JP4115149B2 - Invisible information recording ink - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ink suitable for recording invisible information, a method for forming invisible information using the ink, a medium on which invisible information is formed, and a medium on which invisible information is formed.
[0002]
Unless otherwise specified, “invisible” means invisible to the naked eye under visible light.
[0003]
[Prior art]
As ink for recording invisible information such as confidential information, authentication information, anti-counterfeiting information, and entertainment information, for example, ink containing an ultraviolet light-emitting phosphor has been put into practical use. The invisible information formed with the ultraviolet light-emitting phosphor-containing ink cannot be viewed under visible light, so the secret of the invisible information can be kept, and the invisible information can be read by irradiating ultraviolet rays when necessary.
[0004]
As a simple device for irradiating ultraviolet rays, for example, a black light or the like is used. Black light is widely used because it is relatively inexpensive and easy to use, and is a tool suitable for reading invisible information formed with ultraviolet light emitting phosphor-containing ink. However, in recent years, with the widespread use of black light, it has become a concern that the safety of invisible information formed with ultraviolet light-emitting phosphor-containing ink may be reduced because black light can be easily obtained by many people. .
[0005]
Therefore, development of an infrared light emitting phosphor-containing ink has been attempted as an alternative to the ultraviolet light emitting phosphor-containing ink. For example, JP-A-7-310072 describes an infrared phosphor pigment that emits infrared light having a wavelength of 950 to 1050 nm. JP-A-9-59615 describes a phosphorescent phosphor having an emission peak wavelength of 630 nm or more. Japanese Unexamined Patent Publication No. 2000-43449 describes an infrared light emitting phosphor having an emission spectrum at a wavelength of 980 to 1020 nm or more. Japanese Patent Application Laid-Open No. 3-255852 describes an ink containing a phosphor having a fluorescence wavelength of 980 nm.
[0006]
Furthermore, the phosphor handbook (published by the same group of phosphors, published in December 1987) describes infra-red excitation phosphors on pages 343 to 345. Such infrared excitation phosphors are used for invisible information. It is not described to be used as an ink.
[0007]
[Problems to be solved by the invention]
As described above, many proposals have been made for ink for invisible information. However, the following problems may occur.
[0008]
First, in the case of conventional inks, there are cases where the invisible information cannot be fully read due to insufficient light emission intensity and brightness. In some cases, the security of invisible information is insufficient. Secondly, in the case of conventional ink, since the durability after forming invisible information is insufficient, the invisible information may become unreadable after a time has elapsed since the invisible information was recorded. Third, even though invisible information is not visible under visible light, when the invisible information is recorded, pen impressions and print marks are formed on the medium, and the pen impressions and print marks are visually observed. Invisible information could be leaked due to other factors.
[0009]
Therefore, an object of the present invention is to eliminate these problems.
[0010]
[Means for Solving the Problems]
  According to the present invention for achieving the above object, an ink for recording invisible information, comprising a photoluminescent material that absorbs infrared rays and emits visible light.Because
Invisible information recording ink characterized by being a pressure-sensitive transfer inkIs provided.
[0011]
When invisible information is formed using an ink (also called infrared or visible luminescence ink) containing a photoluminescent material (also called infrared or visible luminescence material) that absorbs infrared rays and emits visible light, Since the emission intensity and brightness of the outer / visible luminescent material when irradiated with infrared rays are high, the invisible information can be sufficiently read by irradiation with infrared rays. Moreover, since the infrared irradiation apparatus has a low penetration rate compared with black light or the like, the safety of invisible information formed with infrared / visible luminescence ink is high.
[0012]
In addition, since the emission intensity and brightness of infrared / visible luminescent materials when irradiated with infrared rays are high, invisible information recorded with infrared / visible luminescence inks can be invisible by infrared irradiation even when camouflaged or opaque. It is fully legible and information is not impaired.
[0013]
For this reason, the safety of invisible information can be further improved without sacrificing the legibility of invisible information by camouflaging or opacifying the invisible information.
[0014]
Further, by camouflaging or opaque the invisible information, the durability of the ink can be improved, and the invisible information can be read even after a long time has passed since the invisible information was recorded.
[0015]
Also, by camouflaging or opaque the invisible information, it is difficult to see or hide the pen impressions and print marks formed when recording the invisible information. It is possible to prevent the leakage of invisible information due to this.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below.
[0017]
Infrared / visible luminescent materials absorb infrared rays and emit visible light, so invisible information created using infrared / visible luminescence inks cannot be seen under visible light. Visible light is emitted and invisible information can be read with the naked eye. And since the emitted light intensity and brightness | luminance at the time of infrared irradiation of an infrared and visible luminescent body are high, the invisible information recorded using infrared and visible luminescence ink has favorable readability.
[0018]
Among such infrared / visible luminescent materials, those that absorb infra-red light having a wavelength of 900 to 1100 nm and emit visible light are preferable because the emission intensity and luminance of invisible information when irradiated with infrared light are particularly high.
