JP2018087327A - Wavelength conversion ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wavelength conversion ink that can change its hue by infrared irradiation; allows the hue to be controlled as desired by the irradiation or non-irradiation, to prevent the replication or forgery of an object coated with the ink; and can be prepared regardless of the polarity of a dispersion medium, and also provide an object coated with the wavelength conversion ink, a determination device, and a determination method using the determination device.SOLUTION: A wavelength conversion ink contains a lanthanoid-containing inorganic material fine particle having a wavelength conversion function from long-wavelength light to short-wavelength light, and a colorant.SELECTED DRAWING: None

Description

The present invention can change the hue by infrared irradiation, and by arbitrarily adjusting the hue at the time of non-infrared irradiation and infrared irradiation, it is possible to prevent the duplication of the coated material, forgery prevention, The present invention relates to a wavelength conversion ink that can be produced regardless of the polarity of a dispersion medium. The present invention also relates to a coated material having the wavelength conversion ink, a determination device, and a determination method using the determination device.

Inorganic fine particles having an “up-conversion” function for converting long-wavelength light such as infrared light into short-wavelength light such as visible light and ultraviolet light are expected to be applied to medical uses such as biomarkers. In recent years, highly functional materials that have been provided with an up-conversion function by dispersing such inorganic fine particles in a matrix material have attracted attention.

As inorganic fine particles having an upconversion function, those containing mainly lanthanoid elements are known, and a phenomenon called “multiphoton excitation” due to the energy level difference of these elements is used.
Inorganic particulate host materials with an up-conversion function are required to have low phonon energy and high chemical stability so as not to inhibit the light absorption, energy transfer, and light emission processes of lanthanoid elements. Oxide materials and fluoride materials are known as materials.

Patent Document 1 proposes an anti-counterfeit medium containing inorganic fine particles having an upconversion function as a highly functional material having an upconversion function. In such an anti-counterfeit medium, an infrared fluorescent ink containing inorganic material fine particles having an up-conversion function is used. Since such infrared fluorescent ink is transparent to visible light, the second information can be added to the printed matter in addition to the information that can be visually recognized by visible light, thus preventing forgery and information leakage, etc. It is used for security purposes. Further, the conventional ultraviolet fluorescent ink has a problem that the printed material is deteriorated by irradiation of ultraviolet rays, but has an advantage that the deterioration of the printed material can be suppressed by using infrared rays.

JP-A-2006-91121

On the other hand, even in the forgery prevention medium that reveals the second information by irradiating infrared light, it is possible to specify the wavelength range of light emitted by continuously changing the wavelength, and only the hue emitted by infrared irradiation can be specified. There is a problem that the anti-counterfeiting function and the anti-duplication function are insufficient, such as a similar hue being easily reproduced.
Therefore, there has been a demand for a means for preventing forgery and preventing copy more reliably.
Furthermore, the inorganic material fine particles having an up-conversion function have low water resistance, and when used in infrared fluorescent ink, the inorganic fine particles deteriorate due to moisture in the environment, and the luminescence behavior changes over time, or the substrate to be printed has moisture. There was a problem that the inorganic particles were eluted by touching and the up-conversion function was lowered. Therefore, as inorganic fine particles, fine particles using a hydrophobic material or fine particles surface-treated with a hydrophobic material are used. Infrared fluorescent ink using such fine particles is nonpolar as a solvent. However, there is a problem that printing cannot be performed depending on the type of the substrate to be printed, or printing failure occurs.

The present invention can change the hue by infrared irradiation, and by arbitrarily adjusting the hue at the time of non-infrared irradiation and infrared irradiation, it is possible to prevent the duplication of the coated material, forgery prevention, An object of the present invention is to provide a wavelength conversion ink that can be produced regardless of the polarity of the dispersion medium. It is another object of the present invention to provide a coated material having the wavelength conversion ink, a determination device, and a determination method using the determination device.

The present invention is a wavelength conversion ink containing lanthanoid-containing inorganic material fine particles having a function of converting wavelength from long wavelength light to short wavelength light and a colorant.
The present invention is described in detail below.

As a result of intensive studies, the present inventor has found that the hue of the printed pattern can be changed depending on the presence or absence of infrared irradiation by using a combination of lanthanoid-containing inorganic material fine particles having a wavelength conversion function and a colorant. In addition, the present inventors have found that counterfeit prevention and duplication prevention can be more reliably achieved by arbitrarily changing the composition of the colorant and the lanthanoid-containing inorganic material fine particles and adjusting the hue before and after infrared irradiation, thereby completing the present invention. It came.

The wavelength conversion ink of the present invention contains lanthanoid-containing inorganic material fine particles having a function of wavelength conversion from long wavelength light to short wavelength light.
The lanthanoid-containing inorganic material fine particles preferably have core particles containing a lanthanoid having a light absorption function and a lanthanoid having a light emission function.
By having the lanthanoid having the light absorbing function and the lanthanoid having the light emitting function, it absorbs light having a long wavelength such as infrared rays and converts the energy of the absorbed light to light having a short wavelength such as visible light or ultraviolet light. "Up-conversion function" that can be converted.

