Bleaching and dyeing; fluid treatment and chemical modification – Nontextile – dyeing process or product – including inorganic... – Oil – fat – wax – or gasoline dyeing
Reexamination Certificate
2002-12-03
2004-11-02
Einsmann, Margaret (Department: 1751)
Bleaching and dyeing; fluid treatment and chemical modification
Nontextile, dyeing process or product, including inorganic...
Oil, fat, wax, or gasoline dyeing
C436S056000, C436S169000, C252S408100, C044S312000
Reexamination Certificate
active
06811575
ABSTRACT:
BACKGROUND
This invention relates generally to a method for marking petroleum hydrocarbons with anthraquinone compounds for subsequent identification.
U.S. Pat. No. 4,755,012 discloses a ray absorption filter comprising a 1,4,5,8-tetra(arylamino)anthraquinone. This reference, however, does not suggest a method for marking petroleum hydrocarbons.
Phthalocyanine dyes having absorption maxima above 700 nm are known as petroleum markers, but these materials suffer from disadvantages, including difficulty of preparation and high cost. The problem addressed by this invention is to find an improved method for marking petroleum hydrocarbons with compounds having an absorption maximum above 700 nm.
STATEMENT OF INVENTION
The present invention is directed to a method for invisibly marking a liquid petroleum hydrocarbon. The method comprises adding to the liquid petroleum hydrocarbon at least one dye selected from the group consisting of 1,4,5,8-tetrasubstituted anthraquinones and anthraquinone dimers. The absorption maximum of the dye(s) is in the range from 710 nm to 850 nm.
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Jurgen Fabian, Hiroyuki Nakazumi and Masaru Matsuoka: Near-Infrared Absorbing Dyes: Chem. Rev. 1992: vol. 92, No. 6; p. 1197-1226; 1992.
Chen Yu-Min
Ho Kim Sang
Crimaldi Kenneth
Einsmann Margaret
Rohm and Haas Company
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