Dual function heat indicator and method of manufacture

Patent metadata

Field	Value
Publication number	US-10031086-B2
Application number	US-201514943600-A
Country	US
Kind code	B2
Filing date	Nov 17, 2015
Priority date	May 11, 2012
Publication date	Jul 24, 2018
Grant date	Jul 24, 2018

Abstract

A dual-function heat indicator for monitoring two or more modes of heat exposure is described. A manufacturing process for the dual-function heat indicator is also described. Dual-function heat indicators as described may be useful for monitoring the exposure of host products, with which the dual-function heat indicators may be associated, to cumulative ambient heat exposure and to a peak ambient heat exposure, and for other purposes.

First claim

We claim:

1. A dual-function heat indicator comprising:
a substrate;
a cumulative exposure indicator supported by the substrate in a viewable, layered configuration, wherein the cumulative exposure indicator is configured to undergo an optical change in appearance in response to a cumulative heat exposure;
a peak exposure indicator supported by the substrate in the viewable, layered configuration, the peak exposure indicator comprising a meltable solid configured to melt upon exposure to a predetermined peak heat exposure, the meltable solid configured to change color or transparency in response to the melting of the meltable solid, the color or transparency change persisting after the meltable solid re-solidifies; and
a colored background under the meltable solid that is dark relative to the meltable solid, wherein the meltable solid is initially opaque, obscuring the background, and is configured to become transparent after melting and to remain transparent after re-solidifying, revealing the background;
wherein the cumulative exposure indicator and the peak exposure indicator are functionally separate with the visual outputs of the cumulative exposure indicator and the peak exposure indicator integrated in a single overlapping display.

2. The dual-function heat indicator of claim 1 , wherein there is a short delay between exposure to a peak temperature and response of the peak exposure indicator.

3. The dual-function heat indicator of claim 1 , wherein the peak exposure indicator is color-changeable in response to melting of the meltable solid.

4. The dual-function heat indicator of claim 1 , wherein the peak exposure indicator is color-changeable in response to a peak temperature in a range of about 30-60° C.

5. The dual-function heat indicator of claim 1 , wherein the meltable solid has a melting point below about 60° C.

6. The dual-function heat indicator of claim 1 , wherein the meltable solid has a melting point above about 30° C.

7. The dual-function heat indicator of claim 1 , further comprising a reference ring which has an appearance that is similar to the appearance of the cumulative exposure indicator that has undergone the optical change in appearance.

8. The dual-function heat indicator of claim 1 , further comprising a reference ring which has an appearance that is similar to the appearance of the peak exposure indicator after melting of the meltable solid.

9. The dual-function heat indicator of claim 1 , further comprising a reference ring which has an appearance that is similar to the appearance of the cumulative exposure indicator that has undergone the optical change in appearance and that is similar to the appearance of the peak exposure indicator after responding to a peak exposure event.

10. The dual-function heat indicator of claim 1 , further comprising a transparent film that overlies the cumulative exposure indicator and the peak exposure indicator.

11. The dual-function heat indicator of claim 1 , further comprising an adhesive layer contacting the substrate on a side opposite the cumulative exposure indicator and the peak exposure indicator.

12. The dual-function heat indicator of claim 1 , wherein the cumulative exposure indicator is affected by a temperature that is below a peak temperature of the peak exposure indicator.

13. The dual-function heat indicator of claim 1 , wherein the cumulative exposure indicator overlies the peak exposure indicator.

14. The dual-function heat indicator of claim 1 , wherein the cumulative exposure indicator darkens in response to the cumulative heat exposure.

15. The dual-function heat indicator of claim 1 , wherein the cumulative exposure indicator comprises a heat sensing agent that darkens in response to the cumulative heat exposure.

16. The dual-function heat indicator of claim 1 , wherein the cumulative exposure indicator comprises a polymerizable diacetylenic compound that darkens in response to the cumulative heat exposure.

17. The dual-function heat indicator of claim 1 , wherein melting of the meltable solid reveals a background, the background remaining visible after the meltable solid resolidifies.

18. The dual-function heat indicator of claim 17 , wherein the meltable solid is in the form of particles that obscure a background by scattering light.

19. The dual-function heat indicator of claim 18 , wherein melting of the meltable solid causes a color to become more apparent due to a loss of light scattering.

20. The dual-function heat indicator of claim 1 , wherein the meltable solid comprises a polymer.

21. The dual-function heat indicator of claim 20 , wherein the polymer is a side-chain crystalline polymer.

22. The dual-function heat indicator of claim 1 , wherein the peak exposure indicator overlies the cumulative exposure indicator.

23. The dual-function heat indicator of claim 1 , wherein melting of the meltable solid results in the meltable solid darkening in color.

24. The dual-function heat indicator of claim 23 , wherein the meltable solid is in the form of particles that scatter light.

25. The dual-function heat indicator of claim 23 , wherein the peak exposure indicator further comprises a colorant.

26. The dual-function heat indicator of claim 25 , wherein the colorant is dissolved in the particles that scatter light.

27. The dual-function heat indicator of claim 25 , wherein melting of the meltable solid causes the colorant to become dissolved in the meltable solid.

28. The dual-function heat indicator of claim 1 , wherein the cumulative exposure indicator darkens in color in response to the cumulative heat exposure.

29. The dual-function heat indicator of claim 1 , wherein the optical change in appearance comprises a reduction in opacity of the cumulative exposure indicator.

30. The dual-function heat indicator of claim 1 , wherein the optical change in appearance reveals a background.

31. The dual-function heat indicator of claim 30 , wherein the background is the substrate.

32. The dual-function heat indicator of claim 1 , wherein a layer of aluminum is disposed on the substrate.

33. The dual-function heat indicator of claim 30 , wherein revealing the background allows the background to be read.

34. The dual-function heat indicator of claim 1 , wherein the optical change in appearance comprises a lightening of the cumulative exposure indicator.

35. The dual-function heat indicator of claim 1 , wherein the peak exposure indicator further comprises an oil-soluble reducing agent or a meltable or sensitizer-soluble, primary or secondary amine having low water solubility.

36. The dual-function heat indicator of claim 1 , wherein the peak exposure indicator further comprises an oil-soluble reducing agent, oxalic acid, phosphite ester, hydroxybenzoic acid ester, hydrohydroquinone, a hydroquinone derivative such as dimethyhydroquinone, di-tert-butyl hydro quinone, dialkylhydroquinone, 3-ethoxyphenol, 1,2-diethyl-3-hydroxybenzene, 1,3-diethyl-2-hydroxybenzene, 2,2′-methylenebis(3,4,6 trichlorophenol), 4-butyl-aniline, a phenol derivative, an organic acid, an acid clay, reactive acid hectorite clay, a phenolic resin, a phenol-acetylene resins, a polyvalent metallic salts of a phenolic resin, a zinc-including modified alky

Assignees

• Temptime Corp

Inventors

• Prusik Thaddeus
• Smith Dawn E
• Taylor Dene H
• Arnold Raquiba Hoque

Classifications

• G01K11/06

  using melting, freezing, or softening · CPC title

• G01K11/12 Primary

  using changes in colour, translucency or reflectance · CPC title

• G01K3/04

  in respect of time · CPC title

• G01K1/02

  Means for indicating or recording specially adapted for thermometers · CPC title

• G01N21/78 Primary

  producing a change of colour · CPC title