heterocycle include a pyridine ring, a triazine ring, a piperidine ring, a furan ring, a furfuran ring, a Meldrum's acid ring, a barbituric acid ring, a succinimide ring, a thiophene ring, a pyrrole ring, a quinoline ring, a morpholine ring, a thiomorpholine ring, an indole ring, an imidazole ring, a pyrazole ring, a carbazole ring, a phenothiazine ring, a phenoxazine ring, an indoline ring, a pyrrolidone ring, a thiazole ring, a pyrazine ring, a thiadiazine ring, a benzoquinoline ring, and a thiadiazole ring.

[0066] The heterocycle may form a salt structure. For example, the pyridine ring may form a pyridinium salt or may exist as a pyridinium ion.

[0067] The aryl group and the monovalent heterocyclic group may have a substituent. Examples of the substituent include an alkyl group, an alkoxy group, a halogen atom, an alkenyl group, an alkynyl group, an aryl group, a monovalent heterocyclic group, a nitro group, a cyano group, -OR T , -C(=O)R T , -C(=O)OR T , -OC(=O)R T , -N(R T )2, -NHC(=O)R T , -C(=O)N(R T )2, -NHC(=O)OR T , -OC(=O)N(R T )2, -NHC(=O)N(R T )2, -SR T , -S(=O)2R T , -S(=O)2OR T , -NHS(=O)2R T , and -S(=O)2N(R T )2 are examples.

[0068] R T each independently represents a hydrogen atom, an alkyl group, an aryl group, or a monovalent heterocyclic group, and is preferably a hydrogen atom, an alkyl group, or an aryl group.

[0069] R T The alkyl group in is preferably an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms, and further preferably a methyl group or an ethyl group.

[0070] R T The aryl group in is preferably an aryl group having 6 to 20 carbon atoms, more preferably a phenyl group or a naphthyl group, and further preferably a phenyl group.

[0071] R T The heterocycle in the monovalent heterocyclic group in the formula (I) is preferably a 5- or 6-membered ring. The heterocycle may form an aliphatic ring, an aromatic ring, or a condensed ring with another heterocycle.

[0072] Examples of the heteroatom in the hetero ring include a N atom, an O atom, and a S atom, and a N atom is preferred.

[0073] Examples of the heterocycle include a pyridine ring, a piperidine ring, a piperazine ring, a pyrrolidine ring, a furan ring, a tetrahydrofuran ring, a tetrahydropyran ring, a thiophene ring, a pyrrole ring, a quinoline ring, a morpholine ring, an indole ring, an imidazole ring, a pyrazole ring, a carbazole ring, a phenothiazine ring, a phenoxazine ring, an indoline ring, a pyrrolidone ring, a thiazole ring, a pyrazine ring, a thiadiazine ring, a benzoquinoline ring, and a thiadiazole ring.

[0074] R T The monovalent heterocyclic group in may further have a substituent. The substituent may be R T The preferred embodiments are also the same.

[0075] Examples of the amino group include an unsubstituted amino group and a substituted amino group, and a diarylamino group or a diheteroarylamino group is preferable.

[0076] The substituent in the substituted amino group may be an alkyl group, an aryl group, or a monovalent heterocyclic group. The alkyl group, the aryl group, or the monovalent heterocyclic group in the substituted amino group may be T A The meanings and preferred embodiments of the alkyl group, aryl group, or monovalent heterocyclic group in

[0077] The trialkylsilyl group is preferably a trialkylsilyl group in which the alkyl group has 1 to 10 carbon atoms, and more preferably a trialkylsilyl group in which the alkyl group has 1 to 4 carbon atoms. Examples of the trialkylsilyl group include a trimethylsilyl group, a dimethylbutylsilyl group, a triethylsilyl group, and a triisopropylsilyl group.

[0078] The trialkoxysilyl group is preferably a trialkoxysilyl group having an alkoxy group with 1 to 10 carbon atoms, and more preferably a trialkoxysilyl group having an alkoxy group with 1 to 4 carbon atoms. Examples of the trialkoxysilyl group include a trimethoxysilyl group and a triethoxysilyl group.

[0079] S A represents a single bond or an alkylene group, and T A When represents an alkyl group, S A and T A From the viewpoint of invisibility, the total number of carbon atoms contained in is preferably 3 or more, more preferably 4 or more, and even more preferably 5 or more.

[0080] From the viewpoint of dispersibility, the total number of carbon atoms is preferably 20 or less, and more preferably 10 or less. A is preferably a nitrogen-containing heterocyclic group, an aryl group, or a halogen atom.

[0081] Specific examples of the substituent represented by formula A (substituent A) include the following substituents A-1 to A-55. However, the substituent A in the present disclosure is not limited thereto. Among the following substituents A-1 to A-55, iC 10 represents an isodecyl group, i-C8 represents an isooctyl group, and * represents L 1 The binding site is shown.

[0082] [ka]

[0083] [ka]

[0084] [ka]

[0085] Among the substituents A-1 to A-55, the substituents A-1, A-4, A-5, A-8, A-10, A-24, A-34, A-39, A-41 to A-43, A-48, and A49 to A55 are preferred from the viewpoint that the cyanine dye is more likely to form an aggregate.

[0086] Below, L 1 Specific examples of methine chains represented by the formula: 1 The methine chain represented by the following specific examples is not limited to the following specific examples. In the following specific examples, each wavy line portion independently represents L 1 It indicates the bonding position with structures other than the above. Note that Me represents a methyl group, Et represents an ethyl group, and Ph represents a phenyl group.

[0087] [ka]

[0088] [ka]

[0089] L 1 From the viewpoint that the cyanine dye can more easily form an aggregate, the methine chain represented by the following formula is preferably LA1 to LA8, LA11 to 19, LA21 to 24, or LA27 to 30.

[0090] [R 1 and R 2 ] R 1 and R 2 each independently represents an aliphatic group or an aromatic group. The aliphatic group and the aromatic group may have a substituent. The substituent may be a halogen atom (e.g., a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom), a cyano group, a nitro group, an aliphatic group, an aromatic group, a heterocyclic group, -OR 10 , -COR 11 , -COOR 12 , -OCOR 13 , -NR 14 R15 , -NHCOR 16 , -CONR 17 R 18 , -NHCONR 19 R 20 , -NHCOOR 21 , -SR 22 , -SO2R 23 , -SO2OR 24 , -NHSO2R 25 , and SO2NR 26 R 27 Examples include: R 10 ~R 27 Each independently represents a hydrogen atom, an aliphatic group, an aromatic group, or a heterocyclic group. Examples of the substituent include a hydroxyl group, a carboxyl group, a sulfo group, an alkoxy group, and an amino group. Among them, the substituent is an aliphatic group, an aromatic group, -OR 10 , -COOR 12 OR -SO2OR 24 is preferably an aromatic group, -SO2OR 24 It is more preferable that -COOR 12 R 12 When -SO2OR is a hydrogen atom (i.e., a carboxy group), the hydrogen atom may be dissociated (i.e., a carboxylate group) or may be in the form of a salt. 24 R 24 When is a hydrogen atom (ie, a sulfo group), the hydrogen atom may be dissociated (ie, a sulfonate group) or may be in the form of a salt.

[0091] Aliphatic groups include alkyl, alkenyl, alkynyl, and aralkyl groups. Aromatic groups include aryl groups.

[0092] R 1 and R 2The alkyl group represented by each of the above may be cyclic or chain-like. The chain-like alkyl group may be a linear alkyl group or a branched alkyl group. The number of carbon atoms of the alkyl group (when the alkyl group has a substituent, the number of carbon atoms of the portion excluding the substituent) is preferably 1 to 20, more preferably 1 to 12, and further preferably 1 to 8. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a butyl group, a t-butyl group, a cyclopropyl group, a cyclohexyl group, and a 2-ethylhexyl group. Examples of the alkyl group having a substituent include a 2-hydroxyethyl group, a 2-carboxyethyl group, a 2-methoxyethyl group, a 2-phenoxyethyl group, a 2-(1-naphthoxy)ethyl group, a 2-diethylaminoethyl group, a 2-sulfoethyl group, a 2-methoxypropyl group, a 3-methoxypropyl group, a 3-sulfopropyl group, a 3-sulfobutyl group, and a 4-sulfobutyl group.

[0093] R 1 and R 2 The alkenyl group represented by each of the above may be cyclic or chain-like. The chain-like alkenyl group may be a straight-chain alkenyl group or a branched-chain alkenyl group. The number of carbon atoms in the alkenyl group (when the alkenyl group has a substituent, the number of carbon atoms in the portion excluding the substituent) is preferably 2 to 20, more preferably 2 to 12, and further preferably 2 to 8. Examples of the alkenyl group include a vinyl group, an allyl group, a 1-propenyl group, a 2-butenyl group, a 2-pentenyl group, and a 2-hexenyl group.

[0094] R 1 and R 2 The alkynyl group represented by each of the above may be cyclic or chain-like. The chain-like alkynyl group may be a straight-chain alkynyl group or a branched-chain alkynyl group. The number of carbon atoms in the alkynyl group (when the alkynyl group has a substituent, the number of carbon atoms in the portion excluding the substituent) is preferably 2 to 20, more preferably 2 to 12, and further preferably 2 to 8. Examples of the alkynyl group include an ethynyl group and a 2-propynyl group.

