JP6541400B2 - Anti-counterfeit ink and printed matter thereof - Google Patents

Description

  BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an anti-counterfeit ink, its printed matter, an authenticity determination method, and an authenticity determination device.

  Paper money, securities, cards and the like are partially printed with an ink having infrared absorptivity for the purpose of preventing forgery. The ink having infrared absorbing properties is formed by adding an infrared absorber to a commonly used printing ink.

  As the infrared ray absorbing agent, infrared ray absorbing organic materials such as cyanine compounds, naphthoquinone compounds and the like; infrared ray absorbing inorganic materials such as pigments of carbon black and antimony-doped tin oxide (ATO) are known. In recent years, an ATO-containing infrared-absorbing ink exhibiting a pale white color has been proposed as a forgery-preventing ink that has little influence on the color tone of other process inks (Patent Document 1).

  By the way, a dispersion liquid of tungsten (W) -cesium (Cs) complex oxide fine particles is known as a material for forming a solar radiation shield having visible light transmittance and infrared absorptivity (Patent Document 2).

JP, 2010-006999, A JP, 2005-187323, A

  The infrared absorption effect of the infrared absorber is not necessarily constant in the wavelength range of 852 nm to 2500 nm. For example, infrared absorbing inorganic materials such as ATO, tungsten-cesium complex oxide, and the like have significantly different infrared absorbing effects in the wavelength range of 852 nm to 2500 nm. On the other hand, various infrared detectors do not necessarily detect infrared rays of the same wavelength.

  As a result, in the printing unit printed with the ATO-containing infrared absorbing ink described in Patent Document 1, an error may occur in the reading accuracy depending on the type of the infrared detector. In addition, the degree of freedom of the authenticity judgment method using the observation results in the infrared wavelength range is also limited.

  In addition, since the dispersion liquid of patent document 2 is formed by disperse | distributing tungsten-cesium complex oxide microparticles | fine-particles in nonpolar organic solvents, such as toluene, the rubber blanket of a printing machine melt | dissolves with nonpolar organic solvents. And could not be used as a common printing ink, especially an offset printing ink.

  Therefore, the problem to be solved by the present invention is that the infrared absorption profile in the infrared wavelength range of the printed matter can be arbitrarily set, and the reading accuracy of the printed matter is not influenced by the type of infrared detector. An authentication method and an authentication device capable of performing an authentication determination based on an ink, a printed matter thereof, and an infrared absorption profile set arbitrarily.

The present inventors have found that an infrared absorption profile in an infrared wavelength range of a printed material can be arbitrarily set by two types of infrared absorbing pigments different from each other in infrared absorption, and completed the present invention. That is, the present invention is as follows.
[1] An anti-counterfeit ink comprising: two types of infrared absorbing pigments different from each other in infrared absorbing properties; and a vehicle.
[2] When the forgery prevention ink is printed on a substrate, dried, and a printed portion is formed, and the reflectance of the printed portion is measured, the maximum reflectance and the minimum reflectance in the wavelength range of 852 nm to 2500 nm The anti-counterfeit ink according to [1], wherein the absolute value of the difference in rate is 22.90% or less.
[3] The two types of infrared absorbing pigments are
General formula Cs _x W _y O _z (wherein, x, y and z are each a positive number, 0 <x / y ≦ 1 and 2.2 ≦ z / y ≦ 3.0) Tungsten oxide particles represented by the formula: and antimony doped tin oxide particles containing tin oxide and antimony oxide;
The anti-counterfeit ink according to [1] or [2].
[4] The anti-counterfeit ink according to [3], wherein the cesium tungsten oxide fine particles are contained in a ratio of 1/3 part by mass or more to 1 part by mass of the antimony-doped tin oxide fine particles.
[5] Printed matter by flexographic printing, letterpress printing, offset printing, intaglio printing, gravure printing, silk screen printing, or inkjet printing using the anti-counterfeit ink according to any one of [1] to [4] How to get
[6] A printed material provided with a printing unit printed with the forgery prevention ink according to any one of [1] to [4].
[7] observing the printing section for at least two infrared wavelengths; and performing an authenticity determination based on the observation results at the at least two infrared wavelengths;
How to judge the authenticity, including
[8] The authenticity determination method according to [7], wherein authenticity is determined based on a difference between observation results at the at least two infrared wavelengths.
[9] The authenticity determination method according to [8], wherein authenticity is determined based on the absolute value of the difference between the maximum reflectance and the minimum reflectance in the selected infrared wavelength range.
[10] The authenticity determination method according to [9], wherein it is determined that the printing unit is authentic when the absolute value is a value within a specific range.
[11] An authenticity determination apparatus including an observation unit that observes a printing unit for at least two infrared wavelengths.
[12] The authenticity determination apparatus according to [11], further including an authenticity determination unit configured to perform authenticity determination based on observation results at the at least two infrared wavelengths.

  According to the present invention, since the infrared absorption profile of the printed matter can be arbitrarily set by two types of infrared absorbing pigments different from each other in infrared absorptivity, forgery in which the reading accuracy of the printed matter is not influenced by the type of infrared detector. An ink for prevention can be obtained. Furthermore, according to the present invention, the authenticity determination of the printed matter can be performed based on the infrared absorption profile set arbitrarily.

