Process for generation of squaric acid and for imaging, and imaging medium for use therein
AssigneePolaroid Corporation
InventorsJurgen M. Grasshoff, Mark R. Mischke, Stephen J. Telfer
Life of this patent
Estimating the term…
Abstract
Acid can be generated by exposing a superacid precursor to actinic radiation effective to generate superacid from the superacid precursor and heating the superacid in admixture with a squaric acid derivative in which there is bonded to the squaric acid ring, via an oxygen atom, an alkyl or alkylene group, a partially hydrogenated aryl or arylene group, or an aralkyl group. The superacid catalyzes decomposition of the squaric acid derivative, thus increasing the quantity of strong acid present in the medium. The resultant acid can be used to effect a color change in an acid-sensitive material, so providing an imaging process.
Claims16
A process for generation of squaric acid or an acidic derivative thereof, which process comprises:
- exposing a superacid precursor to actinic radiation effective to generate superacid from the superacid precursor;
- and
- heating the superacid while the superacid is admixed with a 3,4-disubstituted-cyclobut-3-ene-1,2-dione in which at least one of the 3- and 4-substituents consists of an oxygen atom bonded to the squaric acid ring, and an alkyl or alkylene group, a partially hydrogenated aryl or arylene group, or an aralkyl group, bonded to said oxygen atom, said 3,4-disubstituted cyclobut-3-ene-1,2-dione being capable of decomposing so as to cause replacement of the or each original alkoxy, alkyleneoxy, aryloxy, aryleneoxy, or aralkyloxy group of the derivative with a hydroxyl group, thereby producing squaric acid or an acidic squaric acid derivative having one hydroxyl group, the heating being continued for a temperature and time sufficient to cause the superacid to produce, from the 3,4-disubstituted-cyclobut-3-ene-1,2-dione, squaric acid or said acidic derivative thereof.
Dependencies are inferred from the claim text.