[0095] R 1 and R2 The alkyl portion of the aralkyl group represented by each of the above is the same as the alkyl group. The aryl portion of the aralkyl group which may have a substituent is the same as the aryl group described below. Examples of the aralkyl group include a benzyl group and a phenethyl group.

[0096] R 1 and R 2 The number of carbon atoms in the aryl group represented by each of the above (when the aryl group has a substituent, the number of carbon atoms in the portion excluding the substituent) is preferably 6 to 25, more preferably 6 to 15, and further preferably 6 to 10. Examples of the aryl group include a phenyl group and a naphthyl group.

[0097] Examples of the aryl group having a substituent include a 4-carboxyphenyl group, a 4-acetamidophenyl group, a 3-methanesulfonamidophenyl group, a 4-methoxyphenyl group, a 3-carboxyphenyl group, a 3,5-dicarboxyphenyl group, a 4-methanesulfonamidophenyl group, and a 4-butanesulfonamidophenyl group.

[0098] [T 1 and T 2 ] T 1 and T 2 each independently represents a group of non-metallic atoms forming an optionally condensed 5- or 6-membered nitrogen-containing heterocycle.

[0099] The nitrogen-containing heterocycle may be condensed with another heterocycle, an aromatic ring, or an aliphatic ring.

[0100] The nitrogen-containing heterocycle is preferably a 5-membered ring, and more preferably a benzene ring or a naphthalene ring condensed to the 5-membered nitrogen-containing heterocycle.

[0101] Examples of the nitrogen-containing heterocycle include an oxazole ring, an isoxazole ring, a benzoxazole ring, a naphthoxazole ring, an oxazolocarbazole ring, an oxazolodibenzofuran ring, a thiazole ring, a benzothiazole ring, a naphthothiazole ring, an indolenine ring, a benzoindolenine ring, an imidazole ring, a benzimidazole ring, a naphthoimidazole ring, a quinoline ring, a pyridine ring, a pyrrolopyridine ring, a furopyrrole ring, an indolizine ring, an imidazoquinoxaline ring, and a quinoxaline ring. Among these, the nitrogen-containing heterocycle is preferably a quinoline ring, an indolenine ring, a benzoindolenine ring, a benzoxazole ring, a benzothiazole ring, or a benzimidazole ring, and more preferably an indolenine ring, a benzoindolenine ring, a benzothiazole ring, or a benzimidazole ring.

[0102] The nitrogen-containing heterocycle and the ring condensed therewith may have a substituent.

[0103] The substituents include halogen atoms, cyano groups, nitro groups, aliphatic groups, aromatic groups, heterocyclic groups, -OR 10 , -COR 11 , -COOR 12 , -OCOR 13 , -NR 14 R 15 , -NHCOR 16 , -CONR 17 R 18 , -NHCONR 19 R 20 , -NHCOOR 21 , -SR 22 , -SO2R 23 , -SO2OR 24 , -NHSO2R 25 , and SO2NR 26 R 27 Examples include: R 10 ~R 27 Each independently represents a hydrogen atom, an aliphatic group, an aromatic group, or a heterocyclic group. 12 R 12When -SO2OR is a hydrogen atom (i.e., a carboxy group), the hydrogen atom may be dissociated (i.e., a carboxylate group) or may be in the form of a salt. 24 R 24 When is a hydrogen atom (i.e., a sulfo group), the hydrogen atom may be dissociated (i.e., a sulfonate group) or may be in the form of a salt. 12 OR -SO2OR 24 Preferably, -SO2OR 24 It is more preferable that:

[0104] Halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0105] R 10 ~R 27 The aliphatic and aromatic groups represented by R 1 and R 2 The aliphatic and aromatic groups are the same as those represented by the following formulae:

[0106] The heterocyclic group may have a substituent. Examples of the substituent include the substituents that the aliphatic group may have, and the preferred ranges are also the same.

[0107] The heterocycle of the heterocyclic group is preferably a 5-membered or 6-membered ring. The heterocycle may be a single ring or a condensed ring. Examples of the heterocycle include a pyridine ring, a piperidine ring, a furan ring, a furan ring, a thiophene ring, a pyrrole ring, a quinoline ring, a morpholine ring, an indole ring, an imidazole ring, a pyrazole ring, a carbazole ring, a phenothiazine ring, a phenoxazine ring, an indoline ring, a thiazole ring, a pyrazine ring, a thiadiazine ring, a benzoquinoline ring, and a thiadiazole ring.

[0108] Among them, the substituent is -COOR 12 OR -SO2OR 24 Preferably, -SO2OR 24 It is more preferable that:

[0109] [Cy] Cy is an anionic moiety. Cy has one or more anionic groups so that the charge of the anionic moiety as a whole is negative. When the anionic group is a monovalent anionic group, Cy has two or more anionic groups. The position of the anionic group is not particularly limited. The anionic group is L 1 , R 1 , and R 2 may be included in T 1 and T 2 The anionic group is preferably a sulfo group or a carboxy group, and more preferably a sulfo group.

[0110] Cy is preferably an anion moiety represented by the following formula 3:

[0111] [ka]

[0112] In formula 3, Y 1 and Y 2 are each independently 3 R 4 -, -O-, -S-, -Se-, or -NR 5 - stands for R 3 , R 4 , and R 5 R each independently represents a hydrogen atom, an aliphatic group, or an aromatic ring group. 3 and R 4 may be bonded to each other to form a ring. 1 and A 2 Each independently represents a non-metallic atomic group forming an aromatic ring or an aromatic heterocycle. 1 , R 1 , and R 2 is L in Eq. 1 , R 1 , and R 2 is synonymous with.

[0113] [Y 1 and Y 2 ] Y 1 and Y 2 are each independently 3 R 4 -, -O-, -S-, -Se-, or -NR 5 - stands for Y. 1 and Y 2 are each independently 3 R 4 -, -O-, -S- are preferred, and CR 3 R 4 It is even more preferable that

[0114] R 3 , R 4 , and R 5 The aliphatic and aromatic groups represented by R 1 and R 2 The aliphatic and aromatic groups are the same as those represented by the following formulae:

[0115] Among them, R 3 , R 4 , and R 5 are each preferably an alkyl group. The number of carbon atoms in the alkyl group is preferably 1 to 10, more preferably 1 to 5, and further preferably 1 to 3. The alkyl group may be any of a linear alkyl group, a branched alkyl group, and a cyclic alkyl group. Among them, R 3 , R 4 , and R 5 are each independently preferably a linear alkyl group or a branched alkyl group, more preferably a linear alkyl group, further preferably a methyl group or an ethyl group, and particularly preferably a methyl group.

[0116] [A 1 and A 2 ] A 1 and A 2 each independently represents a non-metallic atomic group forming an aromatic ring or an aromatic heterocycle. The aromatic ring and the aromatic heterocycle may have a substituent.

[0117] A1 and A 2 The aromatic ring and the aromatic heterocycle formed by each of the above may have a substituent, for example, T 1 and T 2 and the substituents which may be possessed by the nitrogen-containing heterocycle formed by each of the above and the ring condensed thereto.

[0118] Among them, the substituent is -COOR 12 OR -SO2OR 24 Preferably, -SO2OR 24 It is more preferable that:

[0119] A 1 and A 2 Examples of the aromatic ring formed by each of the above include a benzene ring and a naphthalene ring.

[0120] A 1 and A 2 The aromatic heterocycle formed by each of the above is preferably an aromatic heterocycle in which at least one of the atoms forming the ring is a nitrogen atom, an oxygen atom, or a sulfur atom. 1 and A 2 The aromatic heterocycle formed by each of the above may be condensed with another ring (an aliphatic ring, an aromatic ring, or a heterocycle).

[0121] A 1 and A 2 The aromatic heterocycle formed by each of the above is preferably a 5- to 10-membered ring.

[0122] A 1 and A 2 Examples of the aromatic heterocycle formed by each of the above include a pyridine ring, a dibenzofuran ring, and a carbazole ring.

[0123] From the viewpoint that cyanine dyes are more likely to form aggregates, A 1 and A 2are each independently preferably a non-metallic atomic group forming an aromatic ring, and more preferably a non-metallic atomic group forming a benzene ring or a naphthalene ring.

[0124] The anion moiety represented by formula 3 is preferably an anion moiety represented by formula 3A or 3B below.

[0125] [ka]

[0126] [ka]

[0127] In formula 3A, R 1 , R 2 , Y 1 , and Y 2 is R in Equation 3 1 , R 2 , Y 1 , and Y 2 is synonymous with.

[0128] V 1A and V 2A each independently represents a hydrogen atom or a substituent.

[0129] V 1A and V 2A The substituents represented by each of the formulas are a halogen atom, a cyano group, a nitro group, an aliphatic group, an aromatic group, a heterocyclic group, -OR 10 , -COR 11 , -COOR 12 , -OCOR 13 , -NR 14 R 15 , -NHCOR 16 , -CONR 17 R 18 , -NHCONR 19 R 20 , -NHCOOR 21 , -SR 22 , -SO2R 23 , -SO2OR24 , -NHSO2R 25 , and SO2NR 26 R 27 Examples include: R 10 ~R 27 Each independently represents a hydrogen atom, an aliphatic group, an aromatic group, or a heterocyclic group. 12 R 12 When -SO2OR is a hydrogen atom (i.e., a carboxy group), the hydrogen atom may be dissociated (i.e., a carboxylate group) or may be in the form of a salt. 24 R 24 When is a hydrogen atom (ie, a sulfo group), the hydrogen atom may be dissociated (ie, a sulfonate group) or may be in the form of a salt.

