JP5591515B2 - Near-infrared absorbing dispersion, near-infrared absorbing ink, and printed matter - Google Patents

Description

  The present invention relates to a near-infrared absorbing dispersion, a near-infrared absorbing ink prepared from the dispersion, and a printed matter using the same.

  Near-infrared absorbing dyes can be used for plasma display panels (PDP), infrared cut films for CCDs and optical filters as heat-shielding films, write-once optical disks (CD-R) and photothermal conversion materials as flash fusion fixing materials, It is used as an information display material as security ink and invisible barcode ink. Security ink uses prepaid carts, cash vouchers, gift certificates, securities based on near infrared (700-1800 nm) detection by utilizing the fact that the obtained image is less colored in the visible region and has a large absorption in the near infrared region. It is an ink for the purpose of preventing forgery such as OCR reading, OCR reading by near infrared detection, position confirmation, device malfunction prevention and the like. In addition to prevention of counterfeiting, it is inconspicuous and can be used as a hidden ink that does not impair the design of the printed matter.

  In particular, as a characteristic characteristic of the near-infrared absorbing dye, there is a high demand for invisibility that it is invisible in addition to having strong absorption in the near-infrared region. At the same time, high fastness is required as a performance required for all dyes.

Examples of the dye having excellent invisibility that hardly absorbs in the wavelength region of 400 nm to 700 nm include cyanine methine dye and its J aggregate. However, a long methine conjugated chain is flexible, so it easily undergoes degradation due to a change in absorption form accompanying isomerization and reaction with heat, oxygen, and a nucleophile, and has low robustness.
As a highly robust near-infrared absorbing dye having a rigid skeleton, there are vanadyl phthalocyanine dye and quaterrylene dye. However, vanadyl phthalocyanine has insufficient invisibility. Further, although quarterrylene has good invisibility in a molecular dispersion state such as a solution, when the concentration is increased, absorption occurs in the visible region due to association, the invisibility is lost, and the use form is limited.
As a pigment that is excellent in invisibility and covers a wide infrared region, there is a diimmonium pigment. However, this dye is easily reduced, has insufficient fastness, and uses are limited.
As described above, there is no near-infrared absorbing dye that satisfies both invisibility and fastness performance at the same time, a material having strong absorption in the near-infrared region and at the same time high invisibility, and sufficient fastness. Development is desired.

  As the near-infrared absorbing ink, an organic solvent type ink in which a dissolving near-infrared absorbing dye is dissolved is known. However, the conventional organic solvent type near-infrared absorbing ink has a problem that the durability of the applied ink is low, and the ink is decomposed in a short period of time and does not absorb and cannot be distinguished. Patent Documents 1 and 2 propose a method using an acrylic binder resin to improve durability and a method of adding an ultraviolet absorber. However, these methods are still insufficient in terms of performance. In addition, since these near infrared absorbing inks use an organic solvent, there are problems in terms of safety and environmental hygiene. Therefore, an aqueous near-infrared absorbing ink is desired.

  On the other hand, Patent Documents 3, 4, 5, and 6 describe examples of water-based near-infrared absorbing paints and inks. However, near-infrared absorbing paints and inks using naphthalocyanine, diimmonium, and croconium-based dyes described in these documents are not sufficient in terms of durability and invisibility.

JP-A-6-248213 JP 7-164729 A JP 2002-187955 A Japanese Patent Laid-Open No. 9-263717 JP 2002-309131 A JP 2002-146254 A

  An object of the present invention is to provide a near-infrared-absorbing fine particle dispersion capable of forming a coating film having high invisibility and near-infrared absorbing ability, and further having high light resistance, a near-infrared absorbing ink using the same, It is to provide an ink jet ink. Furthermore, this invention makes it a subject to provide the printed matter which printed the near-infrared absorption image printed using these inks.

The problems of the present invention have been solved by the following means.
<1> A near-infrared absorbing dispersion liquid in which a near-infrared absorbing compound represented by the following general formula (1) is finely dispersed in a dispersion medium.

(Wherein, R ^1a and R ^1b may be the same or different, and each independently represents an alkyl group, or an alkyl group, an aryl group, a branched alkoxy group, an acyloxy group, an acylamino group, an alkylthio group, a hydroxy group, R ² and R ³ each independently represents a hydrogen atom, a cyano group, an acyl group, an alkyl , or an aryl group or a heteroaryl group which may have a substituent selected from the group consisting of a halogen atom and a cyano group Represents an oxycarbonyl group, an aryloxycarbonyl group, an alkylsulfonyl group, an arylsulfonyl group, a sulfamoyl group, a sulfinyl group, a carboxyl group or a heterocyclic group, at least one of which is an electron-withdrawing group having a Hammett σp value of 0.2 or more There, ^{R 2} and ^{R 3} may be bonded to form a ring .R ⁴ is hydrogen, a Kill group, an aryl group, a heteroaryl group, a substituted boron (substituent of the substituted boron halogen atom, an alkoxy group, an aryloxy group, an alkyl group, an aryl group or a heteroaryl group) or an metal atom, R ^1a , ^{R 1b} and / or ^{R 3} and covalent or may be coordinate bond.)
< 2> The near-infrared absorbing dispersion liquid according to <1>, wherein R ⁴ is the substituted boron.
<3> The near-infrared absorbing dispersion liquid according to <1> or <2>, wherein the dispersion medium is an aqueous solvent.
<4> The near-infrared absorbing dispersion liquid according to any one of <1> to <3>, wherein an average particle diameter of the fine particles is 0.5 μm or less.
<5> The near-infrared absorbing dispersion liquid according to any one of <1> to <4>, wherein the maximum absorption wavelength is 700 nm to 1000 nm.
<6> The near-infrared absorbing dispersion liquid according to any one of <1> to < 4 >, wherein the absorbance at 550 nm is 1/5 or less of the absorbance at the maximum wavelength.

（式中、Ｒ^１ａ及びＲ^１ｂは同じであっても異なっても良く、各々独立にアルキル基、または、アルキル基、アリール基、分岐アルコキシ基、アシルオキシ基、アシルアミノ基、アルキルチオ基、ヒドロキシ基、ハロゲン原子およびシアノ基からなる群から選択される置換基を有してもよいアリール基、または、ヘテロアリール基を表す。Ｒ^２及びＲ^３は各々独立に水素原子、シアノ基、アシル基、アルキルオキシカルボニル基、アリールオキシカルボニル基、アルキルスルホニル基、アリールスルホニル基、スルファモイル基、スルフィニル基、カルボキシル基またはヘテロ環基を表し、少なくとも一方はＨａｍｍｅｔｔのσｐ値が０．２以上の電子吸引性基であり、Ｒ^２及びＲ^３は結合して環を形成しても良い。Ｒ^４は水素原子、アルキル基、アリール基、ヘテロアリール基、置換ホウ素（該置換ホウ素の置換基はハロゲン原子、アルコキシ基、アリールオキシ基、アルキル基、アリール基またはヘテロアリール基である）または金属原子を表し、Ｒ^１ａ、Ｒ^１ｂ及び／又はＲ^３と共有結合もしくは配位結合しても良い。） <7> An ink comprising the near infrared absorbing dispersion liquid according to any one of the above items <1> to <6>.
<8> An ink for ink jet recording comprising the near infrared absorbing dispersion liquid according to any one of the above items <1> to <6>.
<9> A printed matter obtained by printing a near-infrared absorption image using the ink according to <7>.
<10> A printed matter obtained by printing a near-infrared absorption image using the ink for ink jet recording described in <8>.
<11> A method for producing a near-infrared absorbing dispersion, wherein the near-infrared absorbing compound represented by the following general formula (1) is finely dispersed in a dispersion medium. .

(Wherein, R ^1a and R ^1b may be the same or different, and each independently represents an alkyl group, or an alkyl group, an aryl group, a branched alkoxy group, an acyloxy group, an acylamino group, an alkylthio group, a hydroxy group, R ² and R ³ each independently represents a hydrogen atom, a cyano group, an acyl group, an alkyl , or an aryl group or a heteroaryl group which may have a substituent selected from the group consisting of a halogen atom and a cyano group Represents an oxycarbonyl group, an aryloxycarbonyl group, an alkylsulfonyl group, an arylsulfonyl group, a sulfamoyl group, a sulfinyl group, a carboxyl group or a heterocyclic group, at least one of which is an electron-withdrawing group having a Hammett σp value of 0.2 or more There, ^{R 2} and ^{R 3} may be bonded to form a ring .R ⁴ is hydrogen, a Kill group, an aryl group, a heteroaryl group, a substituted boron (substituent of the substituted boron halogen atom, an alkoxy group, an aryloxy group, an alkyl group, an aryl group or a heteroaryl group) or an metal atom, R ^1a , ^{R 1b} and / or ^{R 3} and covalent or may be coordinate bond.)

  The coating film produced using the near-infrared absorbing dispersion liquid of the present invention has high invisibility and near-infrared absorbing ability. Moreover, the near-infrared absorbing dispersion liquid of the present invention has sufficient dispersion stability. Moreover, the near-infrared absorbing dispersion liquid of the present invention has little influence on the environment. Furthermore, a printed matter obtained by printing a near infrared absorption image using an ink containing the dispersion has high invisibility and light resistance.

