JP2022148277A - Fluid dispersion, ink composition, and printed matter - Google Patents

Abstract

To provide an ink composition discharged by inkjet system, which prevents luminosity of a fluorescent material from being lost and has high discharge stability.SOLUTION: An ink composition discharged by inkjet system includes water, an organic solvent, and a fluorescent emission complex containing a rare earth metal element. The organic solvent contains an organic solvent A having a higher boiling point than water. The fluorescent emission complex is dispersed in the ink composition.SELECTED DRAWING: Figure 1

Description

The present invention relates to dispersions, ink compositions, and printed matter.

2. Description of the Related Art Printed materials requiring security, such as lottery tickets, gift certificates, transit tickets, tickets, and other valuable securities, printed with information patterns composed of numbers, characters, figures, symbols, pictures, etc., are known.

In such printed materials, theft and damage caused by fraudulent copying of printed materials using copiers have become a social problem. there is

For example, Patent Documents 1 to 5 describe techniques related to ink compositions dissolved in fluorescent dyes. However, these ink compositions are prepared by dissolving the fluorescent dye, but the problem is that the dissolved dye has poor light resistance, heat resistance, chemical resistance, and the like.

Further, Patent Documents 6 to 8 describe techniques related to ink compositions containing resins colored with fluorescent dyes. However, these ink compositions use dyes (fluorescent dyes) as phosphors, and have the problem of being extremely weak in light resistance and chemical resistance.

JP 2003-261804 A Japanese Patent Application Laid-Open No. 2008-303196 JP 2010-215686 A JP 2019-056111 A JP 2018-095750 A JP 2013-241565 A JP 2014-047227 A JP 2016-035047 A

Since the inkjet method does not require a printing plate and is compatible with digital printing, it is a printing method that allows the printing pattern to be freely changed. Since such an ink jet method can freely change the printing pattern, it is particularly useful as an ink composition for producing printed matter that requires security.

However, since the ink composition ejected by the inkjet method is ejected from an inkjet nozzle, ejection stability is required. In the ink composition dissolved in the fluorescent dye as described above, the fluorescent dye in the dissolved state in the ink composition is decomposed and the luminescence is lost. In some cases, stability decreased.

Furthermore, when the phosphor contains a metal element, luminescence may disappear due to changes in the physical or chemical environment around the metal element. According to the present invention, the phosphor dissolved in a solvent (water or organic solvent) may lose its light emission mechanism due to changes in the physical or chemical environment, and the phosphor may lose its light emission. It was clarified by their research.

An object of the present invention is to provide an ink composition that suppresses the loss of the luminescent property of a phosphor and has high ejection stability even when the ink composition is ejected by an inkjet method.

As a result of intensive studies by the present inventors in order to solve the above problems, it has been found that an ink composition containing an organic solvent A having a boiling point higher than that of water and having a fluorescent light-emitting complex containing a rare earth metal element dispersed therein , found that the above problems can be solved, and completed the present invention. Specifically, the present invention provides the following.

(1) An ink composition that is ejected by an inkjet method, and contains water, an organic solvent, and a fluorescent light-emitting complex containing a rare earth metal element, and the organic solvent is an organic solvent having a boiling point higher than that of water. An ink composition containing a solvent A, wherein the fluorescent light-emitting complex is dispersed in the ink composition.

(2) The ink composition according to (1), wherein the organic solvent A has a flash point of 40° C. or higher and a boiling point of 250° C. or lower.

(3) The ink composition according to (1) or (2), wherein the fluorescence emission complex has a median diameter D50 of 5 μm or less.

(4) The rare earth metal element consists of Eu ³⁺ , Eu ²⁺ , Tb ³⁺ , Sm ³⁺ , Yb ³⁺ , Nd ³⁺ , Er ³⁺ , Pr ³⁺ , Tm ³⁺ , Dy ³⁺ , Ce ³⁺ , Ho ³⁺ and Gd ³⁺ The ink composition according to any one of claims 1 to 3, containing at least one selected from the group.

(5) A dispersion used for producing the ink composition according to any one of (1) to (4), wherein the fluorescence-emitting complex is dispersed in the dispersion.

(6) A printed matter in which a printed layer of the ink composition according to any one of (1) to (4) is formed on the surface of a substrate.

(7) The printed matter according to (6), wherein the substrate is an absorbent substrate, and at least a portion of the ink composition is absorbed by the absorbent substrate.

(8) The printed matter according to (6) or (7), wherein the substrate does not contain a brightening agent.

(9) The printed matter according to (6) or (7), wherein the substrate contains a whitening agent, and the ink composition contains a fluorescent complex that does not emit blue light.

(10) An overcoat layer is provided on the surface of the printed layer, and the total light transmittance of the overcoat layer measured according to JIS K 7361-1 is 50% or more. Any printed matter described.

(11) The printed matter according to any one of (6) to (10), wherein the color of the substrate and the color of the information pattern on the printed layer are the same.

(12) A recording method comprising ejecting the ink composition according to any one of (1) to (4) onto the surface of a substrate by an inkjet method.

(13) A method for producing a printed matter, comprising ejecting the ink composition according to any one of (1) to (4) onto the surface of a substrate by an inkjet method.

According to the present invention, even if the ink composition is ejected by an inkjet method, it is an ink composition that suppresses the loss of the luminescent property of the phosphor and has high ejection stability.

FIG. 2 is a plan view showing an example of printed matter according to the embodiment; 2 is a cross-sectional view of the print of FIG. 1 along line XX; FIG.

Hereinafter, specific embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments at all, and can be implemented with appropriate modifications within the scope of the purpose of the present invention. can do.

≪1. Outline of the present invention>>
The ink composition according to the present embodiment is an ink composition that is ejected by an inkjet method, and contains water, an organic solvent having a boiling point higher than that of water, and a fluorescent complex containing a rare earth metal element. and an ink composition in which a fluorescent light-emitting complex is dispersed.

With such an ink composition, it is possible to suppress the loss of the luminescent property of the phosphor and improve the ejection stability of the ink composition.

≪2. Dispersion≫
Prior to the description of the ink composition according to the present embodiment, the dispersion used in the production of the ink composition will be described below. The dispersion liquid according to the present embodiment is a dispersion liquid in which a fluorescence-emitting complex containing a rare earth metal element is dispersed. Thus, by dispersing the fluorescent light-emitting complex in the dispersion liquid, it is possible to suppress the loss of the luminescent property of the phosphor (fluorescent light-emitting complex) and to produce an ink composition with high ejection stability. .