[0130] Among them, V 1A and V 2A The substituents represented by each of the following are -COOR 12 OR -SO2OR 24 Preferably, -SO2OR 24 It is more preferable that:

[0131] V 1A and V 2A may be the same or different from each other, but from the viewpoint of ease of production, it is preferable that they are the same.

[0132] V 1A is a substituent, V to the benzene ring 1A The bonding position of R is not particularly limited. From the viewpoint of making the cyanine dye more likely to form an aggregate, 1 It is preferable that the nitrogen atom bonded to V is the most distant position. 2A is a substituent, V to the benzene ring 2A The bonding position of R is not particularly limited. From the viewpoint of making the cyanine dye more likely to form an aggregate, 2 It is preferable that the nitrogen atom bonded to the nitrogen atom be the farthest position.

[0133] In formula 3B, R 1 , R2 , Y 1 , and Y 2 is R in Equation 3 1 , R 2 , Y 1 , and Y 2 Synonymous with V. 1B and V 2B each independently represents a hydrogen atom or a substituent.

[0134] V 1B and V 2B The substituents represented by each of the formulas are V 1A and V 2A The substituents are the same as those represented by each of the following formulas.

[0135] Among them, V 1B and V 2B The substituents represented by each of the following are -COOR 12 OR -SO2OR 24 Preferably, -SO2OR 24 It is more preferable that:

[0136] V 1B and V 2B may be the same or different from each other, but from the viewpoint of ease of production, it is preferable that they are the same.

[0137] V 1B is a substituent, V to the naphthalene ring 1B The bonding position of R is not particularly limited. From the viewpoint of making the cyanine dye more likely to form an aggregate, 1 It is preferable that the nitrogen atom bonded to V is the most distant position. 2B is a substituent, V to the naphthalene ring 2B The bonding position of R is not particularly limited. From the viewpoint of making the cyanine dye more likely to form an aggregate, 2 It is preferable that the nitrogen atom bonded to the nitrogen atom be the farthest position.

[0138] From the viewpoint that the cyanine dye can more easily form an aggregate, Cy is more preferably an anion moiety represented by the following formula 4.

[0139] [ka]

[0140] In equation 4, Y 1 and Y 2 are each independently 3 R 4 -, -O-, -S-, -Se-, or -NR 5 - stands for R 3 , R 4 , and R 5 R each independently represents a hydrogen atom, an aliphatic group, or an aromatic ring group. 3 and R 4 may be bonded to each other to form a ring. 1 and A 2 each independently represents a nonmetallic atomic group forming an aromatic ring or an aromatic heterocycle. 2 each independently represents a methine chain consisting of one, two or three methine groups; L 2 R has no substituents. 6 and R 7 R each independently represents a hydrogen atom or an aliphatic group. 6 and R 7 may be linked together to form a ring. 8 is expressed by the following formula A. -S A -T A Formula A In formula A, S A is a single bond, an alkylene group, an alkenylene group, an alkynylene group, -O-, -S-, -NR L1 -, -C(=O)-, -C(=O)O-, -C(=O)NR L1 -, -S(=O)2-, -OR L2 - or a group formed by combining at least two of these, R L1 each independently represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, or a monovalent heterocyclic group; R L2represents an alkylene group, an arylene group, or a divalent heterocyclic group; T A represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, a monovalent heterocyclic group, a cyano group, a hydroxyl group, a formyl group, a carboxy group, an amino group, a thiol group, a sulfo group, a phosphoryl group, a boryl group, a vinyl group, an ethynyl group, a trialkylsilyl group, or a trialkoxysilyl group.

[0141] In formula 4, R 1 , R 2 , R 3 , R 4 , R 5 , Y 1 , and Y 2 is R in Equation 3 1 , R 2 , R 3 , R 4 , R 5 , Y 1 , and Y 2 is synonymous with.

[0142] L 2 each independently represents a methine chain consisting of 1, 2 or 3 methine groups. 2 are preferably each independently a methine chain consisting of one or two methine groups.

[0143] Two L's 2 may be the same or different from each other, but from the viewpoint of ease of production, it is preferable that they are the same.

[0144] R 6 and R 7 R each independently represents a hydrogen atom or an aliphatic group. 6 and R 7 R is preferably a hydrogen atom or an aliphatic group, and is preferably linked to each other to form a ring. 6 and R 7 The ring formed by linking together is preferably a 5-membered aliphatic ring or a 6-membered aliphatic ring. 6 and R 7 -R 6 R 7Examples of - include -CH2CH2- and -CH2C(Z)2-CH2-. Z is preferably a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, more preferably a hydrogen atom or a methyl group. Two Zs may be bonded to form a ring structure.

[0145] R 8 represents a substituent represented by formula A. Preferred embodiments of the substituent represented by formula A are as described above.

[0146] Below, in formula 1, L 1 Specific examples of basic nucleus 1 and basic nucleus 2 bonded to methine chains represented by the formula are shown below. In formula 1, for convenience, basic nucleus 1 is described as a cationic structure in which the nitrogen atom is cationic, and basic nucleus 2 is described as a neutral structure in which the nitrogen atom is not charged. Since the nitrogen atom contained in basic nucleus 1 and the nitrogen atom contained in basic nucleus 2 are connected by a conjugated carbon chain, it is considered that electrons are actually delocalized. Therefore, in formula 1, basic nucleus 1 can be described as a neutral structure and basic nucleus 2 can be described as a cationic structure. In the following specific examples, all are described as cationic structures, but in the dye compound represented by formula 1, when one basic nucleus is a cationic structure, the other basic nucleus is described as a neutral structure. Note that basic nucleus 1 and basic nucleus 2 are not limited to the following specific examples. In the following specific examples, the wavy line parts each independently represent L in formula 1. 1 represents the bonding position with

[0147] [ka]

[0148] [ka]

[0149] [ka]

[0150] In Cy, from the viewpoint of ease of production, it is preferable that basic nucleus 1 and basic nucleus 2 have the same structure. Here, "basic nucleus 1 and basic nucleus 2 have the same structure" means that the constituent atoms are the same and the skeleton is the same. As described above, even when basic nucleus 1 and basic nucleus 2 have the same structure, one is described as a cationic structure and the other is described as a neutral structure in the structural formula.

[0151] The basic nucleus 1 and the basic nucleus 2 are preferably TA1 to TA13, TA16, TA28, TA29, or TA31 to TA36, from the viewpoint that the cyanine dye is more likely to form an aggregate.

[0152] [X 1 ] X 1 represents an organic cation represented by the following formula 2-1, 2-2, or 2-3, or an organic cation having a structure represented by formula 2-4.

[0153] <Formula 2-1>

[0154] [ka]

[0155] In formula 2-1, A 11 and A 12 Each independently represents a nitrogen atom or a phosphorus atom. 11 R each independently represents a divalent linking group. 1a , R 1b , R 1c , R 1d , E 11 , and E 12 Each independently represents an aliphatic group or an aromatic group. 1a , R 1b , R 1c , and R 1d may be bonded to each other to form a ring. m1 is an integer of 1 or more.

[0156] A 11 and A12 Each independently represents a nitrogen atom or a phosphorus atom. 11 and A 12 is preferably a nitrogen atom.

[0157] A 11 and A 12 may be the same or different from each other, but from the viewpoint of ease of production, it is preferable that they are the same.

[0158] B 11 Each of B independently represents a divalent linking group. 11 The divalent linking group represented by the formula (I) is preferably a group having 2 or more carbon atoms, and more preferably a group having 2 to 8 carbon atoms. When the number of carbon atoms is 2 or more, the molecular structure becomes more flexible, and it is presumed that the effect of linking the cyanine dyes together at positions where they can appropriately form an aggregate is high. As a result, the cyanine dyes tend to easily form aggregates, and the infrared absorbing ability tends to be maintained for a long period of time.

[0159] B 11 Examples of the divalent linking group represented by the formula (1) include an alkylene group having 1 to 30 carbon atoms, an arylene group having 6 to 30 carbon atoms, a heterocyclic linking group, -CH=CH-, -O-, -S-, -C(=O)-, -COO-, -NR-, -CONR-, -OCO-, -SO-, -SO2-, and linking groups formed by linking two or more of these. R represents a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group.

[0160] Among them, B 11 The divalent linking group represented by the following formula is preferably an alkylene group. The number of carbon atoms in the alkylene group is preferably 2 to 20, and more preferably 2 to 15. The alkylene group is preferably a linear alkylene group.

[0161] R 1a , R 1b , R 1c , R 1d , E 11 , and E 12each independently represents an aliphatic group or an aromatic group.

[0162] Aliphatic groups include alkyl groups, alkenyl groups, alkynyl groups and aralkyl groups. Aromatic groups include aryl groups.

[0163] Among them, R 1a , R 1b , R 1c , and R 1d is preferably an alkyl group. The alkyl group preferably has 1 to 10 carbon atoms, and more preferably has 1 to 6 carbon atoms.

[0164] Also, E 11 and E 12 are each independently preferably an alkyl group or an aryl group. The number of carbon atoms in the alkyl group is preferably 1 to 10, and more preferably 1 to 6. The aryl group is preferably a phenyl group.

