Nonreversible freeze-thaw indicator
First Claim
1. A nonreversible freeze indicator adapted to detect whether an article has been subjected to freezing conditions comprising an encapsulated translucent to opaque colloidal dispersion of organic solid particles suspended in a liquid medium, said colloidal dispersion having the property of becoming nonreversibly destabilized upon freezing which thereafter coagulates to form a non-flowing waxy gel when raised above its freezing temperature thereby providing a telltale visual sign that said indicator has been subjected to freezing conditions, said organic solid particles having a diameter of about 0.7 microns or less and said dispersion having from about 10 weight percent to about 50 weight percent of said organic solid particles.
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Abstract
A nonreversible freeze-thaw indicator which will detect whether an article has been subjected to freezing or thawing conditions comprising an encapsulated translucent to opaque colloidal dispersion of organic solid particles suspended in a liquid medium, said colloidal dispersion having the property of becoming nonreversibly destablized upon freezing which thereafter provides a telltale visual sign if said dispersion rises through its freeze-thaw temperature. After the colloidal dispersion has once been frozen to trigger its irreversible destabilization and is again thawed, it coagulates to form a non-flowing waxy gel, flocculates and precipitates leaving a clear liquid and a coagulated solids layer or partially flocculates to transform a translucent dispersion to a substantially opaque dispersion.
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Citations
12 Claims
- 1. A nonreversible freeze indicator adapted to detect whether an article has been subjected to freezing conditions comprising an encapsulated translucent to opaque colloidal dispersion of organic solid particles suspended in a liquid medium, said colloidal dispersion having the property of becoming nonreversibly destabilized upon freezing which thereafter coagulates to form a non-flowing waxy gel when raised above its freezing temperature thereby providing a telltale visual sign that said indicator has been subjected to freezing conditions, said organic solid particles having a diameter of about 0.7 microns or less and said dispersion having from about 10 weight percent to about 50 weight percent of said organic solid particles.
- 5. A nonreversible freeze-thaw indicator adapted to detect whether an article has been subjected to freezing or thawing conditions comprising an encapsulated translucent to opaque colloidal dispersion of organic solid particles suspended in a liquid medium, said colloidal dispersion having the property of becoming nonreversibly destabilized upon freezing which thereafter flocculates and precipitates leaving a clear liquid and a coagulated solids layer when raised above its freezing temperature thereby providing a telltale visual sign that said indicator has been subjected to freezing or thawing conditions, said organic solid particles having a diameter of about 0.3 microns or less and said dispersion having from about 0.1 weight percent to about 10 weight percent of said organic solid particles.
- 9. A nonreversible freeze indicator adapted to detect whether an article has been subjected to freezing conditions comprising an encapsulated translucent colloidal dispersion of organic solid particles suspended in a liquid medium, said colloidal dispersion having the property of becoming nonreversibly destabilized upon freezing which thereafter partially flocculates to form a substantially opaque dispersion when raised above its freezing temperature thereby providing a telltale visual sign that said indicator has been subjected to freezing conditions, said organic solid particles having a diameter of about 0.1 microns or less and said dispersion having from about 0.1 weight percent to about 10 weight percent of said organic solid particles.
Specification