The lanthanoid having a light absorption function constituting the lanthanoid-containing inorganic material fine particles is not particularly limited as long as it is a lanthanoid capable of absorbing long-wavelength light such as infrared rays. For example, ytterbium (Yb), neodymium (Nd ) And the like. In particular, ytterbium is preferable because it has strong absorption in the vicinity of 10,000 cm ⁻¹ when used as light that absorbs near-infrared light. These lanthanoids may be used alone or in combination of two or more.

The lanthanoid having a light emitting function constituting the lanthanoid-containing inorganic material fine particles is not particularly limited as long as it is a lanthanoid capable of emitting light by being excited by energy from a lanthanoid having a light absorbing function. For example, erbium ( Er), holmium (Ho), thulium (Tm) and the like. In particular, erbium, holmium, and thulium whose wavelengths are in the visible light region or the ultraviolet light region are preferable. These lanthanoids may be used alone or in combination of two or more.

The combination of the lanthanoid having the light absorption function and the lanthanoid having the light emission function constituting the fine particles of the lanthanoid-containing inorganic material is not particularly limited. A combination of ytterbium having strong absorption in the vicinity of 10,000 cm ⁻¹ and erbium, holmium, or thulium that emits light upon receiving energy transfer from ytterbium, and the wavelength of the light obtained is in the visible light region or the ultraviolet light region. It is preferable when absorbing long wavelength light such as infrared light and converting it into short wavelength light such as visible light or ultraviolet light.

The lanthanoid-containing inorganic material fine particles are not particularly limited as long as they contain the lanthanoid having the light absorption function and the lanthanoid having the light emission function. For example, the lanthanoid having the light absorption function and the light emission function are provided. Examples include those containing lanthanoid oxides, halides, and the like. As the halide, a fluoride is preferable.

The lanthanoid-containing inorganic material fine particles preferably contain a lanthanoid having a light absorption function, an element having an ionic radius similar to that of the lanthanoid having a light emission function or a structure at the time of crystallization, or a compound thereof. The lanthanoid having the light absorption function and the element having an ionic radius similar to that of the lanthanoid having the light emission function and the structure at the time of crystallization include rare earth elements other than the lanthanoid, and the compound includes those other than the lanthanoid. Examples include rare earth oxides and halides. The halide is preferably a fluoride, and a fluoride containing an alkali metal and a rare earth element, or a fluoride containing oxygen, an alkali metal and a rare earth element is preferred.
Examples of the rare earth element other than the lanthanoid include yttrium (Y), gadolinium (Gd), scandium (Sc), and the like. Examples of the rare earth element compounds other than the lanthanoids include oxides or halides of yttrium, gadolinium, and scandium.
Among them, since high efficiency can be expected with respect to energy transfer between lanthanoids and light emission efficiency can be expected, the core particles preferably contain yttrium, an oxide of yttrium, or a halide of yttrium. Y ₂ O ₃ is preferred as the yttrium oxide, and NaYF ₄ is preferred as the yttrium halide.

The lanthanoid-containing inorganic material fine particles contain Y ₂ O ₃ or NaYF ₄ as a compound of an element having an ionic radius similar to that of the lanthanoid having the light-absorbing function and a structure at the time of crystallization. It is preferable to do. Moreover, it is preferable to contain ytterbium as the lanthanoid having the light absorption function and at least one selected from the group consisting of erbium, holmium and thulium as the lanthanoid having the light emission function.

The content of the lanthanoid having the light absorbing function in the lanthanoid-containing inorganic material fine particles is the sum of the lanthanoid contained in the lanthanoid-containing inorganic material fine particles and an element having an ionic radius similar to that of the lanthanoid and a structure at the time of crystallization. On the other hand, the preferable lower limit is 2 mol% and the preferable upper limit is 50 mol%. A more preferred lower limit is 2.5 mol%, and a more preferred upper limit is 25 mol%. When the content of the lanthanoid having the light absorption function is not less than the above preferable lower limit and not more than the above preferable upper limit, the energy of light reaching the lanthanoid-containing inorganic material fine particles can be efficiently absorbed.
The content of the lanthanoid constituting the lanthanoid-containing inorganic material fine particles can be measured using, for example, a fluorescent X-ray analyzer (manufactured by Shimadzu Corporation, EDX-800HS).

The content of the lanthanoid having the light emitting function in the lanthanoid-containing inorganic material fine particle is the sum of the lanthanoid contained in the lanthanoid-containing inorganic material fine particle and an element having an ionic radius similar to that of the lanthanoid and a structure at the time of crystallization. On the other hand, the preferable lower limit is 0.005 mol%, and the preferable upper limit is 20 mol%. A more preferred lower limit is 0.01 mol%, and a more preferred upper limit is 10 mol%. When the content of the lanthanoid having the light emitting function is not less than the above preferable lower limit and not more than the above preferable upper limit, the absorbed energy can be received and the light emitting function can be efficiently exhibited.

