JPH10250214A - Fluorescent image formed product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluorescent image formed product of which a security level is raised. SOLUTION: A fluorescent image formed product having at least one fluorescent image formed layer 4 and at least one visible light absorption layer 2 on a base material 1 is constituted as follows: the fluorescent image formed layer 4 contains a first phosphor emitting fluorescence of a wavelength within a first visible light area with irradiation of a first wavelength ultraviolet radiation, and a second phosphor emitting fluorescence of a wavelength within a second visible light area different from the wavelength of the first visible light area with irradiation of a second wavelength ultraviolet radiation, and is substantially transparent to visual light: the visual light absorption layer 2 is formed on at least either side of an upside or a downside of the fluorescent image formed layer 4, and has different absorption characteristics or transmission characteristics to the light of the wavelength within the first visible light area and the light of the wavelength within the second visible light area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent image formed by a fluorescent image forming layer containing a fluorescent material which is hardly visible under visible light and becomes visible by emitting fluorescent light in a visible region upon irradiation with ultraviolet rays. Fluorescent image formation.

[0002]

2. Description of the Related Art In recent years, with respect to printed materials, such as securities such as cash vouchers and prepaid cards, for which counterfeiting has been required to be prevented, micro-characters, copy check patterns, infrared absorbing inks, etc. Fluorescent inks and the like are used. Among the above, the fluorescent light-emitting ink is an ink that is hard to be visually recognized under normal visible light, and is capable of visually detecting an image by irradiating ultraviolet rays or infrared rays. , And is also a known technique.

[0003] In the above-mentioned fluorescent light-emitting ink, a fluorescent pigment is used in place of a colored organic pigment or an inorganic pigment having absorption in the visible light region used for ordinary printing ink. Other components of the fluorescent ink include vehicles and adjuvants. The above-mentioned fluorescent light-emitting ink can form a fluorescent image forming layer on a substrate by offset printing, thermal transfer printing, or the like, similarly to a normal printing ink. Here, the fluorescent pigment is a phosphor that emits light of each color such as red, green, and blue.

The phosphor is a substance that emits fluorescence when irradiated with ultraviolet rays, and can be roughly classified into an inorganic phosphor and an organic phosphor. Colorless phosphors that absorb little or no visible light can be broadly classified into colored phosphors that have a certain absorption band in the visible light region.

In order to cause a fluorescent image to appear on the above-mentioned fluorescent image formed product, ultraviolet light serving as excitation light is irradiated.
By irradiating the ultraviolet rays, the phosphor of the fluorescent image-forming product absorbs the ultraviolet rays and emits fluorescent light in a visible light region. The fluorescence image can be confirmed visually or by using a camera or the like. As the wavelength of the ultraviolet light to be irradiated,
An appropriate wavelength is determined depending on the type of phosphor used, and various light sources can be selected depending on the type of phosphor. In particular, a small black light that emits ultraviolet light having a wavelength of 365 nm is widely used.

[0006]

However, as described above, 365 nm black light is commercially available,
Since it is easily available to anyone, anyone can check whether or not the fluorescent light-emitting ink is used in the printed matter that is required to prevent forgery as described above. As a result, there has been a problem that the security level of a fluorescent image formed product using the fluorescent light-emitting ink is becoming lower.

[0007] In recent years, it has become relatively easy to obtain fluorescent light-emitting inks and the like, so that forgery has become easy. Thus, there has been a problem that the security level is further reduced.

[0008] The present invention has been made in view of the above-mentioned problems, and accordingly, the present invention is not applied to printed matter, such as securities such as cash vouchers and prepaid cards, which are used for printed matter which is required to prevent forgery. An object of the present invention is to provide a fluorescent image-formed product having an increased security level by using a fluorescent light-emitting ink which is difficult to obtain.

[0009]

In order to achieve the above-mentioned object, at least one fluorescent image-forming product of the present invention is provided on a substrate.
A fluorescent image forming layer having a fluorescent image forming layer and at least one visible light absorbing layer, wherein the fluorescent image forming layer emits a fluorescent light having a wavelength in a first visible light region by irradiation with ultraviolet light having a first wavelength. And a second phosphor that emits fluorescent light of a wavelength in a second visible light region different from the wavelength of the first visible light region by irradiation with ultraviolet light of a second wavelength. The visible light absorbing layer is substantially transparent to visible light, and the visible light absorbing layer is formed on at least one of an upper side and a lower side of the fluorescent image forming layer, and has a wavelength of the first visible light region. Have different absorption characteristics or transmission characteristics for light having a wavelength in the second visible light region.

The above-mentioned fluorescent image formed article of the present invention has a fluorescent image forming layer containing two kinds of phosphors. The wavelength range of the fluorescence emitted from each phosphor is different,
By mixing colors of the fluorescent light emitted by the different types of phosphors, it is possible to obtain a fluorescent image formed product having a fluorescent image forming layer that emits a color that has not been obtained conventionally.

Here, the phrase "the fluorescent image forming layer is substantially transparent to visible light" means that the fluorescent image forming layer has the property of transmitting visible light, and that the fluorescent image forming layer partially or entirely transmits visible light over the entire visible light region. The case where the fluorescent image forming layer is white (colorless) due to the characteristic of reflection and the case where the color of the fluorescent image forming layer is substantially the same as the color of the substrate on which the fluorescent image forming layer is formed are visually observed. This includes cases where it is substantially difficult to confirm the presence or absence.

The fluorescent substance contained in the fluorescent image forming layer of the present invention includes a fluorescent substance excited by ultraviolet light having a wavelength of about 254 nm which is used as ultraviolet light having a relatively short wavelength (germicidal lamp), and a fluorescent substance having a relatively long wavelength. It can be broadly classified into two types of phosphors, which are widely excited in both wavelength regions of near 365 nm and near 254 nm, which are often used as ultraviolet light. In the fluorescent image forming layer of the present invention, by selecting one or more phosphors from each of the two types of phosphors having different excitation wavelengths, the wavelength region of the fluorescence emitted by changing the excitation wavelength is selected. , That is, a fluorescent image formed product having a fluorescent image forming layer that emits different colors of fluorescent light.

