Light sensitive invisible ink compositions and methods for using the same

• US 6,513,921 B1
• Filed: 05/12/2000
• Issued: 02/04/2003
• Est. Priority Date: 10/28/1998
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Houle, William A.
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): Shah, Manish S
• Application Number:
  US09/569,517
• Time in Patent Office: 998 Days
• Field of Search: 347/100, 347/96, 347/101, 106/31.14, 106/31.15, 106/31.58
• US Class Current: 347/96
• CPC Class Codes: B41M 3/144 using fluorescent, luminescent or iridescent effects
• CPC Class Codes: C09D 11/328 characterised by dyes
• CPC Class Codes: C09D 11/50 Sympathetic, colour changing or similar inks

Abstract

A high-reliability invisible ink printing system is provided which generates high-definition, lightfast images that are easily read or otherwise detected using far red, infrared, and/or ultraviolet light. The inks contain an uncomplexed invisible metal phthalocyanine far red/infrared fluorophore (optimally chloroaluminum [III] phthalocyanine tetrasulfonic acid or salts thereof). An ultraviolet fluorophore can also be included. The inks are invisible to the unaided eye. However, when exposed to far red or infrared light (wavelength=about 650-715 nm) they will fluoresce at a wavelength of about 670-720 nm. If an ultraviolet fluorophore is employed, the inks can also be detected by applying ultraviolet light (wavelength=about 250-380 nm) which results in fluorescent emission at a wavelength of about 400-650 nm. The inks are well suited for delivery using inkjet technology to efficiently form invisible images.

Claims

1. A method for producing an invisible printed image on a substrate and thereafter causing said printed image to fluoresce comprising:

providing an ink delivery system comprising;

a housing comprising at least one ink retaining chamber therein, said ink retaining chamber comprising a supply of an invisible ink composition therein, said ink composition comprising an invisible dye comprised of at least one uncompleted invisible metal phthalocyanine fluorophore which absorbs light within a wavelength range of about 650-715 nm and emits light within a wavelength range of about 670-720 nm, said ink composition further comprising an ink vehicle comprised of water and at least one organic solvent; and

a printhead operatively connected to said ink retaining chamber in said housing, said printhead comprising at least one ink ejector for expelling said invisible ink composition on-demand from said ink retaining chamber;

providing a substrate;

activating said printhead of said ink delivery system in order to deliver said invisible ink composition from said ink retaining chamber onto said substrate; and

applying light having a wavelength of about 650-715 nm to said invisible ink composition on said substrate, said applying of said light causing said ink composition to emit fluorescent light having a wavelength of about 670-720 nm.

12. The method of claim 1 wherein said ink composition in said ink delivery system comprises about 0.0001-0.02% by weight said phthalocyanine fluorophore.

2. A method for producing an invisible printed image on a substrate and thereafter causing said printed image to fluoresce comprising:

providing an ink delivery system comprising;

a housing comprising at least one ink retaining chamber therein, said ink retaining chamber comprising a supply of an invisible ink composition therein, said ink composition comprising an invisible dye comprised of a phthalocyanine fluorophore selected from the group consisting of chloroaluminum (III) phthalocyanine tetrasulfonic acid and salts thereof, said ink composition further comprising an ink vehicle comprised of water and at least one organic solvent; and

a printhead operatively connected to said ink retaining chamber in said housing, said printhead comprising at least one ink ejector for expelling said invisible ink composition on-demand from said ink retaining chamber;

providing a substrate;

activating said printhead of said ink delivery system in order to deliver said invisible ink composition from said ink retaining chamber onto said substrate; and

applying light to said invisible ink composition on said substrate having a wavelength sufficient to cause said ink composition to emit fluorescent light therefrom.

3. The method of claim 2 wherein said light applied to said invisible ink composition on said substrate has a wavelength range of about 650-715 nm, with said fluorescent light having a wavelength range of about 670-720 nm.

4. A method for producing an invisible printed image on a substrate and thereafter causing said printed image to fluoresce comprising:

providing an ink delivery system comprising;

a housing comprising at least one ink retaining chamber therein, said ink retaining chamber comprising a supply of an invisible ink composition therein, said ink composition comprising a first invisible dye comprised of at least one uncomplexed invisible metal phthalocyanine fluorophore which absorbs light within a wavelength range of about 650-715 nm and emits light within a wavelength range of about 670-720 nm, and a second invisible dye comprised of at least one invisible ultraviolet fluorophore, said ink composition further comprising an ink vehicle comprised of water and at least one organic solvent; and

a printhead operatively connected to said ink retaining chamber in said housing, said printhead comprising at least one ink ejector for expelling said invisible ink composition on-demand from said ink retaining chamber;

providing a substrate;

activating said printhead of said ink delivery system in order to deliver said invisible ink composition from said ink retaining chamber onto said substrate; and

applying light to said invisible ink composition on said substrate having a wavelength sufficient to cause said ink composition to emit fluorescent light therefrom.