The total content of the lanthanoid having the light absorption function and the lanthanoid having the light emission function is the same as that of the lanthanoid contained in the fine particles of the lanthanoid-containing inorganic material and an element having an ionic radius similar to that of the lanthanoid or a structure at the time of crystallization. The preferable lower limit with respect to the total is 2 mol% and the preferable upper limit is 50 mol%. A more preferred lower limit is 2.5 mol%, and a more preferred upper limit is 25 mol%. When the total content of lanthanoids constituting the lanthanoid-containing inorganic material fine particles is not less than the preferred lower limit and not more than the preferred upper limit, the lanthanoid in the core particles has an ionic radius similar to that of the lanthanoid or at the time of crystallization. Substitution and doping can be performed without breaking the crystal structure constituted by the element having a structure. Therefore, the energy transfer efficiency in the lanthanoid-containing inorganic material fine particles can be maintained without impairing.

In the lanthanoid-containing inorganic fine particles, the ratio of the content of the lanthanoid having the light absorption function and the content of the lanthanoid having the light emission function (content of the lanthanoid having the light absorption function / the content of the lanthanoid having the light emission function) The preferred content is 2 in terms of molar ratio, and the preferred upper limit is 100. A more preferred lower limit is 5, and a more preferred upper limit is 75.
Since the above ratio is not less than the preferable lower limit and not more than the preferable upper limit, the energy absorbed by the lanthanoid having the light absorption function can be uniformly transferred to the lanthanoid having the light emission function without excess or deficiency, and thus the obtained wavelength conversion function The efficiency of can be increased.

The content of an element having an ionic radius similar to that of the lanthanoid or a structure at the time of crystallization is preferably 5 mol%, more preferably 10 mol%, more preferably the lower limit relative to the total of rare earth elements contained in the core particles. An upper limit is 98 mol%, and a more preferable upper limit is 80 mol%. When the content of an element having an ionic radius similar to that of the lanthanoid or a structure at the time of crystallization is not less than the preferable lower limit and not more than the preferable upper limit, the ordered arrangement of the crystal structure as a host material for doping the lanthanoid A structure can be formed, the efficiency of energy transfer in the lanthanoid-containing inorganic material fine particles can be increased, and the light emission efficiency is improved.
The content of an element having an ionic radius similar to that of the lanthanoid constituting the lanthanoid-containing inorganic fine particles and the structure at the time of crystallization is measured using, for example, a fluorescent X-ray analyzer (manufactured by Shimadzu Corporation, EDX-800HS). can do.

As for the average particle diameter of the lanthanoid-containing inorganic material fine particles, a preferred lower limit is 5 nm, a more preferred lower limit is 7.5 nm, a preferred upper limit is 250 nm, and a more preferred upper limit is 200 nm. When the average particle diameter of the lanthanoid-containing inorganic material fine particles is not less than the above preferable lower limit and not more than the above preferable upper limit, dispersibility can be improved when used in combination with other materials. The average particle size of the lanthanoid-containing inorganic material fine particles can be determined by measuring the particle size of the core particles using an electron microscope.

In the lanthanoid-containing inorganic material fine particles, the preferable upper limit of the CV value of the average particle diameter is 20%, and the more preferable upper limit is 15%.
When the CV value of the average particle diameter is 15% or less, it is possible to suppress variations in the composite form when composite with other materials.

The emission wavelength region of the lanthanoid-containing inorganic material fine particles is preferably 350 to 750 nm, and more preferably 400 to 700 nm.

The fine particles of the lanthanoid-containing inorganic material may have a shell layer on the surface. By having the shell layer, it is possible to suppress the loss of outflow in energy transfer between lanthanoids, adjust the affinity when compounding with other materials, and further suppress the deterioration of the lanthanoid-containing inorganic material fine particles due to ultraviolet rays. In addition, moisture resistance can be improved. Such a shell layer is formed of a shell layer formed of a polymer, a lanthanoid having a light absorption function, an element having an ionic radius similar to that of the lanthanoid having a light emission function or a structure at the time of crystallization, or a compound thereof. Or a shell layer formed of an oxide.

Above all, the shell layer preferably contains a metal oxide. When the shell layer contains a metal oxide, the resulting lanthanoid-containing inorganic material fine particles are easily dispersed in both polar and nonpolar solvents, and are reactive with dispersants such as silane coupling agents. And the printability of the resulting wavelength conversion ink can be improved.
The band gap of the metal oxide has a preferable lower limit of 3.0 eV and a preferable upper limit of 4.5 eV.
When the band gap of the metal oxide is not less than the above lower limit and not more than the above upper limit, the ultraviolet transmittance of the resulting shell layer can be lowered, and the transmittance of visible light and infrared light is sufficiently high. It is possible to achieve both suppression of deterioration of the lanthanoid-containing inorganic material fine particles and high emission intensity.

