JP2011241335A - Infrared absorptive composition, infrared absorptive ink, recorded matter, method for recording image, and method for detecting image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: an infrared absorptive composition excellent in dispersibility and dispersion stability of an infrared absorptive dye and excellent in light resistance; an infrared absorptive ink excellent in printability and enabling stable readout of image information for a long period of time; a recorded matter; a method for recording an image; and a method for detecting an image.SOLUTION: The composition includes: (A) at least one infrared absorptive dye represented by following formula (1); and (B) at least one ion of a metal belonging to group 1 or 2 of the periodic table, wherein the content of the metal ion (B) is 30 ppm or more and 10,000 ppm or less (in formula (1), Ar, Ar, Ar, Ar, Ar, Ar, Ar, and Areach independently represents an aryl group).

Description

  The present invention relates to an infrared absorbing composition, and an infrared absorbing ink, a recorded material, an image recording method, and an image detection method using the same.

  Near-infrared absorbing dyes that do not substantially absorb visible light but absorb infrared light are widely used in various optoelectronic products such as near-infrared absorbing filters.

  Optoelectronic products may be exposed to high temperatures, high humidity, or light irradiation depending on the usage mode such as outdoor use such as security-related equipment such as authentication of characters and images. For this reason, it is important that the near-infrared absorbing dye used is stable over a long period of time, and it is required to have a stability that hardly degrades performance due to decomposition over time. In particular, it is indispensable that the pigment itself has resistance to light in order to maintain high product quality for a long period of time.

  As techniques related to the above, naphthalocyanine near-infrared absorbing dyes and alkylphthalocyanine near-infrared absorbing dyes having a specific structure have been proposed as near-infrared absorbing dyes excellent in light resistance, weather resistance, and heat resistance (for example, Patent References 1-2).

  Further, as a near-infrared-absorbing ink that hardly absorbs visible light, a near-infrared-absorbing ink that is excellent in light resistance by containing a specific naphthalocyanine compound has been disclosed (for example, see Patent Document 3).

JP-A-2-43269 JP-A-2-138382 JP-A-3-79683

  However, the above-mentioned conventional infrared absorbing dyes do not have sufficient performance required for infrared absorbing dyes such as absorption wavelength and weather resistance, and further improvement in performance is required particularly with respect to light resistance.

  In addition, in the infrared absorbing ink containing the infrared absorbing dye, from the viewpoint of improving the reading accuracy by infrared light, etc., good printing characteristics such as ink coating properties are required. Further, the dispersibility and dispersion stability of the infrared absorbing dye are not sufficient, and it is difficult to obtain the required printing characteristics.

  The present invention has been made in view of the above, and is an infrared-absorbing composition excellent in dispersibility and dispersion stability of an infrared-absorbing dye and excellent in light resistance, and excellent in printing characteristics and stably over a long period of time. An object of the present invention is to provide an infrared absorbing ink, a recorded material, an image recording method, and an image detection method capable of reading image information, and to achieve the object.

Specific means for achieving the above object are as follows.
<1> (A) containing at least one infrared absorbing dye represented by the following general formula (1) and (B) at least one metal ion belonging to Group 1 or Group 2 of the periodic table. The (B) infrared ray absorbing composition having a metal ion content of 30 ppm or more and 10,000 ppm or less.

In General Formula (1), Ar ¹ , Ar ² , Ar ³ , Ar ⁴ , Ar ⁵ , Ar ⁶ , Ar ⁷ , and Ar ⁸ each independently represent an aryl group.

<2> The infrared absorbing composition according to <1>, wherein the content of the (B) metal ion is 10 ppm or more and 10,000 ppm or less.
<3> The infrared absorbing composition according to <1> or <2>, wherein the metal ion (B) is at least one selected from the group consisting of lithium, sodium, potassium, calcium, and magnesium. It is.

<4> An infrared absorbing ink containing the infrared absorbing composition according to any one of <1> to <3>.
<5> A recorded matter having an image made of the infrared absorbing ink according to <4> on a recording medium.
<6> An image recording method including a step of recording an image by applying the infrared absorbing ink according to <4> on a recording medium.
<7> An image detection method including a step of detecting image information of the image formed on the recording medium by an infrared detector by the image recording method according to <6>.

ADVANTAGE OF THE INVENTION According to this invention, the infrared absorptive composition excellent in the dispersibility and dispersion stability of an infrared absorption pigment | dye, and excellent in light resistance can be provided. Also,
According to the present invention, it is possible to provide an infrared absorbing ink, a recorded material, an image recording method, and an image detection method that have excellent printing characteristics and can stably read image information for a long period of time.

  Hereinafter, the infrared absorbing composition of the present invention, the infrared absorbing ink, the recorded matter, the image recording method, and the image detection method will be described in detail.

<Infrared absorbing composition>
The infrared absorbing composition according to the present invention includes (A) at least one infrared absorbing dye represented by the following general formula (1) (hereinafter sometimes referred to as “(A) IR dye”), and (B) at least one metal ion belonging to Group 1 or Group 2 of the Periodic Table. Content of the said (B) metal ion in the infrared rays absorptive composition of this invention is 30 ppm or more and 10000 ppm or less.

  In addition, the infrared ray absorbing composition of the present invention uses an organic solvent, a resin, a polymerizable compound other than the organic solvent, and a polymerization initiator, which will be described in detail later, according to various conditions such as use and use environment or as necessary. Further, it may be constituted by using other components such as a surfactant, a solvent, and a resin curing agent.

The infrared absorbing composition of the present invention contains the above (A) IR dye and (B) contains at least one metal ion belonging to Group 1 or Group 2 of the Periodic Table from 30 ppm to 10,000 ppm. It is presumed that the (B) metal ion in the infrared absorbing composition achieves good dispersibility and dispersion stability of the (A) IR dye in the infrared absorbing composition. And since the (A) IR pigment has good dispersibility and dispersion stability, the infrared absorbing composition can be improved in light resistance (light resistance), and the infrared absorbing composition can be improved. It is presumed that improvement of printing suitability (including coating properties) of the infrared absorbing ink can be achieved.
Further, it is presumed that a recorded matter having an image made of the infrared absorbing ink of the present invention is excellent in printing characteristics and can stably read image information for a long period of time. Furthermore, an image recording method using the infrared absorbing ink of the present invention and an image detection method including a step of detecting image information of an image formed on a recording medium by the image recording method are stable over a long period of time. It is estimated that the image information can be read.

