Fluorescent additives for ink

1. A fluorescent inkjet composition, comprising:

a visible ink composition including a visible colorant, wherein said visible colorant is detectable in a visible spectrum, and present at about 0.5% to about 10% by weight of the fluorescent inkjet composition; and

a fluorescent dispersion including an invisible fluorescent colorant;

wherein said invisible fluorescent colorant absorbs light having a wavelength of 250 to 400 nm, emits light in the range of 450 to 700 nm, and is invisible to incident light in the visible spectrum of 380 to 750 nm,

wherein said invisible fluorescent colorant is present between 0.01% to 1.5% by weight of the fluorescent inkjet composition, and

wherein said fluorescent inkjet composition emits light at a first intensity I 1 in the range of 450 nm to 700 nm upon excitation by incident light having a wavelength in the range of 250 to 400 nm and said fluorescent inkjet composition is capable of emitting light at a second intensity I 2 upon exposure to a temperature of 60° C. for 8 weeks, wherein

I 2 =(0.50 to 1.0)* I 1 .

2. The fluorescent inkjet composition of claim 1 , wherein said invisible fluorescent colorant is a pigment.

3. The fluorescent inkjet composition of claim 1 , wherein said invisible fluorescent colorant is a UV fluorescent pigment.

4. The fluorescent inkjet composition of claim 1 , wherein said invisible fluorescent colorant exhibits a particle size in the range of 25 to 200nm.

5. The fluorescent inkjet composition of claim 1 , wherein said fluorescent dispersion includes a dispersant selected from the group consisting of a polymeric dispersant, alkali salts, lignin, lignin derivatives, and combinations thereof.

6. The fluorescent inkjet composition of claim 1 , wherein said invisible fluorescent colorant comprises an organic pigment containing exclusively aromatic groups.

7. The fluorescent inkjet composition of claim 6 , wherein said organic pigment comprises xanthene.

8. The fluorescent inkjet composition of claim 6 , wherein said organic pigment comprises thio-xanthene.

9. The fluorescent inkjet composition of claim 6 , wherein said invisible fluorescent colorant is in particle form and said particles are encapsulated in a polysiloxane polymer.

10. A fluorescent inkjet composition, comprising:

a visible ink composition including a visible colorant, wherein said visible colorant is detectable in a visible spectrum, and present at about 0.5% to about 10% by weight of the fluorescent inkjet composition; and

an aqueous dispersion including an invisible fluorescent colorant;

wherein said invisible fluorescent colorant absorbs light having a wavelength of 250 to 400 nm, emits light in the range of 450 to 700 nm, and is invisible to incident light in the visible spectrum of 380 to 750 nm,

wherein said invisible fluorescent colorant is present between 0.01% to 1.5% by weight of the fluorescent inkjet composition, and

wherein said fluorescent inkjet composition emits light at a first intensity I 1 in the range of 450 nm to 700 nm upon excitation by incident light having a wavelength in the range of 250 to 400 nm and said fluorescent inkjet composition is capable of emitting light at a second intensity I 2 upon exposure to a temperature of 60° C. for 8weeks, wherein

I 2 =(0.50 to 1.0)* I 1 .

11. The fluorescent inkjet composition of claim 10 , wherein said invisible fluorescent colorant comprises a metal complex organic pigment.

12. The fluorescent inkjet composition of claim 10 , wherein said invisible fluorescent colorant comprises an aromatic organic pigment.

13. The fluorescent inkjet composition of claim 12 , wherein said invisible fluorescent colorant is in particle form and said particles are encapsulated in a polysiloxane polymer.

14. A method of providing a fluorescent inkjet composition, comprising:

combining a fluorescent dispersion including an invisible fluorescent colorant with a visible ink composition including a visible colorant;

wherein said visible colorant is detectable in a visible spectrum, and present at about 0.5% to about 10% by weight of the fluorescent inkjet composition,

wherein said invisible fluorescent colorant absorbs light having a wavelength of 250 to 400 nm, emits light in the range of 450 to 700 nm, and is invisible to incident light in the visible spectrum of 380 to 750 nm,

wherein said invisible fluorescent colorant is present between 0.01% to 1.5% by weight of the fluorescent inkjet composition, and

wherein said fluorescent inkjet composition emits light at a first intensity I 1 in the range of 450 nm to 700 nm upon excitation by incident light having a wavelength in the range of 250 to 400 nm and said fluorescent inkjet composition is capable of emitting light at a second intensity I 2 upon exposure to a temperature of 60° C. for 8weeks, wherein

I 2 =(0.50 to 1.0)* I 1 .

15. The method of claim 14 , wherein said invisible fluorescent colorant is a pigment.

16. The method of claim 14 , wherein said invisible fluorescent colorant is a UV fluorescent pigment.

17. The method of claim 14 , wherein said invisible fluorescent colorant exhibits a particle size in the range of 25 to 200 nm.

18. The method of claim 14 , wherein said fluorescent dispersion includes a dispersant selected from the group consisting of a polymeric dispersant, alkali salts, lignin, lignin derivatives, and combinations thereof.

19. The fluorescent inkjet composition of claim 1 , wherein said visible colorant exhibits a color including black, cyan, magenta or yellow, and combinations thereof.

20. The fluorescent inkjet composition of claim 10 , wherein said visible colorant exhibits a color including black, cyan, magenta or yellow, and combinations thereof.

21. The method of claim 14 , wherein said visible colorant exhibits a color including black, cyan, magenta or yellow, and combinations thereof.