Further, the fluorescent image formed article of the present invention has a visible light absorbing layer, and has a wavelength in a visible light range where the first phosphor emits light and a visible light which emits the second phosphor. The fluorescent image formed by the fluorescent image forming layer can be further patterned depending on the presence or absence of the visible light absorbing layer because it has different absorption characteristics or transmission characteristics with respect to the light of the wavelength of the region. Can be changed for each color of the fluorescent light emitted by the phosphor.

For example, visible light having a characteristic of strongly absorbing light having a wavelength in the visible light region emitted by the first phosphor and transmitting light having a wavelength in the visible light region emitted by the second phosphor. When the absorption layer is formed, the pattern formed by the fluorescent image forming layer becomes the fluorescent image as it is in the fluorescent image formed by the color emitted by the second phosphor, but is formed by the color emitted by the first phosphor. In the fluorescent image to be formed, a fluorescent image is formed in a pattern obtained by removing the overlapping portion between the fluorescent image forming layer and the visible light absorbing layer from the pattern formed by the fluorescent image forming layer.

Therefore, the color of the emitted fluorescent light can be changed according to the wavelength of the ultraviolet light to be irradiated, and the pattern of the fluorescent image can be changed for each color of the emitted fluorescent light. Forgery is very difficult when applied to printed matter where it is necessary to prevent forgery such as cash vouchers, and can have a very high security level.

For example, in the case of 365 nm ultraviolet ray irradiation, the first
Only emits blue light and emits blue fluorescent light. When the ultraviolet light of 254 nm is irradiated, both the first fluorescent material and the second fluorescent material emit fluorescent light, which is a mixed color of the fluorescent light of both fluorescent materials. Suppose that a red fluorescent light is emitted, and a green base print having a characteristic of further absorbing the red light is provided below the fluorescent image forming layer, and a fluorescent image pattern having a different fluorescent image pattern with blue and red fluorescent light is formed. I do. Even if the counterfeiter forges using a phosphor that emits blue light by irradiating ultraviolet rays of 365 nm, the authenticity determiner can confirm the fluorescence image using ultraviolet rays of both 365 nm and 254 nm. It is possible to determine the authenticity. In the above case, especially 3
Since the forgery is imitated by imitating the fluorescence with respect to the ultraviolet light of 65 nm, the forgery is irradiated with ultraviolet light of 254 nm, and it is examined whether a predetermined fluorescent image having a pattern different from that of the fluorescent image of blue fluorescent light is emitted by red fluorescent light. This makes it possible to judge the authenticity.

In the above-mentioned fluorescent image formed article of the present invention, preferably, the visible light absorbing layer has an absorption characteristic for light having a wavelength in the first visible light range, and a wavelength in the second visible light range. Or the visible light absorbing layer has a transmission characteristic for light having a wavelength in the first visible light region, and has an absorption characteristic for light having a wavelength in the second visible light region. By setting the transmission characteristics of light having a wavelength in the first visible light region or light having a wavelength in the second visible light region, an image formed by the visible light absorbing layer can be made visible.

The fluorescent image formed article of the present invention preferably has the visible light absorbing layer below the fluorescent image formed layer. If a visible light absorbing layer is provided above the fluorescent image forming layer, the visible light absorbing layer may be difficult to see even if the fluorescent light has a wavelength that does not absorb the fluorescent light. It is preferred to provide it below the layer.

In the above-mentioned fluorescent image formed article of the present invention, preferably, the first wavelength is shorter than the second wavelength, and the second phosphor is the first wavelength and the second wavelength. Fluorescence is emitted by ultraviolet light of a wavelength. When both the first phosphor and the second phosphor are irradiated with ultraviolet light having a wavelength that can be excited, the colors of the fluorescent light emitted by the first phosphor and the second phosphor are mixed, and thus cannot be obtained conventionally. Thus, a fluorescent light-emitting ink that emits light in different colors can be obtained.

In the above-described fluorescent image formed article of the present invention, preferably, the first wavelength is longer than the second wavelength, and the second phosphor is substantially exposed to ultraviolet light of the first wavelength. Does not emit fluorescence. When one of the first phosphor and the second phosphor is irradiated with an ultraviolet ray having a wavelength that can excite one of the phosphors and does not substantially excite the other, only the fluorescence of one of the phosphors is emitted, and the color of the fluorescence at that time is emitted. Can be different from the color of the fluorescence when the other phosphor is irradiated with ultraviolet light having a wavelength that can be excited. As described above, by changing the excitation wavelength, the wavelength region of the emitted fluorescent light is different, that is, it is possible to obtain a fluorescent image formed product having a fluorescent image forming layer in which the color of the emitted fluorescent light is different. it can.

The above-mentioned fluorescent image formed article of the present invention is preferably
Means that the first phosphor is an oxide or oxyacid salt type
Wherein the second phosphor is an oxide or an acid.
Includes citrate-based inorganic phosphors. More preferably, the second
One phosphor is Sr_Three(PO_Two)_ThreeCl: Eu, ZnO: Zn, Zn_TwoSiO_Four: Mn,
Zn_TwoGeO_Four: Mn, Y_TwoO_Three: Eu, Y (P, V) O_Four: Eu, Y_TwoO_TwoS: Eu, and
ZnS: an inorganic phosphor selected from Cu (Mn),
The two phosphors are Sr_Three(PO _Two)_ThreeCl: Eu, ZnO: Zn, Zn_TwoSiO_Four: Mn,
Zn_TwoGeO_Four: Mn, Y_TwoO_Three: Eu, Y (P, V) O_Four: Eu, Y_TwoO_TwoS: Eu, and
ZnS: An inorganic phosphor selected from Cu (Mn). Oxide
Or, oxyacid salt-based inorganic phosphors have heat resistance and moisture resistance
In terms of weather resistance, aging characteristics (durability), light resistance, etc.
Excellent, stable material with relatively large particle size and high brightness
Since it is a charge, the printability can be improved.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a fluorescent image formed product according to an embodiment of the present invention. A visible light absorbing layer 2 which is a base printing is formed on an upper layer of the base 1. An intermediate layer 3 is formed so as to cover the visible light absorbing layer 2, and a fluorescent image forming layer 4 is formed thereon. The overcoat 5 covers the fluorescent image forming layer. The fluorescent image forming layer 4 contains two types of phosphors having different emission wavelengths of fluorescent light, and the visible light absorbing layer 2 has different absorption characteristics or different absorption characteristics for the light of the emission wavelengths of the two types of phosphors. It has transmission characteristics. For example, it has a characteristic of absorbing the fluorescent light emitted by one phosphor and transmitting the fluorescent light emitted by the other phosphor.