It is a graph showing the solution absorption spectrum of exemplary compound D-10 and D-28. It is a graph showing the transmission spectrum of aqueous dispersion A-1 and A-4. It is a graph showing the transmission spectrum of aqueous dispersion A-7 and A-8. It is a graph which shows a time-dependent change of the viscosity of aqueous dispersion A-1. It is a graph which shows a time-dependent change of the average particle diameter of aqueous dispersion A-1. It is a graph which shows a time-dependent change of the HPLC purity of aqueous dispersion A-1. It is a graph which shows the reflection spectrum of application | coating sample B-1. It is a graph which shows the reflection spectrum of the inkjet printing sample C-1.

The near-infrared absorbing dispersion liquid of the present invention is characterized by containing fine particles of a near-infrared absorbing compound represented by the general formula (1) in a dispersed state (contained in a fine particle-dispersed state) in a dispersion medium. Other materials may be included. The dispersion medium is preferably an aqueous solvent.
The near-infrared absorbing compound is dispersed (preferably aqueous-dispersed) using a dispersion medium, whereby a highly durable near-infrared absorbing dispersion liquid having excellent dispersion stability and high invisibility can be prepared. .

  Hereinafter, the near-infrared absorbing compound represented by the general formula (1) will be described.

(In the formula, R ^1a and R ^1b may be the same or different and each independently represents an alkyl group, an aryl group or a heteroaryl group. R ² and R ³ each independently represents a hydrogen atom or a substituent. And at least one is an electron-withdrawing group, and R ² and R ³ may combine to form a ring, and R ⁴ represents a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, a substituted boron or a metal atom. And R ^1a , R ^1b and / or R ³ may be covalently bonded or coordinated.)

In general formula (1), the alkyl group represented by R ^1a and R ^1b is preferably 1 to 30 carbon atoms (in the present invention, “A to B” is used to mean “A or more and B or less”. ), More preferably an alkyl group having 1 to 20 carbon atoms, particularly preferably 1 to 10 carbon atoms, such as methyl, ethyl, iso-propyl, tert-butyl, n-octyl, n-decyl, n-hexadecyl. , 2-methylbutyl, 2-ethylcyclohexyl, cyclopentyl, cyclohexyl and the like.
Moreover, as an aryl group represented by R ^{< 1a>} , R ^<1b >, Preferably it is C6-C30, More preferably, it is C6-C20, Most preferably, it is a C6-C12 aryl group, for example, phenyl, o-methylphenyl, p-methylphenyl, biphenyl, naphthyl, anthranyl, phenanthryl and the like can be mentioned.
The heteroaryl group represented by R ^1a and R ^1b is preferably a heteroaryl group having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms. Examples of the hetero atom include a nitrogen atom, an oxygen atom, A sulfur atom, specifically, for example, imidazolyl, pyridyl, quinolyl, furyl, thienyl, benzoxazolyl, benzimidazolyl, benzthiazolyl, naphthothiazolyl, benzoxazolyl, m-carbazolyl, azepinyl and the like can be mentioned.
R ^1a and R ^1b in the general formula (1) may be the same as or different from each other.

R ² and R ³ each independently represent a hydrogen atom or a substituent, at least one of which is an electron-withdrawing group, and R ² and R ³ may combine to form a ring. Examples of the substituent include an alkyl group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, and particularly preferably 1 to 10 carbon atoms such as methyl, ethyl, iso-propyl, tert-butyl, n-octyl, n-decyl, n-hexadecyl, 2-methylbutyl, 2-ethylcyclohexyl, cyclopentyl, cyclohexyl, etc.), an alkenyl group (preferably having 2 to 30 carbon atoms, more preferably 2 to 2 carbon atoms). 20, particularly preferably 2 to 10 carbon atoms, such as vinyl, allyl, 2-butenyl, 3-pentenyl, etc.), an alkynyl group (preferably 2 to 30 carbon atoms, more preferably 2 to 2 carbon atoms). 20, particularly preferably 2 to 10 carbon atoms, such as propargyl and 3-pentynyl). Group (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenyl, p-methylphenyl, biphenyl, naphthyl, anthranyl, phenanthryl and the like. An amino group (preferably having 0 to 30 carbon atoms, more preferably 0 to 20 carbon atoms, particularly preferably 0 to 10 carbon atoms, including an alkylamino group, an arylamino group, and a heterocyclic amino group; For example, amino, methylamino, dimethylamino, diethylamino, dibenzylamino, diphenylamino, ditolylamino, etc.), an alkoxy group (preferably having 1 to 30 carbons, more preferably 1 to 20 carbons, particularly preferably carbon For example, methoxy, ethoxy, butoxy, 2-ethylhexyloxy An aryloxy group (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, and particularly preferably 6 to 12 carbon atoms, such as phenyloxy, 1-naphthyloxy, 2- Naphthyloxy, etc.), aromatic heterocyclic oxy groups (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as pyridyloxy, pyrazyloxy, Pyrimidyloxy, quinolyloxy, etc.),

An acyl group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as acetyl, benzoyl, formyl, pivaloyl, etc.), an alkoxycarbonyl group ( Preferably it has 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 12 carbon atoms, and examples thereof include methoxycarbonyl, ethoxycarbonyl and the like, and an aryloxycarbonyl group (preferably having a carbon number). 7 to 30, more preferably 7 to 20 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonyl, and acyloxy groups (preferably 2 to 30 carbon atoms, more preferably carbon atoms). 2 to 20, particularly preferably 2 to 10 carbon atoms, for example, acetoxy, benzoyloxy An acylamino group (preferably having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms, and examples thereof include acetylamino and benzoylamino). An alkoxycarbonylamino group (preferably having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 12 carbon atoms such as methoxycarbonylamino), aryloxycarbonylamino group (Preferably 7 to 30 carbon atoms, more preferably 7 to 20 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonylamino), sulfonylamino group (preferably 1 carbon atom) To 30, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, Methanesulfonylamino, benzenesulfonylamino, etc.), sulfamoyl groups (preferably having 0 to 30 carbon atoms, more preferably 0 to 20 carbon atoms, particularly preferably 0 to 12 carbon atoms, such as sulfamoyl, methyl And carbamoyl group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, and particularly preferably 1 to 12 carbon atoms). For example, carbamoyl, methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl, etc.), alkylthio group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, Methylthio, ethylthio, etc.), ants Ruthio group (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, and particularly preferably 6 to 12 carbon atoms, and examples thereof include phenylthio and the like. ),

Aromatic heterocyclic thio group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as pyridylthio, 2-benzimidazolylthio, 2-benzoxazolyl And sulfonyl group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, and particularly preferably 1 to 12 carbon atoms, such as mesyl and tosyl). ), Sulfinyl groups (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methanesulfinyl, benzenesulfinyl, etc.) A ureido group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, Ureido, methylureido, phenylureido, etc.), phosphoric acid amide group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, for example diethyl phosphorus Acid amide, phenylphosphoric acid amide, etc.), hydroxy group, mercapto group, halogen atom (eg fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxam An acid group, a sulfino group, a hydrazino group, an imino group, a heterocyclic group (preferably having a carbon number of 1 to 30, more preferably a carbon number of 1 to 12, and examples of the hetero atom include a nitrogen atom, an oxygen atom, a sulfur atom, Specifically, for example, imidazolyl, pyridyl, quinolyl, furyl, thienyl, piperidyl, morpholino, ben Oxazolyl, benzimidazolyl, benzthiazolyl, carbazolyl group, azepinyl group, etc.), silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms, Examples thereof include trimethylsilyl and triphenylsilyl). These substituents may be further substituted.

The electron withdrawing group represented by R ² or R ³ represents a substituent having a positive Hammett σp value (sigma para value), preferably a cyano group, an acyl group, an alkyloxycarbonyl group, an aryloxycarbonyl group, A sulfamoyl group, a sulfinyl group, a heterocyclic group and the like can be mentioned. These electron withdrawing groups may be further substituted.

  Hammett's substituent constant σ value will be described. Hammett's rule is a method described in 1935 by L. E. in order to quantitatively discuss the effect of substituents on the reaction or equilibrium of benzene derivatives. P. A rule of thumb proposed by Hammett, which is widely accepted today. Substituent constants determined by Hammett's rule include σp value and σm value, and these values can be found in many general books. For example, J. et al. A. Dean, “Lange's Handbook of Chemistry”, 12th edition, 1979 (Mc Graw-Hill) and “Areas of Chemistry”, No. 122, 96-103, 1979 (Nankodo), Chem. Rev. 1991, 91, 165-195. The substituent having Hammett's substituent constant σp value of 0.2 or more in the present invention is an electron-attracting group. The σp value is preferably 0.25 or more, more preferably 0.3 or more, and particularly preferably 0.35 or more. The upper limit is not particularly limited, but is preferably 0.80.

Specific examples include cyano group (0.66), carboxyl group (—COOH: 0.45), alkoxycarbonyl group (—COOMe: 0.45), aryloxycarbonyl group (—COOPh: 0.44), carbamoyl. A group (—CONH ₂ : 0.36), an alkylcarbonyl group (—COMe: 0.50), an arylcarbonyl group (—COPh: 0.43), an alkylsulfonyl group (—SO ₂ Me: 0.72), or arylsulfonyl group _(-SO 2 Ph: 0.68) and the like. Particularly preferred is a cyano group.
In the present specification, Me represents a methyl group, and Ph represents a phenyl group. The values in parentheses are the σp values of typical substituents in Chem. Rev. 1991, Vol. 91, pp. 165-195.