[0019]
For the same reason, it is preferable that the infrared / visible luminescent material emits blue light, green light or red light as visible light. More specifically, it is preferable to emit visible light having a wavelength of 400 to 500 nm as blue light, visible light having a wavelength of 500 to 580 nm as green light, or visible light having a wavelength of 580 to 800 nm as red light. In addition, infrared / visible luminescent materials that emit visible light of multiple wavelengths can be used. If necessary, multiple infrared / visible luminescent materials can be used together to emit visible light of multiple wavelengths. Invisible information can also be formed by infrared / visible luminescence ink.
[0020]
As the above infrared / visible luminescent material, those containing one or more rare earths are preferable, and in particular, Yb (ytterbium) is used as the rare earth since the emission intensity and luminance of the obtained invisible information are high. What is contained is preferable. Further, the proportion of Yb in the whole rare earth is preferably 5 atomic% or more, more preferably 10 atomic% or more, further preferably 15 atomic% or more, on the other hand, 60 atomic% or less is preferable, and 55 atomic% or less is more preferable. 45 atom% or less is more preferable.
[0021]
In addition to realizing higher emission intensity and luminance, an infrared / visible luminescent material containing a rare earth other than Yb is preferable in order to adjust the wavelength of emitted visible light. Specifically, Y (yttrium) is preferable. ), Er (erbium), Tm (thulium) and the like are preferable, and two or more of them are used in combination as necessary.
The proportion of Y in the entire rare earth is preferably 40 atomic percent or more, more preferably 50 atomic percent or more, still more preferably 60 atomic percent or more, while 90 atomic percent or less is preferable, 85 atomic percent or less is more preferable, 80 More preferably, it is at most atomic%.
[0022]
Further, the ratio of Er to the whole rare earth is preferably 0.1 atomic% or more, more preferably 0.5 atomic% or more, still more preferably 0.8 atomic% or more, while 10 atomic% or less is preferable, 8 Atomic% or less is more preferable, and 5 atomic% or less is still more preferable.
[0023]
Further, the proportion of Tm in the total rare earth is preferably 0.01 atomic% or more, more preferably 0.05 atomic% or more, still more preferably 0.08 atomic% or more, while 1 atomic% or less is preferable. Is more preferably 8 atomic% or less, still more preferably 0.5 atomic% or less.
[0024]
The average particle size of the infrared / visible luminescent material as described above is also carefully selected because it affects the emission intensity and luminance of the invisible information obtained. Specifically, it is preferably 0.1 μm or more, more preferably 1 μm or more, further preferably 2 μm or more, on the other hand, preferably 10 μm or less, more preferably 8 μm or less, and even more preferably 5 μm or less. In addition, as an average particle diameter, a volume average particle diameter can be measured, for example using Coulter Electronics (UK) coulter multi-cider.
[0025]
The infrared / visible luminescence ink is prepared by mixing the infrared / visible luminescence material as described above, a vehicle, an auxiliary agent, and the like, and using other colorants as necessary. The proportion of the infrared / visible luminescent material in the infrared / visible luminescence ink is preferably 5% by mass or more, more preferably 10% by mass or more, and more preferably 15% by mass or more in order to achieve sufficient emission intensity and luminance. Is more preferable. On the other hand, 60% by mass or less is preferable, 50% by mass or less is more preferable, and 40% by mass or less is more preferable in order to ensure the performance necessary for forming invisible information of the obtained infrared / visible luminescence ink. Yes.
[0026]
Vehicles are carefully selected to achieve the desired performance of infrared and visible luminescence inks, for example, water; vegetable oils such as drying oils, semi-drying oils, non-drying oils; processing oils; mineral oils; natural resins, processing Resins such as resins and synthetic resins; plasticizers; waxes; solvents such as hydrocarbons, alcohols, glycols, esters, ketones; ultraviolet curable monomers, ultraviolet curable oligomers, electron beam curable monomers, electron beams A curable vehicle such as a curable oligomer is used.
[0027]
Auxiliary agents include drying control agents such as dryers and anti-skinning agents; viscosity control agents such as compounds, thickeners and waist-cutting agents; dispersion control agents such as dispersants, color separation inhibitors and stabilizers; toners, Color control agents such as matting agents; reaction control agents such as initiators, sensitizers, catalysts, and crosslinking agents; wetting agents; antifoaming agents;
[0028]
As other colorants, pigments such as organic pigments, inorganic pigments, extender pigments; dyes such as oil-soluble dyes, aqueous dyes, and disperse dyes are used.
[0029]
Examples of the invisible information recorded using the infrared / visible luminescence ink as described above include confidential information, authenticity determination information, forgery prevention information, and entertainment information. Further, these information can be combined and recorded as necessary.
