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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
First Claim
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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.

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