  Details of each component will be described below.

(A) Infrared absorbing dye represented by the general formula (1) The infrared absorbing composition of the present invention is an infrared absorbing dye represented by the following general formula (1) (hereinafter referred to as (A) IR) as an infrared absorbing dye. At least one kind of dye).

In the general formula (1), Ar ¹ , Ar ² , Ar ³ , Ar ⁴ , Ar ⁵ , Ar ⁶ , Ar ⁷ , and Ar ⁸ each independently represent an aryl group. Ar ^{1 to} Ar ⁸ may be the same or different from each other.

The aryl group represented by Ar ^{1 to} Ar ⁸ may be unsubstituted or substituted, and is preferably an aryl group having 6 to 16 carbon atoms, more preferably an aryl group having 6 to 12 carbon atoms. preferable. Among these, an alkylphenyl group and / or an alkoxyphenyl group (preferably, the number of carbon atoms in the alkyl moiety is 1 to 10 is preferred). Examples of the aryl group include a phenyl group, 2,4-dimethylphenyl group, 2-methylphenyl group, 2-ethylphenyl group, 4-methoxyphenyl group, 2-methoxyphenyl group, 4-octyloxyphenyl group, 4 -T-butylphenyl group, etc. are mentioned.

  Specific examples of the (A) IR dye represented by the general formula (1) are shown below. However, the present invention is not limited to these dyes.

  The (A) IR dye contained in the infrared absorbing composition in the present invention can be synthesized using a conventionally known synthesis method.

  As content in the infrared absorptive composition of (A) IR pigment | dye contained in the infrared absorptive composition in this invention, 0.1 mass%-90 mass% with respect to the infrared absorptive composition total mass. Is preferable, and 1.0 mass%-80 mass% is more preferable. (A) When the content of the IR dye is 0.1% by mass or more, good light resistance is obtained, and excellent readability when images are recorded. This is advantageous in terms of dispersion stability.

(Infrared absorbing dyes that can be used in combination)
In addition, in addition to said (A) IR pigment | dye, the infrared absorptive pigment | dye represented by following General formula (2) can be used together with the infrared absorptive composition in this invention as an infrared absorptive pigment | dye. When the infrared absorbing dye represented by the following general formula (2) is used in combination, the content of the infrared absorbing dye represented by the following general formula (2) in the infrared absorbing composition in the present invention is: The range of 0.1 mass% or more and 50 mass% or less is mentioned.

  In the general formula (2), R represents a hydrogen atom or an aliphatic group having 1 to 12 carbon atoms, and n represents 1 or 2. X represents an anion.

  Hereinafter, specific examples of the infrared absorbing dye represented by the general formula (2) will be shown. However, the present invention is not limited to these.

(B) At least one metal ion belonging to Group 1 or Group 2 of the periodic table The infrared absorbing composition of the present invention comprises (B) at least one metal ion belonging to Group 1 or Group 2 of the periodic table. Contains seeds.
When the infrared absorbing composition of the present invention contains the metal ion (B), the dispersibility of the (A) IR dye in the infrared absorbing composition is improved and the dispersion of the (A) IR dye is increased. Stability can be improved.

Content of the said (B) metal ion in the infrared rays absorptive composition of this invention is 30 ppm or more and 10000 ppm or less.
When the content of the (B) metal ion in the infrared absorbing composition of the present invention is 30 ppm or more, (A) the dispersibility and dispersion stability of the IR dye can be improved, and (B) the content of the metal ion. Is 10000 ppm or less, the effect of storage stability of the printed matter can be obtained.

  When the infrared absorbing composition contains two or more types of metal ions belonging to Group 1 or Group 2 of the periodic table as (B) metal ions, the content of (B) metal ions is as follows. The total content of metal ions belonging to Group 1 or Group 2 of the Periodic Table contained in the infrared absorbing composition.

In addition, although the content of the (B) metal ion in the infrared absorbing composition of the present invention is essential to be within the above range, the dispersibility stability and the storage stability of the printed matter are further improved. From the viewpoint, it is more preferably within the range of 10 ppm or more and 10,000 ppm or less, and particularly preferably within the range of 15 ppm or more and 5000 ppm or less.
The (B) metal ion may be at least one metal ion belonging to Group 1 or Group 2 of the periodic table, but from the viewpoint of dispersibility and dispersion stability, lithium, sodium, potassium, calcium, And at least one selected from the group consisting of magnesium and calcium, sodium, potassium, and magnesium are more preferable.

  (B) Metal ions are contained in the infrared absorbing composition by adding a metal component that dissociates into ions in the system. Examples of the metal component include a liquid in which the amount of metal ions is intentionally adjusted. For example, a liquid containing a salt of an alkali metal or an alkaline earth metal or a tap water in which the content of metal ions is intentionally adjusted. Water etc. are mentioned.

  The infrared-absorbing composition of the present invention includes other components in addition to the essential component (A) IR dye and (B) at least one metal ion belonging to Group 1 or Group 2 of the Periodic Table. May be included.

(C) Organic solvent The above-described (A) IR dye and (B) metal ion are dispersed in a dispersion medium to form an infrared absorbing composition. Examples of the dispersion medium include an organic solvent.
Examples of the organic solvent that may be contained in the infrared absorbing composition of the present invention include organic solvents having a solubility parameter (hereinafter abbreviated as SP value) in the range of 7.3 to 12.1.