Further, when R ² and R ³ are combined to form a ring, a 5- to 7-membered ring (preferably a 5- to 6-membered ring) is formed, and the formed ring is usually a merocyanine dye and an acidic nucleus. Are preferably used, and specific examples thereof include the following.
(A) 1,3-dicarbonyl nucleus: For example, 1,3-indandione nucleus, 1,3-cyclohexanedione, 5,5-dimethyl-1,3-cyclohexanedione, 1,3-dioxane-4,6- Zeon etc.
(B) pyrazolinone nucleus: for example 1-phenyl-2-pyrazolin-5-one, 3-methyl-1-phenyl-2-pyrazolin-5-one, 1- (2-benzothiazoyl) -3-methyl-2 -Pyrazolin-5-one and the like.
(C) Isoxazolinone nucleus: For example, 3-phenyl-2-isoxazolin-5-one, 3-methyl-2-isoxazolin-5-one and the like.
(D) Oxindole nucleus: For example, 1-alkyl-2,3-dihydro-2-oxindole and the like.
(E) 2,4,6-triketohexahydropyrimidine nucleus: for example, barbituric acid or 2-thiobarbituric acid and its derivatives. Examples of the derivatives include 1-alkyl compounds such as 1-methyl and 1-ethyl, 1,3-dialkyl compounds such as 1,3-dimethyl, 1,3-diethyl and 1,3-dibutyl, 1,3-diphenyl, 1,3-diaryl compounds such as 1,3-di (p-chlorophenyl) and 1,3-di (p-ethoxycarbonylphenyl), 1-alkyl-1-aryl compounds such as 1-ethyl-3-phenyl, Examples include 1,3-di (2-pyridyl) 1,3-diheterocyclic substituents and the like.
(F) 2-thio-2,4-thiazolidinedione nucleus: for example, rhodanine and its derivatives. Examples of the derivatives include 3-alkylrhodanine such as 3-methylrhodanine, 3-ethylrhodanine and 3-allylrhodanine, 3-arylrhodanine such as 3-phenylrhodanine, and 3- (2-pyridyl) rhodanine. And the like.
(G) 2-thio-2,4-oxazolidinedione (2-thio-2,4- (3H, 5H) -oxazoledione nucleus: for example, 3-ethyl-2-thio-2,4-oxazolidinedione and the like.
(H) Tianaphthenone nucleus: For example, 3 (2H) -thianaphthenone-1,1-dioxide and the like.
(I) 2-thio-2,5-thiozolidinedione nucleus: For example, 3-ethyl-2-thio-2,5-thiazolidinedione and the like.
(J) 2,4-thiozolidinedione nucleus: For example, 2,4-thiazolidinedione, 3-ethyl-2,4-thiazolidinedione, 3-phenyl-2,4-thiazolidinedione and the like.
(K) Thiazolin-4-one nucleus: For example, 4-thiazolinone, 2-ethyl-4-thiazolinone and the like.
(L) 4-thiazolidinone nucleus: for example, 2-ethylmercapto-5-thiazoline-4-one, 2-alkylphenylamino-5-thiazoline-4-one, and the like.
(M) 2,4-imidazolidinedione (hydantoin) nucleus: for example, 2,4-imidazolidinedione, 3-ethyl-2,4-imidazolidinedione, etc.
(N) 2-thio-2,4-imidazolidinedione (2-thiohydantoin) nucleus: for example, 2-thio-2,4-imidazolidinedione, 3-ethyl-2-thio-2,4-imidazolidinedione Such.
(O) Imidazolin-5-one nucleus: For example, 2-propylmercapto-2-imidazolin-5-one and the like.
(P) 3,5-pyrazolidinedione nucleus: for example, 1,2-diphenyl-3,5-pyrazolidinedione, 1,2-dimethyl-3,5-pyrazolidinedione, and the like.
(Q) Benzothiophen-3-one nucleus: for example, benzothiophen-3-one, oxobenzothiophen-3-one, dioxobenzothiophen-3-one and the like.
(R) Indanone nucleus: For example, 1-indanone, 3-phenyl-1-indanone, 3-methyl-1-indanone, 3,3-diphenyl-1-indanone, 3,3-dimethyl-1-indanone, and the like.

Note that the σp values of R ² and R ^{3 in} the case of forming a ring cannot be defined, but in the present invention, it is considered that R ² and R ³ are each substituted with a partial structure of the ring. In this case, the σp value is defined. For example, when a 1,3-indandione ring is formed, it is considered that R ² and R ³ are each substituted with a benzoyl group.

The ring formed by combining R ² and R ³ is preferably a 1,3-dicarbonyl nucleus, a pyrazolinone nucleus, a 2,4,6-triketohexahydropyrimidine nucleus (including a thioketone body), 2- Thio-2,4-thiazolidinedione nucleus, 2-thio-2,4-oxazolidinedione nucleus, 2-thio-2,5-thiazolidinedione nucleus, 2,4-thiazolidinedione nucleus, 2,4-imidazolidinedione nucleus 2-thio-2,4-imidazolidinedione nucleus, 2-imidazolin-5-one nucleus, 3,5-pyrazolidinedione nucleus, benzothiophen-3-one nucleus, or indanone nucleus, more preferably 1,3-dicarbonyl nucleus, 2,4,6-triketohexahydropyrimidine nucleus (including thioketone body), 3,5-pyrazolidinedione nucleus, benzothiophen-3-one nucleus Or the Indanone nucleus.

R ³ is particularly preferably a heterocycle. Particularly preferably, the hetero ring is a pyrazole ring, thiazole ring, oxazole ring, imidazole ring, oxadiazole ring, thiadiazole ring, triazole ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, benzo condensed ring or naphth condensed ring. It is a ring or a complex of these condensed rings.
Two R ² in the general formula (1) may be the same or different from each other, and two R ³ may be the same or different from each other.

The alkyl group, aryl group, and heteroaryl group represented by R ⁴ have the same meanings as the substituents described for R ^1a and R ^1b , and the preferred ranges are also the same. The substituent of the substituted boron represented by R ⁴ has the same meaning as the substituent described above for R ² and R ³ , and is preferably an alkyl group, an aryl group, or a heteroaryl group. The metal atom represented by R ⁴ is preferably a transition metal, magnesium, aluminum, calcium, barium, zinc, or tin, and more preferably aluminum, zinc, tin, vanadium, iron, cobalt, nickel, copper Palladium, iridium, or platinum, particularly preferably aluminum, zinc, vanadium, iron, copper, palladium, iridium, or platinum.
R ⁴ is particularly preferably substituted boron.
R ⁴ may be covalently bonded or coordinated to R ^1a , R ^1b and / or R ³ .
Two R ⁴ in the general formula (1) may be the same as or different from each other.

  The compound represented by the general formula (1) is preferably a near-infrared absorbing compound represented by any of the following general formulas (2), (3), or (4).

(In the formula, Z ^1a and Z ^1b each independently represent an atomic group that forms an aryl ring or a heteroaryl ring. R ^5a and R ^5b each independently represent an aryl group having 6 to 20 carbon atoms, or 4 to 20 carbon atoms. Heteroaryl group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkoxycarbonyl group having 1 to 20 carbon atoms, a carboxyl group, a carbamoyl group having 1 to 20 carbon atoms, a halogen atom, or cyano Any one of the groups, R ^5a or R ^5b and Z ^1a or Z ^1b may combine to form a condensed ring, R ²² and R ²³ each independently represent a cyano group, Represents an acyl group having 6 carbon atoms, an alkoxycarbonyl group having 1 to 6 carbon atoms, an alkyl or arylsulfinyl group having 1 to 10 carbon atoms, or a nitrogen-containing heteroaryl group having 3 to 20 carbon atoms, or R ²² and R ²³ are bonded Cyclic acid .R ⁴ representing the nuclei of hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a heteroaryl group having 4 to 20 carbon atoms, a metal atom, or a halogen atom as a substituent, the carbon number This represents a substituted boron having an alkyl group of 1 to 10, an aryl group of 6 to 20 carbon atoms, or a heteroaryl group of 4 to 20 carbon atoms, and may have a covalent bond or a coordinate bond with R ²³ . The compound may further have a substituent.)

(In the formula, R ^31a and R ^31b each independently represent an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms or a heteroaryl group having 3 to 20 carbon atoms. R ³² represents a cyano group or a carbon atom. Represents an acyl group having 1 to 6 carbon atoms, an alkoxycarbonyl group having 1 to 6 carbon atoms, an alkyl or arylsulfinyl group having 1 to 10 carbon atoms, or a nitrogen-containing heteroaryl group having 3 to 10 carbon atoms R ⁶ and R ⁷ Each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a heteroaryl group having 4 to 10 carbon atoms, and R ⁶ and R ⁷ are bonded to form a ring. The ring to be formed is an alicyclic ring having 5 to 10 carbon atoms, an aryl ring having 6 to 10 carbon atoms, or a heteroaryl ring having 3 to 10 carbon atoms, wherein R ⁸ and R ⁹ are each independently carbon. An alkyl group having 1 to 10 carbon atoms and 1 to 10 carbon atoms Represents an alkoxy group, an aryl group having 6 to 20 carbon atoms, or a heteroaryl group having 3 to 10 carbon atoms, X represents an oxygen atom, a sulfur atom, -NR-, -CRR'-, -CH = CH-, R and R ′ represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms.)