FIG. 1 is a graph showing the influence of the mass ratio of two types of infrared absorbing pigments in the ink on the reflectance of printed matter in the wavelength range of 352 nm to 2500 nm.

<Printing ink>
The printing ink of the present invention (hereinafter simply referred to as "ink") can be used to prevent forgery of printed matter by using infrared absorption. The ink of the present invention contains two types of infrared absorbing pigments having different infrared absorbing properties, and a vehicle. The ink of the present invention may further contain an adjuvant, a colorant and the like.

  The ink of the present invention is an oil-based ink, an ultraviolet-curable ink (hereinafter abbreviated as "UV ink"), or an oil-ultraviolet-curable combined ink (hereinafter, "oil-based / UV combined ink" according to the type of vehicle component. "Abbreviated as" can be used.

  An oil-based ink is an ink which can be cured by oxidative polymerization of a vehicle component. In general, an oil-based ink contains a solvent, a resin and the like as a vehicle component.

  UV inks are inks that can be cured by photopolymerization of vehicle components. Generally, the UV ink contains a resin, a photopolymerizable monomer or oligomer, a photopolymerization initiator and the like as a vehicle component, but does not contain a volatile component such as a solvent.

  The oil-UV combination ink is an ink having the curing characteristics of both oil-based ink and UV ink.

  The ink of the present invention can also be used as an aqueous ink containing water as a main solvent or a solvent ink containing an organic solvent as a main solvent, depending on the type of solvent usable as a vehicle.

  The water-based ink is an ink containing water as a main solvent, but may contain an organic solvent. The solvent ink is an ink containing an organic solvent as a main solvent, but may be substantially free of water. The phrase "substantially free of water" means that the content of water in the ink is 0% by mass, or that the ink unavoidably contains 1% by mass or less of water.

  The ink of the present invention may be used as a general printing ink, for example, offset printing ink, gravure printing ink, intaglio printing ink, letterpress printing ink, silk screen printing ink, flexographic printing ink, inkjet printing ink, etc. it can. The intaglio printing ink can be used for press printing using a direct printing plate surface or an etching plate surface.

  The two types of infrared absorbing pigments, vehicles, adjuvants and colorants contained in the ink of the present invention are described below.

[Two types of infrared absorbing pigments different from each other in infrared absorbing property]
The two infrared absorbing pigments may have different infrared absorbing properties, in particular in the wavelength range of 852 nm to 2500 nm, different infrared absorbing profiles.

  Printed matter containing one type of infrared absorbing pigment has only one type of infrared absorption profile in the wavelength range of 852 nm to 2500 nm when measured under the same conditions, and the infrared absorption profile is not flat. The type of detector may affect the reading accuracy of the printed matter.

  On the other hand, it is possible to provide an infrared absorption wavelength suitable for the detection wavelength of the infrared detector to the printed matter by combining two types of infrared absorbing pigments having different infrared absorption properties with each other.

  The two types of infrared absorbing pigments are preferably blended in the ink of the present invention so that the infrared absorptivity of printed matter approaches a constant in the wavelength range of 852 nm to 2500 nm. To eliminate the difference in absorption intensity between one infrared absorbing pigment and the other infrared absorbing pigment at a specific infrared wavelength, and to make the infrared absorptivity of printed matter close to constant, two types of infrared absorbing properties in ink It is also preferable to adjust the mass ratio of the pigment.

  In order to suppress an error in the reading accuracy of the printed matter by the infrared detector, a forgery prevention ink containing two types of infrared absorbing pigments and a vehicle is printed on a substrate and dried to form a printing portion, When the reflectance of the printed portion is measured, the absolute value of the difference between the maximum reflectance and the minimum reflectance in the wavelength range of 852 nm to 2500 nm is less than 22.94%, 22.90% or less, 22.00% or less Or less, 20.00% or less, 18.00% or less, 16.00% or less, 14.00% or less, 12.00% or less, or 10.00% or less. This absolute value may be 0% or 5% or more. The reflectance of the printing section is measured by the method described in the examples.

  The two infrared absorbing pigments can be selected from the group consisting of an infrared absorbing organic material and an infrared absorbing inorganic material, as long as they have different infrared absorbing properties.

  Examples of the infrared-absorbing organic material include polymethine compounds, cyanine compounds, phthalocyanine compounds, naphthalocyanine compounds, naphthoquinone compounds, anthraquinone compounds, dithiol compounds, immonium compounds, diimonium compounds, aminium compounds Compounds, pyrylium compounds, cerylium compounds, squarylium compounds, dithiol metal complexes and the like can be mentioned.

  As the infrared absorbing inorganic material, for example, carbon black, indium oxide, magnesium oxide, titanium oxide, chromium oxide, zirconium oxide, nickel oxide, aluminum oxide, zinc oxide, iron oxide, iron oxide, antimony oxide, lead oxide, bismuth oxide, oxide Lanthanum, tungsten oxide, tin-doped indium oxide (ITO), antimony-doped tin oxide (ATO), composite tungsten oxide and the like can be mentioned.