[0165] m1 is an integer of 1 or more. m1 is preferably an integer of 1 to 3, and more preferably 1 or 2.

[0166] Among them, the organic cation represented by formula 2-1 is A 11 and A 12 is a nitrogen atom, and B 11 is an alkylene group, and R 1a , R 1b , R 1c and R 1d is an alkyl group, and E 11 and E 12 More preferred is an organic cation in which the alkyl group is an alkyl group.

[0167] Specific examples of the organic cation represented by formula 2-1 are shown below, but the organic cation represented by formula 2-1 is not limited to the following specific examples. Note that Me represents a methyl group, Et represents an ethyl group, and Ph represents a phenyl group.

[0168] [ka]

[0169] <Formula 2-2>

[0170] [ka]

[0171] In formula 2-2, A 21 , A 22 , and A 23 Each independently represents a nitrogen atom or a phosphorus atom. 21 and B. 22 R each independently represents a divalent linking group. 2a and R 2b Each independently represents an aliphatic group or an aromatic group. m2 is an integer of 0 or more. G 21 A 21 It represents a group of non-metallic atoms forming an aromatic ring containing G 22 A 23 represents a group of non-metallic atoms forming an aromatic ring containing

[0172] A 21 , A 22 , and A 23 Each independently represents a nitrogen atom or a phosphorus atom. 21 , A 22 , and A 23 is preferably a nitrogen atom.

[0173] A 21 , A 22 , and A 23 may be the same or different from each other, but from the viewpoint of ease of production, it is preferable that they are the same.

[0174] B 21 and B. 22 Each of B independently represents a divalent linking group. 21 and B. 22The divalent linking group represented by the formula (I) is preferably a group having 2 or more carbon atoms, and more preferably a group having 2 to 8 carbon atoms. When the number of carbon atoms is 2 or more, the molecular structure becomes more flexible, and it is presumed that the effect of linking the cyanine dyes together at positions where they can appropriately form an aggregate is high. As a result, the cyanine dyes tend to easily form aggregates, and the infrared absorbing ability tends to be maintained for a long period of time.

[0175] B 21 and B. 22 Examples of the divalent linking group represented by the formula (1) include an alkylene group having 1 to 30 carbon atoms, an arylene group having 6 to 30 carbon atoms, a heterocyclic linking group, -CH=CH-, -O-, -S-, -C(=O)-, -COO-, -NR-, -CONR-, -OCO-, -SO-, -SO2-, and linking groups formed by linking two or more of these. R represents a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group.

[0176] Among them, B 21 and B. 22 Each of the divalent linking groups represented by the following formula (I) is preferably an alkylene group. The number of carbon atoms in the alkylene group is preferably 2 to 20, and more preferably 2 to 15. The alkylene group is preferably a linear alkylene group.

[0177] R 2a and R 2b each independently represents an aliphatic group or an aromatic group.

[0178] R 2a and R 2b Examples of the aliphatic group represented by the formula (I) include an alkyl group, an alkenyl group, an alkynyl group, and an aralkyl group. Examples of the aromatic group include an aryl group.

[0179] Among them, R 2a and R 2b are each independently preferably an alkyl group. The alkyl group preferably has 1 to 10 carbon atoms, and more preferably has 1 to 6 carbon atoms.

[0180] m2 is an integer of 0 or more. It is preferable that m2 is an integer of 0 to 2.

[0181] G 21 A 21 It represents a group of non-metallic atoms forming an aromatic ring containing G 22 A 23 A represents a group of non-metallic atoms forming an aromatic ring containing 21 The aromatic ring containing A in the ring is preferably a pyridine ring, an imidazole ring, an oxazole ring, or a thiazole ring. 21 The aromatic ring containing A may be condensed with another ring (an aliphatic ring, an aromatic ring, or a heterocyclic ring). 23 The aromatic ring containing A in the ring is preferably a pyridine ring, an imidazole ring, an oxazole ring, or a thiazole ring. 23 The aromatic ring containing the following may be condensed with another ring (an aliphatic ring, an aromatic ring, or a heterocyclic ring).

[0182] Among them, the organic cation represented by formula 2-2 is A 21 , A 22 and A 23 is a nitrogen atom, and B 21 and B. 22 are each independently an alkylene group, m2 is 0 or 1, and G 21 and G 22 It is more preferable that is a pyridine ring, an imidazole ring, an oxazole ring, or a thiazole ring.

[0183] Specific examples of the organic cation represented by formula 2-2 are shown below, but the organic cation represented by formula 2-2 is not limited to the following specific examples, in which Me represents a methyl group.

[0184] [ka]

[0185] <Formula 2-3>

[0186] [ka]

[0187] In formula 2-3, A 31 and A 32 Each independently represents a nitrogen atom or a phosphorus atom. 31 R represents a divalent linking group. 3a and R 3b Each independently represents an aliphatic group or an aromatic group. 31 A 31 It represents a group of non-metallic atoms forming an aromatic ring containing G 32 A 32 represents a group of non-metallic atoms forming an aromatic ring containing

[0188] A 31 and A 32 Each independently represents a nitrogen atom or a phosphorus atom. 31 and A 32 is preferably a nitrogen atom.

[0189] A 31 and A 32 may be the same or different from each other, but from the viewpoint of ease of production, it is preferable that they are the same.

[0190] B 31 represents a divalent linking group. 31 The divalent linking group represented by the following formula (1) preferably has 2 or more carbon atoms, and more preferably has 2 to 8 carbon atoms. When the divalent linking group has 2 or more carbon atoms, the association formed between the cyanine dyes tends to be held at an appropriate position, and infrared absorbing ability tends to be maintained for a long period of time.

[0191] B 31Examples of the divalent linking group represented by the formula (1) include an alkylene group having 1 to 30 carbon atoms, an arylene group having 6 to 30 carbon atoms, a heterocyclic linking group, -CH=CH-, -O-, -S-, -C(=O)-, -COO-, -NR-, -CONR-, -OCO-, -SO-, -SO2-, and linking groups formed by linking two or more of these. R represents a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group.

[0192] Among them, B 31 The divalent linking group represented by the following formula is preferably an alkylene group. The number of carbon atoms in the alkylene group is preferably 2 to 20, and more preferably 2 to 15. The alkylene group is preferably a linear alkylene group.

[0193] R 3a and R 3b each independently represents an aliphatic group or an aromatic group.

[0194] Aliphatic groups include alkyl groups, alkenyl groups, alkynyl groups and aralkyl groups. Aromatic groups include aryl groups.

[0195] Among them, R 3a and R 3b are each independently preferably an alkyl group. The alkyl group preferably has 1 to 10 carbon atoms, and more preferably has 1 to 6 carbon atoms.

[0196] G 31 A 31 It represents a group of non-metallic atoms forming an aromatic ring containing G 32 A 32 A represents a group of non-metallic atoms forming an aromatic ring containing 31 The aromatic ring containing A in the ring is preferably a pyridine ring. 31 The aromatic ring containing A may be condensed with another ring (an aliphatic ring, an aromatic ring, or a heterocyclic ring). 32 The aromatic ring containing A in the ring is preferably a pyridine ring. 32The aromatic ring containing the following may be condensed with another ring (an aliphatic ring, an aromatic ring, or a heterocyclic ring).

[0197] The organic cation represented by formula 2-3 is A 31 and A 32 is a nitrogen atom, and B 31 is an alkylene group, and R 3a and R 3b are each independently an alkyl group; G 31 and G 32 More preferred is an organic cation in which the ring is a pyridine ring.

[0198] Specific examples of the organic cation represented by formula 2-3 are shown below, but the organic cation represented by formula 2-3 is not limited to the following specific examples.

[0199] [ka]

[0200] <Formula 2-4>

[0201] [ka]

[0202] In formula 2-4, A 41 each independently represents a nitrogen atom or a phosphorus atom. 41 R each independently represents a single bond or a divalent linking group. 4a , R 4b and R 4c Each independently represents an aliphatic group or an aromatic group. 41 and E 42 R each independently represents a single bond or an aliphatic group. 4a , R 4b and R 4c One of them is E 41 Or E 42 may be bonded to form a ring. m4 is an integer of 2 or more.

[0203] The organic cation having the structure represented by formula 2-4 has a flexible molecular structure and the cationic moieties are regularly arranged, so it is considered that the cyanine dyes are regularly arranged at appropriate positions to form aggregates, which tends to maintain infrared absorption ability for a long period of time.

[0204] A 41 Each independently represents a nitrogen atom or a phosphorus atom. 41 is preferably a nitrogen atom.

[0205] B 41 Each of B independently represents a single bond or a divalent linking group. 41 Examples of the divalent linking group represented by the formula (1) include an alkylene group having 1 to 30 carbon atoms, an arylene group having 6 to 30 carbon atoms, a heterocyclic linking group, -CH=CH-, -O-, -S-, -C(=O)-, -COO-, -NR-, -CONR-, -OCO-, -SO-, -SO2-, and linking groups formed by linking two or more of these. R represents a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group.

[0206] Among them, B 41 The divalent linking group represented by the following formula is preferably an alkylene group. The number of carbon atoms in the alkylene group is preferably 1 to 6, and more preferably 1 to 4. The alkylene group is preferably a linear alkylene group.

[0207] R 4a , R 4b and R 4c each independently represents an aliphatic group or an aromatic group.