When an organic solvent is used as a dispersion medium, by using an organic solvent having an SP value in the above range, even when the infrared absorbing composition of the present invention contains the organic solvent, (A) IR The dispersibility of the dye and the dispersion stability can be improved.
Further, when the infrared absorbing composition contains an organic solvent, the (A) IR dye is stabilized in a solid state in the infrared absorbing composition by using an organic solvent having an SP value in the above range. It is considered that the dye state in the infrared absorbing composition is stabilized, the decomposition of the dye by light is sufficiently suppressed, and the light resistance to light is improved.

The SP value is a solubility parameter [unit: (cal / cm ₃ ) ^1/2 ] calculated by the Fedors method, and is a value represented by the following equation.
SP value (δ) = (ΔH / V) ^1/2
In the formula, ΔH represents the heat of vaporization [cal], and V represents the molar volume [cm ³ ]. In addition, ΔH and V are each the heat of molar evaporation of the atomic group (Δei) described in “POLYMER ENGINEERING AND SCIENCE, 1974, Vol. 14, No. 2, ROBERT F. FEDORS. ) Total ΣΔei (= ΔH) and molar volume (Δvi) total ΣΔvi (V), which can be obtained from (ΣΔei / ΣΔvi) ^1/2 .

  Examples of the organic solvent having an SP value within the above range include aromatic or aliphatic hydrocarbons, ketones, esters, ethers, alcohols, and liquid polymerizable compounds.

  Examples of the aromatic or aliphatic hydrocarbon include n-hexane (SP value: 7.3), n-octane (SP value: 7.6), toluene (SP value: 8.9), ethylbenzene ( SP value: 8.8), xylene (SP value: 8.8), benzene (SP value: 9.2) and the like.

  Examples of the ketone include methyl isobutyl ketone (SP value: 8.3), methyl isopropyl ketone (SP value: 8.5), methyl ethyl ketone (SP value: 9.3), and methyl propyl ketone (SP value: 8. 7) and the like.

  Examples of the ester include ethyl acetate (SP value: 9.1), butyl acetate (SP value: 8.5), isobutyl acetate (SP value: 8.3), and isopropyl acetate (SP value: 8.4). Ethylene glycol monobutyl ether acetate (SP value: 8.9), ethylene glycol monobutyl ether acetate (BMGAC) (SP value: 8.9), diethylene glycol monoethyl ether acetate (EDGAC) (SP value: 9.0), etc. Can be mentioned.

  Examples of the ether include diethyl ether (SP value: 7.4).

  Examples of the alcohol include n-butanol (SP value: 11.4), n-hexanol (SP value: 10.7), isopropyl alcohol (SP value: 11.5), and cyclohexanol (SP value: 11.1). 4), diethylene glycol monobutyl ether (BDG) (SP value: 10.5), diethylene glycol monoethyl ether (EDG) (SP value: 10.5), ethylene glycol monoethyl ether (EMG) (SP value: 11.5) Etc.

The polymerizable compound used as the dispersion medium is a monomer compound having a polymerizable group such as an ethylenic double bond, and examples thereof include (meth) acrylic monomers.
Examples of (meth) acrylic monomers include methyl methacrylate (SP value: 8.6), cyclohexyl methacrylate (SP value: 9.1), n-butyl methacrylate (SP value: 8.6), methacrylic acid. Examples include t-butyl acid (SP value: 8.3), n-butyl acrylate (SP value: 9.2), and allyl methacrylate (SP value: 8.8).

  Commercially available products that are marketed as the polymerizable compound may be used. Examples of the commercially available products include Kayrad series (for example, Kayrad TMPTA, DPHA, TPGDA, etc.) manufactured by Nippon Kayaku Co., Ltd. Can be used.

  As an organic solvent that may be contained in the infrared absorbing composition of the present invention, an organic solvent having an SP value in the range of 7.3 to 11.5 is preferable, and a range of 7.4 to 11.4 is preferable. Organic solvents are more preferred. Among these, as the organic solvent, aromatic or aliphatic hydrocarbons, ketones, esters, alcohols, and the like having a SP value in the above range and polymerizable compounds are preferable, and aromatic or aliphatic having an SP value in the above range. More preferred are hydrocarbons, ketones, esters, and polymerizable compounds.

Moreover, although an organic solvent may be used individually by 1 type, it is preferable to use 2 or more types of organic solvents together from a viewpoint of improving the light-resistant improvement effect more.
As a preferable embodiment when two kinds of organic solvents are used in combination, an aromatic or aliphatic hydrocarbon and a ketone are preferably used in combination with the low solubility of the IR dye and the effect of improving light resistance in the present invention. Is more preferably a combination of an aromatic hydrocarbon and a ketone, and particularly preferably an embodiment in which toluene and methyl isobutyl ketone are used in combination.
When a polymerizable compound (monomer) is used as the organic solvent, it is preferable to use two or more polymerizable compounds in combination.

    As content in the infrared absorptive composition of the organic solvent which may be contained in the infrared absorptive composition of this invention, 1-1,000,000 mass% is with respect to IR dye in the said this invention. Preferably, 10 to 500,000 mass% is more preferable. When the content of the organic solvent is 1% by mass or more, the dispersibility of the IR dye and its stability over time are good, and when it is 1,000,000% by mass or less, desired IR absorption reading This is advantageous in terms of sensitivity.

(D) Resin The infrared ray absorbing composition of the present invention may have a configuration containing at least one kind of resin. There is no restriction | limiting in particular as resin which may be contained in the infrared rays absorptive composition of this invention, According to a use, an objective, etc., it can select.

  Preferred examples of the resin include rosin and modified rosin and derivatives thereof, rosin and modified products thereof, petroleum resins, dicyclopentadiene resins and modified products thereof.

  The rosin is a natural resin mainly composed of rosin acid. Examples of the modified rosin and the derivative of the modified rosin include polymerized rosin (for example, rosin acid ester resin), disproportionated rosin, hydrogenated rosin, maleic acid-modified rosin and the like.

  The petroleum resin is obtained by polymerizing an unsaturated compound having a large number of carbon atoms when naphtha is decomposed, and includes an aliphatic system using a C5 fraction as a raw material, an aromatic system using a C9 fraction as a raw material, and a copolymer system. included. Examples of petroleum resins include dicyclopentadiene petroleum resins and aromatic petroleum resins.