  In order to ensure the weather resistance of the forgery prevention ink and the printed matter, it is preferable to use an infrared-absorbing inorganic material. The infrared absorbing inorganic material may be in the form of particles or microparticles. It is preferable to use an infrared-absorbing inorganic material other than carbon black exhibiting a dark dark color, in order to provide a forgery-preventing ink that has less influence on the color tone of other process inks.

  FIG. 1 is a graph showing the influence of the mass ratio of two types of infrared absorbing pigments in the ink on the reflectance of printed matter in the wavelength range of 352 nm to 2500 nm. As shown in FIG. 1, while the infrared absorptivity of cesium tungsten oxide is high in the wavelength range of 852 nm to 1900 nm and low in the wavelength range exceeding 1900 nm, the infrared absorptivity of ATO is 852 nm to 1900 nm Low in the wavelength range and high in the wavelength range above 1900 nm.

  Therefore, it is preferable to use cesium tungsten oxide and ATO as two types of infrared absorbing pigments, since the infrared absorption profile of the printed matter in the wavelength range of 852 nm to 2500 nm can be easily made flat.

  In order to reduce the difference in absorption intensity between cesium tungsten oxide and ATO at a specific infrared wavelength and obtain a flat infrared absorption profile in the wavelength range of 852 nm to 2500 nm, the content of tungsten oxide particles in the ink is It may be 1/3 part by mass or more, 1/2 part by mass or more, or 3/4 part by mass or more with respect to 1 part by mass, and the content thereof is 9/2 parts by mass or less, 4 parts by mass or less, 3 parts by mass Hereinafter, 2 parts by mass or less, or 3/2 parts by mass or less may be sufficient. Cesium tungsten oxide and ATO will be described below.

[Cesium tungsten oxide]
Known cesium tungsten oxide used for anti-counterfeiting, infrared shielding or solar shading may be contained in the ink of the present invention. In terms of combined use with ATO, the general formula Cs _x W _y O _z (wherein x, y and z are each a positive number, 0 <x / y ≦ 1, and 2.2 ≦ z / The cesium-tungsten oxide represented by y <= 3.0 is preferable.

In the general formula Cs _x W _y O _z , the value of x / y is preferably 0.2 or more or 0.30 or more, and this value is preferably 0.5 or less or 0.35 or less . The value of x / y is ideally 0.33. In the general formula Cs _x W _y O _z , the value of z / y more preferably satisfies the relationship 2.45 ≦ z / y ≦ 3.0.

  In order to improve visible light transmittance and infrared absorptivity in the near infrared wavelength range (750 nm to 1400 nm), it is preferable that cesium tungsten oxide has a hexagonal crystal structure or consists of a hexagonal crystal structure. It is also preferable that cesium tungsten oxide be treated with a silane coupling agent in order to balance dispersibility, visible light transparency and near infrared absorptivity.

More specifically, the general formula _Cs x _W y _{O z} cesium tungsten oxide particles represented by can be obtained by the production method described in JP 2005-187323.

[Antimony-doped tin oxide (ATO)]
ATO contains tin oxide and antimony oxide. Known ATOs used for anti-counterfeit, infrared shielding or antistatic may be included in the ink of the present invention. For example, the following materials (1) to (3) may be used as ATO.
(1) Commercially available ATO powder, for example, ELCOM TL-30 (JGC Catalysts and Chemicals Inc.)
(2) ATO fine particles obtained by firing commercially available ATO powder under aeration (3) ATO satisfying the following (a) and / or (b):
(A) The half width (Δ2θ) around 2θ = 27 ° obtained by X-ray diffraction measurement is 0.35 or less; and / or (b) the content of antimony oxide is based on the weight of ATO The crystallinity degree is 0.5 to 10.0% by weight, and is a value obtained by dividing the peak value of the peak around 2θ = 27 ° obtained by X-ray diffraction measurement by the half width (Δ2θ), It is 18092 or more.

  In the material of the above (2) or (3), the half width at around 2θ = 27 ° obtained by X-ray diffraction measurement in order to sufficiently exert the infrared absorption effect while reducing the amount of antimony oxide used (Δ2θ) is preferably 0.30 or less, 0.25 or less, 0.21 or less, 0.20 or less, or 0.19 or less. The degree of crystallinity in the vicinity of 2θ = 27 ° is preferably at least 58,427, and more preferably at least 78020. In more detail, the material of said (2) or (3) is obtained by the manufacturing method as described in WO2013 / 168812.

[Vehicle]
The vehicle is a medium for transferring the infrared absorbing pigment and / or the colorant to the substrate and for fixing the infrared absorbing pigment and / or the colorant to the substrate after printing. The vehicle used in the present invention may include known vehicle components used for printing, such as resins, solvents, photopolymerized components, and the like.

〔resin〕
In embodiments of the present invention, known resins used for printing may be used. For example, a resin contained in an oil-based ink or a resin contained in a UV ink may be used.