The fluorescent light-emitting ink for forming the fluorescent image forming layer 4 contains, as its components, a fluorescent pigment, a vehicle, an auxiliary agent, and the like, like the ordinary printing ink. Here, the fluorescent pigment is a phosphor that emits light of each color such as red, green, and blue, and contains two types of phosphors that emit light of different wavelengths.

The phosphor is a substance that emits fluorescence when irradiated with ultraviolet light, and can be roughly classified into an inorganic phosphor and an organic phosphor. Colorless phosphors that absorb little or no visible light can be broadly classified into colored phosphors having a certain absorption band in the visible region. In the present invention, it is preferable to use a colorless phosphor that absorbs little or no visible light.

As the colorless inorganic phosphor, Ca, Ba,
Mg, Zn, Cd and other oxides, sulfides, silicates, phosphates, tungstates, and other crystals as main components;
A pigment obtained by adding a metal element such as g, Ag, Cu, Sb, or Pb or a rare earth element such as a lanthanoid as an activator and calcining the same can be used.

Examples of the inorganic phosphor that emits red light include Y ₂ O ₃ : Eu, YVO ₄ : Eu, Y ₂ O ₂ S: Eu, 3.5MgO, 0.5MgF
₂ GeO ₂ : Mn, (Y, Gd) BO ₃ : Eu, Y (P, V) O ₄ : Eu or the like can be used.

Examples of the inorganic phosphor that emits green light include ZnO: Zn, Zn ₃ SiO ₂ : Mn, Zn ₃ S: Cu, Al, (Zn, Cd) S: Cu,
Al, ZnS: Cu, Au, Al, Zn ₂ SiO ₄ : Mn, ZnS: Ag, Cu, (Zn, Cd)
S: Cu, ZnS: Cu, Gd ₂ O ₂ S: Tb, La ₂ O ₂ S: Tb, Y ₂ SiO ₅ : Ce, T
b, Zn ₂ GeO ₄ : Mn, CeMgAl ₁₁ O ₁₃ : Tb, SrGa ₂ S ₄ : Eu ²⁺ , ZnS: C
u, CO, MgO ・ nB ₂ O ₃ : Ce, Tb, LaOBr: Tb, Tm, La ₂ O ₂ S: Tb
, ZnS: Cu (Mn) or the like can be used.

Examples of inorganic phosphors that emit blue light include ZnS: Ag, CaWO ₄ , Y ₂ SiO ₅ : Ce, ZnS: Ag, Ga, Cl, Ca ₂
B ₅ O ₃ Cl: Eu ²⁺ , BaMgAl ₁₄ O ₂₃ : Eu ²⁺ , Sr ₃ (PO ₂ ) ₃ Cl: Eu, or the like can be used.

The organic phosphors include diaminostilbene disulfonic acid derivatives, imidazole derivatives, coumarin derivatives, triazoles, carbazoles, pyridines, and the like.
Derivatives such as naphthalic acid and imidazolone, dyes such as fluorescein and eosin, and compounds having a benzene ring such as anthracene can be used.

The fluorescent light-emitting ink of the present invention can be obtained by including two kinds of phosphors having different fluorescence wavelength ranges from the above compounds and the like. Three or more kinds of phosphors can be contained, but at least two kinds of phosphors having different fluorescence wavelength regions are required. Here, in order to have different fluorescence wavelength regions, it is sufficient that there is a wavelength region in which only one of them emits fluorescence, and preferably, there is no overlapping portion between the fluorescence emission wavelength regions.

In terms of weather resistance such as heat resistance and moisture resistance, and aging characteristics (durability), inorganic phosphors are excellent. On the other hand, organic phosphors have good wettability of the ink vehicle, and therefore have excellent suitability for producing inks without any particular surface treatment. Among the above-mentioned phosphors, in order to improve durability, weather resistance, especially light resistance or printability, a stable oxide or oxyacid salt-based inorganic phosphor having a relatively large particle size and high luminance. Is preferred. For example, Sr ₃ (PO ₂ ) ₃ Cl: Eu (blue), ZnO: Zn (green), Zn ₂ S
iO ₄ : Mn (green), Zn ₂ GeO ₄ : Mn (green), Y ₂ O ₃ : Eu (red), Y (P, V) O ₄ : Eu (red), Y ₂ O ₂ S: Eu ( Red), ZnS:
Cu (Mn) (green) can be preferably used.

It is preferable to adjust the particle size of the phosphor particles in order to improve the fluorescence characteristics such as luminance and the printability of the ink. As the phosphor particles, those composed of particles having an average particle diameter of 0.7 to 4 μm are preferably used, and more preferably, an average particle diameter of 0.7 to 2 μm.
m, most preferably from 1 to 2 μm. In general, it is expected that the smaller the particle size of the pigment particles, the better the ink properties will be. However, when the particle size of the phosphor particles is less than 0.7 μm, a phenomenon in which the brightness of the fluorescence is significantly reduced is observed. Therefore,
It is preferable to use phosphor particles having a particle size of 0.7 μm or more. On the other hand, when the particle size exceeds 4 μm, the transparency of the obtained fluorescence image may be reduced.

The content of the phosphor relative to the entire composition excluding the solvent constituting the fluorescent ink is preferably 15 to 80% by weight in order to improve both the luminance and the transferability (adhesion) to the printing substrate. And a more preferable range is 20 to 50% by weight. When the content of the phosphor is less than 15% by weight, the fluorescent brightness in the ink composition state is extremely lowered depending on the type of the fluorescent material. It may decrease to about 10.

Further, the properties of the phosphor (hiding power, coloring power,
It is preferable to perform a surface treatment to improve oil absorption, durability, etc.). In particular, when an inorganic phosphor is used, its surface is hydrophilic and has poor affinity for an oily polymer. Therefore, it is preferable to perform a surface treatment to improve the affinity for the polymer. For example, the following method is available.

