High-intensity, persistent thermochromic compositions and objects, and methods for creating the same

a thermochromic composition and persistent technology, applied in the field of thermochromic compositions, can solve the problems of luminescent emission, color change, and the inability to optionally choose the color of the object, and achieve the effect of high intensity and persisten

Inactive Publication Date: 2006-07-20
PERFORMANCE INDICATOR LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0038] It has now been found that formulations comprising an effective amount of thermochromic materials, at least one liquid carrier medium, at least one polymeric resin, and at least one formulation stabilizing additive, wherein said thermochromic materials are uniformly distributed within said formulation provide thermochromic formulations with high intensity and persistence.

Problems solved by technology

Color change can also result from luminescent emissions.
Of course, the kind of color cannot be optionally chosen and the difference between colors before and after thermochromism is small.
Moreover, since these metal complex crystals are not light-transmitting, it is not possible to use them as optical switches to hide / reveal an indicia, pattern or color in the layer below.
These materials have heretofore been used as thermochromic materials but their applications are limited.
Thermochromic substances further include cholesteric liquid crystals and mixtures of cholesteric liquid crystals and nematic liquid crystals, but these substances also find greatly limited use because they are low in color density, have no selectivity in color and in color change temperature and are very expensive.
Liquid crystals generally exhibit thermochromism at temperatures ranging from −10° C. to +200° C. However, the number of liquid crystals undergoing thermochromism at a temperature not exceeding 0° C. is very limited, namely 1 or 2.
Thermochromic liquid crystal materials tend to be expensive and generally exhibit low color density.
Hence, their use is not widespread, occurring in specialized situations
It can be seen that there are a wide variety of thermochromic materials but which are generally very sensitive to their physical and chemical environment, which can comprise solvents, polymeric resin binders, stabilizing additives, pigments, dyes etc., which if not controlled, can quickly result in a degradation of the degree of color change, or even complete loss of thermochromic performance.
For single layer constructions, even if the thermochromic material environment is carefully selected so that the thermochromic performance is not degraded, the solvents used can leach harmful materials from the substrate over which these materials are applied.
Even though progress has been made over the years in expanding the colors and temperature ranges available, since thermochromic materials have generally been deployed as single layer applications, the color gamut is still fairly limited.
However, when color results from absorption of electromagnetic radiation, creating colors with combinations of thermochromic materials of limited color range, and pigment colorants, is still quite restrictive in the range of bright colors that can be achieved.

Method used

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  • High-intensity, persistent thermochromic compositions and objects, and methods for creating the same
  • High-intensity, persistent thermochromic compositions and objects, and methods for creating the same
  • High-intensity, persistent thermochromic compositions and objects, and methods for creating the same

Examples

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example 1

[0143] A formulation was made consisting of a thermochromic pigment in a binder of nitrocellulose and diluted with 2-methoxyethanol. This gave pigment solids of 40% of dry pigment to 60% Nitrocellulose binder. The solids were contained in a solvent mixture at 45% solids. This material was coated over plasticized PVC to give a dry coating thickness of 18 microns using a screen printing process. The color of the thermochromic pigment at room temperature was selected so that it contrasted the color of the PVC. The opacity of the thermochromic layer at room temperature masked the PVC layer below it. The thermochromic layer became translucent when heated through normal body contact to reveal the contrasting base color of the PVC underneath.

example 2

[0144] A formulation was made consisting of 52% thermochromic pigment in 48% Nitrocellulose binder. The pigment and binder were prepared in a solvent mixture containing Toluene, Hexane, and Hydrocarbon solvents at a solids content of 40%. This material was applied using a silk screen to give a dry coating thickness of 22 microns.

example 3

[0145] A yellow fluorescent pigment was dispersed in 2-methoxyethanol at 50% solids using the wetting agent TegoWet 550. This dispersion was added to an acrylic binder (NeoCryl B-735) to give solids of 20% in 2-methoxyethanol. The ink was then applied to plasticized PVC using a screen print to achieve a 15 micron thickness, which provided for an image that contrasted the base color of the PVC. Over this was applied the formulation from Example 2 at a thickness of 26 microns. The color of the thermochromic layer at room temperature contrasted with the fluorescent layer below it. In this case, the thermochromic layer was dark blue compared to the fluorescent yellow of the layer below the thermochromic layer. The opacity of the thermochromic layer masked the fluorescent layer below it. The image was such that when warmed, the thermochromic pigment became translucent and revealed the fluorescent layer printed underneath.

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Abstract

Disclosed are thermochromic formulations, comprising an effective amount of thermochromic materials, which exhibit high luminous intensity and persistence. Also disclosed are thermochromic objects formed by applying at least one thermochromic layer, formed from thermochromic formulations, to preformed articles. Further disclosed are methods for creating thermochromic objects.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to U.S. Provisional Patent Application Ser. No. 60 / 637,535, filed Dec. 20, 2004 (Attorney Docket No. 7044531001), titled, “Layered Envirochromic Materials, Applications and Methods of Preparation Thereof,” which is incorporated by reference herein for all purposes.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention is directed to thermochromic compositions comprising an effective amount of thermochromic materials formulated to yield change in color of high intensity. The present invention is also directed to thermochromic objects comprising at least one envirochromic layer, wherein said envirochromic layer comprises at least one thermochromic composition. Thermochromic objects may also additionally comprise at least one reflective layer, at least one colorant layer, and / or at least one protective layer. Such protective layers comprise photoluminescent fluorescent mat...

Claims

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Application Information

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IPC IPC(8): B32B27/20
CPCA63B37/0003A63B37/0022A63B43/06A63B2207/00B05D5/06B05D7/542B05D7/546C09K9/02C09K11/02C09K11/06C09K11/7792C09K2211/1007C09K2211/1088A63B37/0024A63B37/0051Y10T428/31663Y10T428/31786Y10T428/31935Y10T428/31504A63B2225/76
InventorAGRAWAL, SATISHOSINSKI, ROBB J.WINSKOWICZ, ROBERTPARKER, CLIFFORD
OwnerPERFORMANCE INDICATOR LLC