Activatable temperature indicator with time delay

Patent metadata

Field	Value
Publication number	US-2023251237-A1
Application number	US-202318108865-A
Country	US
Kind code	A1
Filing date	Feb 13, 2023
Priority date	May 11, 2018
Publication date	Aug 10, 2023
Grant date	—

Abstract

Disclosed herein are delayed reaction threshold temperature indicators and methods of making and activating the same, the delayed reaction threshold temperature indicators including a first substrate, first and second layers, and a housing secured to the substrate. The first layer includes a first reactant and an optional meltable polymer, and the second layer includes a meltable polymer and a second reactant. The meltable polymer is configured to keep the first and second reactants from interacting with each other. When exposed to temperatures at and/or above a desired threshold for a period of time, the meltable polymer melts and allows the first and second reactants to come into contact with each other, thereby producing a visual change in appearance.

First claim

1 . A delayed reaction threshold temperature indicator comprising:
a first substrate a first layer further comprising a first reactant, the first layer positioned on top of the substrate; a second layer further comprising a meltable polymer and a second reactant, the second layer positioned on top of the first layer; a removable barrier layer between the first layer and the second layer, the barrier layer substantially impermeable to and preventing contact between the first and second reactants; a housing secured to the substrate, the housing including a viewing window through which the first and second layers are visible; wherein after removal of the barrier layer, exposure to a temperature at and/or above the melting point of the meltable polymer for a predetermined period of exposure time allows the first reactant and/or second reactant to migrate toward each other; and wherein the first and second reactants produce a visual change in appearance after they come into contact with each other.

2 . The indicator of claim 1 , wherein the visual change in appearance is a change in color.

3 . The indicator of claim 2 , wherein the change in color is a darkening of the first and second layers visible through the viewing window.

4 . The indicator of claim 1 , wherein the first layer comprises a second substrate infused or impregnated with the first reactant.

5 . The indicator of claim 1 , wherein the first layer comprises the meltable polymer with the first reactant initially contained therein.

6 . The indicator of claim 1 , wherein the first includes a background comprising a pattern, an indicia, or a color darker than an initial color of the first and second reactants prior to their contacting each other.

7 . The indicator of claim 6 , wherein the background is initially visible through the viewing window and is at least partially obscured by the visual change in appearance.

8 . The indicator of claim 1 , wherein the melting point of the meltable polymer is in a range from -10° C. to 50° C.

9 . (canceled)

10 . The indicator of claim 1 , wherein the predetermined period of time is in the range from 5 minutes to 60 minutes.

11 - 12 . (canceled)

13 . The indicator of claim 10 , wherein the exposure occurs during two or more exposures to a temperature at and/or above the melting point of the meltable polymer.

14 . The indicator of claim 13 , wherein the meltable polymer resolidifies rapidly when exposed to a temperature below the melting point of the meltable polymer.

15 . The indicator of claim 14 , wherein resolidification of the meltable polymer comprises recrystallization.

16 . The indicator of claim 14 , wherein the resolidification of the meltable polymer inhibits migration of the first and/or second reactants through the first and/or second layers.

17 . The indicator of claim 1 ,
wherein the molecular weight of the meltable polymer is in the range from 5,000 Da to 30,000 Da.

18 . The indicator of claim 1 ,
wherein the first reactant is bromothymol blue or resorcinol.

19 . The indicator of claim 1 ,
wherein the weight percent of the first reactant in the first layer is in the range of 0.1% to 10%.

20 . (canceled)

21 . The indicator of claim 1 ,
wherein the second reactant is butylamine or 5-(hydroxymethyl)furfural (HMF).

22 - 32 . (canceled)

33 . The indicator of claim 1 , further comprising a reference area surrounding or adjacent to the viewing window.

34 . The indicator of claim 33 , wherein the reference area comprises a pattern, a color, or a printed indicia that contrasts with or corresponds to the visual change in appearance caused by the reaction between the first and second reactants.

35 . The indicator of claim 1 , further comprising;
at least one of a freeze indicator, a second temperature threshold exposure indicator with a different temperature threshold, and a cumulative time-temperature exposure indicator.

36 - 45 . (canceled)

Assignees

• Temptime Corp

Inventors

• Abdo Mohannad
• Newport John
• Olson John
• Huffman Brian

Classifications

• G01N31/229 Primary

  for investigating time/temperature history · CPC title

• G01K1/02 Primary

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

• G01K3/04 Primary

  in respect of time · CPC title

• G01K11/06

  using melting, freezing, or softening · CPC title