Time-temperature indicators comprising crystallized diacetylenic indicator compounds

摘要

Crystallized diacetylenic compounds having certain crystallographic and other characteristics; diacetylenic compounds and mixtures crystallized from diacetylenic solutions; methods of preparing and identifying solvent systems for dissolving diacetylenic compounds; diacetylenic solutions; methods of recrystallizing diacetylenic compounds; crystals of 2,4-hexadiyn-1,6-bis(alkylurea) compounds; and ambient condition indicators and time-temperature condition indicators comprising crystallized diacetylenic compounds.

主权项

1. A time-temperature indicator comprising:
a crystallized diacetylenic compound capable of polymerizing in the solid state to provide an irreversible appearance change in an environmental condition indicator; and a substrate onto which the crystallized diacetylenic compound is applied; wherein a change in appearance of the crystallized diacetylenic compound is detectable in a manner that is useful to indicate a time-temperature condition; wherein the crystallized diacetylenic compound is symmetrically substituted and having the structural formula:
R3NHCONH—R4—C≡C═C≡C—R4—NHCONHR3 wherein R4 is methylene, ethylene, propylene or butylene, R3 is ethyl or propyl, the crystallized diacetylenic compound having a crystal structure wherein the crystallized diacetylenic compound molecules have a center-to-center separation, referring to the geometric centers of diacetylene units in adjacent molecules, of less than 4.7 Å, the center-to-center separation being in a direction wherein solid-state polymerization can occur.