(In the formula, R ^41a and R ^41b represent different groups, and each represents an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a heteroaryl group having 3 to 20 carbon atoms. R ⁴² represents cyano. group represents an acyl group having 1 to 6 carbon atoms, an alkoxycarbonyl group having 1 to 6 carbon atoms, alkylsulfinyl or arylsulfinyl group having 1 to 10 carbon atoms, or a nitrogen-containing heteroaryl group having 3 to 10 carbon atoms .Z ² Represents an atomic group that forms a nitrogen-containing hetero 5 or 6-membered ring with —C═N—, and the nitrogen-containing hetero ring includes a pyrazole ring, a thiazole ring, an oxazole ring, an imidazole ring, an oxadiazole ring, a thiadiazole ring, and a triazole. A ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a benzo-fused ring or a naphtho-fused ring thereof, or a complex of these condensed rings, and R ⁴⁴ represents a hydrogen atom. Children, alkyl groups having 1 to 20 carbon atoms, aryl groups having 6 to 20 carbon atoms, heteroaryl groups having 4 to 20 carbon atoms, metal atoms, or halogen atoms as substituents, alkyl groups having 1 to 10 carbon atoms, carbon This represents a substituted boron having an aryl group of 6 to 20 or a heteroaryl group of 4 to 20 carbon atoms, and may have a covalent bond or a coordinate bond with the nitrogen-containing heterocycle formed by Z ² . The compound may further have a substituent.)

The general formula (2) will be described.
In the general formula (2), Z ^1a and Z ^1b each independently represent an atomic group that forms an aryl ring or a heteroaryl ring. The aryl ring and heteroaryl ring formed are synonymous with the aryl group and heteroaryl group described as the substituents for R ² and R ³ in the general formula (1), and the preferred ranges are also the same. Z ^1a and Z ^1b are preferably the same.
R ^5a and R ^5b are each independently an aryl group having 6 to 20 carbon atoms, a heteroaryl group having 4 to 20 carbon atoms, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, It represents any one of 20 alkoxycarbonyl groups, carboxyl groups, carbamoyl groups having 1 to 20 carbon atoms, halogen atoms, or cyano groups. Specific examples are synonymous with the examples described for R ² and R ³ in the general formula (1), and preferred ranges are also the same. R ^5a and R ^5b are preferably the same.
R ^5a or R ^5b and Z ^1a or Z ^1b may combine to form a condensed ring, and examples of the condensed ring include a naphthyl ring and a quinoline ring.
By introducing a group represented by R ^5a or R ^5b into the aryl ring or heteroaryl ring formed by Z ^1a or Z ^1b , invisibility can be greatly improved.

R ²² and R ²³ are each independently a cyano group, an acyl group having 1 to 6 carbon atoms, an alkoxycarbonyl group having 1 to 6 carbon atoms, an alkyl or arylsulfinyl group having 1 to 10 carbon atoms, or 3 to 20 carbon atoms. It represents a nitrogen-containing heteroaryl group, or R ²² and R ²³ are combined to represent a cyclic acidic nucleus. Specifically, it is synonymous with the example demonstrated by R < ² > and R < ³ > in the said General formula (1), and its preferable range is also the same. R ⁴ has the same meaning as R ⁴ in the general formula (1), and the preferred range is also the same. R ⁴ may have a covalent bond or a coordinate bond with R ²³ .

The compound represented by the general formula (2) may further have a substituent, and the substituent is synonymous with the substituents of R ² and R ³ , and the preferred range is also the same.

As a preferable combination in the general formula (2), Z ^1a and Z ^1b each independently form a benzene ring or a pyridine ring, and R ^5a and R ^5b each independently represent an alkyl group, an alkoxy group, a halogen atom, a cyano group. R ²² and R ²³ are each independently a heterocyclic group, a cyano group, an acyl group, an alkoxycarbonyl group, or a cyclic acidic nucleus in which R ²² and R ²³ are bonded, and R ⁴ is a hydrogen atom, a substituted boron, This is the case of transition metal atoms, magnesium, aluminum, calcium, barium, zinc, and tin. As a particularly preferred combination, Z ^1a and Z ^1b together form a benzene ring, R ^5a and R ^5b are both an alkyl group, a halogen atom, or a cyano group, and R ²² and R ²³ are each independently a nitrogen-containing heterocycle. A combination of a cyclic group and a cyano group or an alkoxycarbonyl group, or a cyclic acidic nucleus in which R ²² and R ²³ are bonded, and R ⁴ is a hydrogen atom, substituted boron, aluminum, zinc, vanadium, iron, copper, palladium, iridium This is the case of platinum.

The general formula (3) will be described.
In General Formula (3), R ^31a and R ^31b each independently represent an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a heteroaryl group having 3 to 20 carbon atoms, specifically, These are synonymous with the examples described for R ^1a and R ^1b in the general formula (1), and the preferred ranges are also the same. R ^31a and R ^31b are preferably the same.
R ³² is a cyano group, an alkoxycarbonyl group having 1 to 6 carbon atoms, an alkyl or arylsulfinyl group having 1 to 10 carbon atoms, or a nitrogen-containing heteroaryl group having 3 to 10 carbon atoms. it is the same as examples of R ² in the formula (1), and preferred ranges are also the same.

R ⁶ and R ⁷ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a heteroaryl group having 4 to 10 carbon atoms. (1) have the same meanings as examples of the substituents of R ² and R ³ in the preferred range is also the same. R ⁶ and R ⁷ may combine to form a ring, and the ring formed is an alicyclic ring having 5 to 10 carbon atoms, an aryl ring having 6 to 10 carbon atoms, or a heteroaryl ring having 3 to 10 carbon atoms. Preferred examples include a benzene ring, naphthalene ring, and pyridine ring.
By introducing a 5-membered nitrogen-containing heterocycle substituted with R ⁶ and R ⁷ and further forming a boron complex, an infrared absorbing dye that achieves both high fastness and high invisibility can be realized.

R ⁸ and R ⁹ are each independently an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a heteroaryl group having 3 to 10 carbon atoms. to are the same as examples of the substituents R ² and R ³ in the general formula (1), and preferred ranges are also the same.
X represents an oxygen atom, a sulfur atom, -NR-, -CRR'-, -CH = CH-. R and R ′ each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms, preferably a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a phenyl group. .

As a preferable combination in the general formula (3), R ^31a and R ^31b are each independently an alkyl group having 1 to 10 carbon atoms, a benzene ring or a pyridine ring, R ³² is a cyano group, an alkoxycarbonyl group, R ⁶ and R ⁷ are bonded to form a benzene ring or a pyridine ring, a pyrazine ring, a pyrimidine ring, and R ⁸ and R ⁹ are each independently an alkyl group having 1 to 6 carbon atoms, a phenyl group, a naphthyl group, When X is an oxygen atom, a sulfur atom, -NR-, -CRR'-, -CH = CH-, and R and R 'are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a phenyl group It is. As a particularly preferred combination, R ^31a and R ^31b are both an alkyl group having 1 to 10 carbon atoms or a benzene ring, R ³² is a cyano group, and R ⁶ and R ⁷ are bonded to form a benzene ring or a pyridine ring. And R ⁸ and R ⁹ are each independently an alkyl group having 1 to 6 carbon atoms, a phenyl group, or a naphthyl group, and X is oxygen or sulfur.

The general formula (4) will be described.
In the general formula (4), R ^41a and R ^{41b each} represents an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a heteroaryl group having 3 to 20 carbon atoms. It is synonymous with the example ^demonstrated by R ^{< 1a>} and R ^<1b> in Formula (1), and its preferable range is also the same. However, R ^41a and R ^41b represent different groups.
R ⁴² is a cyano group, an alkoxycarbonyl group having 1 to 6 carbon atoms, an alkyl or arylsulfinyl group having 1 to 10 carbon atoms, or a nitrogen-containing heteroaryl group having 3 to 10 carbon atoms. it is the same as examples of R ² in the formula (1), and preferred ranges are also the same.
Z ² represents an atomic group that forms a nitrogen-containing hetero 5 or 6-membered ring with —C═N—, and the nitrogen-containing hetero ring includes a pyrazole ring, a thiazole ring, an oxazole ring, an imidazole ring, an oxadiazole ring, and a thiadiazole ring. , A triazole ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a benzo condensed ring or a naphth condensed ring, or a complex of these condensed rings.
R ⁴⁴ is a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a heteroaryl group having 4 to 20 carbon atoms, a halogen atom as a metal atom or a substituent, and an alkyl having 1 to 10 carbon atoms. Represents a substituted boron having a group, an aryl group having 6 to 20 carbon atoms, or a heteroaryl group having 4 to 20 carbon atoms, and may have a covalent bond or a coordinate bond with the nitrogen-containing heterocycle formed by Z ^2. .
By introducing different groups represented by R ^41a and R ^41b and introducing a nitrogen-containing hetero 5- or 6-membered ring formed by Z ² with —C═N—, high robustness and high invisibility are obtained. High dispersibility and high organic solvent solubility can be imparted.