[0208] Aliphatic groups include alkyl groups, alkenyl groups, alkynyl groups and aralkyl groups. Aromatic groups include aryl groups.

[0209] Among them, R 4a , R 4b and R 4care each independently preferably an alkyl group. The alkyl group preferably has 1 to 6 carbon atoms, and more preferably has 1 to 4 carbon atoms.

[0210] E 41 and E 42 each independently represents a single bond or an aliphatic group.

[0211] Also, E 11 and E 12 are each preferably independently a single bond or an alkyl group. The number of carbon atoms in the alkyl group is preferably 1 to 6, and more preferably 1 to 4. The aryl group is preferably a phenyl group.

[0212] m4 is an integer of 2 or more. m4 is preferably an integer of 50 to 3,000, and more preferably 100 to 2,000.

[0213] Among them, the organic cation having the structure represented by formula 2-4 is A 41 is a nitrogen atom, and R 4a , R 4b and R 4c One of them is E 41 Or E 42 More preferred is an organic cation which is bonded to form a ring.

[0214] Specific examples of organic cations having the structure represented by formula 2-4 are shown below. X 1 The organic cation represented by the formula (I) is not limited to the following specific examples. In addition, Me represents a methyl group, and m4 has the same meaning as m4 in formula 2-4.

[0215] [ka]

[0216] X 1is preferably an organic cation represented by formula 2-1 or an organic cation having a structure represented by formula 2-4. It is believed that the aggregate formed by the cyanine dye is held in an appropriate position for a long period of time by the organic cation represented by formula 2-1 or the organic cation having a structure represented by formula 2-4. 1 When is an organic cation represented by formula 2-1 or an organic cation having a structure represented by formula 2-4, the invisibility is excellent and the infrared absorbing ability is maintained for a longer period. [n] n is not 0 and represents the number necessary to neutralize the charge. For example, when the anionic portion is a monovalent anion and the organic cation is a divalent cation, n is 0.5.

[0217] Specific examples of the dye compound represented by formula 1 are shown below. However, the dye compound represented by formula 1 in the present disclosure is not limited to the following specific examples.

[0218] [ka]

[0219] [ka]

[0220] The content of the dye compound represented by formula 1 is preferably 0.3% by mass to 3% by mass, and more preferably 0.5% by mass to 1.0% by mass, relative to the total amount of the ink.

[0221] <Dispersant> The inks of the present disclosure include at least one dispersant, which is a polymer that contains acidic functional groups and ethylene oxide chains.

[0222] The dispersant may be a low molecular weight compound having a molecular weight of less than 1000, or may be a high molecular weight compound (i.e., a polymer) having a molecular weight of 1000 or more. In the case of a low molecular weight compound, the molecular weight can be calculated from the type and number of atoms constituting the compound. In the case of a high molecular weight compound, the molecular weight is expressed as a weight average molecular weight, as described below.

[0223] From the viewpoint of enhancing hydrophobic interaction with the dye compound represented by formula 1, the dispersant is preferably a polymer.

[0224] When the dispersant contains an acidic functional group, the dye compound represented by formula 1 is likely to transition from a state in which it is slightly dissolved in the dispersion medium (water and water-soluble organic solvent) to a state in which the dye compound represented by formula 1 forms an aggregate. In addition, when the dispersant contains an ethylene oxide chain, it is considered that the formed aggregate is stabilized by the hydrophobic interaction between the ethylene oxide chain and the dye compound represented by formula 1. Examples of the acidic functional group contained in the dispersant include a carboxy group, a sulfo group, a phosphonic acid group, a phosphoric acid group, and a sulfonamide group.

[0225] In the present disclosure, the term "acidic functional group" encompasses both an unneutralized acidic functional group (e.g., a carboxy group) and a neutralized acidic functional group (e.g., a salt of a carboxy group (e.g., -C(=O)ONa)).

[0226] The neutralized acidic functional group is preferably a -C(=O)OM group (wherein M represents an alkali metal, an ammonium ion, or an organic cation). Examples of the organic cation include alkylammonium cations having 1 to 10 carbon atoms, hydroxy-substituted alkylammonium cations having 1 to 10 carbon atoms, carboxy-substituted alkylammonium cations having 2 to 10 carbon atoms, and organic cations having 2 to 10 alkyleneimine units having 2 to 4 carbon atoms.

[0227] The non-neutralized acidic functional group is preferably a carboxy group (-C(=O)OH group).

[0228] The acidic functional group can be neutralized by reacting an unneutralized dispersant with a base (hereinafter also referred to as a "neutralizing base").

[0229] Examples of the neutralizing base include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; ammonia; and organic amines such as dimethylethanolamine and diisopropylethylamine.

[0230] The repeat number of the ethylene oxide chain contained in the dispersant is preferably 3 or more, and more preferably 5 or more, from the viewpoint of enhancing the hydrophobic interaction with the dye compound represented by Formula 1. The upper limit of the repeat number is, for example, 50.

[0231] Among these, the dispersant is preferably a polymer containing a structural unit derived from at least one selected from the group consisting of styrene and styrene derivatives, and more preferably a polymer containing a structural unit derived from styrene.

[0232] The aggregate is further stabilized by π-π interaction between the dye compound represented by formula 1 and at least one structural unit derived from styrene and styrene derivatives.

[0233] Examples of styrene derivatives include alkyl-substituted styrenes such as α-methylstyrene, 4-methylstyrene, 2-methylstyrene, 3-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, and 4-ethylstyrene; halogen-substituted styrenes such as 2-chlorostyrene, 3-chlorostyrene, and 4-chlorostyrene; fluorine-substituted styrenes such as 4-fluorostyrene and 2,5-difluorostyrene; and vinylnaphthalene.

[0234] From the viewpoint of further stabilizing the aggregate, the content of the structural unit derived from at least one selected from the group consisting of styrene and styrene derivatives is preferably 1 mol % to 60 mol %, and more preferably 1 mol % to 50 mol %, based on the total amount of the dispersant.

[0235] When the structural unit derived from at least one selected from the group consisting of styrene and styrene derivatives is 60 mol % or less, aggregation between the pigments is suppressed and the aggregate tends to be stabilized. On the other hand, when the structural unit is 1 mol % or more, the aggregate is further stabilized by π-π interaction with the colorant compound represented by formula 1.

[0236] From the viewpoint of facilitating the formation of aggregates, the acid value of the dispersant is preferably 20 mgKOH / g or more, more preferably 30 mgKOH / g or more. From the viewpoint of dispersion stability, the upper limit of the acid value of the dispersant is preferably 100 mgKOH / g or more.

[0237] The dispersant may be a commercially available product. Commercially available products include, for example, SOLSPERSE41000, DISPERBYK-190, DISPERBYK-191, DISPERBYK-180, DISPERBYK-187, DISPERBYK-194, SOLSPERSE54000, and SOLSPERSE55000.

[0238] When the dispersant is a polymer, the weight average molecular weight is preferably from 3,000 to 200,000, and more preferably from 5,000 to 100,000.

[0239] In the present disclosure, the weight average molecular weight (Mw) is measured by gel permeation chromatography (GPC). GPC is performed using HLC-8220GPC (manufactured by Tosoh Corporation), with three columns (TSKgel SuperHZM-H, TSKgel SuperHZ4000, and TSKgel SuperHZ2000, all of which are product names manufactured by Tosoh Corporation) connected in series, and THF (tetrahydrofuran) as the eluent. The conditions are as follows: sample concentration 0.45% by mass, flow rate 0.35 ml / min, sample injection amount 10 μL, measurement temperature 40° C., and a differential refractive index detector. In addition, the calibration curve is created from eight samples of "Standard sample TSK standard, polystyrene" manufactured by Tosoh Corporation: "F-40", "F-20", "F-4", "F-1", "A-5000", "A-2500", "A-1000", and "n-propylbenzene".

[0240] In the ink of the present disclosure, the mass ratio of the content of the dispersant to the content of the dye compound represented by formula 1 (dispersant / dye compound) is preferably 0.1 to 3, more preferably 0.2 to 2, and even more preferably 0.3 to 1.5.

[0241] <Water-soluble organic solvents, water> The inks of the present disclosure comprise at least one water-soluble organic solvent and water. In the present disclosure, "water-soluble" means the property of dissolving 1 g or more in 100 g of water at 25°C.

[0242] Specific examples of the water-soluble organic solvent are as follows: Alcohol (e.g., methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, pentanol, hexanol, cyclohexanol, benzyl alcohol, etc.), 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, 2-methylpropanediol, etc.). Polyhydric alcohol ethers (e.g., ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, tripropylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, ethylene glycol (ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, ethylene glycol monophenyl ether, propylene glycol monophenyl ether, etc.).

[0243] From the viewpoint of preventing the ink from drying, the water-soluble organic solvent preferably has a boiling point of at least 100° C. The boiling point is the value at atmospheric pressure (101.325 kPa).

[0244] From the viewpoint of containing fewer impurities, the water is preferably distilled water, ion-exchanged water, ion-exchanged distilled water, or pure water.

[0245] The SP value of the mixed solvent consisting of water and a water-soluble organic solvent is 40.0MPa. 1 / 2 It is preferable that the pressure is 41.5MPa or more. 1 / 2 The upper limit of the SP value of the mixed solvent is not particularly limited, and is, for example, 47.0 MPa. 1 / 2 It is.