Examples of the metal oxide include titanium oxide, zinc oxide, cerium oxide, and the like.

In the lanthanoid-containing inorganic material fine particles, the metal oxide contained in the shell layer has a preferable lower limit of 25 mol% and a preferable upper limit of 100 mol%. When the content of the metal oxide in the shell layer is equal to or more than the preferable lower limit, ultraviolet transmission through the shell layer can be sufficiently suppressed.

A preferable lower limit of the thickness of the shell layer is 2 nm, and a preferable upper limit is 20 nm. When the thickness of the shell layer is not less than the above preferable lower limit and not more than the above preferable upper limit, it is possible to inhibit light having a long wavelength such as infrared rays from reaching the lanthanoid-containing inorganic material fine particles having a light absorption function. In addition, loss during light emission can be reduced. Further, it is possible to sufficiently suppress the transmission of ultraviolet rays and to suppress a decrease in the wavelength conversion function of the lanthanoid-containing inorganic material fine particles. The thickness of the shell layer has a more preferable lower limit of 2.5 nm and a more preferable upper limit of 10 nm. The thickness of the shell layer is measured by measuring the particle diameter of the fine particles having the shell layer formed on the surface of the core particle using an electron microscope and calculating the difference from the average particle diameter of the core particle. can do.

The ratio of the average particle size of the lanthanoid-containing inorganic material fine particles to the thickness of the shell layer (the average particle size of the core particles / the thickness of the shell layer) is preferably 2 and more preferably 2.5. The upper limit is 50, and a more preferable upper limit is 25. When the ratio to the thickness is not less than the preferable lower limit and not more than the preferable upper limit, the loss of energy can be reduced without impeding the arrival of light to the core particles. In addition, energy loss during light emission can be further reduced. Furthermore, it is possible to sufficiently suppress the deterioration of the wavelength conversion function of the core particles by suppressing the transmission of ultraviolet rays.

The preferable lower limit of the content of the lanthanoid-containing inorganic material fine particles in the wavelength conversion ink of the present invention is 0.01% by weight, and the preferable upper limit is 75% by weight. When the content of the lanthanoid-containing inorganic material fine particles is not less than the preferable lower limit and not more than the preferable upper limit, the wavelength conversion function can be sufficiently exhibited. The more preferable lower limit of the content of the lanthanoid-containing inorganic material fine particles is 0.05% by weight, and the more preferable upper limit is 50% by weight.

The method for producing the lanthanoid-containing inorganic material fine particles containing the lanthanoid having the light absorption function and the lanthanoid having the light emission function is not particularly limited. For example, a metal salt containing a lanthanoid having a light absorption function, a metal salt containing a lanthanoid having a light emitting function, a metal salt containing an element having an ionic radius similar to that of a lanthanoid or a structure at the time of crystallization, an alkaline solution, And a fluoride solution is melt | dissolved in the solvent which consists of an organic compound, and a metal ion containing solution is prepared. Furthermore, the method of depositing the core particle which consists of fluorides by heating the obtained metal ion containing solution at high temperature is mentioned.

Examples of the metal salt containing a lanthanoid having a light absorbing function and the metal salt containing a lanthanoid having a light emitting function include, for example, nitrates, sulfates, phosphates, borates, silicates, and vanadic acids of lanthanoids. Examples thereof include oxyacid salts such as salts. Also, carboxylic acid salts such as lanthanoid acetate, sulfonate, phenol salt, sulfinate, 1,3-diketone compound salt, thiophenol salt, oxime salt, aromatic sulfonamide salt, primary And organic acid salts such as salts of secondary nitro compounds, lanthanoid chlorides, and the like. Of these, carboxylates such as acetate are preferable.

The solvent used in the metal ion-containing solution is, for example, a mixed solvent containing at least two organic compounds among organic compounds selected from the group consisting of fatty acids, organic phosphorus compounds, organic sulfur compounds, and amine compounds. preferable. By using the mixed solvent, it is possible to effectively suppress contamination due to oxidation or the like on the surface of the obtained core particles by firmly coordinating to the surface of the inorganic material fine particles.
The mixed solvent preferably further contains an organic solvent for dilution such as octadecene.

As a metal salt containing an element having an ionic radius similar to that of the lanthanoid or a structure at the time of crystallization, nitrates, sulfates, phosphates of elements having an ionic radius similar to the lanthanoid or a structure at the time of crystallization, Examples thereof include oxyacid salts such as borate, silicate, and vanadate, and carboxylates such as acetate. Also, sulfonate, phenol salt, sulfinate, salt of 1,3-diketone compound, thiophenol salt, oxime salt, aromatic sulfonamide salt, primary and secondary nitro compound salt, etc. Examples include organic acid salts and chlorides. Of these, carboxylates such as acetate are preferable.

