Granted Patent B2

US 9,297,706 · App. 13/968,895 · Granted Mar 29, 2016

Abstract

Claims (26)

1. An indicator dispersion comprising:

a liquid medium; and

particles of a colored indicator agent dispersed in the liquid medium, the colored indicator agent particles having an inherent color;

wherein the indicator dispersion exhibits the inherent color of the colored indicator agent particles after freezing and is configured to have a less colored appearance before freezing and wherein light scattering masks the inherent color of the colored indicator agent particles before freezing; and

wherein the indicator dispersion is free of color-changing chemical co-reactants.

2. The indicator dispersion of claim 1 , wherein the liquid medium is a hydrophobic liquid medium.

3. The indicator dispersion of claim 1 , wherein the liquid medium is an aqueous liquid medium.

4. The indicator dispersion of claim 3 , wherein the particles of the colored indicator agent comprise a colorant dissolved or dispersed in a hydrophobic liquid.

5. The indicator dispersion of claim 4 , wherein the colorant is a dye and the hydrophobic liquid is an oil.

6. The indicator dispersion of claim 1 , wherein the particles of the colored indicator agent comprise solid particles of a colorant dissolved or dispersed in a solid material.

7. The indicator dispersion of claim 1 , wherein the indicator dispersion coalesces in response to exposure of the indicator dispersion to a freezing temperature.

8. The indicator dispersion of claim 1 , wherein the particles of the colored indicator agent have an absorbance at 500 nm of about 1 to about 30.

9. The indicator dispersion of claim 1 , wherein the particles of the colored indicator agent have an average particle size of at least about 100 nm, and of not more than about 2 μm.

10. The indicator dispersion of claim 1 , wherein the thickness of the dispersion is less than 1 mm.

11. The indicator dispersion of claim 1 , wherein the after-freezing appearance of a layer of the indicator dispersion having a thickness of 1 mm is at least 0.4 optical density units darker than the before-freezing appearance of the layer of the indicator dispersion.

12. The indicator dispersion of claim 1 , wherein the particles of the colored indicator agent are homogenous and no other indicator particles are present in the indicator dispersion.

13. The indicator dispersion of claim 1 , wherein the indicator dispersion comprises an ice-nucleating agent.

14. A freeze indicator comprising:

a housing; and

the indicator dispersion of claim 1 within the housing, the housing being configured for the indicator dispersion to be optically readable externally of the freeze indicator.

15. The freeze indicator of claim 14 , comprising a substrate supporting the housing, the housing and substrate optionally being flexible.

16. An article of manufacture comprising the freeze indicator of claim 14 .

17. The article of manufacture of claim 16 , which is a host product having the freeze indicator associated with the host product to monitor the host product for exposure to a freezing temperature.

18. The article of manufacture of claim 16 , which is a label for a perishable good, comprising the freeze indicator.

19. The article of manufacture of claim 16 , which is a package for a perishable good, comprising the freeze indicator.

20. The article of manufacture of claim 16 , which is a package containing a perishable good, comprising the freeze indicator of.

Assignments (9)