  The resin may be a natural or synthetic resin and may be a homopolymer or copolymer. In order to ensure the viscosity of the oil-based ink, the resin is preferably solid. When the resin is used as a binder for UV ink, the weight average molecular weight of the resin is preferably about 1000 to about 3,000,000.

  Examples of natural resins include rosin, agate, shellac, and gylsonite.

  As the synthetic resin, for example, rosin, phenol resin, modified alkyd resin, polyester resin, petroleum resin, maleic acid resin such as rosin modified maleic resin, cyclized rubber, acrylic resin, one-component urethane resin, two-component urethane And resins and other synthetic resins.

  When the ink of the present invention is a water-based ink, the water-based ink may contain, for example, a water-soluble resin, a colloidal dispersion resin, an emulsion resin and the like.

  The resins listed above can be used alone or in combination of two or more.

〔solvent〕
Examples of the solvent include organic solvents, drying oils, semi-drying oils, mineral oils, water and the like.

(Organic solvent)
In consideration of various properties such as solvency to resin, drying speed, viscosity, fluidity, wettability to printed material, presence or absence of odor, influence on environment or human body, the ink of the present invention can be used for printing. It may contain known organic solvents used. Further, in order to adjust various properties of the organic solvent, it is preferable to use not only one type of organic solvent but also a mixture of a plurality of types of organic solvents.

(Drying oil, semi-drying oil)
Drying oils and semi-drying oils are oil-based materials that polymerize and harden by air oxidation. The dry oil refers to a vegetable oil or vegetable oil-derived component having an iodine value of 130 or more. Moreover, a semi-drying oil means the vegetable oil or vegetable oil origin component which has an iodine value of 100-130. The drying oil or the semi-drying oil can be used alone or in combination of two or more.

(mineral oil)
As mineral oil, spindle oil, machine oil, white kerosene, non-aromatic petroleum solvents and the like can be mentioned. In particular, the mineral oil is preferably a non-aromatic petroleum solvent which is not compatible with water and has a boiling point of 180 ° C. or higher. As a non-aromatic petroleum solvent, n-dodecane mineral oil etc. are mentioned, for example.

(water)
Water is an essential component of water-based ink. Water can form an aqueous dispersion together with an infrared absorbing pigment, a resin, an organic solvent, a drying oil, a semi-drying oil, a mineral oil, a photopolymerization component, a coloring agent, an adjuvant and the like. Examples of water used as a vehicle for aqueous ink include pure water, deionized water, distilled water, drinking water, tap water and the like.

  The content of water relative to the total amount of solvent in the ink of the present invention may be 50% by mass or more, or 70% by mass or more, in consideration of the balance of performance required for the aqueous ink. The content may be less than or equal to 85% by mass.

[Photopolymerization component]
The photopolymerization components used in the present invention include monomers, oligomers, photopolymerization initiators and the like.

(Monomer, oligomer)
The monomer may be a compound having an ethylenically unsaturated bond conventionally used for photopolymerization. Moreover, an oligomer is obtained by oligomerizing the compound which has an ethylenically unsaturated bond.

  Oligomers are resins that govern the basic physical properties of UV inks. On the other hand, the monomer mainly acts as a diluent and can be used to adjust the properties of the ink such as viscosity, curability and adhesion.

  Examples of the compound having an ethylenically unsaturated bond include (meth) acrylic acid compounds; maleic acid compounds; urethane compounds, epoxy compounds, polyester compounds, polyol compounds, vegetable oil compounds, etc. The compound etc. which have a heavy bond are mentioned.

(Photopolymerization initiator)
A photoinitiator is a compound which generate | occur | produces radicals, such as active oxygen, by ultraviolet irradiation. The inks of the present invention may contain known photoinitiators used for printing.

[Auxiliaries]
The ink of the present invention may contain known adjuvants used for printing, such as dispersants, crosslinking agents, drying accelerators, and other additives.

Dispersant
Dispersants are adjuvants for improving the leveling properties, stability and dispersibility of the ink. The dispersing agent may be anionic, cationic or nonionic. As a dispersing agent, a low molecular dispersing agent, a high molecular dispersing agent, a pigment derivative, a coupling agent etc. are mentioned, for example.

  The low molecular weight dispersant is a low molecular weight substance having a portion having high orientation or adsorption to the infrared absorbing pigment or colorant and a portion having high affinity to the vehicle, and is also called a surfactant or a wetting agent.

  The polymeric dispersant is a high molecular weight substance having an anchor group adsorbed on the surface of the infrared absorbing pigment or colorant and a barrier group which exerts a steric hindrance effect in the vehicle. In the polymer dispersant, the barrier group becomes bulky as compared with the low molecular dispersant, so that the dispersion stability of the infrared absorbing pigment or the colorant is improved.

  The pigment derivative is obtained by introducing a polar group such as a carboxyl group, a sulfone group or a tertiary amino group into the pigment skeleton. The pigment skeleton part of the pigment derivative is easy to adsorb to the corresponding pigment, while the introduced polar group is excellent in the affinity to the vehicle or other dispersant.

  As a coupling agent, a silane coupling agent, a titanate coupling agent, etc. are mentioned, for example.