Dispersion is a state of suspension in a dispersion liquid, unlike dissolution, in which a solute is uniformly mixed in a solvent. Specifically, the median diameter D50 of the fluorescence-emitting complex is a predetermined value or more, for example, 0.01 μm or more.

The dispersion medium for dispersing the fluorescence-emitting complex is not particularly limited, and may be, for example, water, an organic solvent, or a mixture thereof. Above all, it is preferable to use a dispersion medium containing an organic solvent as the dispersion medium for dispersing the fluorescence-emitting complex. As a result, the dispersibility of the fluorescence-emitting complex can be improved, and the ejection stability in inkjet ejection can be improved. Further, by using a dispersion medium containing an organic solvent containing organic solvent A having a boiling point higher than that of water, it is possible to adjust the drying property of the dispersion, further improving the storage stability of the dispersion. can be made In addition, by using a dispersion medium containing an organic solvent, it is possible to improve miscibility during preparation of the ink composition, and it is possible to obtain an ink composition having excellent storage stability and ejection stability. can.

[Fluorescence emission complex]
The fluorescence emitting complex contains a rare earth metal element. When this fluorescence-emitting complex absorbs light and reaches an energy excited state, it emits light by emitting energy corresponding to the energy bandgap as light. Typically, a simple light source such as a black light (a light that uses a light source that emits ultraviolet light) can be used as an excitation source to authenticate luminescence with the human eye.

The ligand that coordinates to the rare earth ion is selected from phosphine oxide compounds, oxygen-containing aromatic heterocyclic compounds, nitrogen-containing aromatic heterocyclic compounds, sulfur-containing aromatic heterocyclic compounds, diketo compounds, and halogenated diketo compounds. It preferably contains at least one organic ligand.

一般式（１）中、Ａｒ^１及びＡｒ^２は、それぞれ独立に、置換基を有していてもよい一価の芳香族基である。一般式（１）中、Ａｒ^３は、下記一般式（２ａ）、（２ｂ）及び（２ｃ）で表される二価の基であり、ｎは１又は２である。 Phosphine oxide compounds include those containing a phosphine oxide ligand represented by the following general formula (1).

In general formula (1), Ar ¹ and Ar ² are each independently a monovalent aromatic group optionally having a substituent. In general formula (1), Ar ³ is a divalent group represented by general formulas (2a), (2b) and (2c) below, and n is 1 or 2.

（前記一般式（２ａ）～（２ｃ）中、Ｒ^１はそれぞれ独立に一価の置換基であり、Ｘは硫黄原子又は酸素原子であり、Ｒ^２は、水素原子又は炭化水素基であり、ｍは、０から、Ｒ^１が結合する環における置換可能な部位までの整数である。ｍが２以上の整数である場合、Ｒ^１はそれぞれ同一であってもよく、異なっていてもよい。）

(In general formulas (2a) to (2c) above, R ¹ is each independently a monovalent substituent, X is a sulfur atom or an oxygen atom, R ² is a hydrogen atom or a hydrocarbon group, m is an integer from 0 to a substitutable site on the ring to which R ¹ is bonded, and when m is an integer of 2 or more, each R ¹ may be the same or different. )

E in formula (1) is a hydrogen atom or a phosphine oxide group represented by the following formula (3).

（一般式（３）中、Ａｒ^４及びＡｒ^５はそれぞれ独立に、置換基を有していてもよい一価の芳香族基である。）

(In general formula (3), Ar ⁴ and Ar ⁵ are each independently a monovalent aromatic group which may have a substituent.)

Examples of oxygen-containing aromatic heterocyclic compounds include compounds such as oxol, pyran, 2-pyrone, 4-pyrone, chromene, isochromene, xanthene, and oxepin.

Nitrogen-containing aromatic heterocyclic compounds include, for example, pyrrole, pyridine, 2-methylpyridine, 2,4,6-trimethylpyridine, 4-dimethylaminopyridine, 2,6-lutidine, pyrimidine, pyridazine, pyrazine, oxazole, imidazole , isoxazole, thiazole, isothiazole, imidazole, 1,2-dimethylimidazole, 3-(dimethylamino)propylimidazole, pyrazole, furazane, pyrazine, quinoline, isoquinoline, purine, 1H-indazole, quinazoline, cinnoline, quinoxaline, phthalazine , pteridine, phenanthridine, 2,6-di-t-butylpyridine, 2,2′-bipyridine, 4,4′-dimethyl-2,2′-bipyridyl, 4,4′-dimethyl-2,2′ -bipyridyl, 5,5'-dimethyl-2,2'-bipyridyl, 6,6'-t-butyl-2,2'-dipyridyl, 4,4'-diphenyl-2,2'-bipyridyl, 1,10 -phenanthroline, 2,7-dimethyl-1,10-phenanthroline, 5,6-dimethyl-1,10-phenanthroline, 4,7-diphenyl-1,10-phenanthroline, carbazole, benzo-C-cinnoline, triazole, tetrazole , benzimidazole, benzotriazole and the like.

Examples of sulfur-containing aromatic heterocyclic compounds include tris[1,1,1,5,5,5-hexafluoro-2,4-butanedione 4,4,4,-trifluoro-1-(2-thienyl )-1,3-butanedione], tris[4,4,4,-trifluoro-1-(2-thienyl)-1,3-butanedione], benzothiophene, thiophene, thiepine, thiapyran, thiazole, thiazine, etc. containing compounds can be mentioned.

Examples of diketo compounds include α-, β-, γ-diketone compounds (also called dicarbonyl compounds) such as acetylacetone, trifluoroacetylacetone, hexafluoroacetylacetone, benzoylacetone, and benzoyltrifluoroacetone.

The rare earth metal element contained in the rare earth complex is preferably one capable of forming a complex with the above ligands, and among them, Eu ³⁺ , Eu ²⁺ , Tb ³⁺ , Sm ³⁺ , Yb ³⁺ , Nd ³⁺ , Er ³⁺ , Pr ³⁺ , Tm ³⁺ , Dy ³⁺ , Ce ³⁺ , Ho ³⁺ and Gd ³⁺ .