  Examples of the modified product of the dicyclopentadiene resin include modified products such as unsaturated polyester modification and phenol modification.

  The content of the resin in the infrared absorbing composition is preferably 1% or more and 99% or less, more preferably 10% or more and 98% or less, in terms of mass ratio with respect to the total solid content of the composition. If the resin content is 1% by mass or more, it is advantageous in terms of solvent resistance of the printed material, and if it is 99% by mass or less, it is advantageous in terms of reading sensitivity of the printed material by IR light.

(E) Other components In addition to the above-described components, the infrared-absorbing composition of the present invention includes a surfactant, a solvent other than the organic solvent, a polymerizable compound not contained in the organic solvent, and a resin as necessary. And a curing agent, an electron-donating colored organic compound, an electron-accepting compound, a polar organic compound, and the like.

  Examples of the surfactant include nonionic surfactants such as alkylene oxide, glycerin, glycidol, and alkylphenol ethylene oxide adducts, cyclic amines, ester amides, quaternary ammonium salts, hydantoin derivatives, and heterocyclic rings. , Cationic surfactants such as phosphonium or sulfonium, anionic surfactants containing acidic groups such as carboxylic acid groups, sulfonic acid groups, and sulfate ester groups, or amino acids, aminosulfonic acids, sulfuric acid or phosphorus of amino alcohols Acid esters, amphoteric surfactants such as alkylbetaine type, and the like can be used.

The surfactant is described in detail in “Surfactant Handbook” (published by Sangyo Tosho Co., Ltd.). The surfactant is not necessarily pure, and may contain impurities such as isomers, unreacted materials, side reaction products, decomposition products, and oxides in addition to the main components. These impurities are preferably 30% by mass or less, and more preferably 10% by mass or less.
Surfactants can be used alone or in combination of two or more.

Further, the infrared absorbing composition of the present invention may be prepared by previously dispersing an IR dye in an organic solvent and adding a resin thereto. At this time, the dispersing agent which disperse | distributes IR dye in this invention can be contained. In this case, in addition to adding the surfactant as the additive, the surfactant may be used as a dispersant. The non-surfactant used as a dispersant is preferably a nonionic surfactant, an anionic surfactant, or a cationic surfactant, more preferably a nonionic surfactant or an anionic surfactant, An anionic surfactant is more preferable. Furthermore, it is preferably an organic sulfonic acid metal salt having 40 or less carbon atoms, more preferably an organic sulfonic acid metal salt having 30 or less carbon atoms, and most preferably a sodium or potassium salt of an organic sulfonic acid having 25 or less carbon atoms. It is.
In addition, when adding a dispersing agent, in the process of dispersing the pigment particles, the dispersing agent is added in the solvent together with the IR pigment or after the IR pigment is dispersed in the solvent. Among them, the method of adding a dispersant in the process of dispersing as in the former is most preferable.

  Moreover, you may contain solvents other than the above-mentioned (C) organic solvent in the range which does not impair the effect of this invention. Examples of the solvent include a dispersion medium described in paragraph [0071] of JP-A-2008-105958.

  The infrared absorbing composition of the present invention may contain a curing agent for the resin. Examples of the curing agent include polyisocyanate resins for urethane resins. A hardening | curing agent can be used in 1-70 mass% with respect to resin.

  The infrared absorbing composition of the present invention contains an electron-donating colored organic compound, an electron-accepting compound, and a polar organic compound as main components, so that the color is temporarily changed from transparent due to a change in temperature conditions, and You may comprise so that infrared absorption ability may be reversibly exhibited.

In the infrared absorbing composition of the present invention, the IR dye in the present invention is dispersed in a resin and applied or hard coated on the surface of paper, resin sheet or film, glass, metal plate, etc. to form an infrared absorbing layer. Infrared absorptivity by preparing an infrared absorbing resin by polymerizing the mixture by adding it to a resin raw material such as a monomer, or by adding it to the resin and melting it by heating and dispersing it in the molten resin A desired infrared absorbing material can be produced by applying to a method of preparing a resin or the like.
Among these, the infrared absorptive ink using the infrared absorptive composition of this invention is outlined below.

<Infrared absorbing ink and recorded matter>
The infrared absorbing ink of the present invention is constituted by using the above-described infrared absorbing composition of the present invention. This infrared absorbing ink is excellent in light resistance since the infrared absorbing composition described above is used.

  The infrared-absorbing ink of the present invention contains at least the (A) IR dye and the (B) metal ion, and further includes the (C) organic solvent and (( D) containing a resin, and can be further constituted by using a colorant, a polymerization initiator, a polymerizable compound not contained in the above (C) organic solvent, and other additives, depending on applications and purposes. .

  By containing the colorant, an ink colored in a desired hue can be obtained. Examples of the colorant include pigments and dyes. A coloring agent can be contained in the range which does not impair the effect of this invention.

In addition, when a polymerizable compound or a resin in the ink has a polymerizable group, by containing a polymerization initiator, the polymerizable group contained in the ink can be polymerized to cure the ink. it can. Thereby, the intensity | strength (for example, abrasion resistance) of a recorded image can be improved.
The polymerization initiator can be used as long as it is a compound capable of generating an active species that initiates a polymerization reaction of a polymerizable group such as a monomer component, and can be appropriately selected from known photopolymerization initiators and the like. For example, trihalomethyl group-containing compounds, acridine compounds, acetophenone compounds, bisimidazole compounds, triazine compounds, benzoin compounds, benzophenone compounds, α-diketone compounds, polynuclear quinone compounds, xanthone compounds, diazo compounds Compound, etc. can be mentioned.

  The recorded matter of the present invention is constituted by providing an image using the above infrared absorbing ink. The recorded matter of the present invention uses the above-described infrared absorbing composition, and therefore has better light resistance than conventional ones.