[Crosslinking agent]
A crosslinker can be added to the vehicle to crosslink or gelate the resin described above.

[Drying accelerator]
Examples of the drying accelerator include metal salts of fatty acids contained in a drying oil or semi-drying oil, metal salts of organic carboxylic acids, metal salts of inorganic acids, and the like.

[Other additives]
In the ink of the present invention, if desired, polymerization inhibitors such as phenothiazine, t-butylhydroxytoluene, etc .; waxes; extender pigments; drying inhibitors; antioxidants; surface conditioning assistants; Or surfactants may be included.

[Colorant]
The colorant is a component that colors the ink. The ink of the present invention may contain, in addition to the infrared absorbing pigment, known colorants used in printing. Examples of the colorant include inorganic pigments, organic pigments, dyes, organic dyes for toners, and the like.

  Furthermore, other functional materials such as functional pigments and functional dyes may be added to the ink of the present invention, in addition to the infrared absorbing pigments and colorants described above. The functional material may be inorganic or organic, and may be an additive that imparts functionality to the ink.

<Composition and viscosity of ink>
The total content of the two infrared absorbing pigments in the anti-counterfeit ink is preferably 1% by mass or more, 2% by mass or more, or 3% by mass or more, and the content is 60% by mass or less, The content is preferably 50% by mass, 40% by mass, 30% by mass, 25% by mass, 20% by mass, 15% by mass, 10% by mass, 9% by mass or 8% by mass.

  The content of the dispersant in the forgery prevention ink is preferably 0.25% by mass or more, 0.5% by mass or more, or 1.0% by mass or more, and the content is 15% by mass or less, 10 It is preferable that it is mass% or less, or 8 mass% or less.

  The viscosity of the forgery prevention ink is preferably 0.002 Pa · s or more, 0.02 Pa · s or more, 0.2 Pa · s or more, 2 Pa · s or more, or 5 Pa · s or more, and the viscosity is 200 Pa It is preferable that s or less, 150 Pa · s or less, or 100 Pa · s or less.

  The solvent as the vehicle, the resin and the photopolymerization component may be contained in the forgery prevention ink in an amount such that the viscosity of the forgery prevention ink is 0.002 Pa · s to 200 Pa · s.

  When the forgery prevention ink is an oil-based ink, the preferable composition of the oil-based ink is the total content of the two infrared-absorbing pigments when the ink viscosity is adjusted to about 5 to 100 Pa · s at 25 ° C. Is 1 to 45% by mass, the content of vehicle is 20 to 85% by mass, the content of colorant is 0 to 20% by mass, and the content of adjuvant is 0.25 to 25% by mass It is.

  When the forgery prevention ink is a UV ink, the preferable composition of the UV ink is the total content of the two infrared absorbing pigments when the ink viscosity is adjusted to about 1 to 200 Pa · s at 25 ° C. Is 1 to 45% by mass, the content of vehicle is 10 to 90% by mass, the content of colorant is 0 to 25% by mass, and the content of auxiliary agent is 0 to 25% by mass .

  When the anti-counterfeit ink is an oil-based / UV combined use ink, the blending ratio of each component contained in the oil-based / UV combined use ink is a solvent and when the ink viscosity is adjusted to several hundred Pa · s at 25 ° C. The vehicle for an oil-based ink containing a resin is 25 to 50% by mass, the vehicle for a UV ink containing a resin and a photopolymerization component is 25 to 50% by mass, and the total content of two infrared absorbing pigments is 1 to 45% by weight, 0 to 20% by weight of colorant, and 0 to 20% by weight of adjuvant.

<Method of mixing two types of infrared absorbing pigments>
If desired, before preparing the ink of the present invention, two kinds of infrared absorbing pigments different from each other in infrared absorption may be mixed manually or with a mixing stirrer such as a propeller and a mixer.

<Dispersion of infrared absorbing pigment>
If desired, the infrared absorbing pigment may be dispersed in a solvent to form an infrared absorbing pigment dispersion prior to preparing the ink of the present invention.

In the case of dispersing cesium tungsten oxide fine particles in a solvent, in order to suppress the content of the organic solvent which may dissolve the rubber blanket during printing, the cesium tungsten oxide is formed by a method including the following steps in the following order: It is preferred to obtain a fine particle dispersion:
(1) cesium tungsten oxide fine particles are mixed with an organic solvent having a boiling point of 180 ° C. or less selected from the group consisting of alcohols, ethers, esters, ketones, aromatic hydrocarbons and glycol ethers, and wet Dispersing with a media mill to obtain a first dispersion;
(2) A step of adding a vegetable oil such as a semi-drying oil, a non-drying oil etc., or a compound derived from a vegetable oil such as a fatty acid monoester etc to the first dispersion and mixing to obtain a second dispersion And (3) removing the organic solvent used in step (1) from the second dispersion until the content of the organic solvent used in step (1) becomes 5.0% by mass or less.

  In order to suppress an increase in the viscosity of the first and second dispersions in step (2), a vegetable oil or a fatty acid soluble in a vegetable oil-derived compound is added to the first dispersion and / or the second dispersion. It is preferred to add the dispersant which is in the structure.