Specific examples of the complex include (M(CH3COCHCOCH3) ₃ ( _H2O ) _n , M( _hfa ) ₃ ( _H2O ) _n , M(hfa) ₃ ( _{TPPO)2 ,} M(btfa ) ₃ (H ₂ O) _n , M(btfa) ₃ (TPPO) ₂ , [M(hfa) ₃ (dpbp)] _n etc. (M=Eu, Tb, Sm, Yb, Nd, Er, Pr, Tm, ion of at least one rare earth metal element selected from the group consisting of Dy, Ce, Ho, and Gd, hfa = hexafluoroacetylacetone, TPPO = triphenylphosphine oxide, btfa = benzoyltrifluoroacetone, dpbp = biphenyl-4,4 ′-Diylbis(diphenylphosphine oxide)).The complex constituting the fluorescence emission complex is preferably a mononuclear complex or a polynuclear complex (also called complex polymer or polymer complex).Complex polymer. , the different metals and ligands can be arbitrarily combined in the repeating units of the polymer.

The particle diameter (median diameter D50) of the rare earth complex is preferably 5 μm or less. This can reduce the possibility of the rare earth complex settling and improve the ejection stability of the ink composition. Since the rare earth complex has ligands, it interacts with the dispersant and the dispersion medium to improve its dispersibility, so it is presumed that the possibility of sedimentation can be reduced. Therefore, a wide range of dispersion media can be selected for the dispersion liquid according to the present embodiment. The particle diameter (median diameter D50) of the rare earth complex is more preferably 3 μm or less, and even more preferably 1 μm or less. The median diameter D50 of the rare earth complex is preferably 0.01 μm or more, more preferably 0.1 μm or more. The particle diameter (median diameter D50) of the rare earth complex can be measured by, for example, "Microtrack" by Microtrack Bell, "FPAR" by Otsuka Electronics, "Partica" by HORIBA, and the like.

The content of the fluorescent light-emitting complex in the dispersion is not particularly limited as long as it is an amount that can be dispersed in the dispersion. More preferably, it is 15.0% by mass or more, and most preferably 15.0% by mass or more. The content of the dispersant is preferably 40.0% by mass or less, more preferably 35.0% by mass or less, and most preferably 30.0% by mass or less in the total amount of the dispersion.

[Organic solvent]
The dispersion may contain an organic solvent. The organic solvent is a dispersion medium for the dispersion liquid according to this embodiment, and is capable of dispersing the fluorescence-emitting complex. The organic solvent contains an organic solvent A having a boiling point higher than that of water. By containing the organic solvent A having a boiling point higher than that of water in the dispersion, good storage stability can be maintained. Furthermore, the ink composition obtained from the dispersion necessarily contains the organic solvent A, which has a boiling point higher than that of water. It is possible to effectively prevent the matter from drying and the solid content containing the fluorescence-emitting complex from sticking in the nozzle. As a result, it is possible to suppress missing or bending of the nozzles of the inkjet head, so that ejection stability in inkjet ejection can be improved.

The content of the organic solvent A having a boiling point higher than that of water is preferably 5.0% by mass or more, more preferably 10.0% by mass or more, and 15.0% by mass or more in the total amount of the dispersion. It is more preferable that the content is 20.0% by mass or more.

Further, the organic solvent is preferably a water-soluble organic solvent because the dispersion according to the present embodiment is a dispersion used for producing a water-based ink composition which will be described later. In this specification, the water-soluble organic solvent is 5 parts by mass or more, preferably 20 parts by mass or more, more preferably 50 parts by mass or more, and still more preferably 100 parts by mass of water at 25°C under 1 atmosphere. A substance that can be dissolved in an amount of 70 parts by mass or more.

Examples of organic solvents include organic solvents having a flash point of 40° C. or higher and a boiling point of 250° C. or lower. By including such an organic solvent in the dispersion liquid, it is possible to improve the ejection stability of the obtained ink composition in inkjet ejection, and also to improve the drying property of the obtained printed matter, thereby improving the production efficiency of the printed matter. be able to. Examples of such organic solvents include ethylene glycol (boiling point: 197°C), propylene glycol (boiling point: 187°C), 1,2-butanediol (boiling point: 193°C), and 2-methyl-2,4-pentane. Diol (boiling point: 198°C), dipropylene glycol (boiling point: 232°C), diethylene glycol (boiling point: 244°C), tripropylene glycol monomethyl ether (boiling point: 242°C), diethylene glycol monobutyl ether (boiling point: 231°C), triethylene Glycol monomethyl ether (boiling point: 249°C), diethylene glycol monoisopropyl ether (boiling point: 207°C), ethylene glycol mono-2-ethylhexyl ether (boiling point: 229°C), ethylene glycol monohexyl ether (boiling point: 208°C), dipropylene Glycol monomethyl ether (boiling point: 189°C), dipropylene glycol monopropyl ether (boiling point: 212°C), dipropylene glycol monobutyl ether (boiling point: 229°C), diethylene glycol dimethyl ether (boiling point: 162°C), diethylene glycol diethyl ether (boiling point: 188°C), diethylene glycol ethyl methyl ether (boiling point: 176°C), triethylene glycol dimethyl ether (boiling point: 216°C), triethylene glycol diethyl ether, propylene glycol diethyl ether, dipropylene glycol dimethyl ether (boiling point: 171°C), dipropylene glycol monomethyl ether acetate (boiling point: 209°C), diethylene glycol monobutyl ether acetate (boiling point: 247°C), 3-methoxy-3-methylbutyl acetate (boiling point: 188°C), 1,3-propanediol (boiling point: 214°C), 2-methyl-1,2-propanediol (boiling point: 123-125°C), 1,2-butanediol (boiling point: 192°C), 1,3-butanediol (boiling point: 208°C), 1,4-butane Diol (boiling point: 230°C), 1,2-pentanediol (boiling point: 210°C), 1,2-hexanediol (boiling point: 223°C), 1,5-pentanediol (boiling point: 242°C), 1,6 -hexanediol (boiling point: 250°C), 2,2,4-trimethyl-1,3-pentanediol (boiling point: 232°C), 3-methyl-1,3-butanediol (boiling point: 203°C), 2- Methyl-1,3-pentanediol (boiling point: 214° C.), 2 -ethyl-1,3-hexanediol (boiling point: 244°C), 3-methoxy-3-methyl-1-butanol (boiling point: 173°C), 3-methoxy-1-propanol (boiling point: 148-150°C), 1-methoxy-2-propanol (boiling point: 119°C), 3-methoxy-n-butanol (boiling point: 161°C), 1-dimethylformamide (boiling point: 153°C), dimethylacetamide (boiling point: 165°C), 3- Methoxy-N,N-dimethylpropionamide (boiling point: 189°C), N,N-diethylformamide (boiling point: 177°C), trimethylolethane (boiling point: 193-195°C), 2-pyrrolidone (boiling point: 245°C) , β-propiolactone (boiling point: 162°C), γ-butyrolactone (boiling point: 204°C), δ-valerolactone (boiling point: 226-229°C), N-methyl-2-pyrrolidone (boiling point: 204°C), N- Ethyl-2-pyrrolidone (boiling point: 218°C), 1,3-dimethyl-2-imidazolidinone (boiling point: 220°C), 1,4-dioxane (boiling point: 101°C) and the like can be mentioned.

