Abstract:
Inks have been discovered that may be used for providing additional security to the printed matter to which the ink has been affixed. A single ink provides the foregoing result by being fluorescent and phosphorescent.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Reference is made to commonly assigned copending patent application Docket No. E-316 filed herewith entitled &#34;Luminescent Facing Marks For Enhanced Bar Code Discrimination&#34; in the names of Richard A. Connell, Thyagaraj Sarada and Richard A. Bernard. 
     FIELD OF THE INVENTION 
     The invention relates generally to the field of inks, and more particularly to luminescent inks. 
     BACKGROUND OF THE INVENTION 
     One of the by-products of the business climate being driven by technological advances is the need of greater security i.e., commercially available desk top printers and color photocopiers have been used to forge documents. Thus, additional security is needed for documents that are issued by governments, financial institutions, brokerage houses, postal meter printing and the like i.e., indicia printing and lottery tickets. One scheme that has been proposed for providing security is to print authenticating text in invisible ink so that the same does not interfere with the document upon which such text is printed, but one, nevertheless, is able to determine the authenticity of the document and the holder of the document as well. A luminescent ink may also be used for similar security purposes. 
     Typically luminescence will become visible to the naked eye when stimulated or excited by suitable radiation. Fluorescent inks and phosphorescent inks are types of luminescent inks. The emission of light from a fluorescent ink is caused by the absorption of energy (light or electromagnetic radiation) into the inks molecule that causes an excited state to emit or be fluorescent and ceases abruptly when the energy source is removed. The emission of light from a phosphorescent ink will persist after a time interval in which the energy source has been removed. 
     The United States Postal Service is currently selling stamps that have been printed with a phosphorescent ink and accepting postal indicia that have been printed by a postage meter that uses fluorescent inks. Current fluorescent inks that are used in postage meters approved by the United States Postal Service contain a fluorescent ink that is excited by a 254 nm ultra violet light source that emits a fluorescent light in the orange to red region of the visible spectrum between 580 to 650 nm. Mail sorting equipment like the Advance Facer Cancelling System manufactured by Electricom AEG are being used to cancel stamps that have been affixed to mail pieces and check whether or not the postal indicia affixed to mail pieces were affixed by an authorized meter. Luminescent inks are currently used only to assist Facer Cancelling Systems to face the mail pieces. Luminescent inks may also be used as a deterrent to counterfeiting. Some new technologies like photocopying do not use luminescent toners/inks. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the disadvantages of the prior art by providing an ink that makes it even more difficult to print fraudulent indicia and alphanumeric characters. The ink may also be used to print indicia that contains various markings that may be used for sorting and handling various materials i.e., mail pieces. A single ink provides the foregoing result by being both fluorescent and phosphorescent. Current desk top printers and color photocopiers are not capable of duplicating fluorescence and phosphorescence at the same time. The reason for the above is that while fluorescent inks would add to the brightness of the printing, phosphorescence would not add any enhancement to the print quality. Hence, phosphorescent materials are currently only used in specialty inks. 
     The inks of this invention may be used in current postage meters as well as being detected by current Advance Facer Canceller Systems. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a drawing of an indicia containing normal security features (meter number) printed by conventional printing or bit map generated printing; 
     FIG. 2 is a drawing of a bit map generated postal indicia that was printed with an ink that is fluorescent with or without phosphorescence that has additional control information i.e., encrypted data; 
     FIG. 3 is a drawing of a postal indicia containing special markings in addition to the information contained in FIG. 2; and 
     FIG. 4 is a schematic drawing of the detector portion of a facer canceller that is used to detect the markings on the postal indicia shown in FIGS. 1, 2 and 3. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings in detail, and more particularly to FIG. 1, the reference character 11 represents a postal indicia on mail piece 12 that contains normal security features (meter number) printed by conventional printing or bit map generated printing. The postal indicia 11 contains a dollar amount 13, the date 14 that the postal indicia was affixed to the mail piece, the place the mail piece was mailed from 15 and the postal meter serial number 16 (for authentication) and value of postage 12. 
     FIG. 2 is a drawing of postal indicia 11 that was printed with an ink that is fluorescent with or without phosphorescence that has additional control information i.e., encrypted data. The postal indicia 11 may be printed on mail piece 12 by an ink jet printer or by a thermal printer, or by a laser printer or by any digital printer. The postal indicia 11 contains a dollar amount 13, the date 14 that the postal indicia was affixed to the mail piece, the place the mail piece was mailed from 15 and the postal meter serial number 16 and additionally a security code 10. 
     FIG. 3 is a drawing of a postal indicia containing special markings, besides the information contained in FIG. 2, which in the example shown are bars. Postal indicia 11 was printed with an ink that is fluorescent with or without phosphorescence. The postal indicia may be printed on mail piece 12 by an ink jet printer. The postal indicia 11 contains a dollar amount 13, the date 14 that the postal indicia was affixed to the mail piece, the place the mail piece was mailed from 15 and the postal meter serial number 16 and a security code 10. In addition the postal indicia 11 will include bars 17, 18 and 19. These are printed by conventional printing methods. It would be obvious to one skilled in the art that the presence or absence of various states of luminescence may be used. It would also be obvious to one skilled in the art that any type of markings having any geometric shape may be used for bars 17, 18 and 19, i.e., stars, circles, triangles, etc. 
     In the event that a fluorescent ink currently used for printing postal meter indicia is used, then and in that event sorting information may be encoded into bars 17, 18 and 19. For instance, each of bars 17, 18 and 19 may be printed with the fluorescent ink, none of the bars may be printed with the fluorescent ink, or some of the bars may be printed with the fluorescent ink. Each bar can have two possible states. Hence, eight possible combinations may be encoded in bars 17, 18 and 19. 
     In the event an ink that is fluorescent and phosphorescent at the same time is used, sorting information may be encoded into bars 17, 18 and 19. For instance: each of bars 17, 18 and 19 may be printed with the ink that is fluorescent and phosphorescent; none of the bars 17, 18, and 19 may be printed with the ink that is fluorescent and phosphorescent; or some of the bars 17, 18, and 19 may be printed with the ink that is fluorescent and phosphorescent. Thus, bars 17, 18 and 19, each have four possible states. Hence, 64 possible combinations may be encoded in bars 17, 18, and 19 without using any additional space. It will be obvious to one skilled in the art that additional bars may be utilized to convey additional information. 
     The inks that are used to print postal indicia 11 may be applied using conventional printing methods i.e., impact printing or bit map generated imprints (digital) i.e., thermal transfer, laser or ink jet, etc. The inks used to print postal indicia 11 by conventional printing methods are current fluorescent inks. The inks that are used to print postal indicia 11 in bit map generated or digital printing would be specific for the selected printing mechanism, and would also be fluorescent. 
     The type link (Dispersion ink) of this invention is made from vehicles such as Diisooctyl Phthalate (DIOP), Shellflex 4131 with additives eugenol, lecithin, dispersing agents, polyvinylchloride (PVC) and stearate gels. There will be colorants, fluorescent pigments, non fluorescent red dyes and phosphorescent compounds. 
     The general formula of type I ink of this invention is as follows: 
     