(A) Coating: The coating acts as a surfactant. For example, dispersants for low-molecular or high-molecular fatty acids, fatty acid salts and waxes can be used.

(B) Coupling agent: The coupling agent binds strongly to the phosphor and reacts with the polymer. For example, a silane compound, a titanium compound, a metal chelate compound, or the like can be used.

(C) Polymerizable monomer: An irreversible layer is formed by reacting a low molecular weight monomer or oligomer on the phosphor surface. For example, a polymerizable organic acid, a reactive oligomer, or the like can be used.

As the vehicle of the fluorescent light-emitting ink for forming the fluorescent image forming layer of the present invention, those having substantially no absorption band in the wavelength region of ultraviolet light for exciting the phosphor and the wavelength region of visible light are used. preferable. Examples of the binder resin which is a main component of the vehicle include polyethylene [polyethylene (PE), ethylene-vinyl acetate copolymer (EVA), vinyl chloride-vinyl acetate copolymer], polypropylene (PP), vinyl [ Polyvinyl chloride (PV
C), polyvinyl butyral (PVB), polyvinyl alcohol (PVA), polyvinylidene chloride (PVd)
C), polyvinyl acetate (PVAc), polyvinyl formal (PVF)], polystyrene [polystyrene (P
S), styrene-acrylonitrile copolymer (AS),
Acrylonitrile-butadiene-styrene copolymer (A
BS)], acrylic [polymethyl methacrylate (P
MMA), MMA-styrene copolymer], polycarbonate (PC), cellulosic [ethyl cellulose (E
C), cellulose acetate (CA), propylcellulose (CP), acetic acid / cellulose acetate (CAB), cellulose nitrate (CN)], fluorine type (polychlorofluoroethylene (PCTFE), polytetrafluoroethylene (P
TFE), tetrafluoroethylene-hexafluoroethylene copolymer (FEP), polyvinylidene fluoride (PVdF)], urethane (PU), nylon (type 6, type 66, type 610, type 11), polyester (Alkyd) -based [polyethylene terephthalate (PET), polybutylene terephthalate (PB)
T), polycyclohexane terephthalate (PC
T)], and a thermoplastic resin such as a novolak type phenol resin. It is also possible to use thermosetting resins such as resol type phenolic resins, urea resins, melamine resins, polyurethane resins, epoxies, unsaturated polyesters, and natural resins such as proteins, rubber, shellac, copal, starch, and rosin. it can.

Furthermore, these resins can be emulsions for water-based paints. Examples of emulsions for aqueous paints include vinyl acetate (homo) emulsion, vinyl acetate-acrylate copolymer emulsion, and vinyl acetate-ethylene copolymer resin emulsion (E).
VA emulsion), vinyl acetate-vinyl versatate copolymer resin emulsion, vinyl acetate-polyvinyl alcohol copolymer resin emulsion, vinyl acetate-vinyl chloride copolymer resin emulsion, acrylic emulsion, acrylic silicone emulsion, styrene-acryl copolymer resin emulsion, Polystyrene emulsion, urethane emulsion, chlorinated polyolefin emulsion,
Epoxy-acryl dispersion, SBR latex, or the like can be used.

Further, a plasticizer for stabilizing the flexibility and strength of the print film and a solvent for adjusting the viscosity and drying may be added to the vehicle, if necessary. As the solvent, a low-boiling solvent having a boiling point of about 100 ° C. and a high-boiling petroleum solvent having a boiling point of 250 ° C. or more can be used depending on the printing method. As a solvent having a low boiling point, for example, alkylbenzene or the like can be used.

Further, auxiliary agents such as various reactants for improving drying, viscosity and dispersibility can be appropriately added.
The auxiliary agent is used to adjust the performance of the ink. For example, a compound that improves the friction resistance of the ink surface after drying, a dryer that promotes the drying of the ink, and the like can be used.

A photopolymerization-curable or electron beam-curable resin that does not use a solvent can also be used as a binder resin that is a main component of the vehicle. For example, there is an acrylic resin, and specifically, the followings can be used as those commercially available as acrylic monomers.

Examples of the monofunctional acrylate include 2-ethylhexyl acrylate, 2-ethylhexyl EO adduct acrylate, ethoxydiethylene glycol acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and caprolactone adduct of 2-hydroxyethyl acrylate. Phenoxyethyl acrylate, phenoxydiethylene glycol acrylate, nonylphenol EO adduct acrylate,
Nonylphenol EO adduct caprolactone adduct acrylate, 2-hydroxy-3-phenoxypropyl acrylate, tetrahydrofurfuryl acrylate, furfuryl alcohol caprolactone adduct acrylate, acryloylmorpholine, dicyclopentenyl acrylate, dicyclopentanyl acrylate,
Dicyclopentenyloxyethyl acrylate, isobornia acrylate, acrylate of caprolactone adduct of 4,4-dimethyl-1,3-dioxane, acrylate of caprolactone adduct of 3-methyl-5,5-dimethyl1,3-dioxane Etc. can be used.

The polyfunctional acrylates include hexanediol diacrylate, neopentyl glycol diacrylate, polyethylene glycol diacrylate, tripropylene glycol diacrylate, neopentyl glycol hydroxypivalate diacrylate, and neopentyl glycol hydroxypivalate. A caprolactone adduct diacrylate of
Acrylic acid adduct of 1,6-hexanediol diglycidyl ether, diacrylate of acetal compound of hydroxypivalaldehyde and trimethylolpropane, 2,2-bis [4- (acryloyloxydiethoxy) phenyl] propane, 2,2-bis [4- (acryloyloxydiethoxy) phenyl] methane, diacrylate of hydrogenated bisphenol A ethylene oxide adduct, tricyclodecane dimethanol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, Trimethylolpropane propylene oxide adduct triacrylate, glycerin propylene oxide adduct triacrylate, dipentaerythritol hexaacrylate / pentaacrylate mixture, dipenta Lower fatty acid and esters of acrylic acid Risuritoru, acrylate caprolactone adduct of dipentaerythritol, tris (acryloyloxyethyl) isocyanurate, and the like can be used 2-acryloyloxyethyl phosphate.