The organic solvent may contain an organic solvent different from the organic solvent A having a boiling point higher than that of water. Since the ink composition also contains a large amount of an organic solvent having a boiling point lower than that of water, there is a tendency for ejection stability in inkjet ejection to decrease. Therefore, the content of the organic solvent having a boiling point lower than that of water contained in the dispersion is preferably 10.0% by mass or less, more preferably 5.0% by mass or less, more preferably 3.0% by mass, based on the total amount of the dispersion. More preferred are:

The content of the organic solvent in the dispersion is not particularly limited as long as it is an amount capable of dispersing the fluorescence-emitting complex containing the rare earth metal element. It is more preferably 55.0% by mass or more, and even more preferably 60.0% by mass or more. Moreover, it is preferably 95.0% by mass or less, more preferably 90.0% by mass or less, based on the total amount of the dispersion.

[water]
The dispersion may contain water. As water, it is preferable to use deionized water rather than containing various ions. The content of water is not particularly limited as long as it can disperse or dissolve each component.

[Dispersant]
Dispersants include, for example, polyester-based, polyacrylic-based, polyurethane-based, polyamine-based, and polycaptolactone-based main chains, and side chains containing polar groups such as amino groups, carboxy groups, sulfo groups, and hydroxy groups. and a dispersant having具体例としては、Ｃｒａｙ Ｖａｌｌｅｙ製ＳＭＡ１４４０、ＳＭＡ２６２５、ＳＭＡ１７３５２、ＳＭＡ３８４０、ＳＭＡ１０００、ＳＭＡ２０００、ＳＭＡ３０００、ＢＡＳＦジャパン社製ＪＯＮＣＲＹＬ６７、ＪＯＮＣＲＹＬ６７８、ＪＯＮＣＲＹＬ５８６、ＪＯＮＣＲＹＬ６１１、ＪＯＮＣＲＹＬ６８０、ＪＯＮＣＲＹＬ６８２、ＪＯＮＣＲＹＬ６９０、ＪＯＮＣＲＹＬ８１９、ＪＯＮＣＲＹＬ－ＪＤＸ５０５０、ＥＦＫＡ４５５０、ＥＦＫＡ４５６０、 ＥＦＫＡ４５８５、ＥＦＫＡ５２２０、ＥＦＫＡ６２３０、ルーブリゾール社製ＳＯＬＳＰＥＲＳＥ２００００、ＳＯＬＳＰＥＲＳＥ２７０００、ＳＯＬＳＰＥＲＳＥ４１０００、ＳＯＬＳＰＥＲＳＥ４１０９０、ＳＯＬＳＰＥＲＳＥ４３０００、ＳＯＬＳＰＥＲＳＥ４４０００、ＳＯＬＳＰＥＲＳＥ４６０００、ＳＯＬＳＰＥＲＳＥ４７０００、ＳＯＬＳＰＥＲＳＥ５４０００、ビックケミー社製ＢＹＫＪＥＴ－９１５０、ＢＹＫＪＥＴ－９１５１、ＢＹＫＪＥＴ－９１７０、ＤＩＳＰＥＲＢＹＫ－１６８、ＤＩＳＰＥＲＢＹＫ－１９０ , DISPERBYK-198, DISPERBYK-2010, DISPERBYK-2012, DISPERBYK-2015 and the like. Moreover, the surfactant mentioned later can also be used as a dispersing agent.

The content of the dispersing agent in the dispersion does not need to be contained (0% by mass) as long as the fluorescent complex can be dispersed in the dispersion. When it is contained, it is not particularly limited as long as it is an amount that can disperse the fluorescent light-emitting complex in the dispersion. preferable. The content of the dispersant is preferably 20.0% by mass or less, more preferably 15.0% by mass or less, based on the total amount of the dispersion.

[Other ingredients]
The dispersion liquid according to the present embodiment may further contain other components as necessary within a range that does not impair the effects of the present disclosure. Other components include, for example, antioxidants, pigments, resins, surfactants, antifoaming agents, and the like.

<<3. Dispersion manufacturing method>>
A dispersion can be prepared, for example, by dispersing each component using a paint shaker. The particle diameter (median diameter D50) of the fluorescence-emitting complex can be controlled by the dispersion conditions such as the dispersion time.

<< 4. Ink composition>>
The ink composition according to the present embodiment is an ink composition that is ejected by an inkjet method, and contains water, an organic solvent, and a fluorescent complex containing a rare earth metal element. This fluorescent light-emitting complex is then dispersed in the ink composition. By dispersing the fluorescent light-emitting complex in the ink composition in this way, it is possible to suppress the loss of the luminescent property of the phosphor (fluorescent light-emitting complex) and improve the ejection stability of the ink composition. . In addition, the ink composition ejected by the inkjet method according to the present embodiment has excellent ejection stability and storage stability, and furthermore, has good luminescence and excellent durability. It is suitable for printed materials with excellent security and security.

In addition, since the ink composition according to the present embodiment is a water-based ink composition containing water, it has little impact on the environment and is highly safe for workers because it does not catch fire. Furthermore, since it is a water-based ink composition containing water, there is little bleeding even when it is used on an absorbent substrate. In addition, the use of an absorbent substrate allows the ink composition to be absorbed to prevent tampering with the information pattern.

The organic solvent contains an organic solvent A having a boiling point higher than that of water. By containing the organic solvent A, when the ink composition is ejected by inkjet, the ink composition dries in the nozzle of the inkjet head, and the solid content containing the fluorescence emission complex is effectively prevented from sticking in the nozzle. can be suppressed to As a result, it is possible to suppress missing or bending of the nozzles of the inkjet head, so that ejection stability in inkjet ejection can be improved.