         ______________________________________Type I ink______________________________________Vehicle A Dioctyl Phthalate, or Diisooctyl Phthalate, or     Dioctyl Adipate, or Butyl Acetal RecinoleateVehicle B Extender and Plasticizer containing severely     hydro-treated light naphthenic distillateantioxidant     substituted diphenylaminewetting agent     A mixture of digylcerides or stearic, palmitic     and/or oleic acids linked to chlorine ester of     Phosphoric acidDispersant     Aluminum stearateStabilizing     Polyvinyl chlorideagentDeodorant Eugenol, or Isoeugenol (also used as a     secondary antioxidant) [2 Methoxy-4(2-     propenyl) phenol]Non       Red lake C, sodium lithol (C.I. #15630Fluorescent     BrilliantToning Red) Permanent Red 2Bcolorants (C.I. #15865)Fluorescent     Flushes are custom made for differentFlushes   applications. They contain the following:     Fluorescent pigments that are solid solutions     of dyes in friable organic resins. A typical     example is a powder containing melamine -     sulfonamide and/or melamine - formaldehyde     resin that contains various dissolved fluores-     cent dyes such as Rhodamine B (C.I. #45175).     This will produce a blue shade that can be     blended with another Rhodamine B dye pigment     to produce a yellow shade. A proper mixture     of the above is dispersed in a linseed oil     based alkyd vehicle to produce the     required color.Phosphorescent     Rare earth metal sulfides Yttrium oxysulfide,material  Europium doped (y.sub.2 O.sub.2 S:Eu)     [id #-YSA or YSB].     Yttrium Phosphovanadate, Europium doped     [Y(P,V)O.sub.4 :Eu][id #YPV-A]______________________________________ 
    
