Method for applying chemical watermarks on substrate

• US 6,334,678 B1
• Filed: 09/01/1999
• Issued: 01/01/2002
• Est. Priority Date: 09/01/1999
• Status: Expired due to Term

• Current Assignee: International Paper Company
• Original Assignee: International Paper Company
• Inventors: Koenig, Michael F., Yang, Jiyue, Ondruska, Otto, Daigneault, Robert L., Rogers, Daniel R.
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): Shah, Manish S.
• Application Number:
  US09/388,206
• Time in Patent Office: 853 Days
• Field of Search: 347/107, 347/100, 347/103
• US Class Current: 347/107
• CPC Class Codes: B41J 2/01 Ink jet

Abstract

A method and an apparatus for applying chemical watermarks to a substrate, e.g., paper, using a digital printer which prints ink in a dot matrix pattern. The ink may contain either a translucentizing agent or an opacifying agent. The printer is digitally controlled to print ink in accordance with a computer program corresponding to a desired pattern or image.

Claims

1. A method for applying a chemical watermark on a substrate, comprising the steps of:

supplying a digital printer with an ink comprising a translucentizing agent;

inserting a substrate in the digital printer; and

operating the digital printer to apply said ink to said substrate.

2. The method as recited in claim 1, wherein the digital printer is an ink jet printer.

3. The method as recited in claim 1, wherein the digital printer has a stationary printhead.

4. The method as recited in claim 1, wherein the digital printer has a scanning printhead.

5. The method as recited in claim 2, wherein the ink jet printer is of the thermal variety.

6. The method as recited in claim 2, wherein the ink jet printer is of the piezoelectric variety.

7. The method as recited in claim 2, wherein the ink jet printer is of the continuous variety.

8. The method as recited in claim 1, wherein said translucentizing agent has an index of refraction in the range from 1.0 to 1.6.

9. The method as recited in claim 1, wherein said translucentizing agent is a carbohydrate.

10. The method as recited in claim 1, wherein said translucentizing agent is a sizing agent.

11. The method as recited in claim 1, wherein said translucentizing agent is taken from the group consisting of natural oils and organic oils.

12. The method as recited in claim 1, wherein said translucentizing agent is a radiation-curable polymer.

13. The method as recited in claim 1, wherein said translucentizing agent is an alcohol.

14. The method as recited in claim 1, wherein said translucentizing agent is an alkyd.

15. The method as recited in claim 1, wherein said translucentizing agent is a cross-linkable polymer.

16. The method as recited in claim 1, wherein said ink further comprises a fluorescent agent.

17. The method as recited in claim 1, wherein said ink further comprises an organic solvent.

18. The method as recited in claim 1, wherein said ink is a phase change ink in a molten state.

19. The method as recited in claim 1, wherein said substrate comprises cellulose fibers.

20. The method as recited in claim 1, wherein said substrate comprises synthetic fibers.

21. The method as recited in claim 1, wherein said substrate comprises natural fibers.

22. A method for applying a chemical watermark on a substrate, comprising the steps of:

supplying a digital printer with an ink comprising an opacifying agent;

inserting a substrate in the digital printer; and

operating the digital printer to apply said ink to said substrate.

23. The method as recited in claim 22, wherein the digital printer is an ink jet printer.

24. The method as recited in claim 22, wherein said opacifying agent is titanium oxide.

25. A method for applying a chemical watermark on a substrate, comprising the step of digitally applying an ink comprising a chemical agent on a substrate at locations corresponding to a desired watermark, said chemical agent having the property of changing the translucence of said substrate at said locations.

26. The method as recited in claim 25, wherein said step of digitally applying an ink is carried out using an ink jet printer.

27. The method as recited in claim 25, wherein said chemical agent is a translucentizing agent.

28. The method as recited in claim 27, wherein said translucentizing agent has an index of refraction in the range from 1.0 to 1.6.

29. The method as recited in claim 25, wherein said chemical agent is an opacifying agent.

30. A method for applying a chemical watermark on a substrate, comprising the steps of:

supplying a digital printer with an ink comprising a translucentizing or opacifying agent;

operating the digital printer to apply said ink to a transfer surface; and

bringing a substrate into contact with said transfer surface.