Patent ID: 8067483

Claim:
A thermally reactive indicator ink responsive to ambient temperatures providing a visual indication of a cumulative time-temperature exposure, the thermally reactive indicator ink comprising: a) about 40 to about 95 weight percent of a liquid vehicle, based on the weight of the thermally reactive indicator ink; b) about 1 to about 30 weight percent, based on the weight of the thermally reactive indicator ink, of a solid particulate diacetylenic indicator agent; wherein the solid particulate diacetylenic indicator agent is insoluble in the liquid vehicle, is polymerizable upon exposure to heat, and is a 5,7-dodecadiyn-1,12 diol bis(n-octadecyl urethane) or a co-crystallized mixture of two or more 2,4-hexadiyn-1,6-bis(alkylurea) compounds, wherein the alkyl substituents of the 2,4-hexadiyn-1,6-bis(alkylurea) compounds are linear alkyl substituents selected from the group consisting of ethyl, propyl, butyl, octyl, dodecyl, and octyldecyl; and c) a non-gaseous reactivity-enhancing adjuvant being effective to enhance the ambient temperature thermal reactivity of the indicator agent; wherein the non-gaseous reactivity-enhancing adjuvant comprises: i. about 0.2 to about 10 weight percent, based on the weight of the thermally reactive indicator ink, of a polymerization initiator selected from the group consisting of azonitriles, alkyl peroxides, peroxyesters, hydroperoxides, acyl peroxides, ketone peroxides, peroxyketals, peroxydicarbonates, redox initiators, and mixtures thereof; and ii. about 0.01 to about 5 wt percent, based on the weight of the thermally reactive indicator ink, of a polymerization accelerator selected from the group consisting of a cobalt carboxylate, a calcium carboxylate, a manganese carboxylate, a zirconium carboxylate, a zinc carboxylate, cobalt octoate, calcium octoate, potassium octoate, manganese octoate, a rare earth octoate, zinc octoate, zirconium octoate, strontium octoate; cobalt neodecanoate, calcium neodecanoate, manganese neodecanoate, a rare earth neodecanoate, lithium neodecanoate, cobalt versatate, calcium versatate, manganese versatate, a rare earth versatate, lithium versatate, cobalt naphthenate, calcium naphthenate, manganese naphthenate, zinc naphthenate, lead naphthenate, N,N-dimethyl aniline, amines having not more than about twenty carbon atoms, and mixtures thereof.