As the fluorescent light-emitting complex contained in the ink composition according to the present embodiment, the same fluorescent light-emitting complex as that contained in the dispersion liquid described above can be used.

The content of the fluorescent light-emitting complex in the ink composition according to the present embodiment is not particularly limited as long as it is an amount capable of forming an information pattern in which light emission can be authenticated by the human eye upon irradiation with predetermined ultraviolet rays. For example, it is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 1.0% by mass or more in the total amount of the ink composition. The content of the fluorescence-emitting complex in the ink composition is preferably 20.0% by mass or less, more preferably 15.0% by mass or less, and 10.0% by mass or less in the total amount of the ink composition. is more preferred.

As the organic solvent and water contained in the ink composition according to the present embodiment, the same organic solvent and water as those contained in the dispersion liquid described above can be used.

10. The content of the organic solvent in the ink composition according to the present embodiment is, for example, preferably 5.0% by mass or more, more preferably 8.0% by mass or more, based on the total amount of the ink composition. It is more preferably 0% by mass or more. Further, the total amount of the ink composition is preferably 60.0% by mass or less, more preferably 50.0% by mass or less, even more preferably 40.0% by mass or less, and 30.0% by mass. It is even more preferable that:

Examples of organic solvents include organic solvents having a flash point of 40° C. or higher and a boiling point of 250° C. or lower. By including such an organic solvent in the ink composition, it is possible to improve the ejection stability in inkjet ejection, improve the drying properties of the resulting printed matter, and improve the production efficiency of the printed matter.

The ink composition according to the present embodiment may contain an organic solvent different from the organic solvent A having a boiling point higher than that of water. Since the fluorescence-emitting complex contained in the ink composition is deposited inside the tube inside the inkjet head, there is a tendency for the ejection stability during inkjet ejection to decrease. Therefore, the content of the organic solvent having a boiling point higher than that of water is preferably 50% by mass or more, more preferably 70% by mass or more, and 90% by mass or more, based on the total amount of the organic solvent. is more preferable, and 95% by mass or more is even more preferable. When the content of the organic solvent having a boiling point higher than that of water is within such a range, ejection stability in inkjet ejection can be improved.

In addition, an organic solvent having a boiling point of more than 250 ° C. may be contained, but for example, if a large amount of an organic solvent having a boiling point lower than that of water is contained, the resulting printed matter will have a reduced drying property, and the production efficiency of the printed matter will be reduced. tends to decrease. Furthermore, if the printed matter is processed in a state in which the drying property of the printed matter is insufficient, there is a possibility that problems such as blocking may occur in the product. Therefore, the content of the organic solvent having a boiling point of over 250° C. is preferably 10.0% by mass or less, more preferably 8.0% by mass or less, and even more preferably 6.0% by mass or less in the total amount of the ink composition. .

The content of water in the ink composition according to the present embodiment is, for example, preferably 30.0% by mass or more, more preferably 40.0% by mass or more, more preferably 50.0% by mass or more, based on the total amount of the ink composition. % by mass or more is more preferable. Also, it is preferably 95.0% by mass or less, more preferably 87.0% by mass or less, and even more preferably 85.0% by mass or less in the total amount of the ink composition.

The ink composition according to this embodiment may contain a resin. By containing the resin, it is possible to suppress the penetration of the pigment into the substrate (recording medium) and promote the fixation of the fluorescence emission complex. As the resin, a resin emulsion is preferable from the viewpoint of excellent fixability and excellent water resistance of printed matter. Further, by forming a resin emulsion, the resin can be dispersed in the ink composition as fine resin particles by electrostatic repulsion or steric repulsion.

Specifically, acrylic resin, polystyrene resin, polyester resin, vinyl chloride resin, vinyl acetate resin, vinyl chloride vinyl acetate copolymer resin, polyethylene resin, urethane resin, silicone (silicon) resin, acrylamide resin, epoxy resin, or these can be used. These are preferable because they can improve not only water resistance but also solvent resistance. Among them, it is preferable that the resin contains an acrylic resin because it can be made excellent in ejection stability, water resistance, and solvent resistance.

Commercially available resin emulsions include, for example, Acryt WEM-031U, WEM-200U, WEM-321, WEM-3000, WEM-202U, WEM-3008 (manufactured by Taisei Fine Chemical Co., Ltd., acrylic-urethane resin emulsion). , Acryt UW-550CS, UW-223SX, AKW107, RKW-500 (manufactured by Taisei Fine Chemical Co., Ltd., acrylic resin emulsion), LUBRIJET N240 (manufactured by Lubrizol, acrylic resin emulsion), Superflex 150, 210, 470, 500M, 620, 650, E2000, E4800, R5002 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., urethane resin emulsion), Vinyblan 701FE35, 701FE50, 701FE65, 700, 701, 711, 737, 747 (manufactured by Nisshin Chemical Co., Ltd., chloride vinyl-acrylic resin emulsion), Vinyblan 2706, 2685 (manufactured by Nisshin Chemical Co., Ltd., acrylic resin emulsion), Movinyl 743N, 6600, 7470, 7720, (manufactured by Japan Coating Resin Co., Ltd., acrylic resin emulsion), PRIMAL AC-261P , AC-818 (manufactured by Dow Chemical Company, acrylic resin particle emulsion), etc., but are not limited to these.

The content of the resin (resin emulsion) contained in the ink composition according to the present embodiment is not particularly limited, but the lower limit of the content of the resin is 0.05% by mass or more based on the total amount of the water-based ink. It is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and more preferably 1% by mass or more. The upper limit of the resin content is preferably 15% by mass or less, more preferably 12% by mass or less, and even more preferably 10% by mass or less, based on the total amount of the aqueous ink.

The average particle size of the resin emulsion is preferably 30 nm or more, more preferably 40 nm or more, and even more preferably 50 nm or more, from the viewpoints of dispersion stability in the ink composition and ejection stability in inkjet ejection. The average particle size of the resin emulsion is preferably 300 nm or less, more preferably 270 nm or less, and even more preferably 250 nm or less, from the viewpoints of dispersion stability in the ink composition and ejection stability in inkjet ejection. In the present embodiment, the number average particle size of the pigment can be measured using a concentrated particle size analyzer (manufactured by Otsuka Electronics Co., Ltd., model: FPAR-1000) at a measurement temperature of 25°C.

