Latent image compositions

• US 5,503,665 A
• Filed: 10/04/1994
• Issued: 04/02/1996
• Est. Priority Date: 07/31/1992
• Status: Expired due to Term

• Current Assignee: Binney & Smith Inc.
• Original Assignee: Binney & Smith Inc.
• Inventors: Couch, Charlene, Miller, Richard E.
• Primary Examiner(s): KLEMANSKI, HELENE G
• Application Number:
  US08/317,321
• Time in Patent Office: 546 Days
• Field of Search: 106/21 R, 106/21 A, 106/22 B, 106/20 A
• US Class Current: 106/31.16
• CPC Class Codes: B41J 2/2114 Ejecting transparent or white coloured liquids, e.g. processing liquids B41J2/211 takes precedence
• CPC Class Codes: C09D 11/02 Printing inks C09D11/30 takes precedence
• CPC Class Codes: C09D 11/50 Sympathetic, colour changing or similar inks

Abstract

A coloring system is provided in which an undercolor composition is applied to a substrate to thereby leave a colorless mark. The undercolor composition is then written over with an overcolor composition, thereby causing the undercolor mark to become colored. The overcolor composition may itself contain a colorant. In one embodiment, the color-changing effects are accomplished by employing a dye that is colorless in the presence of high pH and/or a reducing agent, but that becomes colored as the pH is lowered, as the undercolor colorant. In a second embodiment, the color-changing effects are accomplished by employing a dye that is colorless at low pH, but that becomes colored as the pH is raised, as the undercolor colorant.

Claims

1. A coloring system comprising an undercolor aqueous coloring composition and an overcolor aqueous coloring composition,

said undercolor aqueous coloring composition comprising an undercolor colorant which is in its colorless state at a high pH relative to the pH of said overcolor aqueous coloring composition, and an effective amount of a base to yield a pH of the composition sufficiently high to render the undercolor colorant colorless;

said overcolor aqueous coloring composition comprising an effective amount of an acid sufficient to cause a color change of said undercolor aqueous coloring composition from the colorless state to reveal the color of said undercolor colorant upon contact of said overcolor with said undercolor colorant.

2. A coloring system comprising an undercolor aqueous coloring composition and an overcolor aqueous coloring composition;

said undercolor aqueous coloring composition comprising an undercolor colorant which is in its colorless state at a low pH relative to the pH of said overcolor aqueous coloring composition, and an effective amount of an acid to yield a pH of the composition sufficiently low to render the undercolor colorant colorless;

said overcolor aqueous composition comprising an effective amount of a non-volatile base sufficient to cause a color change from the colorless state to reveal the color of the colorant upon contact of said overcolor with said undercolor colorant.

3. A coloring system comprising:

(a) an undercolor aqueous coloring composition comprising an undercolor colorant which is in its colorless state at a pH of about 10.0 or greater; and

an effective amount of a base sufficient to yield a pH of the composition of about 10.0 or greater; and

(b) an overcolor aqueous composition comprising an effective amount of an acid sufficient to cause a color change of said undercolor aqueous coloring composition from the colorless state to reveal the color of said undercolor colorant upon contact of said overcolor with said undercolor colorant.

4. A coloring system according to claim 3, wherein said overcolor coloring composition contains a colorant.

5. An aqueous multiple coloring composition system comprising:

(a) an undercolor aqueous coloring composition comprising an undercolor colorant which is in its colorless state at a pH of about 3.5 or below; and

an effective amount of an acid sufficient to yield a pH of 3.5 or below; and

(b) an overcolor aqueous composition comprising an effective amount of a non-volatile base sufficient to cause a color change from the colorless state to reveal the color of the colorant upon contact of said overcolor with said undercolor colorant.

6. A coloring system according to claim 5, wherein said overcolor coloring composition contains a colorant.

7. An ink composition system comprising:

(a) an undercolor aqueous ink composition comprising an undercolor colorant which is in its colorless state at a high pH in an amount of from about 0.1 to about 15% by weight of said undercolor coloring composition;

a base in an amount of from about 0.1 to about 15% by weight of said undercolor coloring composition to yield a pH greater than 10.0; and

a reducing agent in an amount of from about 1% to about 20% by weight of said first composition; and

(b) a second aqueous ink composition comprising an acid in an amount from about 1% to about 70% by weight of said second composition to change the colorant from its colorless state to reveal the color of the colorant.