The inks composed of these resins are solvent-free and have a composition that causes a chain polymerization reaction by irradiation of electromagnetic waves or electron beams. Among them, those of the ultraviolet irradiation type require a photopolymerization initiator and a photopolymerization initiator. A polymerization inhibitor, a chain transfer agent and the like may be added as a sensitizer and an auxiliary depending on the above.

As the photopolymerization initiator, 1) direct photolysis type such as arylalkyl ketone, oxime ketone, acylphosphine oxide, etc. 2) radical polymerization reaction type such as benzophenone derivative and thioxanthone derivative 3) cationic polymerization reaction As the mold, an aryldiazonium salt, an aryliodonium salt, an arylsulfonium salt, an arylacetophenone salt, or the like can be used. In addition, 4) an energy transfer type, 5) a photo redox type, 6) an electron transfer type, or the like can be used. be able to. For the electron beam curing type, a resin similar to that of the above-described ultraviolet irradiation type may be used, and a photopolymerization initiator may not be required, and various assistants may be added as needed.

The fluorescent light-emitting ink comprising the above-mentioned fluorescent pigment, vehicle and auxiliary agent may further contain an irreversible decolorizable colorant. The decolorizable colorant in this case has an absorption characteristic in the visible region before the operation for decoloring, that is, is colored, but the operation for decoloring, for example, irradiation with near infrared rays Is a colorant that has an almost irreversible absorption in the visible region, that is, changes to a state transparent to visible light. When printing is performed using a fluorescent light-emitting ink containing such a decolorizable colorant, a printed image can be identified with the naked eye without performing ultraviolet irradiation, and printing accuracy can be improved. After that, it can be made transparent to visible light by performing a decoloring operation.

The fluorescent image-forming layer 4 containing a fluorescent substance can be formed on a substrate by various methods conventionally known using the above-mentioned fluorescent light-emitting ink. For example, there are an intaglio printing method such as a relief printing method and a gravure method, a lithographic printing method of an offset method, and a screen stencil (stencil). In addition, a thermal transfer method (for example,
JP-A-1-213195, JP-A-59-54598,
JP-A-62-111800, JP-A-3-187786
Japanese Patent Application Laid-open No.
No. 81376) can also be used. Further, a fluorescent image-containing layer containing a phosphor can be formed by the method described in JP-A-4-338598. When the thermal transfer method is used, it is preferable to secure the amount of light by setting the film thickness of the fluorescent image forming layer to at least 6 μm or more. Therefore, it is preferable to add a binder or wax such as carnauba wax to the image forming layer. Further, since it is preferable that the ink surface is thermally melted, it is preferable to use a thermoplastic resin as a binder resin which is a main component of the vehicle.

The thickness of the fluorescent image forming layer formed of the fluorescent light-emitting ink can be appropriately determined depending on the required fluorescent luminance and the content of the fluorescent substance.
It can be 1 to 10 μm. In the present invention, from the viewpoint of ensuring transparency, the phosphor particles having a relatively small particle size are used as described above, but the shortage of the fluorescence emission intensity due to the small particle size is caused by the thickness of the fluorescent image forming layer. Can be compensated for by increasing.

The fluorescent image formed product of the embodiment of the present invention has the visible light absorbing layer 2 below the fluorescent image forming layer 4.
This position may be formed above the fluorescent image forming layer or both above and below. However, if it is above the fluorescent image forming layer, even if the fluorescent light has a wavelength at which the fluorescent light is not absorbed by the visible light absorbing layer, the portion becomes difficult to see. Therefore, it is preferable to form it below. The visible light absorbing layer 2 has different absorption characteristics for light having a wavelength in the visible light region emitted from one phosphor contained in the fluorescent image forming layer 4 and light having a wavelength in the visible light region emitted from the other phosphor. It has transmission characteristics, for example, it strongly absorbs light having a wavelength in the visible light region emitted by one phosphor and transmits light having a wavelength in the visible light region emitted by the other phosphor. Forming a visible light absorbing layer. As a result, in the fluorescent image formed by the color emitted by the other phosphor, the image pattern formed by the fluorescent image forming layer 2 becomes the fluorescent image as it is, but the fluorescent image formed by the color emitted by the one phosphor is used. In the image, a fluorescent image is formed in a pattern excluding the overlapping portion of the fluorescent image forming layer 4 and the visible light absorbing layer 2 from the image pattern formed by the fluorescent image forming layer 4.

Therefore, the color of the emitted fluorescent light can be changed according to the wavelength of the ultraviolet light to be irradiated, and the pattern of the fluorescent image can be changed for each color of the emitted fluorescent light. Forgery is very difficult when applied to printed matter where it is necessary to prevent forgery such as cash vouchers, and can have a very high security level.

The above visible light absorbing layer 2 can be formed by a conventionally known printing method using a conventionally known coloring paint or ink which is generally used. The thickness of the visible light absorbing layer 2 can be, for example, 2 μm or less. In the case where the thickness of the visible light absorbing layer 2 is increased and the fluorescent image forming layer 4 is provided thereon, for example, the visible light absorbing layer 2 and the fluorescent image forming layer 4
It is preferable to provide an intermediate layer 3 between them so that no step is formed.

In addition to forming the fluorescent image forming layer 4 and the visible light absorbing layer 2 on the substrate by the above method, the substrate used in the present invention, the visible image forming layer other than the visible light absorbing layer 2, the intermediate layer 3, and the protective layer As the layer 5 and the like, a conventionally known layer can be formed.

In the fluorescent image formed article of the present invention, in addition to the visible light absorbing layer 2 for patterning the fluorescent image,
In order to make it more difficult to visually recognize an image formed as a fluorescent image under visible light, it is also preferable to print a camouflage pattern or a tint block using visible ink as a base print in the fluorescent image forming area. The camouflage pattern is preferably a random pattern as much as possible, and its color is preferably a light color that does not affect the color of the fluorescent light emitted by the phosphor as much as possible.