  Examples of the image include various marks such as marks, marks, etc. (eg, copy prevention marks), characters (eg, security authentication characters), pictures, barcodes, and the like.

  Further, in an information recording medium having a phosphor part that emits fluorescence when irradiated with light of a specific wavelength on a desired substrate, the phosphor part is covered so that the general formula (1) An infrared absorption part that contains the compound represented (IR dye in the present invention) and does not emit fluorescence may be formed. The infrared absorption unit can be configured to block the optical reading path of information by the optical information reading unit.

  At least the surface of the base material reflects infrared light in the near-infrared region, and is provided on the base material. The ink layer is substantially absorbed in the visible region but not absorbed in the near-infrared region. As an infrared absorbing material that absorbs infrared rays in the near infrared region, an infrared absorbing ink layer containing the compound represented by the general formula (1) (the IR dye in the present invention) may be formed close to or overlapping. Good.

  The infrared-absorbing ink and recorded matter of the present invention can be applied to security-related fields such as authentication of characters and images, symbols and dots, barcodes and other information exchange fields, for example, It can be used to prevent copying and provide hidden information.

<Image recording method>
The image recording method according to the present invention comprises a step of recording an image by applying the above-described infrared absorbing ink of the present invention on a recording medium. In the image recording method of the present invention, an image is formed with an infrared absorbing ink using the above-described infrared absorbing composition, so that the recorded image is excellent in light resistance.

  The application of the infrared absorbing ink at the time of image recording can be performed using a known method such as a coating method, a printing method, an ink jet method or the like. As a coating method, for example, a bar coat or the like can be applied. As a printing method, gravure printing, lithographic printing or the like can be applied. In addition, as an ink jet method, a charge control method that discharges ink using electrostatic attraction, a drop-on-demand method (pressure pulse method) that uses vibration pressure of a piezo element, and bubbles are formed by heating the ink. Any of the thermal (Bubble Jet (registered trademark)) method using the generated pressure can be applied.

  After applying the ink, other steps such as a step of drying the ink and a step of (thermo) compression of the recorded image can be provided.

<Image detection method>
The image detection method according to the present invention comprises a step of detecting image information of an image formed on a recording medium by the above-described image recording method of the present invention with an infrared detector. Since the image to be detected has good light resistance, the detection ability (readability, etc.) when detected by the infrared detector can be kept stable for a long time.

  In the detection of image information in an image, various image information is detected by irradiating the recording surface of the recorded matter on which the image is recorded with an infrared ray detector. The image part containing the IR dye is not visually recognized or difficult to recognize with an uncolored composition, but the area containing the IR dye absorbs infrared rays when irradiated with infrared rays. By detecting the reflected light and fluorescence, it is possible to read mark information such as symbols and dots, pattern information such as characters, pictures, and barcodes, and image information such as position information.

  As the infrared detector, an apparatus that can detect by irradiating infrared rays and receiving reflected light or the like at the time of irradiation can be used. The detection can be suitably performed using wavelength light having a wavelength of 800 to 1200 nm. As the light source, a light source that emits infrared light may be used, or a light source that emits light including light having a wavelength other than infrared light may be used.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist thereof. Unless otherwise specified, “part” is based on mass.

[Examples and comparative examples]
-Preparation of infrared absorbing composition-
<Preparation of infrared absorbing composition 1>
Infrared absorbing composition 1 was prepared by mixing the following components.
1) Synthesis of the following compound (Z1-B) 100 g of 2,3-dicyano-1,4-dihydroquinone (the following compound (Z1-D)), 259 g of potassium carbonate, and 900 mL of acetone were placed in a 3 L three-necked flask. After adding 262 g of p-toluenesulfonic acid chloride in portions at an internal temperature of 20 ° C. or lower, the mixture was stirred for 2 hours under reflux. Next, after cooling to an internal temperature of 50 ° C., 1000 mL of water was added dropwise, and the mixture was cooled to 10 ° C. over 2 hours. The obtained slurry was filtered and washed with 300 mL of methanol and 300 mL of water to obtain 214 g of the following compound (Z1-C) (yield 73%). Next, 50 g of 4-methylthiophenol, 55.8 g of potassium carbonate, and 590 ml of DMAc were placed in a 2 L three-necked flask, and 90 g of the compound (Z1-C) prepared above was dividedly added at an internal temperature of 30 ° C. or less, followed by stirring for 2 hours. . Furthermore, 1200 mL of water was added dropwise over 10 minutes, and after stirring for 1 hour at room temperature, the resulting slurry was filtered and washed with 4 L of tap water to obtain 46.6 g of the following compound (Z1-B). (Yield 65%). Compound (Z1-B) was synthesized according to the following scheme.

Next, using the compound (Z1-B) prepared above, (B) an infrared absorbing dye as an IR dye was prepared.
Specifically, 30 g of the compound (Z1-B), 16.4 g of lithium chloride, 21.7 g of t-butoxypotassium, and 300 mL of butanol were placed in a 1000 mL three-necked flask and heated at 100 ° C. for 6 hours. Thereafter, 1.3 g of hydroquinone was added and stirred for 1 hour, followed by cooling to 50 ° C., and 210 mL of ion-exchanged water and 105 mL of acetic acid were added. The obtained slurry was filtered and washed with 200 mL of water and 300 mL of methanol to obtain 30 g of compound (Z1-A) (yield 64.6%). When the obtained compound was measured by MS spectrum, a peak corresponding to the molecular weight was obtained.

  15 g of exemplary compound (Z1-A) was dissolved in 1 L of THF, 3.65 g (2.0 equivalents) of copper acetate was added, and the mixture was stirred at 30 ° C. for 4 hours. After cooling the reaction solution, 200 mL of an aqueous solution in which 1 g of calcium chloride is dissolved in 2000 mL of ion-exchanged water is added, and the resulting slurry is filtered, washed with 100 m of methanol and dried to give the following exemplified compound (1) as an infrared absorbing dye. 14.7 g was obtained (94% yield). In addition, exemplary compound (1) was synthesized according to the following scheme.

