Abstract: An activatable time-temperature indicator system useful in tracking the thermal exposure history of a temperature-sensitive perishable product and providing a visually-distinct signal, such as a change in color density, at the expiration of a predetermined time-temperature integral comprises a first element, such as a direct thermal printing label (11), comprising a composition (13) having at least a first co-reactant of a color-forming reaction. A second, activator element, such as an adhesive tab (21) capable of being affixed to the label element, comprises an activator component (25), such as a second co-reactant of the color-forming reaction or a solubilizing agent for prompting the interaction of the co-reactants of the label composition. The activator tab element is affixed to the label composition to activate for reaction at ambient conditions the normally high-temperature color-forming composition (13) of the label at about the same time as the label is affixed to the perishable product.

Abstract: A time-temperature indicator label for measuring the length of time to which a product has been exposed to a temperature above a pre-determined temperature is provided. The period of time of exposure is integrated with the temperature to which the indicator is exposed. The label is a composite of a plurality of layers adapted to be adhered at its underside to a product container. The label includes a printable surface layer, a longitudinal wicking strip that is adhered underneath the surface layer substantially at the opposite extremities only of the wicking strip and a lower substrate layer forming an envelope with said surface layer. A heat-fusible substance, which melts and flows above a pre-determined temperature, is applied on the surface of the wicking strip contiguous to at least one of the ends of the wicking member. When the heat-fusible substance is exposed to a temperature above the pre-determined temperature, the heat-fusible substance flows along the length of the wicking member.

Abstract: A time-temperature indicator label for measuring the length of time to which a product has been exposed to a temperature above a pre-determined temperature is provided. The period of time of exposure is integrated with the temperature to which the indicator is exposed. The label is a composite of a plurality of layers adapted to be adhered at its underside to a product container. The label includes a printable surface layer, a longitudinal wicking strip that is adhered underneath the surface layer substantially at the opposite extremities only of the wicking strip and a lower substrate layer forming an envelope with said surface layer. A heat-fusible substance, which melts and flows above a pre-determined temperature, is applied on the surface of the wicking strip contiguous to at least one of the ends of the wicking member. When the heat-fusible substance is exposed to a temperature above the pre-determined temperature, the heat fusible substance flows along the length of the wicking member.

Abstract: An accurate monitoring of the conditions of a perishable product is achieved by integrating two indicator types - a primary indicator which develops a color change as a result of cumulative time-temperature exposure and a threshold second indicator - into a single device. The combination of the two indicators in the same indicator device provides a human readible signal that gradually and irreversibly develops color as a function of time and temperature and more closely monitors the actual condition of a deteriorative product than does a single indicator. Important features of this integrated monitoring device are reliability and printability. The primary indicator in the system is assisted in color development by the secondary indictor that is set to trigger at a predetermined temperature. When this temperature is reached or exceeded both indicator mechanisms function in an additive mode to cause a break in the typical Arrhenius curve, which a primary indicator alone produces.

Abstract: A photoactivated time-temperature indicator is based on a leuco base system. A thermally insensitive, white ("inactive") leuco base (or a mixture of such leuco bases) is mixed, preferably in a polymeric matrix, with a material that generates acid upon exposure to light. Photoexcitation, preferably by UV or near UV light, causes the formation of a thermally sensitive, color-forming ("active") product. Following this activation step, a progressive color development occurs at a rate that increases with temperature. The indicator is useful for monitoring the freshness of perishable products, particularly those stored at subambient temperature.

Abstract: A new process is described which is useful for producing novel articles of manufacture useful for monitoring the time-temperature history of perishable items. The process initially involves forming a solution comprised of a diacetylenic monomer and a solvent. The solution is frozen, and the frozen solution having crystalline diacetylenic monomer therein is irradiated to partially polymerize the diacetylenic monomer. Partial polymerization of the crystalline diacetylenic monomer admixed with frozen solvent results in the production of a novel article of manufacture having color. The novel article of manufacture is comprised of frozen solvent, diacetylenic monomer, and colored polydiacetylene. Due to the intensity of the color of the polydiacetylene, the entire article of manufacture appears to be colored.The colored article of manufacture may be attached to various perishables to monitor the shelf life of the perishables.

Abstract: An activatable time-temperature indicator consists of an oxygen-sensitive reaction product of a triarylmethane dye and a decolorant that is coated on a substrate and covered by an oxygen barrier. Optinally, an oxygen-permeable layer is between the coating and the oxygen barrier. The indicator is activated by removing the oxygen barrier. Following this activation step, a progressive color development occurs at a rate that increases with temperature. The indicator is useful for monitoring the freshness of perishable products, particularly those stored at sub-ambient temperature.

Abstract: A family of acetylenic complexes especially useful as environmental indicators is provided. The complexes include at least one complexing acid and one acetylenic compound of the formula:[R--(C.tbd.C).sub.a --(CH.sub.2).sub.b --(C.tbd.C).sub.c ].sub.2.dHXwherein, a is 1 or 2; b is about 0-5; c is 0 or 1; d is above 0 to about 2, with the proviso that when a is 1, b and c are 0, and when a is 2, b is about 0-5 and c is 0 or 1; and R is --(CH.sub.2)n--NHC(O)NHR'; wherein n is an integer of about 1 to 10; and R' is selected from a group consisting of hydrogen, cycloalkyl, alkenyl, cycloalkenyl, aklyl, phenyl, alkoxyl, alkoxylcarbonylalkyl, and X is a complexing acid.

Abstract: Acetylenic complexes are disclosed that are useful as environmental indicating materials whereby exposure thereof to environmental stimuli induces a color change. These complexes contain at least one effective complexing metal and at least one acetylenic compound of the general formula:[R--(C"C).sub.a --(CH.sub.2).sub.b --(C"C).sub.c ].sub.2.dHXWherein a is 1 or 2, b is about 0-5; c is 0 or 1; with the proviso that when a is 1, b and c are 0, when a is 2, b is about 0-5 and c is 0 or 1; and R is --(CH.sub.2).sub.n -NHC(O)NHR'; wherein n is an integer of about 1 to 10; and R' is selected from the group consisting of: (a) hydrogen; (b) cycloalkyl; (c) alkenyl; (d) cycloalkenyl; (e) alkyl; (f) phenyl; (g) alkoxy; (h) alkoxy alkyl; and (i) alkoxycarbonylalkyl.

Abstract: A photoactivated time-temperature indicator is based on diacetylenic salts. A thermally unreactive ("inactive") diacetylenic salt (or a mixture of such salts) is mixed, in a polymeric matrix, with a material that generates acid upon exposure to light. Photoexcitation, preferably by UV or near UV light, causes the formation of a thermal reactive ("active") free diacetylenic acid. Following this activation step, a progressive color development occurs at a rate that increases with temperature. The indicator is useful for monitoring the freshness of perishable products, particularly those that require refrigeration.

Abstract: A new process is described which is useful for producing novel articles of manufacture useful for monitoring the time-temperature history of perishable items. The process initially involves forming a solution comprised of a diacetylenic monomer and a solvent. The solution is frozen, and the frozen solution having crystalline diacetylenic monomer therein is irradiated to partially polymerize the diacetylenic monomer. Partial polymerization of the crystalline diacetylenic monomer admixed with frozen solvent results in the production of a novel article of manufacture having color. The novel article of manufacture is comprised of frozen solvent, diacetylenic monomer, and colored polydiacetylene. Due to the intensity of the color of the polydiacetylene, the entire article of manufacture appears to be colored.The colored article of manufacture may be attached to various perishables to monitor the shelf life of the perishables.