[0030]
Examples of confidential information include passwords, PIN numbers, ID numbers, registration numbers, names, addresses, ages, genders, birthdays, blood types, telephone numbers, birthplaces, permanent affiliations, nationalities, personal information, etc. Examples of the described medium (invisible information carrier) include an ID card, an application form, an application form, a registration form, a notification form, a form, and a mail as shown in FIG. The secret information 21 recorded on the medium 20 is not visible under visible light, but can be read by irradiating infrared rays.
[0031]
Examples of authenticity determination information include hidden characters, hidden symbols, hidden patterns, hidden background patterns, hidden patterns, hidden numbers, ruled lines, halftone dots, etc., and a medium (invisible information carrier) on which authentication information is described Can be exemplified by admission tickets, tickets, certificates, certificates, cash vouchers, securities, etc. as shown in FIG. The authenticity determination information 23 recorded on the medium 22 is not visible under visible light. For this reason, when a pattern or the like that is visible under visible light is formed on the medium 22, the authenticity determination information 23 can be recorded without damaging these patterns, and the information can be held on the medium 22. Then, if necessary, the authenticity determination information 23 is irradiated with infrared rays and read to determine the authenticity of the medium 22.
[0032]
Examples of anti-counterfeiting information include hidden characters, hidden symbols, hidden patterns, hidden background patterns, hidden pictures, hidden numbers, ruled lines, halftone dots, etc., and a medium (invisible information carrier) on which information for forgery prevention is described Can be exemplified by gold vouchers, securities, tickets, admission tickets, certificates, certificates, etc. as shown in FIG. The anti-counterfeit information 25 recorded on the medium 24 is not visible under visible light. For this reason, when the pattern etc. which can be seen under visible light are formed in the medium 24, the forgery prevention information 25 can be recorded without impairing these patterns, and the information can be held in the medium 24.
[0033]
Examples of entertainment information include hidden characters, hidden symbols, hidden patterns, hidden background patterns, hidden patterns, hidden numbers, ruled lines, halftone dots, etc. As a medium (invisible information carrier) on which entertainment information is described, Examples include greeting cards, greeting cards, guidance cards, tickets, lotteries, gimmick books, gimmick stationery, etc. as shown in FIG. The entertainment information 27 recorded on the medium 26 is not visible under visible light. For this reason, in the case where symbols and the like that are visible under visible light are formed on the medium 26, the entertainment information 27 can be recorded without damaging these symbols, and the information can be held on the medium 26. Then, if necessary, the entertainment information 27 is irradiated with infrared rays to read hidden characters and the like.
[0034]
The method for recording the invisible information as described above on the medium is selected from printing, writing, pressure-sensitive transfer, stamping, pasting and the like in consideration of the type and use of the invisible information. Further, these methods can be used in combination as necessary.
[0035]
FIG. 5 shows how the medium 31 on which the invisible information is printed is manufactured by the printing machine 30 as a method for forming the invisible information by printing. Invisible information carriers that can be manufactured by printing include ID cards with confidential information recorded, application forms, application documents, registration documents, notification documents, forms, mails, etc .; admission tickets and tickets with authentication information recorded Certificates, certificates, gold vouchers, securities, etc .; Gold vouchers, securities, tickets, admission tickets, certificates, certificates, etc. with information for preventing counterfeiting; Greeting cards with greeting information, greeting cards , Guidance letters, tickets, lotteries, gimmick books, gimmick stationery, and the like.
[0036]
The infrared / visible luminescence ink for printing can be prepared by using an appropriate vehicle or the like. Such printing inks include flexographic printing inks, letterpress printing inks, photographic letterpress printing inks, PS printing inks, offset printing inks and other relief printing inks; gravure printing inks and halftone dots. Intaglio printing ink, such as gravure printing ink, PS printing ink, offset printing ink; flat printing ink, such as PS printing ink, offset printing ink; screen printing ink, copying printing ink, PS Stencil printing inks such as printing plate inks and offset printing inks; UV curable inks, electron beam curable inks, sheet-fed inks, offset rotary inks, newspaper inks, tinplate inks, etc. Can be mentioned.
[0037]
FIG. 6 shows how the invisible information is written on the application form 33 by the recording tool 32 as a method of forming the invisible information by writing. In this case, the invisible information is directly written on the medium by using a recording tool including an infrared / visible luminescence ink for drawing. Examples of such a recording tool include writing tools such as a marking pen, a water-based pen, an oil-based pen, a water-based marker, an oil-based marker, a ballpoint pen, a fountain pen, and a desk pen. In addition, these infrared and visible luminescence inks for writing instruments can be prepared by using an appropriate vehicle, specifically, marking pen ink, aqueous pen ink, oil-based pen ink, aqueous marker. Ink for writing instruments such as ink for ink, ink for oil-based marker, ink for ballpoint pen, ink for fountain pen and ink for desk pen can be prepared.
