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Composition for invisible ink responsive to infrared light

  • US 5,684,069 A
  • Filed: 09/22/1994
  • Issued: 11/04/1997
  • Est. Priority Date: 01/12/1994
  • Status: Expired due to Fees
First Claim
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1. A thermal transfer ink composition that is transparent or nearly transparent having more than 60% reflectance or transmission % T in the visible range between 400 and 700 nm comprising:

  • a) 0.5 to 5% of a phthalocyanine dye having OR, SR, OH or NR2 donor groups absorbs light between 700 nm to 1200 nm that is transparent or nearly transparent having more than 60% reflectance in the visible range of the spectrum;

    b) 60 to 80% of a urethane derivative of a modified oxidized synthetic petroleum wax that solubilized the phthalocyanine dye;

    c) 4 to 15% carnauba wax; and

    d) 10 to 20% ethyl vinyl acetate polymer;

    whereby the ink composition may be detected by a IR sensor detecting light in the IR range of 700 to 1200 nm, and able to be printed on non porous surfaces.

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