As a preferable combination in the general formula (4), R ^41a and R ^41b are each independently an alkyl group having 1 to 10 carbon atoms, a benzene ring or a pyridine ring, and R ⁴² is a cyano group and having 1 to 10 carbon atoms. An alkyl or arylsulfinyl group, an alkoxycarbonyl group, and Z ² together with —C═N— is a thiazole ring, an oxazole ring, an imidazole ring, a thiadiazole ring, a triazole ring, a pyridine ring, a pyrimidine ring, a pyrazine ring, or a benzo-condensation thereof. This is a case where a ring or a naphtho condensed ring is formed, and R ⁴⁴ is a hydrogen atom, a substituted boron, a transition metal atom, magnesium, aluminum, calcium, barium, zinc, or tin. As a particularly preferred combination, R ^41a and R ^41b each independently represents an alkyl group having 1 to 10 carbon atoms or a benzene ring, R ⁴² represents a cyano group, Z ² together with —C═N— represents a thiazole ring, oxazole A ring, an imidazole ring, a triazole ring, a pyridine ring, a pyrimidine ring, or a benzo condensed ring or a naphth condensed ring thereof, R ⁴⁴ is a hydrogen atom, a substituted boron (as a substituent, an alkyl group having 1 to 10 carbon atoms, A benzene ring, a pyridine ring, or a thiophene ring), aluminum, zinc, vanadium, iron, copper, palladium, iridium, or platinum.

  Specific examples of the compound (dye compound) represented by any one of the general formulas (1) to (4) are shown below, but the present invention is not limited to the following specific examples. In this specification, Et represents an ethyl group, and Bu represents a butyl group.

Next, a method for synthesizing the compound represented by any one of the general formulas (1) to (4) will be described.
The compound represented by any one of the general formulas (1) to (4) may be obtained by condensing an active methylene compound with a corresponding diketopyrrolopyrrole compound and, in some cases, further reacting with boron or a metal. Can be synthesized. The diketopyrrolopyrrole compound can be synthesized by the method described in “High Performance Pigments”, Wiley-VCH, 2002, pages 160 to 163, and more specific examples include US Pat. No. 5,969. No. 154, and Japanese Patent Laid-Open No. 9-323993. In addition, the condensation reaction of the diketopyrrolopyrrole compound and the active methylene compound and the subsequent boronation can be synthesized according to the non-patent document Angewante Chemie International Edition of England, Vol. 46, pages 3750-3653 (2007). Boronating reagents are described in J. Org. Med. Chem. It can be synthesized with reference to Volume 3, pages 356 to 360 (1976). For example, bromocatechol borane can be purchased from Tokyo Chemical Industry Co., Ltd. and used.

The compound represented by any one of the general formulas (1) to (4) is not particularly limited, but preferably has an absorption maximum at 700 to 1200 nm, more preferably 700 to 1000 nm. The compound represented by any one of the general formulas (1) to (4) preferably selectively absorbs infrared rays having a wavelength of 700 nm to 1000 nm.
In addition, the compound represented by any one of the general formulas (1) to (4) has a molar extinction coefficient ε that is not particularly limited, but is preferably 50,000 to 300,000, and more preferably 100,000. ~ 250,000.

  The compound represented by any one of the general formulas (1) to (4) can be preferably used as an IR dye. Since it is invisible, the color of the compound is preferably transparent, but may be slightly colored green or gray.

Next, the dispersion liquid of the present invention will be described.
The dispersion medium of the near-infrared absorbing dispersion liquid of the present invention is preferably an aqueous solvent. Here, the aqueous solvent means water or a solvent containing water as a main component (preferably 60% by mass or more) and a water-soluble organic solvent such as alcohol. Examples of water-soluble organic solvents include methanol, ethanol, propanol, isopropanol, butanol, isobutanol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, glycerin, hexanetriol, and ethylene glycol. Monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, N, N-dimethylacetamide, dimethyl sulfoxide, sulfolane, 2-pyrrolidone, N-methyl-2-pyrrolidone, acetonitrile, etc. Can be given. Moreover, it is preferable to use the near-infrared absorbing compound in an aqueous dispersion fine particle state. Here, the aqueous dispersed fine particles refer to fine particles dispersed in an aqueous solvent as a dispersion medium. At this time, it is preferable that the water solubility of the near-infrared absorbing compound is substantially zero.
When the near-infrared absorbing compound is used in an aqueous dispersed fine particle state, high light resistance and wet heat resistance can be imparted by the association of the compounds inside the fine particles.

In the present invention, a nano-track UPA particle size analyzer (UPA-EX150, trade name, manufactured by Nikkiso Co., Ltd.) can be used as a particle size measuring device. The measurement is performed according to a predetermined measurement method by placing 3 ml of the fine particle dispersion in a measurement cell. As parameters input at the time of measurement, the viscosity of the solvent is used as the viscosity, and the density of the fine particles is used as the density of the dispersed particles.
The average particle size of the fine particles is preferably 0.5 μm or less, more preferably 250 nm or less, more preferably 150 nm or less, and still more preferably 120 nm or less. Although there is no restriction | limiting in particular in the minimum of an average particle diameter, Usually, it is 1 nm or more. The average particle size of the fine particles refers to the particle size of the fine particles themselves, or the particle size to which the additive has adhered when an additive such as a dispersant is attached to the fine particles.

In general pigments and the like, it is known that the smaller the average particle diameter of dispersed fine particles, the larger the surface area of the fine particles, the higher the color developability and the sharper the absorption spectrum, but the lower the fastness. Further, it is known that it is difficult to obtain a dispersion having high storage stability because the smaller the average particle size of the dispersed fine particles, the stronger the cohesive force of the fine particles. However, although the dispersed fine particles in the present invention have a small average particle diameter and a sharp absorption spectrum, they have high fastness and excellent storage stability.
0.01-30 mass% is preferable and, as for content of the said near-infrared absorption compound in the dispersion liquid of this invention, 0.1-5 mass% is more preferable. By setting it as such content, characteristics, such as required near-infrared absorption performance and dispersion stability, are acquired.

The maximum absorption wavelength of the dispersion of the present invention is preferably 700 to 1200 nm, more preferably 700 to 1000 nm.
The absorbance at 550 nm of the dispersion of the present invention is preferably ¼ or less, more preferably 好 ま し く or less, with respect to the absorbance at the maximum absorption wavelength.

When producing the aqueous dispersed fine particles of the near infrared absorbing compound, the quality of dispersion may be improved by using a surfactant and a dispersant. Examples of the surfactant include anionic, nonionic, cationic and amphoteric surfactants, and any surfactant may be used.
It is preferable to use an anionic or nonionic surfactant.

  Examples of the anionic surfactant include fatty acid salts, alkyl sulfate esters, alkylbenzene sulfonates, alkyl naphthalene sulfonates, dialkyl sulfosuccinates, alkyl diaryl ether disulfonates, alkyl phosphates, and polyoxyethylene alkyls. Examples thereof include ether sulfate, polyoxyethylene alkylaryl ether sulfate, naphthalenesulfonic acid formalin condensate, polyoxyethylene alkyl phosphate ester salt, glycerol borate fatty acid ester, polyoxyethylene glycerol fatty acid ester and the like.

  Nonionic surfactants include, for example, polyoxyethylene alkyl ether, polyoxyethylene alkyl aryl ether, polyoxyethylene oxypropylene block copolymer, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin. Examples include fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene alkylamines, fluorine-based resins, and silicon-based resins.

Examples of the dispersing apparatus for producing the aqueous dispersed fine particles include a ball mill, a sand mill, a bead mill, a roll mill, a jet mill, a paint shaker, an attritor, an ultrasonic disperser, and a disper. As a method for preparing the dispersion liquid of the present invention, a method in which the near-infrared absorbing compound is added to a dispersion medium and fine particles are dispersed by the dispersing device is preferable.
Or the method of preparing a dispersion liquid using the said near-infrared absorptive compound made into the microparticles | fine-particles previously can also be employ | adopted. Specifically, for the near-infrared absorbing compound obtained as a crude crystal, for example, fine particle control step by grinding treatment such as solvent salt milling, salt milling, dry milling, solvent milling, acid pasting, solvent heating treatment, etc. Those subjected to a surface treatment step using a resin, a surfactant, a dispersant, or the like can be used.

The ink of the present invention is an ink jet recording ink or a printing ink comprising the above near infrared absorbing dispersion liquid.
The ink of the present invention can be prepared by using a near-infrared absorbing dispersion liquid in which dispersed fine particles of the near-infrared absorbing compound are dispersed in an ink medium. At this time, it is preferable to use an aqueous medium. You may contain another additive as needed. Examples of additives include resins, anti-drying agents (wetting agents), anti-fading agents, emulsion stabilizers, penetration enhancers, antiseptics, anti-fungal agents, pH adjusting agents, surface tension adjusting agents, antifoaming agents, and viscosities. Examples thereof include additives such as a regulator, a dispersant, a dispersion stabilizer, a rust inhibitor, and a chelating agent. These various additives are directly added to the ink liquid in the case of water-soluble ink. When the oil-soluble dye is used in the form of a dispersion, it is generally added to the dispersion after the preparation of the dye dispersion, but it may be added to the oil phase or the aqueous phase at the time of preparation.

  As the ink medium, ink media such as flat printing ink, gravure printing ink, ink jet recording ink, and ultraviolet curable ink can be used, and there is no particular limitation. Among them, a particularly preferable ink medium is an aqueous medium containing water as a main component. In addition, the water used for the ink in the present invention is preferably ion-exchanged water or ion-exchanged distilled water.

