System for inkless fingerprinting

• US 5,462,597 A
• Filed: 06/30/1994
• Issued: 10/31/1995
• Est. Priority Date: 06/30/1994
• Status: Expired due to Fees

• Current Assignee: Minnesota Mining and Manufacturing Co (3M Company)
• Original Assignee: 3M Company
• Inventors: Jubran, Nusrallah
• Primary Examiner(s): McMahon, Timothy M.
• Application Number:
  US08/268,625
• Time in Patent Office: 488 Days
• Field of Search: 118/31.5, 427/1, 427/150, 428/914, 503/213, 503/221, 503/225
• US Class Current: 118/31.5
• CPC Class Codes: B41M 5/124 using pressure to make a masked colour visible, e.g. to make a coloured support visible, to create an opaque or transparent pattern, or to form colour by uniting colour-forming components

Abstract

A fingerprinting system comprising means capable of releasably retaining a liquid and a liquid composition releasably retained in said means, said liquid composition comprising a leuco color-former coupound, a dialkyl phthalate wherein the alkyl group contains 1-3 carbon atoms, a substrate for receiving fingerprints associated therewith, said substrate being coated on at least a portion of one surface thereof with a color developing substance comprising a phenol/aldehyde condensation product produced by the reaction together of an alkyl-substituted salicylic acid, an alkyl-substituted phenol, and an aldehyde, said condensation product having been reacted with a metal source.

Claims

1. A fingerprinting system comprising means capable of releasably retaining a liquid and a liquid composition releasably retained in said means, said liquid composition consisting essentially of:

(i) a leuco color-former compound and a solvent selected from the group consisting of;

a dialkyl phthalate wherein the alkyl group contains 1-3 carbon atoms;

said dialkyl phthalate and an alkyl benzoate wherein the alkyl group of said alkyl benzoate contains 10 to 18 carbon atoms; and

said dialkyl phthalate and an alkyl ester of a fatty acid wherein the fatty acid group contains 10 to 18 carbon atoms; and

(ii) a substrate for receiving fingerprints associated therewith, said substrate being coated on at least a portion of one surface thereof with a color developing substance consisting essentially of;

a phenol/aldehyde condensation product produced by the reaction of an alkyl-substituted salicylic acid, an alkyl-substituted phenol, and an aldehyde, said condensation product having been reacted with a metal source.

2. The fingerprinting system according to claim 1 wherein the weight ratio of said dialkyl phthalate/alkyl benzoate is in the range of from 3:

1 to 1;

3.

3. The fingerprinting system according to claim 1 wherein said dialkyl phthalate is diethyl phthalate.

4. The fingerprinting system according to claim 1 wherein the alkyl group of said alkyl benzoate has from 12 to 15 carbon atoms.

5. The fingerprinting system according to claim 1 wherein the weight ratio of said dialkyl phthalate/alkyl ester is in the range of from 3:

1 to 1;

3.

6. The fingerprinting system according to claim 1 wherein said leuco color-former compound is present in said fingerprinting system in an amount of from 8-14 weight percent, based upon the total weight of said fingerprinting system.

7. The fingerprinting system according to claim 1 wherein said leuco color-former compound is a fluoran leuco dye substituted in the 2-position with anilino groups.

8. The fingerprinting system according to claim 1 wherein said alkyl-substituted salicylic acid is substituted with at least one alkyl group containing at least three carbon atoms.

9. The fingerprinting system according to claim 8 wherein said alkyl-substituted salicylic acid is of the formula:

##STR3## wherein R is an alkyl group containing from 4 to 12 carbon atoms.

10. The fingerprinting system of claim 9 wherein R is an alkyl group.

11. The fingerprinting system of claim 10 wherein R is a tertiary alkyl group.

12. The fingerprinting system of claim 10 wherein R is a nonyl group.

13. The fingerprinting system of claim 10 wherein R is a dodecyl group.

14. The fingerprinting system of claim 1 wherein said alkyl-substituted phenol is substituted with at least one alkyl group containing at least three carbon atoms.

15. The fingerprinting system of claim 14 wherein said alkyl-substituted phenol is substituted in the para-position with an alkyl group containing from 4 to 12 carbon atoms.

16. The fingerprinting system of claim 1 wherein said metal source is zinc oxide.