8. An ink composition system comprising:

(a) a first aqueous ink composition comprising an undercolor colorant which is in its colorless state at a low pH in an amount of from about 0.1% to about 15% by weight of said first composition; and

an acid in an amount of from about 1% to about 70% by weight of said first composition to yield a pH less than 3.5; and

(b) a second aqueous ink composition comprising a reducing agent in an amount of from about 1% to about 20% by weight of said second composition; and

a non-volatile base in an amount of from about 0.1% to 15% by weight of said second composition to change the colorant from its colorless state to reveal the color of the colorant.

9. A color revealing marking system comprising at least an undercolor marking instrument which dispenses a colorless mark and an overcolor marking instrument which develops said colorless mark, said undercolor marking instrument containing a first ink composition comprising a colorant which is in its colorless state at a high pH, an effective amount of a base sufficient to yield a pH greater than 10.0, and from about 1% to about 20% by weight of a reducing agent;

and said overcolor marking instrument containing a second ink composition comprising an effective amount of an acid to change the colorant in the first ink composition to its colorless state to reveal the color of the colorant.

10. A color revealing marking system comprising at least an undercolor marking instrument which dispenses a colorless mark and an overcolor marking instrument which develops said colorless mark, said undercolor marking instrument containing a first ink composition comprising a colorant which is in its colorless state at a low pH, and an effective amount of an acid sufficient to yield a pH less than 3.5;

and said overcolor marking instrument containing a second ink composition comprising from about 1% to about 20% by weight of a reducing agent, and an effective amount of a base to change the colorant in the first ink composition to its colorless state to reveal the color of the colorant.

11. A paint composition system comprising:

(a) a first aqueous paint comprising an undercolor colorant which is in its colorless state at a high pH in an amount of from about 0.1 to about 15% by weight of said first composition;

a base in an amount of from about 0.1 to about 15% by weight of said first composition to yield a pH greater than 10;

a reducing agent in an amount of from about 1% to about 20% by weight of said first composition, and a thickener in an amount from about 1% to 5% by weight; and

(b) a second aqueous paint comprising an acid in an amount from about 1% to about 70% by weight of said second composition to change the colorant from its colorless state to reveal the color of the colorant, and a thickener in an amount from about 1% to 10% by weight.

12. A paint composition system comprising:

(a) a first aqueous paint comprising an undercolor colorant which is in its colorless state at a low pH in an amount of from about 0.1% to about 15% by weight of said first composition;

an acid in an amount of from about 1% to about 70% by weight of said first composition to yield a pH less than 3.5; and

a thickener in an amount from about 1% to 10% by weight; and

(b) a second aqueous paint comprising a reducing agent in an amount of from about 1% to about 20% by weight of said second composition;

a base in an amount of from about 0.1% to 15% by weight of said second composition to change the colorant from its colorless state to reveal the color of the colorant, and a thickener in an amount from about 1% to 10% by weight.

13. A paint composition system according to claim 12, wherein said overcolor paint composition contains a colorant.

14. A color revealing marking system comprising at least a first undercolor marking instrument which dispenses a colorless mark and at least one overcolor marking instrument develops said colorless mark, said undercolor marking instrument containing a first ink composition comprising a colorant which is in its colorless state at a low pH, and an effective amount of an acid sufficient to yield a pH less than 3.5;

and said overcolor marking instrument containing a second ink composition comprising from about 1% to about 20% by weight of a reducing agent, and an effective amount of a base to change the colorant in the first ink composition to its colorless state to reveal the color of the colorant.

15. A color revealing marking system comprising at least a first undercolor marking instrument which dispenses a colorless mark and at least one overcolor marking instrument develops said colorless mark, said undercolor marking instrument containing a first ink composition comprising a colorant which is in its colorless state at a high pH, an effective amount of a base sufficient to yield a pH greater than 10, and from about 1% to about 20% by weight of a reducing agent;

and said overcolor marking instrument containing a second ink composition comprising an effective amount of an acid to change the colorant in the first ink composition to its colorless state to reveal the color of the colorant.