Examples of the alkaline solution include those containing sodium hydroxide, calcium hydroxide, ammonium fluoride, and the like.
Moreover, the addition amount of the said alkaline solution can be suitably selected according to the kind and density | concentration of the said metal ion containing solution.

Examples of the fluoride solution include those containing sodium fluoride, ammonium fluoride and the like. Moreover, the addition amount of the said fluoride solution can be suitably selected according to the kind and density | concentration of the said metal ion containing solution.

A method for further forming the shell layer on the surface of the lanthanoid-containing inorganic material fine particles is not particularly limited. For example, an alkaline aqueous solution, a metal is added to a solution obtained by adding a surfactant and core particles to a dispersion medium. A method of forming a shell layer containing a metal oxide on the surface of the core particle by adding a metal oxide precursor such as an alkoxide can be used.

Examples of the dispersion medium include hydrocarbons such as cyclohexane and benzene, linear alcohols such as hexanol, and ketones such as acetone.

As the surfactant, a nonionic surfactant, an anionic surfactant, a cationic surfactant, or the like can be used.
Nonionic surfactants include polyoxyethylene nonylphenyl ether surfactants such as polyoxyethylene (5) nonylphenyl ether, and polyoxyethylene octylphenyl ether interfaces such as polyoxyethylene (10) octylphenyl ether. Examples include activators. In addition, polyoxyethylene alkyl ether surfactants such as polyoxyethylene (7) cetyl ether, polyoxyethylene sorbitan surfactants such as polyoxyethylene sorbitan trioleate, and the like can be mentioned.
Examples of the anionic surfactant include sodium di-2-ethylenehexyl sulfosuccinate, and examples of the cationic surfactant include cetyltrimethylammonium chloride and cetyltrimethylammonium bromide.

Examples of the alkaline aqueous solution include aqueous ammonia.

The metal alkoxide is not particularly limited as long as it becomes a carrier for the metal oxide, and examples thereof include methoxide such as titanium, zinc, and cerium, ethoxide, propoxide, and butoxide.
Specific examples include titanium tetraisopropoxide, zinc dipropoxide, cerium tetraisopropoxide and the like.

The wavelength conversion ink of the present invention contains a colorant.
By containing the colorant, a pattern having a specific hue under visible light can be printed as an arbitrary composition. Also, by combining with fine particles of lanthanoid-containing inorganic material, it is possible to change the hue when irradiated with infrared rays to have a specific hue, and to further improve the functions of preventing duplication and forgery it can.
The colorant may be a light-absorbing colorant that selectively absorbs part of visible light and has a specific hue when confirmed with the naked eye, and a light-emitting colorant having characteristics such as fluorescence and phosphorescence. May be used.

As the light absorbing colorant, pigments and dyes are particularly preferably used. The pigment may be either an inorganic pigment or an organic pigment.

Examples of the organic pigment include azo pigments, diazo pigments, condensed azo pigments, thioindigo pigments, indanthrone pigments, quinacridone pigments, anthraquinone pigments, benzimidazolone pigments, perylene pigments, and perinones. Pigments, phthalocyanine pigments, halogenated phthalocyanine pigments, anthrapyridine pigments, dioxazine pigments, and the like.
Examples of the inorganic pigment include carbon black, titanium dioxide, iron oxide, calcium carbonate, barium carbonate, barium sulfate, clay, talc, and yellow lead.
These may be used alone or in combination of two or more.

Examples of the dye include azo dyes, azomethine dyes (indoaniline dyes, indophenol dyes, etc.), dipyrromethene dyes, quinone dyes (benzoquinone dyes, naphthoquinone dyes, anthraquinone dyes, anthrapyridone dyes). Dyes), carbonium dyes (diphenylmethane dyes, triphenylmethane dyes, xanthene dyes, acridine dyes, etc.), quinoneimine dyes (oxazine dyes, thiazine dyes, etc.), azine dyes, polymethine dyes ( Oxonol dyes, merocyanine dyes, arylidene dyes, styryl dyes, cyanine dyes, squarylium dyes, croconium dyes), quinophthalone dyes, phthalocyanine dyes, subphthalocyanine dyes, perinone dyes, in Gore dyes, thioindigo dyes, quinoline dyes, nitro dyes, nitroso dyes, and their metal complex dyes.
These may be used alone or in combination of two or more.

Examples of the luminescent colorant include inorganic fluorescent pigments such as zinc sulfide, zinc silicate, cadmium sulfide, cadmium selenide, strontium sulfide, and calcium tungstate, and organic fluorescent pigments dyed with quantum dots and polymer compounds. Can be mentioned.