[0246] Water and water-soluble organic solvents are present as dispersion media in the inks of the present disclosure. The SP value of the mixed solvent is 40.0MPa. 1 / 2 If the amount is more than this, the dye compound represented by formula 1 is likely to transition from a state in which it is slightly dissolved in the dispersion medium (water and water-soluble organic solvent) to a state in which it forms an aggregate.

[0247] The SP value of the mixed solvent of water and water-soluble organic solvent contained in the ink is calculated by the following method, specifying the type of water-soluble organic solvent contained in the ink, and the contents of water and water-soluble organic solvent.

[0248] In the present disclosure, the SP value means the Hansen solubility parameter, which is a solubility parameter introduced by Hildebrand, divided into three components, a dispersion term δd, a polar term δp, and a hydrogen bond term δh, and expressed in a three-dimensional space.

[0249] The SP value δ is a value calculated using the following formula E. SP value δ [MPa 1 / 2 ]=(δd 2 +δp 2 +δh 2 ) 1 / 2 …(E)

[0250] The dispersion term δd, the polar term δp, and the hydrogen bond term δh are calculated using HSPiP (version 4.1.07) software.

[0251] The SP value of the mixed solvent is calculated using the following method. First, the weighted average values ​​of the dispersion term, polarity term, and hydrogen bond term of the mixed solvent contained in the ink are calculated as δd, δp, and δh. Then, the SP value is calculated using the above formula E based on the calculated δd, δp, and δh.

[0252] Δd is calculated using the following formula B1: In formula B1, Δdm represents the variance term of m types of components (m is an integer of 1 or more) in the mixed solvent, and Wm represents the content (mass %) of the m types of components relative to the total amount of ink. δd=ΣδdmWm / ΣWm … (B1)

[0253] Similarly, δp and δh are calculated by the following formulas B2 and B3. δp=ΣδpmWm / ΣWm … (B2) δh=ΣδhmWm / ΣWm … (B3) In formula B2, Δpm represents the polarity term of m-th component (m is an integer of 1 or more) in the mixed solvent. In formula B3, Δhm represents the hydrogen bond term of m-th component (m represents an integer of 1 or more) in the mixed solvent.

[0254] The components in the mixed solvent are water and the water-soluble organic solvent. When there are two types of water-soluble organic solvents, the mixed solvent will have three components (water and two types of water-soluble organic solvents).

[0255] The SP value of water-soluble organic solvent is A [MPa 1 / 2 and the proportion of the water-soluble organic solvent to the total content of water and the water-soluble organic solvent is B mass %, it is preferable that A and B satisfy the following formula T1. 10≦B≦1.6×A-7 …(T1)

[0256] In formula T1, when B is 10 or more, the aggregate is more stabilized and the infrared absorbing ability is maintained for a longer period than before. In formula T1, when B is "1.6 x A-7" ​​or less, the invisibility is excellent.

[0257] From the viewpoint of maintaining the infrared absorbing ability for a longer period of time, it is more preferable that A and B satisfy the following formula T2. 10≦B≦1.6×A-12 …(T2)

[0258] The SP value of the water-soluble organic solvent (i.e., A above) is 17 MPa1 / 2 ~40MPa 1 / 2 Preferably, the pressure is 20 MPa. 1 / 2 ~40MPa 1 / 2 It is more preferable that:

[0259] Specific examples of the SP values ​​of water-soluble organic solvents are as follows: Ethylene glycol monohexyl ether: 20.3MPa 1 / 2 Diethylene glycol monoethyl ether: 22.2MPa 1 / 2 1,3-Butanediol: 27.8MPa 1 / 2 Propylene glycol: 29.1MPa 1 / 2 Ethylene glycol monobutyl ether: 20.8MPa 1 / 2 Ethylene glycol monopropyl ether: 22.7MPa 1 / 2 Tripropylene glycol monomethyl ether: 19.3MPa 1 / 2 Dipropylene glycol methyl ether: 20.0MPa 1 / 2 Propylene glycol monomethyl ether: 20.4MPa 1 / 2 Propylene glycol monopropyl ether: 19.6MPa 1 / 2 Propylene glycol monobutyl ether: 18.4MPa 1 / 2 Diethylene glycol monobutyl ether: 20.4MPa 1 / 2 Diethylene glycol diethyl ether: 17.8MPa 1 / 2

[0260] When two or more water-soluble organic solvents are used, the SP value of the water-soluble organic solvents is calculated in the same manner as the SP value of the mixed solvent.

[0261] The proportion of the water-soluble organic solvent to the total content of water and the water-soluble organic solvent (that is, the above B) is preferably 15% by mass to 35% by mass, and more preferably 17% by mass to 30% by mass. When the content of B is 15% by mass or more, the ejection properties are good, whereas when the content of B is 35% by mass or less, the aggregate is more stable and the infrared absorbing ability is maintained for a longer period than before.

[0262] The water content is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more, based on the total amount of the ink. The upper limit of the water content is, for example, 85% by mass.

[0263] The ink of the present disclosure may contain a surfactant, but from the viewpoint of ensuring hydrophobic interaction between the dispersant and the dye compound represented by formula 1, it is preferable that the ink does not contain a surfactant.

[0264] The content of the surfactant is preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.1% by mass or less, based on the total amount of the ink.

[0265] The inks of the present disclosure may contain additives known for use in inks.

[0266] Examples of additives include surfactants, resins, drying inhibitors (in other words, wetting agents), discoloration inhibitors, emulsion stabilizers, penetration enhancers, preservatives, fungicides, pH adjusters, surface tension adjusters, antifoaming agents, viscosity adjusters, rust inhibitors, and chelating agents.

[0267] The ink of the present disclosure may contain other dyes in addition to the dye compound represented by formula 1. The other dyes are not particularly limited, and any dye known in the field of inks can be used.

[0268] From the standpoint of invisibility, the content of other dyes is preferably 0.1% by mass or less, and more preferably 0.05% by mass or less, based on the total mass of the ink.

[0269] (Physical Properties) From the viewpoint of ejection stability, the pH of the ink is preferably 7 to 10, and more preferably 7.5 to 9.5. The pH of the ink is measured at 25° C. using a pH meter, for example, a pH meter manufactured by Toa DKK Corporation (model number "HM-31").

[0270] The viscosity of the ink is preferably 0.5 mPa·s to 30 mPa·s, more preferably 2 mPa·s to 20 mPa·s, preferably 2 mPa·s to 15 mPa·s, and even more preferably 3 mPa·s to 10 mPa·s. The viscosity of the ink is measured at 25°C using a viscometer, for example, a TV-22 viscometer manufactured by Toki Sangyo Co., Ltd.

[0271] The surface tension of the ink is preferably 60 mN / m or less, more preferably 20 mN / m to 50 mN / m, and even more preferably 25 mN / m to 45 mN / m. The surface tension of the ink is measured at 25° C. using a surface tensiometer, for example, an automatic surface tensiometer (product name "CBVP-Z") manufactured by Kyowa Interface Science Co., Ltd., by a plate method.

[0272] <<Inkjet recording method>> The inkjet recording method of the present disclosure includes a step of applying the ink onto a substrate by an inkjet recording method.

[0273] The substrate is not particularly limited as long as it is capable of forming an image, and examples thereof include paper, cloth, wood, a metal plate, and a resin film. The substrate may be previously subjected to a surface treatment.

[0274] Paper includes pure white rolling paper, kraft paper, paperboard, fine paper, OCR paper, art paper, coated paper, mirror coated paper, condenser paper, and wax paper.

[0275] Examples of resin films include polyester film, polypropylene (PP) film, cellophane, acetate film, polycarbonate (PC) film, acrylic resin film, polyethylene terephthalate (PET) film, biaxially oriented polystyrene (OPS) film, biaxially oriented polypropylene (OPP) film, biaxially oriented nylon (ONy) film, polyvinyl chloride (PVC) film, polyethylene (PE) film, and triacetate (TAC) film.

[0276] The inkjet recording method is not particularly limited as long as it is a method capable of recording an image, and may be any of the well-known methods, 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 to eject the ink using radiation pressure, and a thermal inkjet (Bubble Jet (registered trademark)) method in which ink is heated to form bubbles and the resulting pressure is utilized.

[0277] As an inkjet recording method, in particular, the method described in JP-A-54-59936 can be effectively utilized, in which ink undergoes a sudden change in volume when subjected to the action of thermal energy, and the ink is ejected from a nozzle by the force resulting from this change in state.

[0278] In addition, for the inkjet recording method, the method described in paragraphs 0093 to 0105 of JP-A No. 2003-306623 can also be referred to.

[0279] Inkjet heads used in inkjet recording methods include a shuttle method, in which a short serial head is used and recording is performed while the head is scanned in the width direction of the substrate, and a line method, in which a line head is used in which recording elements are arranged to correspond to the entire area of ​​one side of the substrate.

[0280] In the line method, a pattern can be formed over the entire surface of a substrate by scanning the substrate in a direction intersecting the arrangement direction of the recording elements, and a transport system such as a carriage for scanning a short head is not required.

[0281] Furthermore, since complicated scanning control of the carriage movement and the substrate is no longer necessary and only the substrate moves, a higher printing speed can be achieved compared to the shuttle method.

[0282] From the viewpoint of obtaining a high-definition image, the amount of ink droplets ejected from the inkjet head is preferably from 1 pL (picoliter) to 20 pL, and more preferably from 1.5 pL to 10 pL.