  Step (3) can be carried out by a thermal distillation method using the difference in boiling point between the organic solvent used in step (1) and the vegetable oil used in step (2) or a compound derived from a vegetable oil. Furthermore, reduced pressure heating distillation to which a reduced pressure operation is also added is preferable from the viewpoint of safety, energy cost, and stabilization of quality.

<Method of producing ink>
In one embodiment of the method for producing the ink of the present invention, the ink is prepared by mixing and dispersing the components such as two types of infrared absorbing pigments different from each other in infrared absorption, a vehicle, an auxiliary agent, and a coloring agent in any order. You can get The mixing and dispersion of each component can be carried out by a mixer such as a single-screw mixer and a twin-screw mixer; an ink mill such as a three-roller mill, a bead mill, a ball mill, a ball mill, a sand grinder and an attritor.

  In this aspect, the oil-based ink of the present invention, UV ink, oil / UV combination ink, solvent ink or water-based ink may be formed. When forming an oil / UV combination ink, a mixture is obtained by mixing two types of infrared absorbing pigments different from each other in infrared absorptivity, a solvent and a resin, and a photopolymerizable monomer or oligomer is added to this mixture, An additional vehicle, an adjuvant or a colorant is also added to obtain a mill base for ink by milling and dispersing with a bead mill or 3-roll mill or the like. Furthermore, a photoinitiator can be added to the mill base for ink, and if necessary, other materials can be added to obtain the oil-UV combination ink of the present invention.

  The median diameter of the infrared absorbing pigment in the ink can be adjusted according to the type of printing ink, but from the viewpoint of the transparency of the ink in the visible light wavelength range, it is 200 nm or less or 100 nm or less preferable. The median diameter of the infrared absorbing pigment is 3 μm or less for offset printing ink, 30 μm or less for gravure printing ink and flexographic printing ink as measured by laser diffraction scattering method, silk screen printing ink, letterpress printing ink and intaglio printing ink In the ink jet printing ink, it is more preferably about 100 nm or less.

<Printed matter and printing method>
By printing the ink of the present invention on a substrate, a printed material provided with a printing unit can be provided. Therefore, the printed matter comprises a substrate and a printing unit printed with the ink of the present invention.

  The printed matter may comprise one or more printing units. When a plurality of printing units are provided on the substrate, the composition of the ink forming each printing unit, for example, the mass ratio of two types of infrared absorbing pigments having different infrared absorbing properties, all in the ink The total content of the infrared absorbing pigment and the like may be the same or different. The plurality of printing units may be adjacent to or separated from one another.

  Examples of the substrate include paper substrates such as wood free paper, coated paper, art paper, recycled paper, etc .; film substrates such as polyester film, polypropylene film, polystyrene film, vinyl chloride film etc; or cloth substrates such as , Woven fabric, non-woven fabric, etc. may be used. Printed matter may be banknotes, passports, securities, tickets, cards and the like.

  The ink of the present invention can be used to obtain a printed matter by a common printing method, for example, flexographic printing, letterpress printing, offset printing, intaglio printing, gravure printing, screen printing or inkjet printing.

  Among these printing methods, silk screen printing, gravure printing, intaglio printing or offset printing is preferable in order to prevent forgery of the printed matter.

  Since the ink of the present invention has infrared absorptivity, various information management can be performed by printing the printing ink of the present invention in an arbitrary pattern and reading the obtained printed matter with an infrared light detector or the like. .

<Authentication judgment method and authenticity judgment device>
According to the present invention, along with the infrared absorption profile of the printing unit that can be arbitrarily set, there is provided an authenticity determination method including the following steps:
Observing the printing section for at least two infrared wavelengths; and making an authenticity determination based on the observation results at the at least two infrared wavelengths.

  For example, the relationship between observations at at least two infrared wavelengths is predetermined for a true print. After that, using an infrared light detector such as an infrared camera, the printing unit of the observation target formed on the substrate is observed for at least two infrared wavelengths, and the relationship between the observation results is true printing unit and observation It is possible to determine the authenticity of the observation target printing unit by comparing the target printing units.

  In order to improve the determination accuracy of the printing unit, it is preferable that the observation points of the printing unit be the same for at least two infrared wavelengths. In addition, you may perform more complicated authenticity judgment by observing a printing part further in the location different from the observation location regarding at least 2 infrared wavelength.

  The observation of the printed part can be performed with an infrared light detector that can detect infrared light in the near infrared wavelength range (750 nm to 1400 nm), short wavelength infrared wavelength range (1400 nm to 3000 nm), or both. The observation of the printing part can be performed with one or more infrared light detectors.

  The authenticity determination of the printing part is preferably based on the difference between the observation results in at least two infrared wavelengths, more preferably based on the absolute value of the difference between the maximum reflectance and the minimum reflectance in the selected infrared wavelength range. It takes place.