In the wavelength conversion ink of the present invention, the content of the colorant is preferably 0.01% by weight in the preferred lower limit and 75% by weight in the preferred upper limit. When the content of the colorant is not less than the preferable lower limit and not more than the preferable upper limit, the wavelength conversion ink can be sufficiently visually recognized by visible light. The content of the colorant is more preferably a lower limit of 0.05% by weight and a more preferable upper limit of 50% by weight.

In the wavelength conversion ink of the present invention, the difference between the main emission wavelength of the lanthanoid-containing inorganic material fine particles and the main absorption wavelength of the colorant is preferably 25 nm or more, and more preferably 100 nm or more. Here, the main emission wavelength means the peak of the wavelength of light emitted by converting the wavelength of the light absorbed by the lanthanoid-containing inorganic material fine particles, and the main absorption wavelength is the peak of the wavelength of the light absorbed by the colorant. Means.

The wavelength conversion ink of the present invention preferably contains a solvent.
The solvent is not particularly limited as long as the lanthanoid-containing inorganic material fine particles are easily dispersed.For example, alcohols such as ethanol, methyl ethyl ketone, toluene, hexane, cyclohexane, heptane, cycloheptane, octane, decane, undecane, dodecane, Examples include tridecane, trimethylpentane, benzene, xylene and the like. These solvents may be used alone or in combination of two or more.

The preferable lower limit of the content of the solvent in the wavelength conversion ink of the present invention is 1% by weight, and the preferable upper limit is 99.99% by weight.

The wavelength conversion ink of the present invention preferably contains a binder.
Examples of the binder include organopolysiloxanes such as polydimethylsiloxane, polydiethylsiloxane, polydiphenylsiloxane, polymethylphenylsiloxane, and polydichlorosiloxane. Of these, polydimethylsiloxane is preferred.

The preferable lower limit of the binder content in the wavelength conversion ink of the present invention is 0.5% by weight, and the preferable upper limit is 75% by weight.

The wavelength conversion ink of the present invention may further contain additives such as a dispersant and a viscosity modifier.

In the wavelength conversion ink of the present invention, it is preferable that the hue changes in the visible light range (400 nm to 700 nm) when irradiated with infrared rays. By changing the hue of the wavelength conversion ink within the above preferable range, it is possible to determine not only the change by the machine but also the change by visual observation.

The use of the wavelength conversion ink of the present invention is not particularly limited. For example, it exhibits a specific hue under visible light, and can emit information that changes its hue by irradiating light with a long wavelength such as infrared rays. Since the emission spectrum can be adjusted by the composition of the lanthanoid-containing inorganic material fine particles, it is particularly useful as a security ink for the purpose of preventing forgery.

The method for producing the wavelength conversion ink of the present invention is not particularly limited. For example, the lanthanoid-containing inorganic material fine particles, the colorant, and additives such as a binder to be blended as necessary, an ultrasonic disperser, etc. And a method in which the ink is dispersed and dissolved in the above solvent to form an ink.

By coating the substrate with the wavelength conversion ink of the present invention, it is possible to print a pattern that exhibits a specific hue under visible light and emits light with long-wavelength light such as infrared rays to change the hue.
The coated material on which the wavelength conversion ink of the present invention is printed is also one aspect of the present invention.

The coated product of the present invention has the wavelength conversion ink of the present invention and a substrate.
The base material is not particularly limited, and examples thereof include paper using pulp, cotton, and other plant fibers, and plastic films such as polycarbonate, polyethylene, polypropylene, and polyethylene terephthalate.

The method for printing the wavelength conversion ink of the present invention on the substrate is not particularly limited, and a conventionally known printing method can be used.

The hue of the print pattern of the wavelength conversion ink printed on the coated product of the present invention is changed by irradiating infrared rays. By confirming the change in the hue of the print pattern, the authenticity of the substrate can be confirmed. In addition, by determining the hue when the wavelength conversion ink is not irradiated with infrared light and the hue when irradiated with infrared light, the authenticity of the printed material can be analyzed in detail in the coated material.
The determination apparatus for determining the hue of the wavelength conversion ink printed on the coated material of the present invention when not irradiated with infrared rays and the hue when irradiated with infrared rays is also one aspect of the present invention.

The determination apparatus of the present invention includes an irradiation unit that irradiates infrared rays onto the coated material of the present invention, and a detection unit that detects a hue when the infrared ray is not irradiated and a hue when the wavelength conversion ink is printed.

The irradiation means for irradiating the infrared rays is not particularly limited as long as it can irradiate infrared rays capable of emitting the lanthanoid-containing inorganic material fine particles contained in the wavelength conversion ink of the present invention. Can be used.

The detection means constituting the determination device of the present invention only needs to have a function of detecting the hue, infrared rays, and the like of the wavelength conversion ink of the present invention. The detection means may have an authenticity determination function for determining authenticity based on changes in color coordinates, hue, and the like.
The color coordinates indicate chromaticity coordinates of the CIE color system.

