Thermochromic Indicators
3 Assignments
0 Petitions
Accused Products
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.
3 Citations
27 Claims
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13. An assembly which comprises
(1) a substrate which comprises a temperature sensitive product or a packaging material used to contain a temperature sensitive product or a label to be applied to a temperature sensitive product or package, and (2) a temperature indicating film, layer or coating which (a) comprises a first component consisting of a side chain crystalline (SCC) polymer which (i) has a crystalline melting point, Tp, of 0-135° - C., (ii) is in the form of solid particles having a median particle size greater than 0.03□ and
less than 10□
, and (iii) is at least partially cross-linked, and(b) comprises a second component, consisting of air or gas voids, the primary source of light scattering for the temperature indicator, which are mixed with, between and surrounded by the first component, and optionally (c) a third component, consisting of small amount of binder polymer to (i) improve adherence to a substrate, and (ii) maintain mechanical integrity and void structure of the indicating film or coating, which (d) undergoes a change in degree of light scattering, manifested by a visible change in opacity or translucency, wherein the change occurs on first heating to a temperature that is less than 5 degrees C. above Tp and wherein the change in the indicator substantially remains when the temperature is reduced below Tp. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 24, 25)
- C., (ii) is in the form of solid particles having a median particle size greater than 0.03□ and
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23. An assembly which comprises
(1) a substrate which comprises a temperature sensitive product or a packaging material used to contain a temperature sensitive product or a label to be applied to a temperature sensitive product or package, and (2) a temperature indicator which (a) comprises a crystalline polymer or wax which (i) has a crystalline melting point, Tp, of 0-135° - C., (ii) is in the form of solid particles having a median particle size greater than 0.03μ and
less than 10μ
, and(b) comprises a matrix polymer, wherein the matrix polymer is a different polymer than the crystalline polymer particles and wherein the difference between the refractive index of the crystalline polymer and the matrix 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 crystalline polymer and the matrix polymer is not more than 0.03 at a temperature below Tp, and (d) undergoes a change in degree of visible light scattering, manifested by a visible change in opacity or translucency, wherein the change occurs on heating to a temperature that is less than 5 degrees C. above Tp and wherein the change in the indicator substantially returns to its original appearnce when the temperature is reduced below Tp. - View Dependent Claims (26, 27)
- C., (ii) is in the form of solid particles having a median particle size greater than 0.03μ and
Specification