[0283] The inkjet recording method of the present disclosure may include other steps in addition to the step of recording an image on a substrate by an inkjet recording method. For example, the other steps include a step of drying the image after recording the image. In addition, the image recording method of the present disclosure may include a step of irradiating the ink with active energy rays when the ink contains a polymerizable compound. EXAMPLES

[0284] Hereinafter, the present disclosure will be described more specifically with reference to examples. However, the present disclosure is not limited to the following examples as long as it does not depart from the gist of the disclosure.

[0285] Compounds 1 to 5 were synthesized with reference to the examples of International Publication No. 2022 / 049862.

[0286] [ka]

[0287] Compounds 1 to 5 are all dye compounds represented by formula 1, and basic nucleus 1 and basic nucleus 2 have the same structure. 1 , basic nucleus 1 and basic nucleus 2 (referred to as "two basic nuclei in Cy" in the table), and X 1 The following was stated.

[0288] [Table 1]

[0289] <Comparative Compound 1 to Comparative Compound 2> The structures of comparative compounds 1 and 2 are as follows.

[0290] (Comparative compound 1)

[0291] [ka]

[0292] (Comparative compound 2)

[0293] [ka]

[0294] <Ink Preparation> The components were mixed to obtain the compositions shown in Tables 2 to 5. Furthermore, 2.5 g of zirconia beads having a diameter of 0.5 mm were added, and dispersion was carried out for 6 hours using a test tube mixer Se-08 (manufactured by TAITEC Co., Ltd.). After dispersion, the beads were separated using a nylon filter cloth with an aperture of 67 μm to obtain an ink.

[0295] Details of the components other than the coloring matter compounds shown in Tables 2 to 5 are as follows.

[0296] (Dispersant) Dispersant P1: Polymer containing phosphate groups and ethylene oxide chains (product name "SOLSPERSE41000", manufactured by Lubrizol Corporation, solid content concentration 100% by mass), acid value 50 mgKOH / g Dispersant P2: A polymer containing a carboxyl group and an ethylene oxide chain, and a structural unit derived from styrene (product name "DISPERBYK-190", manufactured by BYK, solid content concentration 40% by mass), acid value 10 mg KOH / g Dispersant P3: A polymer containing a carboxyl group and an ethylene oxide chain, and a structural unit derived from styrene (product name "DISPERBYK-191", manufactured by BYK, solid content concentration 98%), acid value 30 mg KOH / g Dispersant P4: A polymer containing a carboxy group and an ethylene oxide chain and a structural unit derived from styrene, synthesized by the following method: The following compounds were prepared as raw material monomers. Styrene: 45 parts by weight Styrene macromonomer (product name "AS-6S", manufactured by Toagosei Co., Ltd.): 20 parts by mass Methacrylic acid: 15 parts by mass Polypropylene glycol monomethacrylate (PO chain repeat number = 9) (product name "Blenmar PP-500", NOF Corporation): 10 parts by mass Poly(ethylene glycol propylene glycol) monomethacrylate (product name "Blenmar 50PEP-300", NOF Corporation): 10 parts by weight 20 parts by mass of methyl ethyl ketone, 10% by mass of the raw material monomers, and 0.03 parts by mass of a chain transfer agent (2-mercaptan ethanol) were placed in a reaction vessel A and mixed. The atmosphere in the reaction vessel A was replaced with nitrogen gas. In addition, 90% by mass of the raw material monomers, 0.27 parts by mass of a chain transfer agent (2-mercaptanethanol), 60 parts by mass of methyl ethyl ketone, and 1.2 parts by mass of 2,2'-azobis(2,4-dimethylvaleronitrile) were placed in a reaction vessel B and mixed. The mixture was added to a dropping device and replaced with nitrogen gas. Reaction vessel A was heated to 65°C, and the mixed liquid in the dropping device was dropped over 3 hours under a nitrogen atmosphere and stirring. After dropping, the mixture was left to stand for 2 hours, and a solution of 0.3 parts by mass of 2,2'-azobis(2,4-dimethylvaleronitrile) dissolved in 5 parts by mass of methyl ethyl ketone was added. The mixture was left to stand for 2 hours at 65°C, and then for another 2 hours at 70°C to obtain a polymer solution. The solvent was dried under reduced pressure, and the polymer was isolated. The isolated polymer was designated as dispersant P4. Dispersant P5: A polymer containing a carboxy group and an ethylene oxide chain and a structural unit derived from styrene, synthesized by the following method: The following compounds were prepared as raw material monomers. Styrene: 30 parts by weight Styrene macromonomer (product name "AS-6S", manufactured by Toagosei Co., Ltd.): 20 parts by mass Methacrylic acid: 30 parts by weight Polypropylene glycol monomethacrylate (PO chain repeat number = 9) (product name "Blenmar PP-500", NOF Corporation): 10 parts by mass Poly(ethylene glycol propylene glycol) monomethacrylate (product name "Blenmar 50PEP-300", NOF Corporation): 10 parts by weight 20 parts by mass of methyl ethyl ketone, 10% by mass of the raw material monomers, and 0.03 parts by mass of a chain transfer agent (2-mercaptan ethanol) were placed in a reaction vessel A and mixed. The atmosphere in the reaction vessel A was replaced with nitrogen gas. In addition, 90% by mass of the raw material monomers, 0.27 parts by mass of a chain transfer agent (2-mercaptanethanol), 60 parts by mass of methyl ethyl ketone, and 1.2 parts by mass of 2,2'-azobis(2,4-dimethylvaleronitrile) were placed in a reaction vessel B and mixed. The mixture was added to a dropping device and replaced with nitrogen gas. Reaction vessel A was heated to 65°C, and the mixed liquid in the dropping device was dropped over 3 hours under a nitrogen atmosphere and stirring. After dropping, the mixture was left to stand for 2 hours, and a solution of 0.3 parts by mass of 2,2'-azobis(2,4-dimethylvaleronitrile) dissolved in 5 parts by mass of methyl ethyl ketone was added. The mixture was left to stand for 2 hours at 65°C, and then for another 2 hours at 70°C to obtain a polymer solution. The solvent was dried under reduced pressure, and the polymer was isolated. The isolated polymer was designated dispersant P5. Dispersant Q1: Polyacrylic acid that does not contain ethylene oxide chains (product name: Aron T-50, manufactured by Toagosei Co., Ltd.) Dispersant Q2: A polymer that does not contain acidic functional groups and contains ethylene oxide chains (product name "DISPERBYK-193", manufactured by BYK, solid content concentration 40% by mass).

[0297] Tables 2 to 5 show the content of structural units derived from at least one selected from the group consisting of styrene and styrene derivatives, contained in the dispersant. The dispersant contents shown in Tables 2 to 5 are the solid content contained in each dispersant.

[0298] (Water-soluble organic solvent) ·PG: Propylene glycol 1,3BD: 1,3-butanediol ·DEGmEE: Diethylene glycol monoethyl ether EGmHE: Ethylene glycol monohexyl ether Tables 2 to 5 show the SP values ​​of water-soluble organic solvents.

[0299] (Surfactant) Acetylene glycol surfactant (product name: Olfin E1010, manufactured by Nissin Chemical Industry Co., Ltd.)

[0300] <Preparation of Image Recording> The prepared ink was filtered using a 5 μm filter. The filtered ink was filled into an ink cartridge attached to an inkjet recording device (water product name "DMP-2850", manufactured by FUJIFILM DIMATIX). OKT104 coated paper (manufactured by Oji Paper Co., Ltd.) was prepared as a substrate. The ink was discharged onto the substrate under conditions of a resolution of 600 dpi, a droplet volume of 10 pL, a nozzle temperature of 25° C., and a dot ratio of 100%, and then dried at 120° C. for 10 seconds using a dryer to obtain a recorded image.

[0301] The obtained image recording was used to evaluate invisibility. The resulting ink was evaluated for dispersibility and long wavelength absorbency by the following methods.

[0302] [Invisibility] The reflectance of the image recording was measured in the wavelength range of 400 nm to 1100 nm using a near infrared visible spectrophotometer V-770 (manufactured by JASCO Corporation) equipped with an integrating sphere unit ISN-923 (manufactured by JASCO Corporation). The K / S value was calculated based on the following formula using the lowest reflectance A (%) among the reflectances for wavelengths of 900 nm or more and the reflectance B (%) for a wavelength of 600 nm. K / S(A)=[{1-(reflectance A / 100)} 2 ) / {2×(reflectance A / 100)} K / S(B)=[{1-(Reflectance B / 100)} 2 ) / {2×(reflectance B / 100)} Invisibility was assessed based on the calculated ratio W of the K / S values. Ratio W={K / S(A)}÷{K / S(B)} The evaluation criteria are as follows: A: Ratio W is 55 or more. B: The ratio W is 45 or more and less than 55. C: The ratio W is 30 or more and less than 45. D: The ratio W is less than 30.

[0303] [Dispersibility] The prepared ink was diluted 1000 times with ultrapure water. The absorbance of the diluted ink was measured in the wavelength range of 400 nm to 1100 nm using an infrared-visible spectrophotometer (product name "V-770", manufactured by JASCO Corporation). Dispersibility was evaluated based on the highest absorbance among the absorbances at wavelengths of 900 nm or more. The evaluation criteria are as follows: A: The absorbance is 2.00 or more. B: The absorbance is 1.50 or more and less than 2.00. C: The absorbance is 0.95 or more and less than 1.50. D: The absorbance is less than 0.95.