  When the absolute value of the difference between the maximum reflectance and the minimum reflectance in the selected infrared wavelength range is a value within a specific range in order to improve the accuracy of the authenticity determination regardless of the type of infrared light detector Preferably, it is determined that the printing unit is genuine. It is preferable to set the absolute value of the difference between the maximum reflectance and the minimum reflectance in the selected infrared wavelength range to 5% or more or 8% or more for an authentic printing portion, and this absolute value is 22.90% or less It is also preferable to set.

  There is also provided an authenticity determination apparatus including an observation unit that observes the printing unit for at least two infrared wavelengths, along with the infrared absorption profile of the printing unit that can be arbitrarily set. The observation unit may be the infrared light detector described above.

  It is preferable that the authenticity determination apparatus further include an authenticity determination unit that performs authenticity determination based on observation results of the printing unit at at least two infrared wavelengths. The authenticity determination unit includes an arithmetic processing unit for executing a program for automatically determining the authenticity of the observation target based on the relationship between the observation results in at least two infrared wavelength ranges preset for the genuine printing unit. Good. The authenticity determination unit may include an output unit that outputs the result of the authenticity determination as sound, an image, light, heat, and the like, and a control unit that controls a signal to be output to the output unit according to the result of the authenticity determination. The output unit may be a display device that displays the result of the authenticity determination, for example, a liquid crystal screen or the like.

<Preparation of cesium-tungsten oxide fine particle dispersion>
A cesium tungsten oxide particulate dispersion was prepared according to the following procedure:
(1) 50 parts by mass of hexagonal cesium oxide tungsten fine particles (Sumitomo Metal Mining Co., Ltd.) represented by the formula Cs _0.33 WO ₃ and 20 parts by mass of a dispersant having a fatty acid in the structure (100% nonvolatile content) The first dispersion was obtained by mixing in polyethylene glycol monomethyl ether acetate (PGMEA) and dispersing in a wet media mill.
(2) 25 parts by mass of sunflower oil was added to the first dispersion and mixed to obtain a second dispersion.
(3) The second dispersion liquid is subjected to pressure reduction and heating distillation at 80 ° C. for 1 hour using a stirring type vacuum dryer, until the content of PGMEA becomes 5.0 mass% or less, PGMEA was removed from the dispersion to obtain a CWO fine particle dispersion having a content of cesium tungsten oxide fine particles (hereinafter, referred to as "CWO fine particles") of 50% by mass.

<Preparation of antimony-doped tin oxide fine particles>
According to the same method as Example 2 described in WO 2013/168812, the antimony oxide content is 2.8% by weight by calcining the antimony-doped tin oxide raw material in a furnace under aeration, and the number of times of integration 1 Antimony-doped oxide whose half width (Δ2θ) near 2θ = 27 ° is 0.18 and the degree of crystallinity (CPS / Δ2θ) around 2θ = 27 ° is 84883 obtained by periodic X-ray diffraction measurement Tin fine particles (hereinafter referred to as "ATO fine particles") were obtained.

<Particle size measurement>
The particle size distribution of the CWO fine particle dispersion was measured under the following particle size measurement conditions. Under the following particle size measurement conditions, powder of ATO fine particles was charged into the measuring device while butanol was circulated in the measuring device, and the particle size distribution of ATO fine particles was measured. The median diameter of CWO particles _{(D 50)} is 0.056Myuemu, the median diameter of the ATO fine particles _{(D 50)} of 0.23 .mu.m.
[Particle size measurement conditions]
Measuring instrument: LMS-2000e (Seishin Co., Ltd.)
Automatic wet dispersion unit: 2000 SR
Measurement method: Laser diffraction method

Preparation of Oil-Based Offset Printing Ink
Comparative Example 1
The ATO fine particles obtained above were dispersed in Best One GIGA medium (T & K TOKA Co., Ltd.) using a triple roll mill to obtain an oil-based offset printing ink having a content of ATO fine particles of 15% by mass.

Comparative Example 2
The CWO fine particle dispersion (CWO fine particles: 50% by mass) obtained above is dispersed in the Best One GIGA medium using a three-roll mill, and the oil offset printing in which the content of the CWO fine particle dispersion is 15% by mass I got the ink.

[Examples 1 to 9]
Using a three-roll mill, the CWO fine particle dispersion obtained above (CWO fine particles: 50% by mass) and the ATO fine particles obtained above are dispersed in the Best One GIGA medium, and the ink shown in Table 1 below The mass ratio of ATO fine particles to CWO fine particles in the mixture was changed to obtain an oil-based offset printing ink having a total content of CWO fine particle dispersion and ATO fine particles of 15% by mass.

<Infrared absorptivity of printed matter>
The oil-based offset printing inks obtained in Examples 1 to 9 and Comparative Examples 1 and 2 were printed under the following printing conditions to obtain printed materials.
[Printing condition]
Printing machine: Offset printing machine RI tester (IHI Machine System Co., Ltd.)
Ink volume: 0.125 ml
Ink film thickness: about 1 μm
Printing substrate: OCR paper (Oji Paper Co., Ltd.)