     The procedure for preparing type links is as follows, along with physical properties and print performance. 
     
         ______________________________________INK PREPARATION: Type I Example 1Red Phosphorescent Red Fluorescent Dispersion Ink                      Weight                      % (incl. WeightIngredient    Manufacturer Vehicle) % (solid)______________________________________Strong Red Orange         Lawter       38.8     19.4D-516Aluminum Stearate         Witco Chem.  4.5      0.45(Gel in PRV*)Sodium Lithol Red         Sherwin Williams                      7.0      2.43Diisoctyl Phthalate         Exxon        34.7     67.25DIOPYttrium       United Mineral                      10.0     10.Phosphovanadate         Chemical Corp.(Europium Doped)The other additivies **    5.0      5.0______________________________________ *PRV is a porous roller vehicle custom blended. ** antioxidant, dedorant, PVC gel 
    
     EQUIPMENT 
     1--Model L Kady Mill Equipped with two speed drive (12,000 and 16,000RPM) Manufactured by Kinetic Dispersion Corp. 
     1--Quart Stainless Mixing Vessel with Cover 
     1--Thermometer 
     1--Balance 
     1--Electric Mixer (low shear &lt;1500RPM) and Blade 
     1--Disposable Weighing Beaker 
     Safety equipment, i.e., goggles, gloves &amp; protective wear. 
     PROCEDURE 
     Weigh out into mixing vessel vehicles A and B liquids then stir with low shear mixer blade at &lt;100 rpm for 5 minutes. 
     Weigh into mixing vessel the wetting agent, antioxidant, deodorants and non fluorescent colorants. Turn on cooling water at 4 liter/minute, lower Kady Mill mixing head into the vessel and close cover. Start mill at low speed and run for 5 minutes. (Be sure to use necessary safety equipment). 
     Weigh into disposable beaker the approximate stabilizing agents dispersing gels then Phosphorescent compound and fluorescent flush. Leave cooling water on. Add one third of this material to mixing vessel, close cover and stir at high speed for 1 minute. Repeat this step until all ingredients are in the container. Stir every 2 minutes until ink reaches 70° C. 
     Allow the ink to cool to ambient conditions and determine the following properties at 25 degrees Celsius. 
     
         ______________________________________Viscosity             300+ or -50 cpsSpecific Gravity      1.1+ or -0.1Fineness of Grind (Gardner - Hegmen)                 &lt;1.5 milsPeak red fluorescence emission                 620 nmPeak ref phosphoescence emission                 620 nmGlass Slide Red Fluor Intensity.                 26 unitsGlass Slide Red Phosphor Intensity                 36 units______________________________________ 
    
     Last two measured with United States Postal Service Luminescence Detecting Equipment. 
     
         ______________________________________Indicia Print Resistance to Mechanical                50 cycle Tabor Test.AbrasionImprint Stability to common materials                Legible after exposure.Stability, shelf life and storage life/per                United States Postal______________________________________ 
    
     Materials compatibility--compatible for porous foam roller applications, all metal and rubber meter print drum, other print elements and all materials in contact. The ink of this invention passes all occupational and user safety regulations of the United States Government. 
     The ink of this invention applied to paper with the results discussed below: meets UPS Advanced Facer Canceller luminescent recognition requirements. The prints are also stable to water and light. 
     