[0038]
As another recording tool that can be used when writing invisible information, there is a recording tool including a drawing agent containing an infrared / visible luminescent material. Examples of such recording tools include writing tools such as pencils, colored pencils and mechanical pencils, water-based paints, oil-based paints, acrylic paints, cake colors, powder paints, granule paints, drawing inks, crayons, passes, comte, pastels, etc. be able to. A drawing agent provided in these recording tools and containing an infrared / visible luminescent material can be prepared by using a solid or semi-solid vehicle, specifically, an aqueous paint, an oil paint, an acrylic paint. Drawing agents such as paint, cake color, powder paint, granule paint, drawing ink, crayon, pass, container, pastel, pencil, colored pencil, and mechanical pencil can be used.
[0039]
FIG. 7 shows how invisible information is stamped on the medium 38 with a stamp 37 or the like as a method of forming invisible information by stamping. In this case, invisible information is printed on a medium by using infrared / visible luminescence ink such as stamp ink, stamp ink, seal ink, and the like. These drawing inks can be prepared by using an appropriate vehicle or the like, and stamps, stamps, seals, etc. can be used as the stamping tools.
[0040]
FIG. 8 shows a state where a label 39 or the like is pasted as a method of forming invisible information by pasting. In this case, the invisible information is formed in advance on the label 39, and the invisible information can be formed on the medium by attaching the label 39.
[0041]
In the case of the invisible information forming method described above, the infrared / visible luminescence ink is directly applied to the medium, and the invisible information is recorded on the medium. For this reason, it is difficult to confirm the state of the formed invisible information with the naked eye under visible light during and immediately after the formation of the invisible information. As a result, for example, even if secret information such as a personal identification number is mistakenly written on the medium, there is a possibility that an error in information will not be noticed on the spot and a problem may occur.
[0042]
As a method for preventing such a problem, as shown in FIG. 9, invisible information is confirmed by irradiating a medium with infrared rays when recording the invisible information. In this case, at least the invisible information entry area 11 of the medium 10 is irradiated with the infrared rays 14 using the infrared ray generation lamp 13, and the contents of the invisible information 12 are confirmed simultaneously with writing. Since the infrared / visible luminescence ink has high emission intensity and brightness, the contents of invisible information during recording can be easily confirmed. The confirmation of the invisible information is not limited to the case where the invisible information is recorded by writing, but is also effective when the invisible information is formed by printing, pressure-sensitive transfer, stamping, and pasting.
[0043]
In addition to the invisible information forming method described above, as shown in FIG. 10, for example, a copy form can be used to record the invisible information by pressure-sensitive transfer. In this case, information is entered on the transfer sheet 35 using a general writing instrument 34 having ink visible with visible light, and the invisible information is copied to the transfer sheet 36 by the writing pressure at the time of entry.
[0044]
When recording invisible information by pressure-sensitive transfer, an invisible information transfer sheet having a pressure-sensitive transfer layer containing an infrared / visible luminescent material is used. A pressure-sensitive transition layer is formed in advance on the back surface of the area where the invisible information is written on the invisible information transfer sheet. If invisible information is entered on the surface of the invisible information transfer sheet on the surface where the invisible information is entered, along with pressure such as writing pressure and printing pressure, pressure is applied by pressure corresponding to the invisible information entered. The pressure-sensitive transferable ink forming the transfer layer is transferred to the invisible information transfer sheet, and the invisible information is copied and formed on the invisible information transfer sheet.
[0045]
Such a pressure-sensitive transition layer can be prepared from a pressure-sensitive transfer ink containing an infrared / visible luminescent material, and the pressure-sensitive transfer ink can be prepared using an appropriate vehicle or the like. As the pressure-sensitive transfer ink, for example, non-aqueous inks are preferable, waxes and fluid oils are used as vehicles, and binders, ultraviolet absorbers, photopolymerization initiators, thickeners, gels are used as necessary. It is prepared using an auxiliary agent such as an agent.
[0046]
Further, in the pressure-sensitive transferable invisible information recording ink, the proportion of the photoluminescent material in the invisible information recording ink is preferably 5% by mass or more and preferably 10% by mass or more in order to obtain visible fluorescence. More preferred is 15% by mass or more. On the other hand, in order to realize sufficient transferability, the content is preferably 60% by mass or less, more preferably 50% by mass or less, and still more preferably 40% by mass or less.
[0047]
As the waxes, colorless ones are preferable, a melting point of 55 to 85 ° C., a penetration of about 5 at 25 ° C. and a relatively high hardness as a base wax, and for the purpose of controlling transferability and contamination, Those prepared by adding a soft wax to this to have a low hardness are preferred. As such waxes, carnauba wax, candelilla wax, beeswax, wood wax, montan wax, mineral wax, paraffin wax, synthetic wax, coconut wax and the like can be used.
[0048]
The proportion of waxes in the pressure-sensitive transferable ink is preferably 20% by mass or more, and more preferably 25% by mass or more in order to suppress contamination. On the other hand, in order to realize sufficient transferability, the content is preferably 50% by mass or less, more preferably 45% by mass or less, and further preferably 40% by mass or less.
