Roylance, Abrams, Berdo & Kaul
Dilactone chromogenic compounds and preparation thereof
 A substantially colorless dilactone chromogenic material having the structural formula ##SPC1## And ##SPC2## Wherein PA1 R represents an alkyl group, an aryl group, an aralkyl group, an acyl group or an aroyl group; and PA1 X represents a hydrogen atom, a halogen atom, an alkyl group or a nitro group. The dilactone compounds are produced from precursor compounds that are formed by reacting pyromellitic dianhydride with a resorcinol having at least the fourth or the sixth position unsubstituted, in the presence of a dehydrating agent to form xanthyl derivatives of isophthalic and terephthalic acid. These precursors are then further reacted to form the dilactones. The dilactones are used in pressure-sensitive copy systems comprising a support bearing microcapsules containing the dilactones, alone, or in combination with other chromogenic materials. 
Champion International Corporation
B C
B41M C09B
inventional inventional
David N. Cheng Hsiung
Vincent Chang