The reflectance of the obtained printed matter was measured under the following reflectance measurement conditions to calculate the absolute value of the difference between the maximum reflectance and the minimum reflectance in the wavelength range of 852 nm to 2500 nm. In addition, the reflectance of the OCR paper (Oji Paper Co., Ltd.) which is a printing base material was set as a reference value of about 100%.
[Reflectance measurement conditions]
Measuring device: UV-visible spectrophotometer U-4000 (Hitachi, Ltd.)
Measurement item: reflectance (%)
Measurement wavelength: 352 nm to 2500 nm

  The results of reflectance measurement for each printed material are shown in FIG. 1 and Table 1 below.

  In Examples 1 to 9, since the content of CWO fine particles in the CWO fine particle dispersion is 50% by mass, and the total content of the CWO fine particle dispersion and ATO fine particles in the ink is 15% by mass, As the amount of CWO particulate dispersion in the ink increases, ie as the example number increases, the total amount of particulates in the ink decreases. However, as long as the mass ratio of ATO fine particles to CWO fine particles in the ink is the same, even if the total amount of fine particles in the ink changes, the graph showing the relationship between the wavelength range of 852 nm to 2500 nm and the reflectance (%) It is conceivable that the position of the reflection profile moves up and down according to the total amount of fine particles, and the absolute value of the difference between the maximum reflectance and the minimum reflectance does not change.

  When the reflectances are compared in the wavelength range of 852 nm to 2500 nm shown in FIG. 1, it can be seen that an infrared absorption profile different from that of one infrared absorbing pigment can be obtained by combining the two infrared absorbing pigments. Therefore, based on the infrared absorption profile of the printed matter printed with the ink of Examples 1-9, authenticity determination can be newly performed.

  Furthermore, from Table 1 and FIG. 1, as the mass ratio of ATO fine particles to CWO fine particles approaches 4.5: 5.25, ie 6: 7, the infrared absorption profile in the wavelength range of 852 nm to 2500 nm approaches flat. Therefore, it is understood that the reading accuracy of the printed matter can be easily secured regardless of the type of the infrared detector.

Claims (13)

A forgery-preventing ink comprising two types of infrared-absorbing pigments different from each other in infrared absorptivity and a vehicle , wherein the forgery-preventing ink is printed on a substrate and dried to form a printing portion, The anti-counterfeit ink, wherein the absolute value of the difference between the maximum reflectance and the minimum reflectance in the wavelength range of 852 nm to 2500 nm is 22.90% or less when the reflectance of the printed portion is measured .   What is claimed is: 1. A forgery-preventing ink comprising two types of infrared-absorbing pigments different from each other in infrared-absorbing properties and a vehicle, wherein the two types of infrared-absorbing pigments are:
  General Formula Cs _x W _y O _z [In the formula, x, y and z each represent a positive number, 0 <x / y ≦ 1, and 2.2 ≦ z / y ≦ 3.0]. ;as well as
  Antimony-doped tin oxide fine particles containing tin oxide and antimony oxide;
Is an anti-counterfeit ink. The difference between the maximum reflectance and the minimum reflectance in the wavelength range of 852 nm to 2500 nm when the forgery prevention ink is printed on a substrate, dried, and a printed portion is formed to measure the reflectance of the printed portion The anti-counterfeit ink according to claim 2 , wherein the absolute value of is less than or equal to 22.90%. The two types of infrared absorbing pigments are
General formula Cs _x W _y O _z (wherein, x, y and z are each a positive number, 0 <x / y ≦ 1 and 2.2 ≦ z / y ≦ 3.0) Tungsten oxide particles represented by the formula: and antimony doped tin oxide particles containing tin oxide and antimony oxide;
In it, the anti-counterfeit ink according to claim 1. The anti-counterfeit ink according to any one of claims 2 to 4 , wherein the cesium tungsten oxide particles are contained in a ratio of 1/3 part by mass or more to 1 part by mass of the antimony-doped tin oxide particles. . A method for obtaining a printed matter by flexographic printing, letterpress printing, offset printing, intaglio printing, gravure printing, silk screen printing or inkjet printing using the anti-counterfeit ink according to any one of claims 1 to 5 . The printed matter provided with the printing part printed by the forgery prevention ink of any one of Claims 1-5 . A printed matter provided with a printing unit printed with the forgery prevention ink according to any one of claims 1 to 5 as a genuine print
Observing the printing section for at least two infrared wavelengths; and making an authenticity determination based on the observations at the at least two infrared wavelengths;
How to judge the authenticity, including The authenticity determination method according to claim 8 , wherein the authenticity determination is performed based on a difference between observation results at the at least two infrared wavelengths. The authenticity determination method according to claim 9 , wherein the authenticity determination is performed based on the absolute value of the difference between the maximum reflectance and the minimum reflectance in the selected infrared wavelength range. The method according to claim 10 , wherein the printing unit is determined to be authentic when the absolute value is a value within a specific range. An authenticity determination apparatus including an observation unit which observes a printing unit for at least two infrared wavelengths for use in the method according to any one of claims 8 to 11 . The authenticity determination apparatus according to claim 12 , further comprising an authenticity determination unit configured to perform authenticity determination based on observation results at the at least two infrared wavelengths.

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