Time-temperature indicator devices
First Claim
1. A time-temperature indicator device for recording the duration of time over which a temperature has been established above a predetermined temperature, comprising:
- a dye-compatible polymer composition having a softening point at or above said predetermined temperature and said polymer composition being in the form of a film or coating layer having top and bottom surfaces and a predetermined thickness; and
a polymer-compatible dye composition in contact with one of said surfaces of said polymer composition, wherein said dye composition is present in a quantity sufficient for diffusion through said polymer composition whenever said polymer composition is above said predetermined temperature, which quantity is selected so that the extent of said diffusion within said polymer composition corresponds to the duration of exposure above said predetermined temperature, and with the diffusion of the dye within the polymer composition being perpendicular to said predetermined thickness.
2 Assignments
0 Petitions
Accused Products
Abstract
A time-temperature indicator device for recording the duration of time over which a temperature has been established above a predetermined temperature, which device includes a dye-compatible polymer composition having a softening point above the predetermined temperature and a polymer-compatible dye composition in contact with the polymer composition and present in a quantity with respect to the polymer composition sufficient for diffusion through the polymer composition whenever the polymer composition is above the predetermined temperature, which quantity is selected so that the extent of diffusion corresponds to the duration of exposure above the predetermined temperature relative to the total time required for substantially complete diffusion. Articles for which a heat history above a predetermined temperature is to be record, in combination with the disclosed time-temperature indicator devices are also described. Methods for recording a duration of time over which a temperature has been established above a predetermined temperature utilizing the disclosed time-temperature indicator devices are also discussed.
-
Citations
27 Claims
-
1. A time-temperature indicator device for recording the duration of time over which a temperature has been established above a predetermined temperature, comprising:
-
a dye-compatible polymer composition having a softening point at or above said predetermined temperature and said polymer composition being in the form of a film or coating layer having top and bottom surfaces and a predetermined thickness; and a polymer-compatible dye composition in contact with one of said surfaces of said polymer composition, wherein said dye composition is present in a quantity sufficient for diffusion through said polymer composition whenever said polymer composition is above said predetermined temperature, which quantity is selected so that the extent of said diffusion within said polymer composition corresponds to the duration of exposure above said predetermined temperature, and with the diffusion of the dye within the polymer composition being perpendicular to said predetermined thickness. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
-
-
14. A method for recording a duration of time over which a temperature has been established above a predetermined temperature, comprising the steps of:
-
providing a time-temperature indicator device comprising a dye-compatible polymer composition having a softening point at or above said predetermined temperature an said polymer composition being in the form of a film or coating layer having top and bottom surfaces and a predetermine thickness; and a polymer-compatible dye composition in contact with one of said surfaces of said polymer composition, wherein said dye composition is present in a quantity sufficient for diffusion through said polymer composition whenever said polymer composition is above said predetermined temperature, which quantity is selected so that the extent of said diffusion within said polymer composition corresponds to the duration of exposure above said predetermined temperature relative to the total time required for substantially complete diffusion through said polymer composition, and with the diffusion of the dye within the polymer composition being perpendicular to said predetermined thickness; exposing said device above said predetermined temperature so that said dye composition diffuses through said polymer composition; and evaluating said extent of diffusion of said dye composition within said polymer composition to determine the duration of time said device was exposed above said predetermined temperature. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
-
-
26. An article for which a heat history above a predetermined temperature is to be recorded comprising a time-temperature indicator device which is integrally connected or affixed to the article in a manner sufficient to indicate the heat history of the article, with the time-temperature indicator device comprising
a dye-compatible polymer composition having a softening point at or above said predetermined temperature and said polymer composition being in the form of a film or coating layer having top and bottom surfaces and a predetermined thickness; - and
a polymer-compatible dye composition in contact with one of said surfaces of said polymer composition, wherein said dye composition is present in a quantity sufficient for diffusion through said polymer composition whenever said polymer composition is above said predetermined temperature, which quantity is selected so that the extent of said diffusion within said polymer composition corresponds to the duration of exposure above said predetermined temperature, and with the diffusion of the dye within the polymer composition being perpendicular to said predetermined thickness. - View Dependent Claims (27)
- and
Specification