The authenticity of the substrate can be determined by checking the hue change of the print pattern of the wavelength conversion ink using the determination device of the present invention.
A determination method for performing authenticity determination using the determination apparatus of the present invention is also one aspect of the present invention.

In the determination method of the present invention, the authenticity of the coated material can be determined by detecting the color coordinates, hue, and the like using a determination device, and analyzing the movement amount of the color constellation and the change in hue.
The criteria for determining the amount of movement of the color coordinates are not particularly limited. For example, a criterion for determining the authenticity when the amount of movement of the color coordinates is 0.1 or more can be used.

According to the present invention, the hue can be changed by infrared irradiation, and by arbitrarily adjusting the hue when infrared irradiation is not performed and when infrared irradiation is performed, it is possible to prevent duplication and prevention of counterfeiting. In addition, a wavelength conversion ink that can be produced regardless of the polarity of the dispersion medium can be provided. Moreover, the coating material which has this wavelength conversion ink, a determination apparatus, and the determination method using this determination apparatus can be provided.

2 is a graph showing fluorescence emission peaks of lanthanoid-containing inorganic material fine particles obtained in Example 1 with respect to 980 nm incident light.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

Example 1
(Preparation of fine particles of lanthanoid-containing inorganic material)
A metal ion-containing solution is prepared by dissolving 0.40 g of yttrium acetate, 0.13 g of ytterbium acetate, and 0.013 g of erbium acetate in a mixed solvent of 11.13 g of oleic acid, 10.39 g of trioctylphosphine, and 46.03 g of octadecene. did. Further, a reaction precursor solution was prepared by adding a solution obtained by dissolving 0.15 g of sodium hydroxide and 0.39 g of ammonium fluoride in 15 g of methanol into a metal ion-containing solution immediately after the preparation.
The methanol is volatilized and removed from the reaction precursor solution by heating with stirring at 50 ° C. for 15 minutes under vacuum, and then the fine particles are added to the solution by heating with stirring at 317 ° C. for 90 minutes under a nitrogen atmosphere. Precipitated.
Further, after cooling to room temperature, 25 g of ethanol was added to precipitate the fine particles, and the fine particles were collected using a centrifuge. The collected fine particles were redispersed in 25 g of toluene, and then 25 g of ethanol was added again to re-aggregate, and washing with a centrifuge was repeated several times to obtain lanthanoid-containing inorganic material fine particles.
The obtained lanthanoid-containing inorganic material fine particles contain a lanthanoid having a light absorption function, a lanthanoid having a light emission function, and an element content having an ionic radius similar to that of the lanthanoid and a structure at the time of crystallization ( It was measured using Shimadzu Corporation EDX-800HS. The content of the lanthanoid having a light absorption function was 19.9 mol% and the content of the lanthanoid having a light emission function was 2.1 mol% with respect to all rare earth elements contained in the lanthanoid-containing inorganic material fine particles.
Further, the obtained lanthanoid-containing inorganic material fine particles were observed using a transmission electron microscope, and the average particle size of 300 particles in the obtained image was calculated. As a result, the average particle size was 38.9 nm and the average particle size was The CV value of 7.9% was a very uniform particle size distribution.

(Production of wavelength conversion ink and coated material)
0.5 g of the obtained lanthanoid-containing inorganic material fine particles, 0.01 g of a red dye (KP PLAST Red H2G (perinone dye), manufactured by Kiwa Chemical Industry Co., Ltd.), 40 g of toluene, and 9.5 g of polydimethylsiloxane are mixed and transmitted. The wavelength conversion ink which has this was produced.
The obtained wavelength conversion ink was applied on a glass substrate so that the thickness after drying was 100 μm, and the solvent was removed by drying to prepare a coated product.

(Example 2)
A wavelength conversion ink and a coated product were prepared in the same manner as in Example 1 except that 0.05 g of a red pigment (TM red 8270 (Fe ₂ O ₃ ), manufactured by Dainichi Seika Kogyo Co., Ltd.) was used instead of the red dye. .

(Example 3)
A wavelength conversion ink and a coated product were prepared in the same manner as in Example 1 except that a blue dye (KP PLAST Blue BR (anthraquinone dye), manufactured by Kiwa Chemical Industry Co., Ltd.) was used instead of the red dye.

Example 4
0.125 g of the lanthanoid-containing inorganic material fine particles obtained in Example 1 and 0.3 g of IGEPAL: CO-520 (polyoxyethylene (5) nonylphenyl ether) as a nonionic surfactant were mixed in 10 g of cyclohexane. . Next, 0.01 g of 10% ammonia water and 0.05 g of titanium tetraisopropoxide were sequentially added and stirred for 1 day to obtain lanthanoid-containing inorganic material fine particles in which a shell layer made of titanium dioxide was formed on the core particle surface. .
A wavelength conversion ink and a coated material were prepared in the same manner as in Example 1 except that the obtained lanthanoid-containing inorganic material fine particles were used.