         ______________________________________Type I Example 2 Red Phosphorescent Red FluorescentDispersion Ink                       Wt %                       (Incl.   Wt %Ingredient     Manufacturer Vehicle) Solid______________________________________Srong Red Orange (D516)          Lawter       27.0     13.5Permanent Red 2B          Sterling Drug                       5.5      1.4Sodium Lithol  Sherwin      7.8      2.7          WilliamsDiisooctyl Phthalate          Exxon        33.0     33.0Shellflex 4131 Hexagon      7.2      7.2          ProductsAluminum Stearate gel          Witco Chemical                       5.0      0.5PVC gel                     7.0      0.2Eugenol        Fisher       0.5      0.5          ScientificWingStay 29    R. T.        1.0      1.0          VanderbiltLecithin (Sta-Sol)          Staley       1.0      1.0YPV-A          United Mineral                       5.0      5.0          and Chemical          Corp.______________________________________ 
    
     The properties of this ink are consistent for the intended application. 
     For certain printing applications currently in use, the type I link is not applicable. In those instances a solution ink of this invention referred to herein as a type II ink is used. The solution ink contains the following: solvents such as tetraethylene glycol, tripropylene glycol, triethylene glycol, diethylene glycol Polyoxyethylene fatty ester (G2109), oleyl alcohol ethoxylate (Ameroxol OE-5). Non ionic surfactants with a HLB between 4 and 10 like: Pluracol or Igepal, [alkyl phenoxy poly (ethylenoxy) ethanol]. The fluorescent toners or pigments are various Rhodamine dyes dissolved in melamine polymer of benzene sulfonamide, aromatic methyl formaldehyde and tetrahydro imidazo [4,5-d]imidazole-2,5 (1H,3H) dione with a molecular weight average of 1000 to 15,000. Certain non fluorescent dyes to adjust color without destroying the luminescence. The rare earth metal sulfide and vanadium phosphorescent compound, Europium doped. Special additives to keep the ink stable. 
     The general formula for the type II ink of this invention is as follows: 
     
         ______________________________________Solvent A tripropylene glycol (TPG) and/or tetraethylene     glycol (TEEG) or triethylene glycol (TEG)     and/or diethylene glycol, (DEG)Solvent B Polyoxyethlene fatty ester (G-2109) or Poly-     hydroxy esters, e.g. dodecyl alcohol ethoxylate     (TDA - 3) or oleyl alcohol ethoxylate     (Ameroxol)Thinning Agent     Propylene carbonate (PC)Surfactant     Igepal CO 530 and/or Igepal CO610 or PluracolFluorescent     Day Glo HMS seriesToner     The toners are fluorescent dyes dissolved in     Amino or Amide-aldehyde resins i.e, for example     Tri-azine modified ortho and paratoluene     sulfonamide resin, with Basic Red 1(CI 45160),     and/or Basonyl Red 482(CI 45160), C.I. Basic     Violet #11 and/or, C.I. Solvent 135, Alberta     Yellow C.I. Solvent Yellow 44, Yukon     Yellow, Elbason Fluorescent Yellow PGPC.I     and or C.I. Solvent Yellow 60:1, , etc.Coloring Dyes     Neptune Red 543 and or Orasol Violet RNPhosphorescent     YSA or YSBMaterials YPV-A     [Zn.sub.2 SiO.sub.4 :Mn]Zinc orthosilicate doped with     Manganese [id # Sylvania 2284C or 2283C]______________________________________ 
    
     PREPARATION OF TYPE II INK 
     
         ______________________________________Type II Example 1 - Red Fluorescent PhosphorescentSolution InkIngredient        Manufacturer                        Weight %______________________________________Fluroescent Toners             Radiant    31.8GF Series #0010 and #0028Neptune Red 543 and or             BASF       0.2Orasolviolet - RN Ciba GeigyPC                Aldrich    4.0G2109             ICI        26.0Igepal CO530      GAF        5.0TEEG              DOW        16.0TPG               DOW        16.0Phosphorescent               1.0material YPV-A or United Minerals &amp; ChemicalSylvania 2284C    Corporation or Sylvania______________________________________ 
    