5. The method of claim 4 wherein said light applied to said invisible ink composition on said substrate has a wavelength range of about 650-715 nm, with said fluorescent light having a wavelength range of about 670-720 nm.

6. The method of claim 4 wherein said light applied to said invisible ink composition on said substrate has a wavelength range of about 250-380 nm, with said fluorescent light having a wavelength range of about 400-650 nm.

7. The method of claim 4 wherein said ultraviolet fluorophore is selected from the group consisting of at least one ultraviolet absorbing stilbene, pyrazoline, coumarin, carbostyril, and pyrene compound.

8. A method for producing an invisible printed image on a substrate and thereafter causing said printed image to fluoresce comprising:

providing an ink delivery system comprising;

a housing comprising at least one ink retaining chamber therein, said ink retaining chamber comprising a supply of an invisible ink composition therein, said ink composition comprising a first invisible dye comprised of a phthalocyanine fluorophore selected from the group consisting of chloroaluminum (III) phthalocyanine tetrasulfonic acid and salts thereof, a second invisible dye comprised of at least one ultraviolet fluorophore, and an ink vehicle comprised of water and at least one organic solvent; and

a printhead operatively connected to said ink retaining chamber in said housing, said printhead comprising at least one ink ejector for expelling said invisible ink composition on-demand from said ink retaining chamber;

providing a substrate;

activating said printhead of said ink delivery system in order to deliver said invisible ink composition from said ink retaining chamber onto said substrate; and

applying light to said invisible ink composition on said substrate having a wavelength sufficient to cause said ink composition to emit fluorescent light therefrom.

9. The method of claim 8 wherein said light applied to said invisible ink composition on said substrate has a wavelength range of about 650-715 nm, with said fluorescent light having a wavelength range of about 670-720 nm.

10. The method of claim 8 wherein said light applied to said invisible ink composition on said substrate has a wavelength range of about 250-380 nm, with said fluorescent light having a wavelength range of about 400-650 nm.

11. The method of claim 8 wherein said ultraviolet fluorophore is selected from the group consisting of at least one ultraviolet absorbing stilbene, pyrazoline, coumarin, carbostyril, and pyrene compound.

13. A method for producing an invisible printed image on a substrate and thereafter causing said printed image to fluoresce comprising:

providing an ink delivery system comprising;

a housing comprising at least one ink retaining chamber therein, said ink retaining chamber comprising a supply of an invisible ink composition therein, said ink composition comprising a phthalocyanine fluorophore selected from the group consisting of chloroaluminum (III) phthalocyanine tetrasulfonic acid and salts thereof, 1,5-pentanediol, 2-ethyl-2-hydroxymethyl-1,3-propanediol, 1,3-propanediol, at least one surfactant, and water; and

a printhead operatively connected to said ink retaining chamber in said housing, said printhead comprising at least one ink ejector for expelling said invisible ink composition on-demand from said ink retaining chamber;

providing a substrate;

activating said printhead of said ink delivery system in order to deliver said invisible ink composition from said ink retaining chamber onto said substrate; and

applying light to said invisible ink composition on said substrate having a wavelength sufficient to cause said ink composition to emit fluorescent light therefrom.

14. A method for producing an invisible printed image on a substrate and thereafter causing said printed image to fluoresce comprising:

providing an ink delivery system comprising;

a housing comprising at least one ink retaining chamber therein, said ink retaining chamber comprising a supply of an invisible ink composition therein, said ink composition comprising a phthalocyanine fluorophore selected from the group consisting of chloroaluminum (III) phthalocyanine tetrasulfonic acid and salts thereof, an ultraviolet fluorophore comprised of benzenesulfonic acid-2,2′

-(1,2-ethenediyl)bis[5-[4-bis(2-hydroxyethyl)amino]-6-[(4-sulfophenyl)amino]-1,3,5-triazin-2yl]amino-tetrasodium salt, 1,5-pentanediol, 2-ethyl-2-hydroxymethyl-1,3-propanediol, 1,3-propanediol, at least one surfactant, and water; and

a printhead operatively connected to said ink retaining chamber in said housing, said printhead comprising at least one ink ejector for expelling said invisible ink composition on-demand from said ink retaining chamber;

providing a substrate;

activating said printhead of said ink delivery system in order to deliver said invisible ink composition from said ink retaining chamber onto said substrate; and

applying light to said invisible ink composition on said substrate having a wavelength sufficient to cause said ink composition to emit fluorescent light therefrom.