In addition to the above-described camouflage pattern, in addition to a visible light absorbing layer for patterning a fluorescent image, a monochromatic or multicolored underlayer (background) printing layer or the like under or above a fluorescent image forming layer. A visible image layer composed of a color may be formed. However, in the fluorescent image forming area, it is preferable that the color constituting the visible image be a light color that does not affect the color of the fluorescent light emitted by the fluorescent substance as much as possible. In particular, when a multicolor visible image is used as the underprint, it is preferable to reduce the difference in reflectance between two or more colors constituting the visible image in the wavelength region of the fluorescent light emitted by the phosphor. For example, it is preferable that the difference in reflectance be within 20%. If the difference in the reflectance between two or more colors constituting the visible image is large, the intensity of the fluorescent light emitted from the phosphor changes greatly according to the image of the underlying printing, and the image constituted by the phosphor is correctly viewed. It becomes difficult.

The visible image forming layer such as the underprinting described above is
It can be formed by a known printing method using a known coloring paint or ink. For example, a coloring paint or ink can be obtained by adding various pigments to a binder according to the color to be colored. As the binder, those exemplified as the resin constituting the vehicle component of the above-mentioned fluorescent light emitting ink for the fluorescent image forming layer can be used. The coloring paint or ink may further include a plasticizer, a stabilizer, a wax, a desiccant, a drying aid, a curing agent,
Thickeners, dispersants, solvents or diluents can be added. Examples of the printing method include a printing method such as a usual gravure method, a roll method, a knife edge method, and an offset method, and a transfer method.
When the transfer method is used, it is preferable to smooth the transfer surface by coating a suitable resin in advance and forming a smooth layer in order to improve the adhesiveness of the transfer pattern.

As the intermediate layer 3 between the fluorescent image forming layer 4 and the visible light absorbing layer 2, a layer having high transmittance with respect to visible light is preferable. As the constituent components, those exemplified as the resin constituting the vehicle component of the above-mentioned fluorescent light emitting ink for the fluorescent image forming layer can be used. In particular, a photopolymerization-curing type or an electron beam-curing type without using a solvent is preferable, and examples thereof include an acrylic resin. this is,
It can be formed using the above-mentioned acrylic monomer. In addition, you may add a solvent and an auxiliary agent as needed.

The intermediate layer 3 is not particularly limited, but the intermediate layer below the fluorescent image forming layer can be an ultraviolet absorbing layer in which an ultraviolet absorbing agent is substantially fixed. This can be, for example, at least an ultraviolet absorber and a resin. By selecting the ultraviolet absorber from the group consisting of particles having an ultraviolet absorbing ability or a resin having an ultraviolet absorbing functional group, the ultraviolet absorber is substantially It is possible to form a fixed ultraviolet absorbing layer.

As the particulate matter having an ultraviolet absorbing ability,
For example, an ultraviolet absorbing inorganic pigment can be used, and for example, zinc oxide, titanium oxide, and the like can be used.
From the viewpoint that these particles are substantially transparent to visible light and do not substantially migrate to the fluorescent image forming layer, the particle diameter is suitably in the range of 0.1 to 1 μm.

There are also organic UV absorbers, and benzophenone, benzotriazole, acrylate, and salicylate UV absorbers can be used. As the benzophenone-based ultraviolet absorber, for example, 2-hydroxy-4-methoxybenzophenone,
2,2′-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone,
2,4-dihydroxybenzophenone, resorcyol monobenzoate, 2,4-di-t-butylphenyl-
3,5-di-t-butyl-4-hydroxybenzoate, 2-hydroxy-4-n-octylbenzophenone and the like. Examples of the benzotriazole-based ultraviolet absorber include, for example, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole (Tinuvin P, manufactured by Ciba-Geigy), 2- (2′-hydroxy-3′-t) −
Butyl-5'-methylphenyl) -5-chlorobenzotriazole (Tinuvin 326, manufactured by Ciba-Geigy), 2
-[2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole (Tinuvin 234, Ciba-Geigy) and the like. Also,
Examples of the acrylate UV absorber include 2-ethylhexyl-2-cyano-3, 3-diphenyl acrylate, ethyl-2-cyano-3, and 3-diphenyl acrylate. As the salicylate-based ultraviolet absorber, for example, phenyl salicylate, 4-t-butylphenyl salicylate, p-octylphenyl salicylate and the like can be used.

It is appropriate to select the thickness of the ultraviolet absorbing layer so that the reflectance of ultraviolet light from the ultraviolet absorbing layer becomes substantially “0”. For example, when the ultraviolet absorber is emulsion tinuvin and the wavelength of the ultraviolet light of the light source is 2
In the case of 54 nm, the thickness of the ultraviolet absorbing layer is sufficient to be 1 μm or less, for example, suitably in the range of 0.1 to 1 μm.

The above-mentioned ultraviolet absorbing layer is a fluorescent image forming layer 4
Can be formed as an excitation light blocking layer on the upper layer. In the region where the excitation light blocking layer is formed, even if irradiated with ultraviolet light, it is absorbed by the excitation light blocking layer and cannot reach the fluorescent image forming layer, so that no fluorescence is emitted. Therefore, by forming a region where the excitation light blocking layer is not formed and a region where the excitation light blocking layer is not formed, it is possible to form a region that does not emit fluorescence and a region that does not emit fluorescent light, thereby forming a fluorescent image. In this case, a fluorescent image may be formed by forming an excitation light blocking layer formed along a pattern or the like on a fluorescent image layer formed to emit uniform fluorescence, and
Further, a fluorescent image may be formed by forming an excitation light blocking layer along another pattern or the like on a fluorescent image layer formed along a certain image pattern.

The protective layer 5 preferably has high transparency to visible light and ultraviolet light, and can be formed by overlamination or overcoating.
The overlaminate can be formed by laminating a transparent film such as polyethylene terephthalate, polyvinyl chloride, polyethylene, or polypropylene by a conventional method.

As the overcoat, those exemplified as the resin constituting the vehicle component of the fluorescent light emitting ink of the fluorescent image forming layer described above can be used. In particular, a photopolymerization-curing type or an electron beam-curing type without using a solvent is preferable, and examples thereof include an acrylic resin. This can be formed using the above-mentioned acrylic monomer.
As described above, additives such as a polymerization initiator are contained, and those additives having high transparency to visible light and ultraviolet light are appropriately selected. Further, an OP layer may be formed on the outermost surface by offset printing of a medium or the like.