The resin is used for the purpose of forming a coating film on a printed material, dispersing and protecting pigment fine particles. Although the preferred resin varies depending on the type of printing ink, it is preferable to use a water-soluble resin or a water-dispersible resin. For example, acrylic resin, styrene acrylic resin, styrene maleic resin, vinyl resin, polyester resin, polyurethane resin, epoxy resin And phenol resin.
Furthermore, from the viewpoints of printing stability and physical properties of the coating film, a water-dispersible resin is preferable. For example, an acrylic resin, a vinyl resin, a polyurethane resin, a polyester resin, or the like can be used.

  Examples of the acrylic resin include acrylic acid esters such as acrylic acid and alkyl acrylate, methacrylic acid esters such as acrylamide, acrylonitrile, methacrylic acid and alkyl methacrylate, and a single monomer of any of methacrylamide and methacrylonitrile. Examples thereof include a copolymer or a copolymer obtained by polymerization of two or more of these monomers. Among these, homopolymers of monomers of acrylic acid esters such as alkyl acrylates and methacrylic acid esters such as alkyl methacrylates, or copolymers obtained by polymerization of two or more of these monomers preferable. For example, mention may be made of homopolymers of monomers of acrylic acid esters and methacrylic acid esters having an alkyl group having 1 to 6 carbon atoms, or copolymers obtained by polymerization of two or more of these monomers. it can. The acrylic resin has the above composition as a main component and, for example, partially uses a monomer having any group of a methylol group, a hydroxyl group, a carboxyl group, and an amino group so that a crosslinking reaction with a carbodiimide compound is possible. The resulting polymer.

  Examples of the vinyl resin include polyvinyl alcohol, acid-modified polyvinyl alcohol, polyvinyl formal, polyvinyl butyral, polyvinyl methyl ether, polyolefin, ethylene / butadiene copolymer, polyvinyl acetate, vinyl chloride / vinyl acetate copolymer, vinyl chloride / ( A meth) acrylic acid ester copolymer and an ethylene / vinyl acetate copolymer (preferably ethylene / vinyl acetate / (meth) acrylic acid ester copolymer) can be mentioned. Among these, polyvinyl alcohol, acid-modified polyvinyl alcohol, polyvinyl polymer, polyolefin, ethylene / butadiene copolymer and ethylene / vinyl acetate copolymer (preferably ethylene / vinyl acetate / acrylic acid ester copolymer). Is preferred. The vinyl resin can be crosslinked with a carbodiimide compound so that, for example, polyvinyl alcohol, acid-modified polyvinyl alcohol, polyvinyl formal, polyvinyl butyral, polyvinyl methyl ether, and polyvinyl acetate leave a vinyl alcohol unit in the polymer. Thus, the polymer having a hydroxyl group is used, and the other polymer is, for example, a crosslinkable polymer by partially using a monomer having any of a methylol group, a hydroxyl group, a carboxyl group, and an amino group.

  Examples of the polyurethane resin include polyhydroxy compounds (eg, ethylene glycol, propylene glycol, glycerin, trimethylolpropane), aliphatic polyester polyols obtained by reaction of polyhydroxy compounds and polybasic acids, polyether polyols (eg, Polyurethane derived from poly (oxypropylene ether) polyol, poly (oxyethylene-propylene ether) polyol), polycarbonate-based polyol, and polyethylene terephthalate polyol, or a mixture thereof and polyisocyanate can be given. In the polyurethane resin, for example, the hydroxyl group remaining unreacted after the reaction between polyol and polyisocyanate can be used as a functional group capable of crosslinking reaction with a carbodiimide compound.

  Examples of the polyester resin include polymers obtained by reaction of polyhydroxy compounds (eg, ethylene glycol, propylene glycol, glycerin, trimethylolpropane) with polybasic acids. In the above-mentioned polyester resin, for example, the hydroxyl group and carboxyl group remaining unreacted after the reaction between the polyol and the polybasic acid can be used as a functional group capable of crosslinking reaction with the carbodiimide compound. Of course, a third component having a functional group such as a hydroxyl group may be added.

  Incidentally, the dispersion state of the aqueous dispersion of the polymer may be one in which the polymer is emulsified in a dispersion medium, emulsion polymerized, micelle-dispersed, or partially hydrophilic in the polymer molecule. Any one having a simple structure may be used. In addition, about the polymer aqueous dispersion (or simply referred to as the aqueous dispersion) in the present invention, “synthetic resin emulsion (Hiraku Okuda, Hiroshi Inagaki, published by Kobunshi Shuppankai (1978))”, “application of synthetic latex ( Sugimura Takaaki, Kataoka Ikuo, Suzuki Junichi, edited by Kasahara Keiji, published by Kobunshi Publishing Co., Ltd. (1993)), “Synthetic Latex Chemistry (written by Soichi Muroi, published by Kobunshi Publishing Co., Ltd. (1970))”, etc. Yes. The average particle size of the dispersed particles is preferably 1 to 50000 nm, more preferably about 5 to 1000 nm. The particle size distribution of the dispersed particles is not particularly limited, and may have a wide particle size distribution or a monodispersed particle size distribution.

In addition, as the aqueous dispersion, the following commercially available polymers may be used.
Superflex 830, 460, 870, 420, 420NS (Polyurethane made by Daiichi Kogyo Seiyaku), Bondick 1370NS, 1320NS, Hydran Hw140SF, WLS201, WLS202, WLS213 (Polyurethane made by Dainippon Ink & Chemicals), Olester UD350, UD500, UD600 (Mitsui Chemicals Polyurethane), Neoletz R972, R966, R9660 (Enomoto Kasei Polyurethane), Finetex Es650, Es2200 (Dainippon Ink Chemicals Polyester), Bironal MD1100, MD1400, MD1480 (Toyobo Polyester), Julimer ET325 ET410, AT-613, SEK301 (Nippon Pure Chemicals Acrylic), Boncoat AN117, AN226 (Dai Nippon Ink Industrial acrylic), Luckstar DS616, DS807 (Dainippon Ink & Chemicals styrene-butadiene rubber), Nippon LX110, LX206, LX426, LX433 (Nippon Zeon styrene-butadiene rubber), Nippon LX513, LX1551, LX550, LX1571 ( Zeon Nippon Acrylonitrile-Butadiene Rubber) (all trade names).

The anti-drying agent is preferably used for the purpose of preventing clogging due to drying of the ink-jet ink at the ink jet port of the nozzle used in the ink-jet recording method.
As the drying inhibitor, a water-soluble organic solvent having a vapor pressure lower than that of water is preferable. Specific examples include ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, thiodiglycol, dithiodiglycol, 2-methyl-1,3-propanediol, 1,2,6-hexanetriol, acetylene glycol derivatives, glycerin. Polyhydric alcohols typified by trimethylolpropane, etc., lower alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monoethyl (or butyl) ether 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, heterocyclic rings such as N-ethylmorpholine, sulfolane, dimethyl sulfoxide, 3 Sulfur-containing compounds such as sulfolane, diacetone alcohol, polyfunctional compounds such as diethanolamine, and urea derivatives. Of these, polyhydric alcohols such as glycerin and diethylene glycol are more preferred. Moreover, said drying inhibitor may be used independently and may be used together 2 or more types. These drying inhibitors are preferably contained in the ink in an amount of 10 to 50% by mass.

  The penetration enhancer is preferably used for the purpose of allowing ink jet ink to penetrate better into paper. Examples of the penetration enhancer include alcohols such as ethanol, isopropanol, butanol, di (tri) ethylene glycol monobutyl ether, 1,2-hexanediol, sodium lauryl sulfate, sodium oleate, and nonionic surfactants. it can. If these are contained in the ink in an amount of 5 to 30% by mass, they usually have a sufficient effect, and it is preferable to use them in a range of addition amounts that do not cause printing bleeding and paper loss (print through).

  The anti-fading agent is used for the purpose of improving image storage stability. As the anti-fading agent, various organic and metal complex anti-fading agents can be used. Organic anti-fading agents include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, heterocycles, etc. Complex, zinc complex and the like. More specifically, Research Disclosure No. No. 17643, No. VII, I to J, ibid. 15162, ibid. No. 18716, page 650, left column, ibid. No. 36544, page 527, ibid. No. 307105, page 872, ibid. The compounds described in the patent cited in No. 15162 and the compounds included in the general formulas and compound examples of the representative compounds described in pages 127 to 137 of JP-A-62-215272 can be used.

  Examples of the antifungal agent include sodium dehydroacetate, sodium benzoate, sodium pyridinethione-1-oxide, p-hydroxybenzoic acid ethyl ester, 1,2-benzisothiazolin-3-one and salts thereof. These are preferably used in the ink in an amount of 0.02 to 1.00% by mass.

  The neutralizer (organic base, inorganic alkali) can be used as the pH adjuster. For the purpose of improving the storage stability of the inkjet ink, the pH adjuster is preferably added so that the inkjet ink has a pH of 6 to 10, and more preferably added to have a pH of 7 to 10.