Here, the powdery exemplary compound (1) containing metal ions obtained by the above scheme is the infrared absorbing composition 1, and the content of alkali metal ions or alkaline earth metal ions is determined by combustion method ion chromatography. Table 1 shows the detected alkali metal ions or alkaline earth metal ions and the total content of detected metal ions.

<Preparation of infrared absorbing composition 2>
Preparation of infrared absorbing composition 1 except that 200 mL of an aqueous solution in which 1 g of calcium chloride used in the final step in the preparation of infrared absorbing composition 1 was dissolved in 2000 mL of ion-exchanged water was replaced with 200 mL of tap water. In the same manner, an infrared absorbing composition 2 was prepared.

  About the prepared infrared absorptive composition 2, the content of alkali metal ions or alkaline earth metal ions is quantified by combustion method ion chromatography, the detected alkali metal ions or alkaline earth metal ions, and the detected metal Table 1 shows the total ion content.

<Preparation of infrared absorbing composition 3>
200 mL of an aqueous solution in which 1 g of calcium chloride used in the final step in the preparation of the infrared absorbing composition 1 was dissolved in 2000 mL of ion-exchanged water was replaced with 200 mL of an aqueous solution in which 0.05 g of calcium chloride was dissolved in 2000 mL of ion-exchanged water. Except for the above, an infrared absorbing composition 3 was prepared in the same manner as the infrared absorbing composition 1 was prepared.

<Preparation of infrared absorbing composition 4>
Except that 200 mL of an aqueous solution obtained by dissolving 1 g of calcium chloride in 2000 mL of ion-exchanged water used in the final step in the preparation of the infrared absorbing composition 1 was replaced with 200 mL of an aqueous solution obtained by dissolving 550 g of calcium chloride in 2000 mL of ion-exchanged water. The infrared absorbing composition 4 was prepared in the same manner as the infrared absorbing composition 1 was prepared.

<Preparation of infrared absorbing composition 5>
Except that 200 mL of an aqueous solution in which 1 g of calcium chloride used in the final step in the preparation of the infrared absorbing composition 1 was dissolved in 2000 mL of ion-exchanged water was replaced with 200 mL of an aqueous solution in which 5 g of calcium chloride was dissolved in 2000 mL of ion-exchanged water. The infrared absorbing composition 5 was prepared in the same manner as the infrared absorbing composition 1 was prepared.

<Preparation of infrared absorbing composition 6>
Except that 200 mL of an aqueous solution in which 1 g of calcium chloride used in the final step in the preparation of the infrared absorbing composition 1 was dissolved in 2000 mL of ion-exchanged water was replaced with 200 mL of an aqueous solution in which 15 g of calcium chloride was dissolved in 2000 mL of ion-exchanged water. The infrared absorbing composition 6 was prepared in the same manner as the infrared absorbing composition 1 was prepared.

<Preparation of infrared absorbing composition 7>
Except that 200 mL of an aqueous solution in which 1 g of calcium chloride used in the final step in the preparation of the infrared absorbing composition 1 was dissolved in 2000 mL of ion-exchanged water was replaced with 200 mL of an aqueous solution in which 105 g of calcium chloride was dissolved in 2000 mL of ion-exchanged water. The infrared absorbing composition 7 was prepared in the same manner as the infrared absorbing composition 1 was prepared.

<Preparation of infrared absorbing composition 8>
Except that 200 mL of an aqueous solution in which 1 g of calcium chloride used in the final step in the preparation of the infrared absorbing composition 1 was dissolved in 2000 mL of ion-exchanged water was replaced with 200 mL of an aqueous solution in which 200 g of calcium chloride was dissolved in 2000 mL of ion-exchanged water. The infrared absorbing composition 8 was prepared in the same manner as the infrared absorbing composition 1 was prepared.

<Preparation of infrared absorbing composition 9>
Except that 200 mL of an aqueous solution in which 1 g of calcium chloride used in the final step in the preparation of the infrared absorbing composition 1 was dissolved in 2000 mL of ion-exchanged water was replaced with 200 mL of an aqueous solution in which 300 g of calcium chloride was dissolved in 2000 mL of ion-exchanged water. The infrared absorbing composition 9 was prepared in the same manner as the infrared absorbing composition 1 was prepared.

<Preparation of infrared absorbing composition 10>
Except that 200 mL of an aqueous solution obtained by dissolving 1 g of calcium chloride in 2000 mL of ion-exchanged water used in the final step in the preparation of the infrared absorbing composition 1 was replaced with 200 mL of an aqueous solution prepared by dissolving 5 g of lithium chloride in 2000 mL of ion-exchanged water. In the same manner as in the preparation of the infrared absorbing composition 1, an infrared absorbing composition 10 was prepared.

<Preparation of infrared absorbing composition 11>
Except that 200 mL of an aqueous solution in which 1 g of calcium chloride used in the final step in the preparation of the infrared absorbing composition 1 was dissolved in 2000 mL of ion-exchanged water was replaced with 200 mL of an aqueous solution in which 5 g of sodium chloride was dissolved in 2000 mL of ion-exchanged water. In the same manner as in the preparation of the infrared absorbing composition 1, an infrared absorbing composition 11 was prepared.

<Preparation of infrared absorbing composition 12>
Except that 200 mL of an aqueous solution obtained by dissolving 1 g of calcium chloride in 2000 mL of ion-exchanged water used in the final step in the preparation of the infrared absorbing composition 1 was replaced with 200 mL of an aqueous solution prepared by dissolving 5 g of potassium chloride in 2000 mL of ion-exchanged water. The infrared absorbing composition 12 was prepared in the same manner as the infrared absorbing composition 1 was prepared.

<Preparation of infrared absorbing composition 13>
Except that 200 mL of an aqueous solution in which 1 g of calcium chloride used in the final step in the preparation of the infrared absorbing composition 1 was dissolved in 2000 mL of ion-exchanged water was replaced with 200 mL of an aqueous solution in which 5 g of magnesium chloride was dissolved in 2000 mL of ion-exchanged water. In the same manner as in the preparation of the infrared absorbing composition 1, an infrared absorbing composition 13 was prepared.