Examples of the substrate 1 include plastics such as vinyl chloride, nylon, cellulose diacetate, cellulose triacetate, polystyrene, polyethylene, polypropylene, polyester, polyimide and polycarbonate; metals such as copper and aluminum; paper;
Impregnated paper or the like can be used alone or in combination as a composite. The material can be appropriately selected from the above materials in consideration of physical properties required for the substrate, for example, strength, rigidity, concealing property, light opacity and the like. The thickness of the substrate is usually about 0.005 to 5 mm.

When a white high-quality paper is used as the substrate of the present invention, a fluorescent whitening agent is usually added to the white high-quality paper to increase the whiteness. It emits blue light when irradiated with ultraviolet light.
Accordingly, when ultraviolet light is applied to visually recognize a fluorescent image by the phosphor contained in the fluorescent image forming layer formed on the paper substrate, the fluorescent whitening agent in the paper substrate also emits fluorescent light, so that the image There is an inconvenience that it is difficult to confirm. Therefore,
As a paper substrate, those without an optical brightener,
Alternatively, it is desirable to select one with the smallest possible amount of addition. In addition, tinuvin (manufactured by Ciba-Geigy) was used on the paper substrate as a base print to suppress the effect of the fluorescent whitening agent.
It is also effective to form an ultraviolet absorbing layer containing, for example, 10% by weight.

As the ultraviolet light irradiating means serving as excitation light for emphasizing the fluorescent image, various light sources can be selected for the wavelength of the ultraviolet light depending on the kind of the fluorescent substance, but ultraviolet light having a wavelength of 365 nm is used. Light emitting black lights are commercially available in small sizes and are easy to use. Further, a germicidal lamp that emits ultraviolet light having a wavelength of 254 nm can be used. In addition, it is preferable to select the type of the phosphor in accordance with the two wavelength ranges because the embodiment of the present invention is easily performed. Table 1 below illustrates the relationship between the phosphor and the wavelength of the excitation light.

[0069]

[Table 1]

As shown in Table 1, depending on the type of the fluorescent substance, the fluorescent substance emits fluorescent light when irradiated with 254 nm ultraviolet light,
phosphor that does not emit fluorescent light with ultraviolet light of 254 nm,
And phosphors that emit fluorescence when irradiated with both ultraviolet rays at 365 nm. In the present invention, two kinds of phosphors having different wavelength ranges of emitted fluorescent light are contained. By selecting the phosphors having different excitable ultraviolet wavelengths, the fluorescent light obtained by the wavelength of the ultraviolet light to be irradiated is selected. The colors of the images are different, for example 254
Fluorescence image obtained by UV irradiation at 365 nm and 365 nm
A fluorescent image forming layer having a different color from the fluorescent image obtained by the ultraviolet irradiation can be formed.

For example, the first fluorescent light is emitted by irradiating ultraviolet light of 254 nm and does not emit fluorescent light by ultraviolet light of 365 nm.
When the fluorescent image forming layer contains a phosphor of the formula (1) and a second phosphor that emits fluorescence by irradiation of both ultraviolet light of 254 nm and 365 nm, the color of the fluorescent light emitted by the second phosphor when irradiated with the ultraviolet light of 365 nm Can be obtained, but an image in which the colors of the fluorescence of both the first phosphor and the second phosphor are mixed can be obtained by the irradiation of the ultraviolet light of 254 nm. When there is only one kind of phosphor contained in the fluorescent image forming layer 2 or, for example, when there are two or more kinds of phosphors, the phosphors can be excited such that both emit light at 254 nm and 365 nm ultraviolet rays. When the ultraviolet rays are of the same type, as shown in FIG.
254 nm even at a wavelength of 365 nm as ultraviolet light to be excited
, Only the same color, for example, red fluorescence can be obtained.
On the other hand, when phosphors having different wavelengths of ultraviolet light that can be excited are contained, as shown in FIG. 4B, different colors are used as the ultraviolet light to be excited between a wavelength of 365 nm and a wavelength of 254 nm, for example, blue at 365 nm. At 254 nm, a fluorescent light-emitting ink that emits red light can be obtained. Examples of such a combination of the first phosphor and the second phosphor include, for example, a combination of a Sr ₃ (PO ₂ ) ₃ Cl: Eu-based fluorescent pigment and a Y ₂ O ₃ : Eu-based fluorescent pigment, Sr ₃ (PO ₂ ) A combination of a ₃ Cl: Eu fluorescent pigment and a Zn ₂ SiO ₄ : Mn fluorescent pigment can be used.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0073] The cross-sectional view of a fluorescent imaging of Example embodiment shown in FIG. FIG.
FIG. 2 is a cross-sectional view taken along the line AA ′ of the plan view of the fluorescent image formed product of the present example shown in FIG. White high-quality paper (90 kg / 46 size) to which a small amount of the fluorescent whitening agent was added was used as a base material. Offset printing was performed on the pattern of the visible light absorbing layer 2 shown in FIG.
Next, the intermediate layer 3 conventionally known was formed by covering the visible light absorbing layer 2. Next, the pattern of the fluorescent image forming layer 4 shown in FIG. 2 was printed by silk printing using the fluorescent light emitting ink D1 having the composition shown in the following table. Sr ₃ (PO ₂ ) ₃ Cl: Eu which emits blue-violet fluorescence is used for the fluorescent light-emitting ink D1.
And a Y ₂ O ₃ : Eu fluorescent pigment which emits red fluorescence. Further, the protective layer 5 was formed by covering the fluorescent image forming layer 4.

[0074]

[Table 2]

The fluorescent image formed article of this example was used.
Fluorescent ink D1 has 254 nm and 3
Sr that emits blue-violet fluorescence when irradiated with 65 nm ultraviolet light
_Three(PO _Two)_ThreeCl: Eu based fluorescent pigment and 254nm UV irradiation
Y that emits more red fluorescence_TwoO_Three: Contains Eu-based fluorescent pigment
I let you. With UV irradiation of 365 nm, blue-violet Sr_Three(PO _Two)
_ThreeAlthough only fluorescent emission of Cl: Eu-based fluorescent pigment can be obtained,
nm-ultraviolet irradiation, blue-violet Sr_Three(PO_Two)_ThreeCl: Eu fireflies
Light pigment and red Y_TwoO_Three: Fluorescence of Eu-based fluorescent pigment is mixed,
Red-violet fluorescent light is obtained.

