Fingerprinting compositions, systems and methods

DETAILED DESCRIPTION The essential components of the instant fingerprinting compositions are the chromogenic compounds, color-developing substances, and the liquid vehicle.
The chromogenic compounds are leuco dye intermediates which possess the unique property of being colorless in neutral or alkaline media, but become colored when they react with an acidic or electron accepting substance.
These dyes are, per se, well known and examples thereof which can be used in this invention are crystal violet lactone (CVL), dilactones, benzoyl leuco methylene blue (BLMB), derivatives of bis-(p-di-alkylaminoaryl) methane, xanthenes, indolyls, auramines, fluorans and bisfluorans such as those described in U.
S.
Pat.
Nos.
2,981,733, 2,981,738, 669,711, 3,681,390, 3819,396, 3,821,010 and 4,302,393.
Additionally, non-leuco, oil-soluble dyes such as Keystone Aniline's Keysolv Black RBM, Keysolv Yellow R, DuPont's Oil Orange B Liquid, Oil Blue B Liquid Dye, Oil Red B Liquid, Oil Yellow Liquid, and Oil Green Liquid Dye, may be used in this invention.
The preferred dyes of the present invention, however, are the leuco chromogenic compounds.
There is a multitude of known electron-accepting color-developing substances capable of reacting with the leuco chromogenic compounds, which can be used in the present invention, and which have been described in the prior art.
Among such electron-accepting substances are acidic clays such as montmorillonites, kaolins, bentonites and attapulgites, low molecular weight phenol-aldehyde condensation products (novolaks) and/or their metal salts as disclosed in U.
S.
Pat.
Nos.
3,427,180, 3,672,935, and 3,723,156, and derivatives of aromatic carboxylic acids and/or their metal salts as disclosed in U.
S.
Pat.
Nos.
3,488,207, 3,864,146, 3,871,900, 3,934,070,3,983,292, 4,303,719, and 4,372,583.
Specific examples of such color-developing materials usable in the present invention are: 3-phenyl salicylic acid, 3,5-di-tertiary butyl salicylic acid, octyl salicylic acid, 2-hydroxy-1-benzyl-3-naphthoic acid, 2-hydroxy-4-methyl-5-isobutyl thiobenzoic acid, 3,3'-thiobis (2-hydroxy-5-methyl) benzoic acid, 2-hydroxy-5-butyl sulfonyl benzoic acid, condensation products of salicylic acid and salicylic acid derivatives, United Catalyst's Copisil, a montmorillonite clay, low molecular weight condensation products of p-phenyl phenol with formaldehyde, p-cyclohexyl phenol-formaldehyde condensation product, and p-tertiary-amylphenol-formaldehyde condensation product