  Examples of the surface tension adjusting agent include nonionic, cationic and anionic surfactants. The surface tension of the inkjet ink of the present invention is preferably 20 to 60 mN / m. Furthermore, 25-45 mN / m is preferable. The viscosity of the inkjet ink of the present invention is preferably 30 mPa · s or less. Furthermore, it is more preferable to adjust to 20 mPa · s or less. Examples of surfactants include fatty acid salts, alkyl sulfate esters, alkyl benzene sulfonates, alkyl naphthalene sulfonates, dialkyl sulfosuccinates, alkyl phosphate ester salts, naphthalene sulfonate formalin condensates, polyoxyethylene alkyl sulfates. Anionic surfactants such as ester salts, polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin fatty acid ester Nonionic surfactants such as oxyethyleneoxypropylene block copolymers are preferred. Further, SURFYNOLS (trade name, manufactured by Air Products & Chemicals) which is an acetylene-based polyoxyethylene oxide surfactant is also preferably used. An amine oxide type amphoteric surfactant such as N, N-dimethyl-N-alkylamine oxide is also preferred. Further, pages (37) to (38) of JP-A-59-157,636, Research Disclosure No. The surfactants described in 308119 (1989) can also be used.

  As the antifoaming agent, fluorine-based, silicone-based compounds, chelating agents represented by EDTA, and the like can be used as necessary.

  As described above, the ink of the present invention preferably contains an aqueous medium. The aqueous medium contains water as a main component, and if desired, a mixture to which a water-miscible organic solvent is added can be used. Examples of the water-miscible organic solvent include alcohols (eg, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, t-butanol, pentanol, hexanol, cyclohexanol, benzyl alcohol), polyvalent Alcohols (eg, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol), glycol derivatives (eg , Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl Ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, ethylene glycol diacetate, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether , Triethylene glycol monoethyl ether, ethylene glycol monophenyl ether), amine (for example, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenetriamine) , Triethylenetetramine, polyethyleneimine, tetramethylpropylenediamine) and other polar solvents (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, sulfolane, 2-pyrrolidone, N-methyl- 2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, acetonitrile, acetone). In addition, the said water miscible organic solvent may use 2 or more types together.

  Regarding the method for preparing the ink for ink jet recording, JP-A-5-148436, JP-A-5-295212, JP-A-7-97541, JP-A-7-82515, JP-A-7-118584, JP-A-11-286637, Details are described in JP-A-11-286737, Japanese Patent Application Nos. 2000-87539, 2000-80259, 2000-78491, and 2000-203857, and are also used for preparing the ink of the present invention. it can.

In the ink of the present invention, the near-infrared absorbing compound is preferably contained in an amount of 0.2 to 20% by mass, and more preferably 0.1 to 10% by mass. In the ink of the present invention, other dyes may be used in combination with the near infrared absorbing compound. When using 2 or more types of pigment | dyes together, it is preferable to make the sum total of content of a pigment | dye into the said range.
When forming a single color image or a full color image, the near infrared absorbing dispersion liquid of the present invention may contain a visible absorbing dye or pigment used in these inks, Or the ink by the near-infrared absorption dispersion liquid of this invention may be used with these inks. Here, in order to form a full-color image, magenta color ink, cyan color ink, and yellow color ink are exemplified, and in order to adjust the color tone, black color ink is further exemplified.

  The recording medium to which the ink of the present invention can be applied is not particularly limited, and various non-absorbent resin materials used for ordinary non-coated paper, coated paper, so-called soft packaging, or a film-like material. It is possible to use a molded resin film. Examples of paper include pure white roll paper, kraft paper, paperboard, fine paper, OCR paper, art paper, coated paper, mirror coated paper, condenser paper, paraffin paper, and the like. Polyester, polypropylene, cellophane, acetate, vinyl chloride A composite paper substrate such as a processed paper in which a plastic film such as polycarbonate or acrylic, or a metal such as copper or aluminum is combined may be used. Examples of the various plastic films include PET film, OPS film, OPP film, ONy film, PVC film, PE film, and TAC film.

  Hereinafter, the present invention will be described in more detail with reference to examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

Synthesis example 1
[Preparation of Exemplified Compound (D-17)]
Exemplified compound (D-17) was prepared according to the following scheme.
In the present specification, Pr represents a propyl group.

  First, a diketopyrrolopyrrole compound (DPP) was synthesized according to a method described in US Pat. No. 5,969,154 using 4- (2-ethylhexyloxy) benzonitrile as a raw material.

3 grams (1 molar equivalent) of a diketopyrrolopyrrole compound and 1.6 grams (2.5 molar equivalent) of 2-benzothiazole acetonitrile are stirred in 60 mL of toluene, and 6.5 grams (8 molar equivalents) of phosphorus oxychloride are added. In addition, the mixture was heated to reflux for 4 hours. After cooling to room temperature (25 ° C.), 50 mL of chloroform and 20 mL of water were added, and the mixture was further stirred for 30 minutes. The organic layer was taken out by a liquid separation operation and washed with an aqueous sodium hydrogen carbonate solution, and then the solvent was distilled off under reduced pressure. The obtained crude product was purified by silica gel column chromatography (solvent chloroform) and recrystallized using chloroform / acetonitrile solvent to obtain 3.3 g of the target compound (D-17) in a yield of 70%. It was.
¹ H-NMR (CDCl ₃ ): δ 0.9-1.0 (m, 12H), 1.35-1.6 (m, 16H), 1.8 (m, 2H), 3.95 (d, 4H), 7.1 (d, 4H), 7.4-7.5 (m, 4H), 7.7 (d, 4H), 7.75 (d, 2H), 8.0 (d, 2H) )

Synthesis example 2
[Preparation of Exemplary Compound (D-10)]
Exemplified compound (D-10) was prepared according to the above scheme.
Titanium chloride (0.9 mL, 3 molar equivalents) was added to a toluene solution (1.2 M) of diphenylborinic acid 2-aminomethyl ester (1.4 g, 3 molar equivalents) and stirred for 30 minutes at an external temperature of 100 ° C. did. Next, the toluene compound liquid (0.2M) of exemplary compound (D-17) (2.3g) was added, and also it stirred on heating-reflux conditions for 2 hours. When the mixture was cooled to room temperature and methanol was added, crystals were precipitated. The crystals were separated by filtration and recrystallized from chloroform / methanol to obtain 3.0 g of Exemplified Compound (D-10) in a yield of 93%.
λmax was 779 nm in chloroform. The molar absorption coefficient was 2.06 × 10 ⁵ dm ³ / mol · cm in chloroform.
¹ H-NMR (CDCl ₃ ): δ 0.9-1.0 (m, 12H), 1.35-1.6 (m, 16H), 1.8 (m, 2H), 3.85 (d, 4H), 6.45 (s, 8H), 7.0 (d, 4H), 7.15 (m, 12H), 7.2 (m, 2H), 7.25 (m, 4H + 4H), 7. 5 (m, 2H)

Synthesis example 3
[Preparation of exemplary compound (D-28)]
Exemplified compound (D-28) was prepared in the same manner except that the raw materials were changed. ¹ H-NMR whose structure has been identified is shown.
Exemplary compound (D-28)
¹ H-NMR (CDCl ₃ ): δ 1.9 (s, 6H), 6.65 (d, 2H), 6.7-6.8 (m, 6H), 6.95 (m, 8H), 7 0.0-7.1 (m, 4H), 7.25-7.35 (m, 12H), 7.5 (m, 2H), 7.85 (d, 2H)
λmax was 752 nm in chloroform. The molar absorption coefficient was 1.53 × 10 ⁵ dm ³ / mol · cm in chloroform.
In addition, the solution absorption spectrum of exemplary compound (D-10) and (D-28) is shown in FIG.
It was found that Exemplified compounds (D-10) and (D-28) were both excellent in near-infrared light absorption, small in absorption at 400 to 500 nm, and very invisible.

Synthesis example 4
[Preparation of exemplary compound (D-133)]
Exemplified compound (D-133) was prepared in the same manner as described above except that the raw materials were changed. The structure identified ¹ H-NMR is shown.
Exemplary compound (D-133)
¹ H-NMR (CDCl ₃ ): δ 0.9-1.0 (m, 12H), 1.35-1.6 (m, 16H), 1.8 (m, 2H), 3.85 (d, 4H), 6.4 (m, 4H), 6.5-6.65 (m, 8H), 7.1 (d, 2H), 7.15-7.3 (m, 4H), 7.65 (D, 2H)
λmax was 716 nm in chloroform. The molar absorption coefficient was 1.24 × 10 ⁵ dm ³ / mol · cm in chloroform.

Synthesis example 5
[Preparation of exemplary compound (D-143)]
Exemplified compound (D-143) was prepared in the same manner except that the raw materials were changed. D-143 had low solubility in DMSO and chloroform, and ¹ H-NMR measurement was difficult. The result of the structure-identified MALDI-MASS spectrum is shown. Calculated value: [M +] = 1100.42, measured value: [M−H] = 1099.5

Synthesis Example 6
[Preparation of exemplary compound (D-147)]
Exemplified compound (D-147) was prepared in the same manner as described above except that the raw materials were changed. The structure identified ¹ H-NMR is shown.
Exemplary compound (D-147)
¹ H-NMR (CDCl ₃ ): δ 0.9-1.0 (m, 12H), 1.35-1.6 (m, 64H), 1.8 (m, 2H), 3.85 (d, 4H), 6.45 (s, 8H), 7.0 (d, 4H), 7.15 (m, 12H), 7.2 (m, 2H), 7.25 (m, 4H + 4H), 7. 5 (m, 2H)
λmax was 779 nm in chloroform. The molar absorption coefficient was 1.60 × 10 ⁵ dm ³ / mol · cm in chloroform.