[0049]
Moreover, you may add about 3-10 mass% of ethylene-vinyl acetate copolymer with high compatibility with these waxes to a pressure sensitive transferable ink. This is because it has a function of increasing the viscosity of the pressure-sensitive transferable ink and enhances the transfer property of the ink.
[0050]
On the other hand, the fluid oil is preferably colorless, low in viscosity, and excellent in coating properties. Examples of such fluid oils include plant non-drying oils such as castor oil, olive oil and safflower oil; white mineral oils such as normal paraffin; paraffinic lubricating oils; In addition, lubricating oils and normal paraffins which do not contain an aromatic component are preferable.
[0051]
The proportion of the fluid oil in the pressure-sensitive transferable ink is preferably 10% by mass or more, and more preferably 20% by mass or more in order to achieve sufficient transferability. On the other hand, in order to suppress contamination, it is preferably 40% by mass or less, and more preferably 30% by mass or less.
[0052]
Manufactures copy-type sheet sets from the invisible information transfer sheet with the pressure-sensitive transfer layer formed using the pressure-sensitive transferable infrared / visible luminescence ink as described above and the invisible information transfer sheet. it can. As such a sheet set, an application form, an application postcard, etc. can be exemplified, and the invisible information transfer sheet on which the invisible information is transferred is circulated and mailed to the other side. On the other hand, the invisible information transfer sheet in which the invisible information is directly entered may be circulated and mailed to the other side, or may be saved as a copy by the entry person.
[0053]
When these invisible information transfer sheet sets are used to form invisible information by the pressure-sensitive transfer method, the invisible information transfer sheet is filled with general ink that is visible under visible light. Writing instruments can be used. For this reason, the entered information can be easily confirmed without requiring a special device such as an infrared lamp.
[0054]
In order to increase the safety of the invisible information, camouflaging may be performed prior to recording the invisible information as necessary in at least the invisible information recording area of the medium on which the invisible information is recorded.
[0055]
Similarly, after recording invisible information, camouflaging or opaque may be applied to at least the invisible information recording area of the medium on which the invisible information is recorded.
[0056]
As a mode of camouflage, for example, halftone dots and background patterns are printed. In particular, if camouflage made of colored halftone dots and tint blocks is applied and it is difficult to counterfeit this camouflage, it is possible to achieve higher safety by using it together with invisible information formed with infrared / visible luminescence ink. In addition, by forming such camouflage, even when printing marks, writing impression marks, stamp marks, etc. are formed when printing, writing, or stamping invisible information, these marks are visually recognized by camouflage. This makes it difficult to achieve higher safety. In addition, when an ultraviolet light-emitting camouflage is applied, this camouflage is not visible under visible light, but can be read for the first time by irradiating with ultraviolet light. For this reason, since the ultraviolet light-emitting camouflage also functions as invisible information, higher safety can be realized by using it together with invisible information formed with infrared / visible luminescence ink.
[0057]
On the other hand, the aspect of opaque is, for example, printing, writing, stamping and pasting on a medium, but after forming invisible information, a label is pasted at least in an area where invisible information is recorded to hide the invisible information. Is most preferable in terms of safety of invisible information. As such a label, a label that transmits infrared light and visible light is used so as not to prevent interpretation of invisible information. By attaching the label and making the invisible information opaque, the safety of the invisible information can be increased in the same manner as when making the opaque by printing, writing, or stamping. Furthermore, if the invisible information is opaque by the label, it is possible to suppress the invisible information from being scratched, directly exposed to room light and outdoor light, and absorbing surrounding moisture. For this reason, deterioration of an infrared and visible luminescent body can be suppressed, and durability of invisible information can be improved.
[0058]
As such a label, a resin film or the like can be produced as a substrate. Further, in order to enhance the effect of opaque, the label can be colored, ultraviolet light emitting, or colored and ultraviolet light emitting. Camouflage can also be produced on the label. The camouflage can be colored, ultraviolet light-emitting, or colored and ultraviolet light-emitting.
[0059]
In particular, if UV light emitting labels, labels with UV light emitting camouflage, etc. are used, UV light emitting opaque and camouflage function as invisible information, so they were formed with infrared and visible luminescence inks. By using it together with invisible information, higher safety can be realized.
[0060]
In addition, when using colored labels, labels with colored camouflage, etc., in order to ensure good legibility of invisible information, the color of visible light emitted by infrared / visible luminescent materials by infrared irradiation is used. In consideration of the color, it is preferable to select a color. As such a color, for example, a complementary color of visible light emitted from an infrared / visible luminescent material is used.
