COLOR-CHANGING EMULSIONS FOR FREEZE INDICATORS
First Claim
1. A color-changing emulsion for use in a freeze indicator, the color-changing emulsion comprising:
- an aqueous liquid dispersion medium;
a first reactant phase dispersed in the dispersion medium, the first reactant phase comprising a hydrophobic liquid and a first reactant dissolved or dispersed in the hydrophobic liquid; and
a second reactant phase dispersed in the dispersion medium, the second reactant phase being unmixed with the first reactant phase and comprising a second reactant, the second reactant being co-reactable with the first reactant to provide a color change;
wherein the first reactant and the second reactant co-react in response to exposure to a freezing temperature to change the color of the color-changing emulsion irreversibly.
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Accused Products
Abstract
A color-changing emulsion for use in a freeze indicator can employ a dispersion medium, for example, an aqueous liquid, a first reactant phase and a second reactant phase, which two reactant phases can both be dispersed in the dispersion medium. The first reactant phase includes a hydrophobic liquid and a first reactant, for example, a color precursor such as a leuco dye. The second reactant phase can include a hydrophobic liquid, and includes, or can be, a second reactant, for example, a color developer such as a leuco dye developer. The first and second reactant phases can be essentially unmixed, and can be co-reactable to provide a color change. In response to a freezing temperature, the color-changing emulsion can coagulate and change color irreversibly. An intense color change can be obtained by using, for example, a suitable leuco dye precursor and developer.
36 Citations
28 Claims
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1. A color-changing emulsion for use in a freeze indicator, the color-changing emulsion comprising:
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an aqueous liquid dispersion medium; a first reactant phase dispersed in the dispersion medium, the first reactant phase comprising a hydrophobic liquid and a first reactant dissolved or dispersed in the hydrophobic liquid; and a second reactant phase dispersed in the dispersion medium, the second reactant phase being unmixed with the first reactant phase and comprising a second reactant, the second reactant being co-reactable with the first reactant to provide a color change; wherein the first reactant and the second reactant co-react in response to exposure to a freezing temperature to change the color of the color-changing emulsion irreversibly. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A method of making a color-changing emulsion for use in a freeze indicator, the method comprising:
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(a) dissolving or dispersing a first reactant in a hydrophobic liquid to provide a first reactant phase; (b) dispersing the first reactant phase in an aqueous liquid dispersion medium to provide a first reactant dispersion; and (c) mixing a second reactant phase comprising a second reactant with the first reactant dispersion to provide the color-changing emulsion, the first reactant and the second reactant being co-reactable to provide a color change; wherein the color-changing emulsion can change color irreversibly in response to exposure to a freezing temperature. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28)
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Specification