[0304] [Long wavelength absorption] The prepared ink was diluted 1000 times with ultrapure water. The absorbance of the diluted ink was measured in the wavelength range of 400 nm to 1100 nm using an infrared-visible spectrophotometer (product name "V-770", manufactured by JASCO Corporation). The ratio Y was calculated based on the following formula using the highest absorbance C among the absorbances at wavelengths of 900 nm or more and the absorbance D at a wavelength of 850 nm. Based on the ratio Y, the long wavelength absorbency was evaluated. Ratio Y=(Absorbance C)÷(Absorbance D) The evaluation criteria are as follows: A: The ratio Y is 5.5 or more. B: The ratio Y is 2 or more and less than 5.5. C: The ratio Y is 0.9 or more and less than 2. D: The ratio Y is less than 0.9.

[0305] Tables 2 to 5 show the evaluation results. In Tables 2 to 5, the SP value of the mixed solvent means the SP value of the mixed solvent consisting of water and a water-soluble organic solvent. B means the ratio (mass%) of the water-soluble organic solvent to the total content of water and the water-soluble organic solvent. A means the SP value (MPa 1 / 2 "Dispersant / colorant compound" means the mass ratio of the content of the dispersant to the content of the colorant compound.

[0306] [Table 2] [Table 3]

[0307] [Table 4]

[0308] [Table 5]

[0309] Examples 1 to 22 contain a dye compound represented by formula 1, a dispersant, a water-soluble organic solvent, and water. The dispersant is a polymer containing an acidic functional group and an ethylene oxide chain. It was therefore found that the invisibility was excellent and the infrared absorption ability was maintained for a longer period than in the past.

[0310] In Comparative Examples 1 and 3, no dispersant was included, and it was found that the invisibility, dispersibility, and long wavelength absorption properties were poor. In Comparative Examples 2 and 3, the dye compound represented by formula 1 was not included, and it was found that the invisibility, dispersibility, and long wavelength absorption properties were poor. In Comparative Example 5, the dispersant did not contain an ethylene oxide chain, and it was found that the invisibility, dispersibility, and long wavelength absorption were poor. In Comparative Example 6, the dispersant did not contain an acidic functional group, and it was found that the invisibility, dispersibility, and long wavelength absorption were poor.

[0311] In Example 3, the dispersant was a polymer containing structural units derived from at least one selected from the group consisting of styrene and styrene derivatives, and therefore it was found that the invisibility, dispersibility, and long wavelength absorption were superior to those of Example 1.

[0312] In Example 14, the content of structural units derived from at least one selected from the group consisting of styrene and styrene derivatives was 60 mol % or less relative to the total amount of the dispersant, and therefore it was found that Example 14 had superior invisibility, dispersibility, and long wavelength absorption properties compared to Example 13.

[0313] In Example 21, the SP value of the mixed solvent was 40.0 MPa. 1 / 2 For these reasons, it was found that the invisibility and long wavelength absorbency were superior to those of Example 22.

[0314] In Example 20, since B was 10 or more and B was "1.6 x A-7" ​​or less, it was found that the invisibility was superior to that of Example 21.

[0315] In Example 18, since B was 10 or more and B was "1.6 x A-12" or less, it was found that Example 18 had superior long wavelength absorptivity compared to Example 19.

[0316] In Example 19, the proportion of the water-soluble organic solvent to the total content of water and the water-soluble organic solvent was 15% by mass to 35% by mass, and therefore it was found that Example 19 had superior dispersibility compared to Example 20.

Claims

1. The composition includes a dye compound represented by the following formula 1, a dispersant, a water-soluble organic solvent, and water, The dispersant is a polymer containing acidic functional groups and ethylene oxide chains. 【Chemistry 1】 In formula 1, L １ represents a methine chain consisting of an odd number of methine groups. １ and R ２ Each independently represents an aliphatic group or an aromatic group. １ and T ２ each independently represents a non-metallic atomic group forming an optionally condensed 5- or 6-membered nitrogen-containing heterocycle; Cy represents an anion moiety; X １ represents an organic cation represented by the following formula 2-1, 2-2, or 2-3, or an organic cation having a structure represented by formula 2-4, where n is not 0 and represents a number necessary to neutralize the charge. 【Chemistry 2】 【Chemistry 3】 【Chemistry 4】 【Chemistry 5】 In formula 2-1, A １１ and A １２ each independently represents a nitrogen atom or a phosphorus atom. １１ R each independently represents a divalent linking group. １ａ , R １ｂ , R １ｃ , R １ｄ , E １１ , and E １２ R each independently represents an aliphatic group or an aromatic group. １ａ , R １ｂ , R １ｃ , and R １ｄ may be bonded to each other to form a ring. m1 is an integer of 1 or more. In formula 2-2, A ２１ , A ２２ , and A ２３ each independently represents a nitrogen atom or a phosphorus atom. ２１ and B ２２ R each independently represents a divalent linking group. ２ａ and R ２ｂ Each independently represents an aliphatic group or an aromatic group. m2 is an integer of 0 or more. ２１ A ２１ represents a group of non-metallic atoms forming an aromatic ring containing ２２ A ２３ represents a group of non-metallic atoms forming an aromatic ring containing In formula 2-3, A ３１ and A ３２ each independently represents a nitrogen atom or a phosphorus atom. ３１ represents a divalent linking group. ３ａ and R ３ｂ Each independently represents an aliphatic group or an aromatic group. ３１ A ３１ represents a group of non-metallic atoms forming an aromatic ring containing ３２ A ３２ represents a group of non-metallic atoms forming an aromatic ring containing In formula 2-4, A ４１ each independently represents a nitrogen atom or a phosphorus atom. ４１ R each independently represents a single bond or a divalent linking group. ４ａ , R ４ｂ and R ４ｃ Each independently represents an aliphatic group or an aromatic group. ４１ and E ４２ Each independently represents a single bond or an aliphatic group. ４ａ , R ４ｂ and R ４ｃ One of them is E ４１ Or E ４２ may be bonded to form a ring. m4 is an integer of 2 or more.

2. The ink-jet ink according to claim 1 , wherein the dispersant further comprises a structural unit derived from at least one selected from the group consisting of styrene and styrene derivatives.

3. 3. The ink-jet ink according to claim 2, wherein the content of the structural unit derived from at least one selected from the group consisting of styrene and styrene derivatives is 1 mol % to 60 mol % based on the total amount of the dispersant.

4. 4. The ink-jet ink according to claim 1, wherein a mass ratio of a content of the dispersant to a content of the dye compound represented by formula 1 is 0.1 to 3.

5. The SP value of the mixed solvent consisting of water and the water-soluble organic solvent is 40.0 MPa. １／２ The ink-jet ink according to any one of claims 1 to 3, wherein

6. The SP value of the water-soluble organic solvent is A [MPa １／２ ]year, When the ratio of the water-soluble organic solvent to the total content of the water and the water-soluble organic solvent is B mass%, The ink-jet ink according to any one of claims 1 to 3, wherein A and B satisfy the following formula T1: 10≦B≦1.6×A-7…(T1)

7. The ink-jet ink according to claim 6 , wherein A and B satisfy the following formula T2: 10≦B≦1.6×A-12…(T2)

8. 4. The ink-jet ink according to claim 1, wherein a ratio of the water-soluble organic solvent to a total content of the water and the water-soluble organic solvent is 15% by mass to 35% by mass.

9. The ink-jet ink according to any one of claims 1 to 3, wherein in formula 1, Cy is represented by the following formula 4: 【Chemistry 6】 In formula 4, Y １ and Y ２ are each independently ３ R ４ -, -O-, -S-, -Se-, or -NR ５ - represents. ３ , R ４ , and R ５ R each independently represents a hydrogen atom, an aliphatic group, or an aromatic ring group. ３ and R ４ may be bonded to each other to form a ring. １ and A ２ each independently represents a nonmetallic atomic group forming an aromatic ring or an aromatic heterocycle. ２ each independently represents a methine chain consisting of 1, 2 or 3 methine groups; L ２ has no substituent. ６ and R ７ R each independently represents a hydrogen atom or an aliphatic group. ６ and R ７ may be linked to each other to form a ring. ８ is represented by the following formula A. -S Ａ -T Ａ Formula A In formula A, S Ａ represents a single bond, an alkylene group, an alkenylene group, an alkynylene group, -O-, -S-, -NR Ｌ１ -, -C(=O)-, -C(=O)O-, -C(=O)NR Ｌ１ -, -S(=O) ２ -, -OR Ｌ２ - or a group formed by combining at least two of these, R Ｌ１ each independently represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, or a monovalent heterocyclic group; R Ｌ２ represents an alkylene group, an arylene group, or a divalent heterocyclic group; T Ａ represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, a monovalent heterocyclic group, a cyano group, a hydroxyl group, a formyl group, a carboxy group, an amino group, a thiol group, a sulfo group, a phosphoryl group, a boryl group, a vinyl group, an ethynyl group, a trialkylsilyl group, or a trialkoxysilyl group.

10. An inkjet recording method comprising a step of applying the inkjet ink according to any one of claims 1 to 3 onto a substrate by an inkjet recording system.

Images