[0061]
On the other hand, as shown in FIG. 11, after invisible information is formed on the medium 60, an opaque layer 61 may be laminated at least in an area where the invisible information is recorded, and the opaque may be applied. As such a concealing layer, a layer that transmits infrared light and visible light is used so as not to prevent interpretation of invisible information. By laminating a concealing layer, the safety of invisible information can be increased in the same manner as when opaque is applied by printing, writing, or stamping. Furthermore, if the invisible information is opaque by the concealing layer, the invisible information can be prevented from being scratched, directly exposed to room light and outdoor light, and absorbing surrounding moisture. For this reason, deterioration of an infrared and visible luminescent body can be suppressed, and durability of invisible information can be improved.
[0062]
In particular, for example, when a medium on which invisible information is recorded is made of a resin plate or the like and a medium (laminate) on which a concealing layer is applied is used as an invisible information carrier carried like an ID card, the concealment is performed. If invisible information is protected by the layer, the lifetime of the invisible information carrier can be extended.
[0063]
As a method for producing the concealing layer, a method in which a raw material resin is laminated on a medium on which invisible information is recorded by a melting method, a casting method, or the like can be employed. Further, in order to enhance the effect of opaque, the concealing layer can be colored, ultraviolet light emitting, or colored and ultraviolet light emitting. Camouflage can also be produced in the concealing layer. The camouflage can be colored, ultraviolet light-emitting, or colored and ultraviolet light-emitting.
[0064]
In particular, if an ultraviolet light-emitting concealment layer, an ultraviolet light-emitting ground pattern concealment layer, an ultraviolet light-emitting camouflage concealment layer, or the like is used, this camouflage functions as ultraviolet light-emitting invisible information. Therefore, even higher safety can be realized by using invisible information formed with infrared / visible luminescence ink.
[0065]
In addition, when using colored concealment layers, concealment layers with colored camouflage, etc., in order to ensure good legibility of invisible information, visible light emitted from infrared and visible luminescent materials by infrared irradiation is used. It is preferable to select a color in consideration of the color. As such a color, for example, a complementary color of visible light emitted from an infrared / visible luminescent material is used.
[0066]
As described above, when invisible information is formed by pressure-sensitive transfer in the same manner as when invisible information is formed by printing, writing, stamping, and pasting, printing, writing, stamping, pasting, and labeling are performed. Camouflage and opaque can be applied by sticking and manufacturing a laminate. As a result, in the same manner as when invisible information is formed by printing, writing, stamping, and pasting, the safety of invisible information formed by pressure-sensitive transfer can be further improved, and durability can be improved.
[0067]
FIG. 12 shows an example in which invisible information created by pressure-sensitive transfer is camouflaged in advance using a copy form. As shown in FIG. 12 (a), the copy form is composed of an invisible information transfer sheet 40 and an invisible information transfer sheet 42. A pressure transition layer 41 is formed. And in the area | region 43 to which the invisible information of the invisible information transfer sheet 42 is transferred, a ground pattern 44 is printed in advance as a camouflage. The invisible information is entered with pressure by writing from the surface of the invisible information transfer sheet as shown in FIG. 12 (b), and copied to the invisible information transfer sheet as shown in 45 of FIG. 12 (c). Is done.
[0068]
FIG. 13 shows an example in which invisible information created by pressure-sensitive transfer is opaque after the fact. Also in this case, as shown in FIG. 13A, the information 52 is written with pressure in the region 51 where the invisible information is written on the invisible information transfer sheet 50. And since the pressure sensitive transfer layer 53 is formed in the back surface of the area | region 51 which fills invisible information as shown in FIG.13 (b), the invisible information 56 is the invisible information of the invisible information transfer sheet 54. Is pressure-sensitively transferred to the region 55 where the toner is transferred. However, unlike the case where camouflage and opaque are performed in advance, the region 55 where the invisible information is transferred is not camouflaged and opaque. As shown in FIG. 13 (c), the opaque sticks a label 57 with a ground pattern 58, for example, after the invisible information is transferred, so that the pressure-sensitive transferred invisible information is hidden (FIG. 13 (d)). )).
[0069]
As described above, when invisible information is recorded by pressure-sensitive transfer with a pressure such as writing, there is a high possibility that a pen impression is formed in a region where the invisible information is transferred. For this reason, it is important to prevent leakage of invisible information due to visual observation of the pen impression by making it difficult to visually check the pen impression by camouflaging or opaque.
[0070]
As a specific mode when opaque information formed by pressure-sensitive transfer is used, the same specific mode as that when opaque information is formed by printing, writing, stamping, and pasting can be adopted. That is, as a method of forming an opaque, printing, writing, stamping, sticking, label sticking, production of a laminate, etc. can be adopted, and camouflage consisting of halftone dots and tint can be applied. Can be.
[0071]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not restrict | limited to a following example. Unless otherwise specified, commercially available high-purity products were used as reagents.
[0072]
(Light emission intensity and brightness of invisible information)
The light emission intensity and luminance when irradiating infrared light with a wavelength of 980 nm to the invisible information were visually observed and evaluated in three levels: sufficiently high (◯), practical level (Δ), and low (×).