<Preparation of infrared absorbing composition 14>
200 mL of an aqueous solution prepared by dissolving 1 g of calcium chloride used in the final step in the preparation of the infrared absorbing composition 1 in 2000 mL of ion-exchanged water was dissolved in 5 g of calcium chloride, 5 g of sodium chloride, and 5 g of potassium chloride in 2000 mL of ion-exchanged water. An infrared-absorbing composition 14 was prepared in the same manner as the infrared-absorbing composition 1 except that the aqueous solution was replaced with 200 mL of the aqueous solution.

<Preparation of Comparative Composition 1>
Infrared absorption except that 200 mL of an aqueous solution in which 1 g of calcium chloride used in the final step in the preparation of the infrared absorbing composition 1 was dissolved in 2000 mL of ion-exchanged water was replaced with 200 mL of an aqueous solution in which 2000 mL of ion-exchanged water was dissolved. Comparative composition 1 was prepared in the same manner as the preparation of the sexual composition 1.

<Preparation of Comparative Composition 2>
Except that 200 mL of an aqueous solution in which 1 g of calcium chloride used in the final step in the preparation of the infrared absorbing composition 1 was dissolved in 2000 mL of ion-exchanged water was replaced with 200 mL of an aqueous solution in which 700 g of calcium chloride was dissolved in 2000 mL of ion-exchanged water. Comparative composition 2 was prepared in the same manner as in the preparation of infrared absorbing composition 1.

<Preparation of Comparative Composition 3>
Instead of the infrared absorptive composition 1, vanadyl 2,3-naphthalocyanine made by Aldrich was prepared as a comparative composition 3.

  About the prepared infrared absorptive compositions 3-14 and comparative compositions 1-3, the content of alkali metal ions or alkaline earth metal ions was quantified by combustion method ion chromatography, and the detected alkali metal ions or alkalis were detected. Table 1 shows the earth metal ions and the total content of the detected metal ions.

(Evaluation of dispersibility and dispersion stability)
The prepared infrared absorbing composition and comparative composition were evaluated for the dispersibility and dispersion stability of the infrared absorbing dye or the comparative dye contained therein.
Specifically, the components in the composition shown below were mixed with the powders as the infrared absorbing composition and the comparative composition obtained above, and dispersed using a three-roll mill, and the infrared absorbing ink and the comparative ink Was prepared.
<Infrared absorbing ink composition>
· Infrared absorbing composition or comparative composition shown in Table 1 ··· 5 parts · Vinyl chloroacetate resin · · 15 parts (trade name: Elex A, manufactured by Sekisui Chemical Co., Ltd.)
・ Saturated polyester (trade name: Byron 103, manufactured by Toyobo Co., Ltd.) ... 5 parts ・ Polyurethane elastomer ... 12 parts (trade name: N-2304, manufactured by Nippon Polyurethane Co., Ltd.)
・ Isocyanate curing agent ・ ・ ・ ・ 3 parts (Product name: JA-960, manufactured by Jujo Chemical Co., Ltd.)
Triethylenediamine 0.5 parts Solvent 70 parts (toluene (SP value: 8.9) / methyl isobutyl ketone (SP value: 8.3) = 70/30 [mass ratio])
Dispersibility and dispersion stability were evaluated by measuring the viscosity of the obtained ink after 1 day (24 hours) of dispersion and 14 days (336 hours). For the measurement of viscosity, a TV-22 viscometer cone plate type (manufactured by Toki Sangyo Co., Ltd.) was used. The evaluation environment was 25 ° C.
A low viscosity value of the dispersion indicates that the infrared absorbing dye or the comparative dye is excellent in dispersibility. In addition, the smaller the viscosity of the dispersion and the smaller the increase in viscosity over time, the better the dispersion stability of the infrared absorbing dye or the comparative dye.
The results are shown in Table 1.

-Preparation of infrared absorbing ink-
<Preparation of infrared absorbing ink and comparative ink>
The components in the composition shown below were mixed to prepare an infrared absorbing ink and a comparative ink.
<Infrared absorbing ink composition>
· Infrared absorbing composition or comparative composition shown in Table 1 · · · 5 parts · Vinyl chloroacetate resin · 15 parts (trade name: Elex A, manufactured by Sekisui Chemical Co., Ltd.)
・ Saturated polyester (trade name: Byron 103, manufactured by Toyobo Co., Ltd.) ... 5 parts ・ Polyurethane elastomer ... 12 parts (trade name: N-2304, manufactured by Nippon Polyurethane Co., Ltd.)
・ Isocyanate curing agent ・ ・ ・ ・ 3 parts (Product name: JA-960, manufactured by Jujo Chemical Co., Ltd.)
Triethylenediamine 0.5 parts Solvent 70 parts (toluene (SP value: 8.9) / methyl isobutyl ketone (SP value: 8.3) = 70/30 [mass ratio])

-Image recording-
A barcode pattern was formed by gravure printing on plain paper MP-120 (manufactured by Plus Co.), which is a base paper, using each of the infrared absorbing inks and comparative inks obtained from the above.

The formed bar code pattern was evaluated for printing characteristics (applicability). In the evaluation, when a barcode pattern with the desired shape is formed, it is judged as “good”, when a part is rubbed, it is judged as “slightly bad”, and when a chip is seen, In some cases, it was judged as “bad”.
The evaluation results are shown in Table 2.

  Subsequently, on the bar code pattern formed, three kinds of process inks having infrared transparency (FDOL yellow, FDOL magenta, FDOL cyan, manufactured by Toyo Ink Manufacturing Co., Ltd.) were applied by gravure printing. By forming a colored layer composed of visible colors (indigo, red, yellow), a recorded matter having a barcode pattern arranged therein was produced.

  In the obtained recorded matter, the entire surface of the colored layer of visible colors (indigo, red, yellow) is visible, but the barcode pattern is almost invisible, so the presence of the barcode pattern itself cannot be discerned with the naked eye. It was a thing.