From the viewpoint of film water resistance, the weight average molecular weight of the resin emulsion is preferably 10,000 or more, more preferably 50,000 or more, and even more preferably 100,000 or more. From the viewpoint of the stability of the ink composition, the weight average molecular weight of the resin emulsion is preferably 1,000,000 or less, more preferably 700,000 or less, and even more preferably 500,000 or less. In the present embodiment, the molecular weight of the resin indicates the mass average molecular weight Mw, which is a value measured by GPC (gel permeation chromatography), using "HLC-8120GPC" manufactured by Tosoh Corporation. , can be measured using a polystyrene standard for a calibration curve as a standard.

[Surfactant]
The ink composition according to this embodiment may contain a surfactant. The surfactant is not particularly limited, but anionic surfactants, nonionic surfactants, silicone (silicon) surfactants, and fluorine-based surfactants are preferred because of their excellent ability to adjust surface tension. Active agents, acetylene glycol-based surfactants, and the like are preferably used.

Specific examples include Emal, Latemul, Pelex, Neoperex, Demol (all of which are anionic surfactants; manufactured by Kao Corporation), Sunol, Liporan, Lipon, and Ripal (all of which are anionic surfactants; Lion Co., Ltd. company), Noigen, Epan, Solgen (all nonionic surfactants; Daiichi Kogyo Seiyaku Co., Ltd.) Emulgen, Amit, Emsol (all nonionic surfactants; Kao Corporation), Naloacty , Emalmin, Sannonic (all nonionic surfactants; manufactured by Sanyo Chemical Industries, Ltd.), Surfynol 104, 82, 465, 485, TG, 2502, Dynol 604, Dynol 607 (all are acetylene glycol-based surfactants agent; manufactured by Evonik), Olfine E1004, E1010, PD004, EXP4300 (all of which are acetylene glycol-based surfactants; manufactured by Nissin Chemical Industry Co., Ltd.), Megafac (fluorine-based surfactant; manufactured by DIC Corporation), Surflon (fluorosurfactant; manufactured by AGC Seimi Chemical Co., Ltd.), BYK302, 306, 307, 331, 333, 345, 346, 347, 348, 349, 3451, 3455 (all silicone (silicon) surfactants; BYK Chemie Co., Ltd.), KP-110, 112, 323, 341, 6004 (all silicone surfactants; manufactured by Shin-Etsu Chemical Co., Ltd.), Silface SAG002, Silface SAG005, Silface SAG008, Silface SAG014 , Silface SAG503A, Silface SJM-002, Silface SJM-003 (all silicone (silicon) surfactants; manufactured by Nissin Chemical Industry Co., Ltd.), TEGO Twin 4000, TEGO Twin 4100, TEGO Wet 240, TEGO Wet 250, TEGO Wet 240 (both of which are silicone surfactants; manufactured by Evonik), and the like.

The content of the surfactant is not particularly limited. It is more preferably within the range, and more preferably within the range of 0.50% by mass or more. The upper limit of the surfactant content is preferably 5.0% by mass or less, more preferably 4.0% by mass or less, and 3.0% by mass in the total amount of the ink composition. % or less is more preferable.

[Other ingredients]
The water-based ink may further contain conventionally known additives as needed. Examples of additives include waxes, viscosity modifiers, pH modifiers, antioxidants, preservatives, antifungal agents, and the like.

The use of the ink composition according to the present embodiment is not particularly limited, but since it is an ink composition with high ejection stability in inkjet ejection, it can be used for personal identification numbers (ID numbers), facial photographs, etc. It is particularly preferable to use it for printing security information that can vary from person to person.

<< 4. Manufacturing method of ink composition >>
The ink composition can be prepared, for example, by dispersing each component using a paint shaker.

This ink composition can be produced from the dispersion according to the above embodiment. Alternatively, the ink composition according to the present embodiment may be produced by directly dispersing the fluorescent light-emitting complex containing the rare earth metal element without using the dispersion liquid according to the above embodiment and containing each component. good.

<<5. Print >>
The printed matter is a laminate in which a printed layer of the above ink composition is formed on the surface of a substrate.

Examples of printed materials include bills, checks, stock certificates, corporate bonds, securities such as various securities, bank notes, merchandise certificates, transportation tickets, admission tickets to facilities and events, lotteries, and voting tickets for public competitions. Examples include tickets, stamps, cards such as credit cards, IC cards, My Number certificates, passports, identification cards, various commercial printed materials, posters, and the like.

Here, the ink composition according to the present embodiment is characterized by being ejected by an inkjet method. Since personal information such as an identification number (ID number) and a face photograph is information that varies depending on the individual, it is preferable to print the information by an ink-jet method that can freely change the printing pattern.

An example of printed matter is shown in FIGS. A printed matter 1 shown in FIG. 1 is an identification card, on which an information pattern 12 called so-called personal information, such as an individual's identification number (ID number), face photograph, etc., is printed with an ordinary ink composition. An information pattern 11 similar to the information pattern 12 is printed on the printed matter 1 with the ink composition according to the present embodiment. Although the information pattern 11 cannot be visually recognized in an environment under ordinary visible light, it becomes visible by irradiating the surface of the printed matter 1 with light emitted from the black light a. Authenticity can be determined by collating the information pattern 11 printed with the ink composition according to the present embodiment and the information pattern 12 . Further, the information pattern 12 is not limited to personal information, and may be a printed pattern.

FIG. 2 is a cross-sectional view along line XX of FIG. A printed layer 11 of the ink composition according to the present embodiment in which a fluorescent light-emitting complex is dispersed is formed (printed) together with the printed layer 12 on a part of the surface of the substrate 13 . Both surfaces of this base material 13 are sandwiched by overcoat layers 14 and 15 . The overcoat layer is a layer that protects the surface of the printed material, and is a layer that is formed, for example, by applying a conventionally known overcoat agent.

Although it is not essential to provide an overcoat layer in the printed matter according to the present embodiment, especially by providing an overcoat layer 14 on the laminated side of the printed layers 11 and 12, the printed layer (information pattern) is protected from scratches and the like. Further, it is possible to prevent the information pattern of the printed layer from being tampered with. In addition, from the viewpoint of improving the visibility of the information patterns 11 and 12, it is preferable that the overcoat layer can transmit light. % or more.