[0073]
(Durability of invisible information)
Irradiation intensity of 0.01 W / mm with respect to the medium surface on which invisible information is recorded²After standing for 1 hour while irradiating with ultraviolet rays under the above conditions, the invisible information is read visually under the above conditions, and evaluated in three levels: possible (○), practical level (△), impossible (×). did.
[0074]
(Non-leakage of information)
The medium on which the invisible information was recorded was visually observed under visible light to determine the presence or absence of writing impressions and printing marks, and evaluated in three levels: none (○), practical level (△), and existence (×). .
[0075]
    (referenceExample 1) Invisible information recording ink 1 for printing, invisible information carrier 1
  NaY with an average particle size of 3.5 μm as infrared / visible luminescent material_0.69Yb_0.30Er_0.01F_Four20 parts by weight, 10 parts by weight of calcium carbonate as an extender, 27 parts by weight of rosin-modified phenolic resin as a synthetic resin, 13 parts of linseed oil and tung oil as vegetable oils, and a petroleum solvent 25 having a boiling point of 280 to 320 ° C. Ink 1 for recording invisible information for printing was prepared by mixing 3 parts by mass of a dryer and 2 parts by mass of a drying regulator as an auxiliary agent. NaY_0.69Yb_0.30Er_0.01F_FourConfirmed that infrared rays having a wavelength of 900 to 1100 nm were absorbed around 978 nm and green light having a wavelength of 520 to 560 nm was emitted.
[0076]
Using the obtained printing invisible information recording ink 1, a personal identification number was printed on a predetermined area of the medium surface by a wet offset method using a PS plate. When the obtained invisible information carrier 1 was evaluated for light emission intensity and luminance of invisible information, the result was good.
[0077]
Further, a red thin label was laminated on the area where the code number of the invisible information carrier 1 was printed to produce a laminate. The obtained laminate was evaluated for durability of invisible information and non-leakage of information, and the results were all good.
[0078]
    (referenceExample 2) Invisible information carrier 2
  The admission ticket was printed by offset printing using offset ink. Using invisible information recording ink 1 for printing, invisible information for authenticity determination was printed in the same manner as in the case of invisible information carrier 1. When the obtained invisible information carrier 2 was evaluated for the emission intensity and luminance of the invisible information, the result was ◯.
[0079]
    (referenceExample 3) Invisible information recording ink 2 for printing, invisible information carrier 3
  Y with an average particle size of 3.5 μm as infrared / visible luminescent material_0.65Yb_0.35Tm_0.001F_Three20 parts by weight, 12 parts by weight of calcium carbonate as an extender, 12 parts by weight of a polyester resin as a synthetic resin, 45.5 parts by weight of a mixture of acrylic ester monomers and oligomers as a curable vehicle, and a photocuring initiator 6.5 parts of benzoyl peroxide and 4 parts by mass of a chain transfer agent as an auxiliary were mixed to prepare UV curable printing ink 2 for invisible information recording. Y_0.65Yb_0.35Tm_0.001F_ThreeConfirmed that infrared rays having a wavelength of 900 to 1100 nm were absorbed around 978 nm and blue light having a wavelength of 400 to 500 nm was emitted.
[0080]
On the other hand, a tint block was printed on a gold voucher by an offset printing method using ultraviolet light-emitting printing ink. Then, invisible information for preventing counterfeiting was printed on the area where the background pattern was printed by the wet offset method using a PS plate using the printing invisible information recording ink 2 and cured with ultraviolet rays. When the obtained invisible information carrier 2 was evaluated for the emission intensity and luminance of the invisible information, the result was ◯. Furthermore, when invisible information was formed and the area was irradiated with ultraviolet rays, a background pattern was confirmed.
[0081]
    (Example1) Pressure-sensitive transferable invisible information recording ink 1, invisible information transfer sheet set 1
  NaY with an average particle size of 3.5 μm as infrared / visible luminescent material_0.69Yb_0.30Er_0.01F_Four35 parts by weight, 30 parts by weight of carnauba wax as a wax, 25 parts by weight of normal paraffin as a fluid oil, 5 parts by weight of an ethylene-vinyl acetate copolymer, 3 parts by weight of an ultraviolet absorber, a thickener 2 parts by mass was mixed to prepare ink 1 for pressure-sensitive transferable invisible information recording.
[0082]
Using the obtained pressure-sensitive transferable invisible information recording ink 1, a pressure-sensitive transfer layer was produced on the back surface of the region where invisible information was written on the invisible information transfer sheet. On the other hand, an invisible information transfer sheet in which a tint block was printed in a region where invisible information was transferred was prepared, and an invisible information transfer sheet set 1 was prepared from the invisible information transfer sheet and the invisible information transfer sheet.
[0083]
The code number was entered on the invisible information transfer sheet of the invisible information transfer sheet set 1 thus obtained, and the code number was copied on the invisible information transfer sheet. When the luminescence intensity and luminance of the transferred invisible information were evaluated, the result was good. Moreover, the non-leakage property of invisible information was also ◯.