  The recorded matter was irradiated with two types of semiconductor laser light having a wavelength of 830 nm and a wavelength of 905 nm, and the emitted light having a wavelength of 950 nm or less was detected through a filter. At this time, the pattern formed with the infrared absorbing ink and the comparative ink could be read.

Subsequently, 70,000 lux of xenon light was continuously irradiated to the recorded matter for 200 hours by a xenon lamp. Thereafter, the degree of reading of the barcode pattern after irradiation was evaluated. In the evaluation, a case where the PCS (print contrast signal) was 0.6 or more was rated as “good”, and a case where the PCS (print contrast signal) was less than 0.6 was rated as “bad”. . The evaluation results are shown in Table 2 below.
“PCS” is defined as PCS = (Rmax−Rmin) / Rmax. Rmax represents the maximum total light reflectance, and Rmin represents the minimum total light reflectance. This is a value obtained by measuring the total light reflectance of the base paper and the total light reflectance of the printed portion.
The evaluation results are shown in Table 2 below.

  As shown in Table 2, when the barcode pattern (that is, the recorded matter) was formed using the infrared absorbing ink of the present invention, the printing characteristics were excellent compared to the case where the comparative ink was used, and Good light resistance was obtained.

-Preparation of UV curable ink having infrared absorption-
Components in the composition shown below were kneaded to prepare an ultraviolet curable ink having infrared absorptivity.
<Composition of UV curable ink>
Photomer 5018 ... 60 parts (aliphatic polyester tetraacrylate; manufactured by San Nopco)
・ Kayarad TMPTA (SP value: 10.5) ... 14 parts (Trimethylolpropane triacrylate; manufactured by Nippon Kayaku Co., Ltd.)
-Kayacure MBP (SP value: 1.7) ... 1 part (3,3'-dimethyl-4-methoxybenzophenone; manufactured by Nippon Kayaku Co., Ltd.)
・ Nisso Cure TX (thioxanthone; manufactured by Nippon Soda Co., Ltd.) ・ ・ ・ 8 parts ・ Sandry 1000 ・ ・ ・ 1 part (4-phenoxydichloroacetophenone: manufactured by Sand Corporation)
White petrolatum 4 partsInfrared absorbing composition or comparative composition shown in Table 1 12 parts

  Using the obtained ultraviolet curable ink, a copy prevention mark was gravure-printed on a base paper in the same manner as the barcode formation using the infrared absorbing ink and the comparative ink.

  The formed copy prevention mark was evaluated for printing characteristics (applicability). In the evaluation, when a copy prevention mark having a target shape is formed, it is determined as “good”, when a part is rubbed, it is determined as “slightly defective”, and when a chip is observed, “ “Bad”. The evaluation results are shown in Table 3.

Next, each of process inks (FDOL yellow, FDOL magenta, FDOL cyan, manufactured by Toyo Ink Manufacturing Co., Ltd.) is formed in layers on the printed copy protection marks by gravure printing, or these three types By providing a mixed ink mixed with process ink in a layer form by gravure printing, the copy protection mark was concealed to obtain a recorded matter.

  Copy protection marks concealed with process ink are irradiated with infrared rays using a linear sensor (TCD1500C, manufactured by Toshiba Corp.) as the detection device instead of the infrared cut filter (IR83, manufactured by HOYA). At the same time, the reflected light was detected.

  The copy protection mark could not be visually recognized in the colored layer of process ink, but by using the detection device described above, the copy prevention mark was not detected in the infrared region without detecting a print layer of three types of process ink. Only was able to be detected. That is, since the three types of process inks do not absorb in the infrared region, only the anti-copy mark having infrared absorptivity existing in the lower part can be detected.

  The value obtained by dividing the reflected light intensity of the area of the anti-copy mark when the anti-copy mark is detected by the reflected light intensity of the area other than the anti-copy mark is normalized to 1 when the comparative infrared absorbent A is used. The ratio was calculated. The results are shown in Table 3 below.

  Further, the obtained recorded matter was continuously irradiated with xenon light of 70,000 lux for 72 hours by a xenon lamp. After irradiation, the value obtained by dividing the reflected light intensity in the area of the copy protection mark by the reflected light intensity in the area other than the copy protection mark is obtained in the same manner as described above, and the rate of change [%] from the value before irradiation is calculated. It was used as an index for evaluating light resistance. The results are shown in Table 3 below.

  As shown in Table 3, when the anti-copy mark (that is, recorded matter) is formed using the ink containing the infrared absorbing composition of the present invention, the printing characteristics are higher than when the comparative ink is used. And good light resistance was obtained.

  The present invention can be applied to security-related fields such as authentication of characters and images, and fields where information is exchanged with marks such as symbols, dots, and barcodes. For example, for prevention of copying and provision of hidden information It is possible to use.

Claims (7)

(A) at least one infrared absorbing dye represented by the following general formula (1), and (B) at least one metal ion belonging to Group 1 or Group 2 of the Periodic Table, B) An infrared absorbing composition having a metal ion content of 30 ppm to 10,000 ppm.

[In General Formula (1), Ar ¹ , Ar ² , Ar ³ , Ar ⁴ , Ar ⁵ , Ar ⁶ , Ar ⁷ , and Ar ⁸ each independently represent an aryl group. ]   The infrared absorbing composition according to claim 1, wherein the content of the (B) metal ion is 50 ppm or more and 10,000 ppm or less.   The infrared absorbing composition according to claim 1 or 2, wherein the metal ion (B) is at least one selected from the group consisting of lithium, sodium, potassium, calcium, and magnesium.   An infrared-absorbing ink comprising the infrared-absorbing composition according to any one of claims 1 to 3.   A recorded matter having an image made of the infrared absorbing ink according to claim 4 on a recording medium.   An image recording method comprising a step of recording an image by applying the infrared absorbing ink according to claim 4 on a recording medium.   An image detection method comprising a step of detecting, with an infrared detector, image information of the image formed on a recording medium by the image recording method according to claim 6.