Defrost indicator

• US 4,892,677 A
• Filed: 12/19/1984
• Issued: 01/09/1990
• Est. Priority Date: 05/03/1982
• Status: Expired due to Term

• Current Assignee: Temptime Corporation (Zebra Technologies Corporation)
• Original Assignee: Lifelines Technology Incorporated (Zebra Technologies Corporation)
• Inventors: Preziosi, Anthony F., Baughman, Ray H., Prusik, Thaddeus
• Primary Examiner(s): Lovering, Richard D.
• Assistant Examiner(s): Kilby, Catherine S.
• Application Number:
  US06/683,443
• Time in Patent Office: 1,847 Days
• Field of Search: 252/408.1, 252/600, 252/962, 116/207, 116/216, 116/217, 116/219, 374/161, 374/162, 374/141, 106/DIG. 6, 526/285, 428/913
• US Class Current: 252/408.1
• CPC Class Codes: G01N 31/229 for investigating time/temperature history
• CPC Class Codes: G07C 1/00 Registering, indicating or recording the time of events or elapsed time, e.g. time-recorders for work people registering or indicating the working of machines or vehicles G07C3/00, G07C5/00
• CPC Class Codes: Y10S 252/962 Temperature or thermal history
• CPC Class Codes: Y10S 428/913 Material designed to be responsive to temperature, light, moisture

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. upon exposure to temperatures above a critical temperature, the frozen solvent melts and extracts unreached monomer from the colored polymer, thereby causing a sharp color transition which indicates that the perishable should possibly be discarded.

Claims

1. Article of manufacture comprising an intimate mixture of a phase of crystalline diacetylenic monomer admixed with a solid solvent phase, said monomer being soluble in said solvent above the melting point of said solid solvent phase.

2. The article of manufacture of claim 1 wherein said monomer is a diurethane diyne.

3. The article of manufacture of claim 2 wherein said diurethane diyne is of the following formula:

##STR1## wherein n is 4-12 and R is an alkyl containing 1-18 carbons or BOOCCH₂, with B an alkyl containing 1-18 carbons.

4. The article of manufacture of claim 2 wherein R is an alkyl group containing 1-4 carbons and n is 4.

5. The article of manufacture of claim 2 wherein R is BOOCCH₂, B is an alkyl group containing 1-4 carbons, and n is 4.

6. The article of manufacture of claim 1 wherein said solvent has a melting point within the range of -20°

C. to 20°

C.

7. The article of manufacture of claim 1 wherein said solvent is acetic acid.

8. A perishable product having attached thereto the article of manufacture of claim 1 or 2 or 3 or 4 or 5 or 6.