Example 1
(Production of aqueous dispersed fine particles of near-infrared absorbing compound)
Water was added to the near-infrared absorbing compound and dispersant of the types and parts by mass shown in Table 1 below to make 500 parts by mass. To this, 500 parts by mass of 0.1 mmφ zirconia beads were added, treated with a planetary ball mill at 300 rpm for 5 hours, the beads were separated by filtration, and aqueous dispersions A-1 to A-8 composed of fine particles. Was made. The absorption spectra of dispersions A-1, A-4, A-7, and A-8 normalized by the maximum absorption wavelength are shown in FIGS. As shown in FIG. 2 and FIG. 3, all of A-1, A-4, A-7, and A-8 have an absorbance at 550 nm of 0.1 or less, have almost no absorption in the visible absorption region, and are high. It was found to have invisibility. In addition, the absorption in the infrared region was found to be very sharp.
Moreover, the particle size of the fine particles in the aqueous dispersions A-1 to A-8 was measured with a Nanotrac UPA particle size analyzer (UPA-EX150, trade name, manufactured by Nikkiso Co., Ltd.). The average particle size is shown in Table 1 below. As shown in Table 1, A-1 to A-8 were fine particle dispersions having an average particle size of 50 nm or less.

(Evaluation of storage stability of aqueous dispersions)
The aqueous dispersion A-1 was placed under conditions of 4 ° C., 25 ° C., and 60 ° C. for 14 days, and changes in dispersion viscosity, average particle size, and HPLC purity were measured. Each result is shown in FIGS.

  As shown in FIGS. 4 to 6, the dispersion viscosity, average particle diameter, and HPLC purity of the aqueous dispersion A-1 hardly change in 14 days, and the storage stability of the aqueous dispersion A-1 is excellent and high. I understood it.

Example 2
(Create water-based ink and apply to paper)
Polyester urethane resin R9660 (trade name, manufactured by Enomoto Kasei) is added to the aqueous dispersion A-1, so that the solid content concentration of D-10 is 1% by mass and the solid content concentration of R9660 is 3% by mass. A water-based ink was prepared by diluting with water.
The prepared water-based ink was placed on a commercial photomat paper with a bar coater No. 3 was applied to obtain a coated sample B-1. The reflection spectrum of the coating sample B-1 is shown in FIG.

  As shown in FIG. 7, the coated sample B-1 has a low average reflectance of 800 to 850 nm as low as 10% and a high average reflectance in the visible region of 450 nm to 650 nm as high as 71%. The boundary was not visually noticeable. Further, when observed with a CCD camera equipped with a visible light cut filter, the boundary between the coated part and the non-coated part could be clearly recognized.

Comparative Example 1
Using the naphthalocyanine compound (R-1) used in Patent Document 5, an aqueous dispersion A-6 was prepared in the same manner as A-1 in Example 1, and a polyester urethane resin R9660 (trade name) And then diluted with water so that the solid content concentration of R-1 is 1% by mass and the solid content concentration of R9660 is 3% by mass to prepare an aqueous ink.

  The prepared water-based ink was placed on a commercial photomat paper with a bar coater No. 3 was applied to obtain a coated sample (B-2). In the coated sample (B-2), the average reflectance at 800 to 850 nm was 16%, and the average reflectance in the visible region at 450 nm to 650 nm was 58%. From the above, it was found that the coating sample B-1 of the present invention was very invisible compared with the comparative sample B-2.

Example 3
(Inkjet printing ink creation and inkjet printing on paper)
To 80 parts by mass of the aqueous dispersion A-1, 5 parts by mass of glycerin, 10 parts by mass of triethylene glycol monobutyl ether and 5 parts by mass of 2-pyrrolidone are added, and the solid content concentration of D-10 is 2.4% by mass. An aqueous ink jet recording ink was prepared.
The prepared ink-jet ink was filled into an empty ink cartridge, and printed on photomat paper with an ink-jet printer (PX-V630, trade name, manufactured by Seiko Epson Corporation) to obtain an ink-jet print sample C-1. The reflection spectrum of C-1 is shown in FIG.

  As shown in FIG. 8, since the inkjet print sample C-1 has a low reflectance of 800 to 850 nm and a high reflectance in the visible region, the boundary between the coated part and the non-coated part was not noticeable at all. Further, when observed with a CCD camera equipped with a visible light cut filter, the boundary between the coated part and the non-coated part could be clearly recognized.

Comparative Example 2
An aqueous inkjet recording ink was prepared in the same manner as in Example 2 except that the aqueous dispersion was changed from A-1 to A-6, and an inkjet printing sample C-2 was obtained using the ink.

(Light resistance test)
The obtained coated sample B-1, ink jet printing sample C-1, and comparative samples B-2 and C-2 were each irradiated with a 220,000 lux xenon lamp for 48 hours. Table 2 shows changes in the minimum reflectance at 800 to 850 nm before and after irradiation. The residual rate was calculated by converting the reflectance value into absorbance. That is, the residual ratio was calculated as (absorbance after irradiation) / (absorbance before irradiation) × 100.

  As can be seen from Table 2, Sample B-1 of the present invention is superior in light resistance to Comparative Example Sample B-2. Moreover, the inkjet printing sample C-1 of this invention is excellent in light resistance with respect to the comparative example sample C-2.

  From the above results, it can be seen that the coating film prepared from the near-infrared absorbing dispersion of the present invention has good near-infrared absorptivity and invisibility. In addition, the near-infrared absorbing dispersion of the present invention has excellent storage stability, and the printed matter on which the ink using the dispersion is applied has high light resistance. By using the near-infrared absorbing dispersion liquid of the present invention, it is possible to prepare a good near-infrared-absorbing aqueous ink and ink jet recording ink that can produce a printed matter having good near-infrared absorptivity and invisibility.

Claims (11)

A near-infrared absorbing dispersion liquid in which a near-infrared absorbing compound represented by the following general formula (1) is finely dispersed in a dispersion medium.

(Wherein, R ^1a and R ^1b may be the same or different, and each independently represents an alkyl group, or an alkyl group, an aryl group, a branched alkoxy group, an acyloxy group, an acylamino group, an alkylthio group, a hydroxy group, R ² and R ³ each independently represents a hydrogen atom, a cyano group, an acyl group, an alkyl , or an aryl group or a heteroaryl group which may have a substituent selected from the group consisting of a halogen atom and a cyano group Represents an oxycarbonyl group, an aryloxycarbonyl group, an alkylsulfonyl group, an arylsulfonyl group, a sulfamoyl group, a sulfinyl group, a carboxyl group or a heterocyclic group, at least one of which is an electron-withdrawing group having a Hammett σp value of 0.2 or more There, ^{R 2} and ^{R 3} may be bonded to form a ring .R ⁴ is hydrogen, a Kill group, an aryl group, a heteroaryl group, a substituted boron (substituent of the substituted boron halogen atom, an alkoxy group, an aryloxy group, an alkyl group, an aryl group or a heteroaryl group) or an metal atom, R ^1a , ^{R 1b} and / or ^{R 3} and covalent or may be coordinate bond.) The near-infrared absorbing dispersion liquid according to claim 1, wherein R ⁴ is the substituted boron.   The near-infrared absorbing dispersion liquid according to claim 1, wherein the dispersion medium is an aqueous solvent.   The near-infrared absorbing dispersion liquid according to any one of claims 1 to 3, wherein an average particle diameter of the fine particles is 0.5 µm or less.   The near-infrared absorbing dispersion liquid according to any one of claims 1 to 4, wherein the maximum absorption wavelength is 700 nm to 1000 nm.   The near-infrared absorbing dispersion liquid according to any one of claims 1 to 4, wherein the absorbance at 550 nm is 1/5 or less of the absorbance at the maximum wavelength.   An ink comprising the near-infrared absorbing dispersion liquid according to any one of claims 1 to 6.   An ink for ink-jet recording comprising the near-infrared absorbing dispersion liquid according to any one of claims 1 to 6.   The printed matter which printed the near-infrared absorption image using the ink of Claim 7.   The printed matter which printed the near-infrared absorption image using the ink for inkjet recording of Claim 8. A method for producing a near-infrared absorbing dispersion, which comprises dispersing a near-infrared absorbing compound represented by the following general formula (1) in a dispersion medium in fine particles.

(Wherein, R ^1a and R ^1b may be the same or different, and each independently represents an alkyl group, or an alkyl group, an aryl group, a branched alkoxy group, an acyloxy group, an acylamino group, an alkylthio group, a hydroxy group, R ² and R ³ each independently represents a hydrogen atom, a cyano group, an acyl group, an alkyl , or an aryl group or a heteroaryl group which may have a substituent selected from the group consisting of a halogen atom and a cyano group Represents an oxycarbonyl group, an aryloxycarbonyl group, an alkylsulfonyl group, an arylsulfonyl group, a sulfamoyl group, a sulfinyl group, a carboxyl group or a heterocyclic group, at least one of which is an electron-withdrawing group having a Hammett σp value of 0.2 or more There, ^{R 2} and ^{R 3} may be bonded to form a ring .R ⁴ is hydrogen, a Kill group, an aryl group, a heteroaryl group, a substituted boron (substituent of the substituted boron halogen atom, an alkoxy group, an aryloxy group, an alkyl group, an aryl group or a heteroaryl group) or an metal atom, R ^1a , ^{R 1b} and / or ^{R 3} and covalent or may be coordinate bond.)

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