It is also a preferred embodiment that the color of the substrate 13 and/or the color of the information pattern 12 and the color of the information pattern 11 are the same. Under ordinary visible light, the information pattern 11 printed with the ink composition according to the present embodiment becomes difficult to visually distinguish, and a printed matter with higher security can be obtained. In addition, when a printed layer other than the information pattern 12 is formed in advance on the information pattern printing side of the base material 13, the color and/or the information pattern 12 of the printed layer other than the information pattern 12 and the information pattern 11 are preferably the same.

The information pattern 12 and the printed layer other than the information pattern 12 may be ejected (printed) by an inkjet method using a normal ink composition. The printed layer may be formed in the form of a laser coloring layer that is printed with.

The information pattern 11 in the printed matter 1 of FIGS. 1 and 2 is printed so as not to overlap the information pattern 12, but the information pattern printed by the ink composition according to the present embodiment and the information pattern printed by the normal ink composition The printed information pattern may partially or wholly overlap in plan view of the substrate. As a result, it is possible to increase the printing area of the information pattern printed with the ink composition according to the present embodiment, and it is possible to irradiate the surface of the printed matter with light to emit light from a larger area. .

The printed matter according to the present embodiment may be provided with other layers such as a base material layer, an adhesive layer, a primer layer, an ultraviolet absorbing layer, and the like, if necessary.

[Base material]
Examples of substrates include woodfree paper, art paper, coated paper, cast-coated paper, synthetic resin or emulsion-impregnated paper, synthetic rubber latex-impregnated paper, synthetic resin-filled paper, cellulose fiber paper, polyolefin (polyethylene , polypropylene, etc.), plastic sheets of various synthetic resins such as polystyrene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, polymethacrylate, etc., opaque films made by adding pigments and fillers to these synthetic resins, or substrates A film (so-called synthetic paper) having fine voids (microvoids) inside may be used. The substrate does not necessarily have to be in the form of a film or sheet, and may be a three-dimensional shaped resin molding or the like.

In addition, it is preferable that the substrate does not contain a whitening agent so that the ink composition can be visually recognized more clearly when irradiated with a black light. When using a substrate containing a whitening agent, it is preferable to use an ink composition in which a fluorescence-emitting complex that does not emit blue light is dispersed.

Furthermore, it is preferable to use an absorbent substrate in order to improve security by printing or printing with the ink composition. Since the ink composition is absorbed inside the base material, there is an advantage that tampering with the information pattern can be prevented. In particular, since the above ink composition is a water-based ink composition containing water, it is possible to print on an absorbent substrate with little bleeding compared to an oil-based ink composition that does not contain water. . Absorbent substrates include, for example, substrates having voids in the substrate such as paper.

<<6. Recording method using ink composition>>
The recording method according to the present embodiment is a recording method in which the ink composition described above is ejected onto the surface of a substrate by an inkjet method. The above non-aqueous ink composition has high ejection stability and can suppress the loss of the luminescent property of the phosphor. It is possible to obtain a printed matter exhibiting the properties. A method of ejecting ink by an inkjet method may be a piezo method using a piezoelectric element or a thermal method using a heating element, and is not particularly limited.

The drying conditions under which the ink composition ejected onto the surface of the substrate may be dried by the drying mechanism are appropriately set according to the boiling point of the solvent contained in the ink composition.

<<7. Method for producing printed matter using ink composition >>
A recording method using the above ink composition can also be defined as a method for producing a printed matter. Also in the method of manufacturing a printed matter according to the present embodiment, a printed matter having high ejection stability and excellent luminescence can be obtained.

The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these descriptions.

<Preparation of dispersion liquid>
The ingredients in Table 1 below were dispersed on a paint shaker. The "average particle diameter (μm)" in Table 1 is the median diameter D50, which was controlled by the dispersion time of the paint shaker. The median diameter D50 of the fluorescence-emitting complex in the ink composition (dispersion) was measured by Otsuka Electronics "FPAR-1000".

<Production of ink composition>
An ink composition was prepared by mixing the components in Table 2 below by dispersing them with a paint shaker.

In Table 1, "Phosphor A" is Lumesis E-300 (Eu(hfa) ₃ (TPPO) ₂ (Tris[1,1,1,5,5,5-hexafluoro-2, 4-Butanedionato]bis(triphenylphosphine oxide) europium(III) complex)). Phosphor A is a fluorescent complex containing a rare earth metal element.

In Table 1, "Phosphor B" includes tris[1,1,1,5,5,5-hexafluoro-2,4-butanedionato]europium (III) and biphenyl-4,4'-diylbis(diphenyl phosphine oxide). Phosphor B is a fluorescent complex containing a rare earth metal element. It was manufactured with reference to known documents such as Japanese Patent No. 4407224 and Japanese Patent No. 5904600.

In Table 1, "phosphor C" includes tris[4,4,4,-trifluoro-1-(2-thienyl)-1,3-butanedionato]europium (III) and biphenyl-4,4'- It is a complex polymer composed of diylbis(diphenylphosphine oxide). Note that the phosphor C is a fluorescence emission complex containing a rare earth metal element. It was manufactured with reference to known documents such as Japanese Patent No. 4407224 and Japanese Patent No. 5904600.

In Table 1, "Phosphor D" includes tris[1,1,1,5,5,5-hexafluoro-2,4-butanedionato]terbium (III) and biphenyl-4,4'-diylbis(diphenyl phosphine oxide). Note that the phosphor D is a fluorescence emission complex containing a rare earth metal element. It was manufactured with reference to known documents such as Japanese Patent No. 4407224 and Japanese Patent No. 5904600.

In Table 1, "Phosphor E" is a phosphor GOF-SS (ZnO:O) manufactured by Nemoto Lumimaterial Co., Ltd. Note that the phosphor E is an inorganic phosphor, not a fluorescence emission complex containing a rare earth metal element.

In Table 1, "Phosphor F" is Rhodamine B, a red-emitting organic dye.

In Table 1, "dispersant" is "SOLSPERSE27000" manufactured by Lubrizol.

In Table 2, "triethene glycol" is an organic solvent having a boiling point of 287°C.
In Table 2, "surfactant" is Olphine E1010 (a surfactant manufactured by Nissin Chemical Industry Co., Ltd.).
In Table 2, "resin" is PRIMAL AC-261P (resin emulsion manufactured by Dow Chemical Company).

In Table 2, "surfactant" is "OLFINE E1010" manufactured by Nissin Kagaku.