(Comparative Example 1)
An ink and a coated product were produced in the same manner as in Example 1 except that the lanthanoid-containing inorganic material fine particles were not added.

(Comparative Example 2)
A wavelength conversion ink and a coated product were prepared in the same manner as in Example 1 except that no red dye was added.

(Evaluation)
The following evaluation was performed on the lanthanoid-containing inorganic material fine particles obtained in Examples and Comparative Examples. The results are shown in Table 1.

(1) Measurement of luminous intensity The lanthanoid-containing inorganic material fine particles obtained in Example 1 were irradiated with infrared light under the conditions of a wavelength of 980 nm and an output of 300 mW using an infrared generator (THORLABS, L980P300J) as an external light source. The obtained fluorescence emission spectrum was measured using a fluorescence spectrophotometer (manufactured by Hitachi High-Tech, U-2700).
The graph which shows the fluorescence emission peak with respect to 980 nm incident light of the lanthanoid containing inorganic material microparticles | fine-particles obtained in Example 1 is shown in FIG.
FIG. 1 shows that the lanthanoid-containing inorganic material fine particles obtained in Example 1 emit visible light when irradiated with infrared rays, and exhibit an up-conversion function.

(2) Hue evaluation The color coordinates of the printing pattern of the ink were measured using a chromaticity meter (CR-410, manufactured by Konica Minolta Co., Ltd.) for the coated materials in each Example and Comparative Example. Moreover, the infrared rays were irradiated to the coating material obtained by each Example and the comparative example on condition of 980 nm and output 300mW using an infrared rays generator (the product made by THORLABS, L980P300J) as an external light source, and the time of infrared irradiation The color coordinates of the ink print pattern were measured. Furthermore, the amount of movement of the color coordinates at the time of non-irradiation with infrared rays and irradiation was calculated. Moreover, the change of the hue at the time of infrared non-irradiation and irradiation was confirmed with the naked eye.
Furthermore, authenticity evaluation was performed based on the following criteria based on the obtained movement amount of the color coordinates.
A: The amount of movement of the color coordinates of X and Y was 0.1 or more.
X: The movement amount of either X or Y or both color coordinates was less than 0.1.

(3) Uniformity evaluation of coated product The surface roughness of the coated product obtained in each Example and Comparative Example was measured using a laser microscope (manufactured by Olympus, LEXTOLS4100).
Further, 50 g of wavelength conversion ink obtained in each of the examples and comparative examples was diluted by adding 40 g of methyl ethyl ketone, applied on a glass substrate so that the thickness after drying was 100 μm, and the solvent was removed by drying to be applied. A workpiece was prepared and the surface roughness was measured in the same manner.
From the obtained surface roughness, the uniformity of the coated product was evaluated according to the following criteria.
A: The surface roughness (Sa) was 15 μm or less.
A: The surface roughness (Sa) was more than 15 μm and 25 μm or less.
X: The surface roughness (Sa) exceeded 25 μm.

According to the present invention, the hue can be changed by infrared irradiation, and by arbitrarily adjusting the hue when infrared irradiation is not performed and when infrared irradiation is performed, it is possible to prevent duplication and prevention of counterfeiting. In addition, a wavelength conversion ink that can be produced regardless of the polarity of the dispersion medium can be provided. Moreover, the coating material which has this wavelength conversion ink, a determination apparatus, and the determination method using this determination apparatus can be provided.

Claims (13)

A wavelength conversion ink comprising lanthanoid-containing inorganic material fine particles having a function of converting wavelength from long wavelength light to short wavelength light and a colorant. The wavelength conversion ink according to claim 1, wherein the content of the lanthanoid-containing inorganic material fine particles is 0.01 to 75% by weight. The wavelength conversion ink according to claim 1 or 2, wherein the lanthanoid-containing inorganic material fine particles contain a lanthanoid having a light absorption function and a lanthanoid having a light emission function. The wavelength conversion ink according to claim 1, wherein the colorant is a pigment. 4. The wavelength conversion ink according to claim 1, wherein the colorant is a dye. 6. The wavelength conversion ink according to claim 1, further comprising a solvent. 7. The wavelength conversion ink according to claim 1, wherein the wavelength conversion ink is a security ink. A coated product comprising the wavelength conversion ink according to claim 1, 2, 3, 4, 5, 6 or 7, and a substrate. An irradiation means for irradiating the coated product according to claim 8 with infrared rays; and a detection means for detecting a hue when the wavelength conversion ink print pattern is not irradiated with infrared rays and a hue when infrared rays are irradiated. Judgment device. The determination device according to claim 9, wherein the detection unit further has an authenticity determination function. 11. A determination method characterized by performing authenticity determination using the determination device according to claim 9 or 10. The determination method according to claim 11, wherein the authenticity determination is performed based on a movement amount of the color coordinates. The determination method according to claim 12, wherein the case where the movement amount of the color coordinates is 0.1 or more is determined to be authentic.

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