[0084]
    (Example2) Invisible information transfer sheet set 2
  An invisible information transfer sheet set 2 was produced in the same manner as in the invisible information transfer sheet set 1 except that the background pattern was not formed on the invisible information transfer sheet.
[0085]
A code number was entered on the invisible information transfer sheet of the invisible information transfer sheet set 2 obtained, and the code number was copied on the invisible information transfer sheet. Subsequently, a label printed with a red background pattern was attached to the transferred invisible information. Thereafter, the emission intensity and luminance of the invisible information were evaluated, and the result was good. Moreover, the non-leakage property of invisible information was also ◯.
[0086]
    (Reference example 4) Invisible information recording ink 1 for writing instruments, marking pen 1
  NaY with an average particle size of 3.5 μm as infrared / visible luminescent material_0.69Yb_0.30Er_0.01F_FourAnd a solvent and a resin can be mixed to prepare the invisible information recording ink 1 for a writing instrument. Furthermore, the marking pen 1 can be manufactured using this. Using the obtained marking pen 1, the invisible information can be written while confirming the invisible information under infrared irradiation.
[0087]
【The invention's effect】
When recording invisible information, by using an ink containing a photoluminescent material that absorbs infrared rays and emits visible light, it is possible to realize high emission intensity and high luminance of invisible information when irradiated with infrared rays, Good secrecy can be achieved. For this reason, highly secure invisible information can be formed.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating an example of a medium on which invisible information is recorded.
FIG. 2 is a schematic diagram illustrating an example of a medium on which invisible information is recorded.
FIG. 3 is a schematic diagram for illustrating an example of a medium on which invisible information is recorded.
FIG. 4 is a schematic diagram for illustrating an example of a medium on which invisible information is recorded.
FIG. 5 is a schematic diagram for explaining a method for recording invisible information.
FIG. 6 is a schematic diagram for explaining a method for recording invisible information.
FIG. 7 is a schematic diagram for explaining a method for recording invisible information.
FIG. 8 is a schematic diagram for explaining a method for recording invisible information.
FIG. 9 is a schematic diagram for explaining a method for recording invisible information.
FIG. 10 is a schematic diagram for explaining a method for recording invisible information.
FIG. 11 is a schematic diagram illustrating an example of a medium on which invisible information is opaque;
FIG. 12 is a schematic diagram for explaining a method of camouflaging invisible information.
FIG. 13 is a schematic diagram for explaining a method of opaquely invisible information.
[Explanation of symbols]
10 Medium
11 Invisible information entry area
12 Invisible information
13 Infrared generator lamp
14 Infrared
20 medium
21 Confidential information
22 Medium
23 Information for authenticity judgment
24 Medium
25 Information for preventing counterfeiting
26 Medium
27 Entertainment Information
30 printing press
31 Medium with invisible information recorded
32 Recording tools
33 Application form
34 Writing Instruments
35 Transfer sheet
36 Transferee sheet
37 stamp
38 Medium
39 Label
40 Invisible information transfer sheet
41 Pressure-sensitive transition layer
42 Invisible information transfer sheet
43 Area where invisible information is transferred
44 Crest
45 Invisible information
50 Invisible information transfer sheet
51 Area for entering invisible information
52 Information
53 Pressure-sensitive transition layer
54 Invisible information transfer sheet
55 Area where invisible information is transferred
56 Invisible information
57 Label
58 Crest
60 medium
61 Concealment layer

Claims (9)

An ink for recording invisible information, containing a photoluminescent material that absorbs infrared rays and emits visible light ,
Invisible information recording ink, which is a pressure sensitive transfer ink.   The invisible information recording ink according to claim 1, wherein the photoluminescent material absorbs light having a wavelength of 900 to 1100 nm.   3. The invisible information recording ink according to claim 1, wherein the photoluminescent material emits at least one visible light selected from blue light, green light, and red light.   4. The invisible information recording according to claim 1, wherein the photoluminescent material contains one or more rare earths, and contains 5 to 60 atomic% of Yb with respect to the entire rare earths. 5. Ink. The rare earth further contains one or more rare earths selected from 40 to 90 atomic% Y, 0.1 to 10 atomic% Er, and 0.01 to 1 atomic% Tm with respect to the entire rare earth. The invisible information recording ink according to claim 4 .   6. The invisible information recording ink according to claim 1, wherein the photoluminescent material has an average particle size of 0.1 to 10 [mu] m.   The invisible information recording ink according to any one of claims 1 to 6, wherein a ratio of the photoluminescent material to the invisible information recording ink is 5 to 60% by mass.   The invisible information recording ink according to any one of claims 1 to 7, wherein the invisible information is at least one selected from confidential information, authenticity determination information, forgery prevention information, and entertainment information.   The invisible information recording ink according to claim 1, wherein the invisible information recording ink is a printing ink, a drawing ink, or a drawing agent.

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