     EQUIPMENT 
     Model L Kady Mill equipped with high shear mixer and temperature control. 
     Top loading balance 
     Thermometer to 100 C 
     Weighing dishes 
     Polyethylene storage bottles and jars 
     Safety equipment (goggles, gloves, apron, etc.) 
     INK PREPARATION: 
     Weigh and record weight of empty container. 
     In the above container weigh in the calculated amount solvent B. 
     Re-zero the balance with solvent B and weigh correct amount of second solvent B. 
     Repeat the above steps until all of solvents A have been added. 
     Weigh out the coloring dyes in a separate container. 
     Weigh out all the fluorescent toners in a separate container. 
     Weigh out the phosphorescent material in a separate container. 
     Transfer the solvents A and B to mixing vessel. Turn on and mix for 1 minute. 
     With mixer still running, add the non fluorescent dyes and mix until temperature reaches 51° C. 
     Add the fluorescent toners slowly. 
     Add the phosphorescent material. 
     Mix all ingredients until temperature of contents reaches 78° C. 
     Stop mixing and wait 10 minutes before filtering through 150 micron nylon bag. 
     
         ______________________________________Properties at 25 degrees Celsius.______________________________________Viscosity           750+ or -75 cpsSurface tension     37+ or -3 dynes/cmFluorescent peak 620 nmPhosphorescent peak 620 nmGlass Slide Red Fluor. Intensity               26 unitsGlass Slide Red Phosphor Intensity               36 units______________________________________ 
    
     Last two measured with United States Postal Service Luminescence Detecting Equipment. 
     Indicia Print Resistance to Mechanical Abrasion 50 cycle Tabor Test. 
     Imprint Stability to common materials Legible after exposure. 
     Materials compatibility--compatible for porous foam pad applications, rubber print plate: Stability, shelf life and storage life per United States Postal Service requirements. The ink passes all safety tests for consumer use. 
     The ink of this invention applied to paper meets USPS Advance Facer Canceller luminescent recognition requirements. The prints are also stable to water and light. 
     
         ______________________________________Type II Example 2 Red Fluorescent PhosphorescentSolution InkIngredient      Manufacturer Weight %______________________________________Fluorescent toners           Day Glo      30.8HMS 30, HMS 34Neptune Red 543 BASF         0.2P.C.            Aldrich      3.0Ameroxol OE5    Americhem    17.5TDA-3           BASF         25.0TPG             Aldrich      15.0Pluracol P 425  BASF         3.5Phosphorescent  United Minerals                        5.0Materials YSA or YSB           &amp; Chemical Corp.______________________________________ 
    
     The above properties of this ink are consistent for the intended application. 
     FIG. 4 is a drawing of the detector portion of a facer canceller (not shown) that is used to detect the markings on the postal indicia shown in FIG. 3. 
     Light source 27 emits light having a wavelength of 254 nm which illuminates indicia 11. Those portions of indicia 11 that will emit red fluorescence, phosphorescence when radiated with light from source 27 will be detected by detector 29 and 30. Similarly detectors 29 and 30 will detect the light emitted by the portions of bars 17, 18 and 19 that exhibited red fluorescence and red phosphorescence i.e. light having wavelengths centered around 620 nm. 
     Those portions of indicia II and bars 17, 18 and 19 that will exhibit green phosphorescence when radiated with light from source 27 will also be detected by detector 30. Detector 30 detects the light emitted by the portions of indicia 11 of bars 17, 18 and 19 that exhibited green phosphorescence i.e. light having wavelengths centered around 540 nm. Both green and red phosphorescence are detected with the UV light source 29 and 30, momentarily turned off. 
     The above embodiments have been given by way of illustration only, and other embodiments of the instant invention will be apparent to those skilled in the art from consideration of the detailed description. Accordingly, limitations on the instant invention are to be found only in the claims.