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US 8,911,861 B2Granted
Thermochromic indicator
AssigneeLandec Corporation
InventorsRobert Parker, Julian E. Schafer, Steven P. Bitler
Life of this patent
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Abstract
A thermochromic indicator includes a coating on the substrate. The coating comprising a solid crystalline particles having a melting point of 0-130° C. At temperatures below the melting point, the coating is opaque. At temperatures above the melting point, the coating becomes translucent. The change in opacity can be reversible or irreversible.
Claims19
An assembly which comprises
- (1) a substrate which comprises a temperature-sensitive product, and
- (2) a temperature indicator which
- (a) comprises a first component comprising a side chain crystalline (SCC) polymer which (i) has a crystalline melting point, Tp, of 0-135° C., and (ii) is not cross-linked
- (b) undergoes a change in translucency, wherein the change first occurs at a temperature that is less than 5 degrees C. above Tp and wherein the change in the indicator remains when the temperature is reduced below Tp, wherein the SCC polymer is in the form of solid particles having a median particle size greater than 0.03μ and less than 10μ;
- and
- (c) comprises a second component, wherein the difference between the refractive index of the SCC polymer and the second component is greater at a temperature below Tp than at a temperature above Tp, wherein the second component comprises air voids or a matrix polymer.
3 more elements
An assembly which comprises
- (1) a substrate which comprises a vaccine, and
- (2) a temperature indicator which
- (a) comprises a side chain crystalline (SCC) polymer which
- (i) has a crystalline melting point, Tp, of 0-135° C.,
- (ii) is not cross-linked,
- (ii) is a copolymer of two or more comonomers, and
- (iv) comprises repeating units in which the side chains comprise linear polymethylene radicals containing 16-30 carbon atoms,
- (v) has a heat of fusion of at least 20 J/g, and
- (b) undergoes an irreversible change in translucency when exposed to a combination of time and temperature wherein the change first occurs when exposed to a temperature less than 5 degrees C. greater than Tp, wherein the change is in the translucency of the indicator and the change remains if the temperature is decreased below Tp after the change occurs, wherein the SCC polymer is in the form of solid particles having a median particle size greater than 0.03μ and less than 10μ;
- and
- (c) comprises a matrix polymer, wherein the difference between the refractive index of the SCC polymer and the matrix polymer is greater at a temperature below Tp than at a temperature above Tp.
8 more elements
An assembly which comprises
- (1) a substrate which comprises a temperature-sensitive product, and
- (2) a temperature indicator which
- (a) comprises a side chain crystalline (SCC) polymer which has a crystalline melting point, Tp, of 0-135° C.,
- (b) the SCC polymer is in the form of solid particles of a median particle size greater than 0.03μ and less than 10μ, and
- (c) comprises a matrix polymer, wherein the matrix polymer is a different polymer than the SCC polymer, the refractive index of the SCC polymer is at least 0.03 greater at a temperature below Tp than at a temperature above Tp and the difference between the refractive index of the SCC polymer and the matrix polymer is not more than 0.03 at a temperature below Tp.
2 more elements
Dependencies are inferred from the claim text.