Erasable inks

• US 5,919,858 A
• Filed: 03/21/1997
• Issued: 07/06/1999
• Est. Priority Date: 12/18/1991
• Status: Expired due to Term

• Current Assignee: Berol Corp (Newell Brands Inc.)
• Original Assignee: Gillette Company (The Procter & Gamble Company)
• Inventors: Loftin, Rachel M.
• Primary Examiner(s): Seidleck, James J.
• Assistant Examiner(s): Asinovsky, Olga
• Application Number:
  US08/821,168
• Time in Patent Office: 837 Days
• Field of Search: 524/575, 523/160, 523/161, 523/164, 106/21 A, 106/20 A, 428/321.1, 428/321.3
• US Class Current: 524/575
• CPC Class Codes: C09D 109/08 Latex
• CPC Class Codes: C09D 11/16 Writing inks
• CPC Class Codes: Y10T 428/249995 Constituent is in liquid form
• CPC Class Codes: Y10T 428/249996 Ink in pores

Abstract

An aqueous-based erasable ink composition suitable for use in highlighters and other writing instruments includes a styrene-butadiene copolymer and a water-insoluble pigment. It preferably also includes a release agent and an anti-oxidant, and has a viscosity of between 10 cps and 30 cps.

Claims

1. An aqueous-based marking ink, comprising water, a colorant, and a latex emulsion comprising a styrene-butadiene copolymer having a styrene content of less than about 35%, said ink being non-shear thinning and erasable from 60 lb. offset printing paper.

2. An aqueous-based marking ink of claim 1, wherein said colorant is a fluorescent colorant.

3. An aqueous-based marking ink of claim 1 wherein said latex emulsion has a viscosity of less than about 50 cps.

4. An aqueous-based marking ink of claim 1 wherein said ink has a viscosity of from about 10 to 30 cps.

5. An aqueous-based marking ink of claim 1 wherein said ink further comprises a release agent.

6. An aqueous-based marking ink of claim 1 wherein said ink further comprises an antioxidant.

7. An aqueous-based marking ink of claim 1, wherein said ink is capable of forming a read-through tracing on 60 lb. offset printing paper.

8. The aqueous-based marking ink of claim 1 wherein said copolymer has a styrene:

butadiene ratio of between 10;

90 and 35;

65.

9. The aqueous-based marking ink of claim 1 wherein said ink has a styrene-butadiene copolymer solids content less than 50% by weight.

10. The aqueous-based marking ink of claim 1 wherein said ink has a styrene-butadiene copolymer solids content between 10% and 40% by weight.

11. The aqueous-based marking ink of claim 1 wherein said styrene-butadiene copolymer has a Mooney value of at least 90.

12. The composition of claim 8 wherein said release agent is a silicone.

13. The composition of claim 1 further comprising an antioxidant.

14. The composition of claim 1 wherein said colorant is a fluorescent pigment.

15. The composition of claim 13 wherein said antioxidant is a cresol.

16. The composition of claim 13 wherein the composition contains a sufficient quantity of water that the viscosity of the composition is between 10 cps and 30 cps.