[Evaluation of sedimentation]
The sedimentation properties were tested for the ink compositions of Examples and Comparative Examples. Specifically, the ink composition was placed in a transparent container, and the state of sediment after storage at room temperature for 3 days was visually evaluated.

(Evaluation criteria)
◯: No sediment was observed.
Δ: A small amount of sediment is present, but it returns to a uniform state when the container is shaken.
x: Sediment is present and does not return even if the container is shaken.
○ and △ are the actual use range.

[Luminescence Evaluation]
Luminescence was evaluated for the ink compositions of Examples and Comparative Examples. Specifically, solid printing is performed using Fujifilm's inkjet printer "Material Printer DMP-2831", the printed part is irradiated with a UV lamp with an irradiation wavelength of 365 nm, and the visibility is visually evaluated for the light emission state. did.

(Evaluation criteria)
◯: Visible under indoor lighting.
Δ: Visible in a dark room.
x: Visual recognition was difficult even in a dark room.
○ and △ are the actual use range.

[Evaluation of Ejection Stability]
Ejection stability was evaluated for the ink compositions of Examples and Comparative Examples. Specifically, using the ink compositions of Examples and Comparative Examples, printing was continuously carried out in the same manner as the evaluation described above, and the ejection stability after 2 hours was evaluated based on the state of the printed matter.

(Evaluation criteria)
◯: Fine lines are correctly reproduced.
Δ: Slight bending is observed.
x: The landing position is displaced and bending is observed.
○ and △ are the actual use range.

[Drying property evaluation]
Drying properties of the ink compositions of Examples and Comparative Examples were evaluated. Specifically, using the ink compositions of Examples and Comparative Examples, the same printing as in the above evaluation was performed on coated paper (Oji Paper Co., Ltd. OK top coat +), and the ink film was touched with a finger. The drying time until the ink composition stopped adhering was measured and evaluated.
(Evaluation criteria)
◯: No adhesion of the ink composition within 5 minutes.
Δ: No adhesion of the ink composition within 10 minutes.
x: 10 minutes or more are required for drying the ink composition.
○ and △ are the actual use range.

[Light resistance evaluation]
The ink compositions of Examples and Comparative Examples were tested for lightfastness. Specifically, the ink composition was ejected onto the surface of the base material by an inkjet method to produce a printed matter in which a printed layer was formed on the surface of the base material. Then, using a xenon lamp (Atlas Ci4000 weather meter, inner filter: quartz, outer filter: soda lime & infrared absorption coating (CIRA)), the illuminance was set to 1.2 mW / m ² , and light emission before and after the irradiation test for 50 hours. The condition was visually evaluated.

(Evaluation criteria)
○: No difference in visibility before and after the test.
Δ: Light emission after the test is slightly decreased, but there is no problem with visibility.
x: The light emission after the test is clearly reduced, and the visibility is poor.
○ and △ are the actual use range.

As can be seen from Tables 1 and 2, the ink compositions of Examples in which the fluorescent light-emitting complex is dispersed suppress the loss of the luminescent property of the phosphor and have high ejection stability in inkjet ejection. It turns out that

In particular, the ink compositions of Examples 1 to 14, which did not contain an organic solvent having a boiling point of over 250° C., had better drying properties than the ink composition of Example 15.

On the other hand, the ink composition of Comparative Example 1, which does not contain an organic solvent, and the ink composition of Comparative Example 2, which does not contain an organic solvent A having a boiling point higher than that of water, have a lower ejection stability in inkjet ejection. In addition, the ink compositions of Comparative Examples 3 and 4, which did not contain an organic solvent and contained an inorganic fluorescent substance as a fluorescent substance, showed a decrease in ejection stability in inkjet ejection, and sedimentation occurred in the ink composition. Met. Further, in the ink compositions of Comparative Examples 5 and 6, in which the fluorescent light-emitting complex was dissolved in the ink composition, the luminescence after the test was clearly reduced in the light resistance evaluation, and printed matter with poor visibility was obtained. .

1 printed matter 11 information pattern (printed layer)
12 information pattern (printing layer)
REFERENCE SIGNS LIST 13 base material 14 overcoat layer 15 overcoat layer a black light

Claims (13)

An ink composition ejected by an inkjet method,
Containing water, an organic solvent, and a fluorescent emission complex containing a rare earth metal element,
The organic solvent contains an organic solvent A having a higher boiling point than water,
An ink composition, wherein the fluorescent light-emitting complex is dispersed in the ink composition. The ink composition according to claim 1, wherein the organic solvent A has a flash point of 40°C or higher and a boiling point of 250°C or lower. 3. The ink composition according to claim 1, wherein the fluorescence emission complex has a median diameter D50 of 5 μm or less. The rare earth metal element is selected from the group consisting of Eu ³⁺ , Eu ²⁺ , Tb ³⁺ , Sm ³⁺ , Yb ³⁺ , Nd ³⁺ , Er ³⁺ , Pr ³⁺ , Tm ³⁺ , Dy ³⁺ , Ce ³⁺ , Ho ³⁺ and Gd ³⁺ 4. The ink composition according to any one of claims 1 to 3, comprising at least one of A dispersion used for producing the ink composition according to any one of claims 1 to 4,
A dispersion, wherein the fluorescence-emitting complex is dispersed in the dispersion. 5. A printed matter having a printed layer of the ink composition according to any one of claims 1 to 4 formed on the surface of a substrate. the substrate is an absorbent substrate,
7. The printed matter of claim 6, wherein at least part of said ink composition is absorbed by said absorbent substrate. 8. The printed matter according to claim 6 or 7, wherein the substrate does not contain a whitening agent. The base material contains a whitening agent,
8. The printed matter according to claim 6, wherein the ink composition contains dispersed therein a fluorescence-emitting complex that does not emit blue light. An overcoat layer is provided on the surface of the printing layer,
The printed matter according to any one of claims 6 to 9, wherein the overcoat layer has a total light transmittance of 50% or more as measured according to JIS K 7361-1. The printed matter according to any one of claims 6 to 10, wherein the color of the base material and the color of the information pattern on the printed layer are the same. A recording method, wherein the ink composition according to any one of claims 1 to 4 is ejected onto the surface of a substrate by an inkjet method. A method for producing a printed matter, wherein the ink composition according to any one of claims 1 to 4 is ejected onto the surface of a substrate by an inkjet method.

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