As the visible light absorbing layer, a green ink capable of absorbing red light is used, and when the ultraviolet light of 254 nm is irradiated, the red-violet fluorescent light emitted is sufficiently absorbed by the visible light absorbing layer. Can be. In this embodiment, when ultraviolet light having a wavelength of 365 nm is irradiated, FIG.
Blue-violet fluorescence was obtained as a character pattern of "T" as shown in (b). This emitted light in a pattern as a fluorescent image forming layer. On the other hand, when ultraviolet light having a wavelength of 254 nm is irradiated, "I" as shown in FIG.
It was confirmed that red-violet fluorescence was emitted in the character pattern of. In FIG. 2C, a dotted line indicates a region where fluorescence is absorbed by the visible light absorbing layer and becomes invisible. In the portion where the green visible light absorbing layer is located, red-violet fluorescence is absorbed, so that portion is not visible,
As a result, the character pattern becomes "I".

As described above, the fluorescent light-emitting ink and the fluorescent image-formed product of the present invention contain two kinds of phosphors and have different wavelength ranges of fluorescence emitted from the respective phosphors. Can emit light in colors that were not
Further, by selecting a type of phosphor having a different excitation wavelength, the wavelength region of the emitted fluorescent light is different by changing the excitation wavelength, that is, the color of the emitted fluorescent light is different, so that ultraviolet rays of different wavelengths can be irradiated. By changing the color of the emitted fluorescent light, and by having a visible light absorbing layer with different absorption characteristics depending on the color of the emitted fluorescent light, the image pattern formed by the fluorescent light emitted by changing the wavelength of the ultraviolet light to be irradiated is changed. Can be changed. Forgery of securities such as cash vouchers and prepaid cards by judging the authenticity of the fluorescent image formed by checking the fluorescent image formed by multiple ultraviolet rays with wavelengths that change the color of the emitted fluorescent light This can be done to increase the security level of the printed material that was required to prevent the problem.

The fluorescent light-emitting ink and the fluorescent image formed product of the present invention are not limited to the above embodiments. For example, the image formed by the fluorescent image forming layer is not only characters,
Anything, such as a picture, a photograph, or a pattern. The light source of the ultraviolet light is not limited to the black light, but may be any light source that emits the ultraviolet light. However, in that case, it is necessary to check in advance whether the wavelength of the ultraviolet light to be used can sufficiently excite the fluorescent light-emitting ink, and to select a phosphor.
In addition, various changes can be made without departing from the spirit of the present invention.

[0079]

According to the present invention, it is possible to use an ultraviolet light source other than 365 nm, which is used for printed matter, such as securities such as cash vouchers and prepaid cards, which are required to prevent forgery. It is possible to provide a fluorescent image formed product having an increased security level by using a fluorescent light-emitting ink which is difficult to obtain.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a fluorescent image formed product according to an embodiment of the present invention.

FIGS. 2A and 2B are (a) a plan view, (b) a fluorescent image pattern formed by irradiation with 365 nm ultraviolet light, and (c) a fluorescent image pattern formed by irradiation with 254 nm ultraviolet light in an example of the present invention. 3 shows a fluorescent image pattern obtained.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Base, 2 ... Visible light absorption layer, 3 ... Intermediate layer, 4 ... Fluorescent image formation layer, 5 ... Protective layer.

Claims (8)

[Claims] 1. A fluorescent image forming product having at least one fluorescent image forming layer and at least one visible light absorbing layer on a substrate, wherein the fluorescent image forming layer is irradiated with ultraviolet light of a first wavelength. A first phosphor that emits fluorescent light of a wavelength in a first visible light region, and a fluorescent light of a second visible light region having a wavelength different from the wavelength of the first visible light region when irradiated with ultraviolet light of a second wavelength. A second phosphor that emits light, is substantially transparent to visible light, and the visible light absorbing layer is formed at least one of above and below the fluorescent image forming layer, A fluorescent image formed article having different absorption characteristics or transmission characteristics for light having a wavelength in the first visible light region and light having a wavelength in the second visible light region. 2. The fluorescent light according to claim 1, wherein said visible light absorbing layer has an absorption characteristic for light having a wavelength in said first visible light region and a transmission characteristic for light having a wavelength in said second visible light region. Image formation. 3. The fluorescent light according to claim 1, wherein said visible light absorbing layer has a transmission characteristic for light having a wavelength in said first visible light region, and has an absorption characteristic for light having a wavelength in said second visible light region. Image formation. 4. A fluorescent image formed article according to claim 1, wherein said visible light absorbing layer is provided below said fluorescent image forming layer. 5. The apparatus according to claim 1, wherein said first wavelength is shorter than said second wavelength, and said second phosphor emits fluorescence by ultraviolet rays of said first wavelength and said second wavelength. Fluorescent image formation. 6. The fluorescent image forming apparatus according to claim 1, wherein said first wavelength is longer than said second wavelength, and said second phosphor does not substantially emit fluorescence by ultraviolet light of said first wavelength. Stuff. 7. The method according to claim 1, wherein said first phosphor comprises an oxide or oxyacid salt-based inorganic phosphor, and said second phosphor comprises an oxide or oxyacid salt-based inorganic phosphor. 7. The fluorescent image formed product according to any one of 6. 8. The method according to claim 1, wherein the first phosphor is Sr ₃ (PO ₂ ) ₃ Cl: Eu, Zn
O: Zn, Zn ₂ SiO ₄ : Mn, Zn ₂ GeO ₄ : Mn, Y ₂ O ₃ : Eu, Y (P, V) O ₄ : E
u, Y ₂ O ₂ S: Eu, and ZnS: an inorganic phosphor selected from Cu (Mn), wherein the second phosphor is Sr ₃ (PO ₂ ) ₃ Cl: Eu, Zn
O: Zn, Zn ₂ SiO ₄ : Mn, Zn ₂ GeO ₄ : Mn, Y ₂ O ₃ : Eu, Y (P, V) O ₄ : E
_{u, Y 2 O 2 S:} Eu, and ZnS: Cu phosphor imaging of claim 7 wherein the inorganic phosphor selected from among (Mn).