Thermochromic coating and method of manufacturing thereof

Abstract

A thermochromic coating that comprises a thermo chromic compound and a polyurea resin. The thermo chromic compound and polyurea resin form a thermochromic layer. The coating optionally has a protective layer containing a resin and a UV-blocking material arranged on top of the thermochromic layer. A reflective layer containing a reflective material is optionally arranged between the thermo chromic layer and the substrate. A thermochromic coating is formed by applying successive reflective, thermochromic, and protective layers on a substrate.

1 . A thermochromic material, comprising:
 a substrate; and   a thermochromic coating arranged on the substrate,   wherein the thermochromic coating comprises:
 a first layer containing:
 a thermochromic compound; and 
 a polyurea resin; and 
 
 a second layer containing:
 a resin; and 
 a UV-blocking material, 
 
   wherein:
 the second layer is arranged over the first layer, 
 the UV-blocking material comprises particles having a diameter of from 0.005 μm to 0.4 μm, 
   the substrate is one selected from the group consisting of: a structural material, a residential building material and an industrial building material; and   the thermochromic compound is at least one selected from the group consisting of leuco dyes, microencapsulated leuco dyes, spirolactones, spiropyrans, fluorans, cholesteryl nonanoates, and cyanobiphenyls.   
     
     
         2 . The thermochromic material of  claim 1 , wherein the thermochromic coating further comprises:
 a third layer containing a reflective layer arranged under the first layer.   
     
     
         3 . The thermochromic material of  claim 1 , wherein the second layer contains a polyurea resin. 
     
     
         4 . The thermochromic material of  claim 1 , wherein the first layer further comprises a UV-blocking material. 
     
     
         5 . The thermochromic material of  claim 1 , wherein the concentration of particles in the second layer is from 0.1 wt % to 50.0 wt % of the total weight of the layer. 
     
     
         6 . The thermochromic material of  claim 1 , wherein the polyurea is an aliphatic polyurea. 
     
     
         7 . The thermochromic material of  claim 1 , wherein the polyurea resin further comprises a dendrimer or hyper-branched compound covalently bonded to the polyurea. 
     
     
         8 . The thermochromic material of  claim 1 , wherein the thermochromic compound has a thermochromic transition temperature of from 5° C. to 90° C. 
     
     
         9 . The thermochromic material of  claim 1 , wherein the particles are comprised of a titanium oxide. 
     
     
         10 . The thermochromic material of  claim 1 , wherein the particles are comprised of an iron oxide. 
     
     
         11 . The thermochromic material of  claim 2 , wherein the reflective layer arranged under the first layer comprises a UV-blocking material. 
     
     
         12 . The thermochromic material of  claim 11 , wherein the UV-blocking material in the reflective layer comprises particles having a diameter of from 0.005 μm to 0.4 μm. 
     
     
         13 . A thermochromic coating comprising:
 a thermochromic compound;   a UV-blocking material; and   a resin comprised of at least one material selected from the group consisting of: polyurethane, epoxy, acrylic, polyvinyl alcohol, polyvinyl chloride, fluoropolymers, silicone polymers, and polyvinyl acetate,   wherein the thermochromic compound and the UV-blocking material are interspersed within the resin material.   
     
     
         14 . A method for forming a thermochromic coating on a substrate comprising the step of:
 a) forming a first layer on the substrate, wherein the first layer comprises a thermochromic compound and a polyurea resin.   
     
     
         15 . The method of  claim 14 , further comprising the step of:
 b) forming on the first layer, a second layer having a UV-blocking material in a second resin.   
     
     
         16 . The method of  claim 15 , wherein the second layer comprises a polyurea resin. 
     
     
         17 . The method of  claim 15 , wherein the second layer comprises a preformed UV blocking layer and is adhered to the first layer with an adhesive. 
     
     
         18 . The method of  claim 14 , wherein the polyurea is an aliphatic polyurea. 
     
     
         19 . The method of  claim 15 , further comprising the step of:
 c) before forming the first layer, forming a third layer on the substrate such that the reflective layer is located between the substrate and the first layer.   
     
     
         20 . The method of  claim 14 , wherein the substrate is one selected from the group consisting of: a carrier film, a scrim structural sheet, a cellulosic carrier sheet, a non-woven carrier sheet, ethylene-propylene diene rubber, chlorosulfonated polyethylene rubber, asphalt shingles, a roof, a pipeline, a delivery pipe, a chemical reactor, a building material, an industrial structure and a residential structure. 
     
     
         21 . The method of  claim 14 , wherein the substrate contains a pattern or an image when the first layer is cycled through its transition temperature. 
     
     
         22 . The method of  claim 14 , wherein the substrate contains infrared reflective pigments that are revealed when the first layer is cycled through its transition temperature. 
     
     
         23 . The method of  claim 14 , wherein the first layer further comprises a UV-blocking material. 
     
     
         24 . The method of  claim 15 , wherein the UV-blocking material comprises a plurality of particles having a diameter of from 0.01 μm to 2.5 μm. 
     
     
         25 . The method of  claim 24 , wherein the concentration of particles in the second layer is from 0.1 wt % to 50.0 wt % of the total weight of the second layer. 
     
     
         26 . The method of  claim 14 , wherein the resin further comprises a dendrimer or hyper-branched compound covalently bonded to the polyurea. 
     
     
         27 . The method of  claim 14 , wherein the thermochromic material has a transition temperature of from 5° C. to 90° C. 
     
     
         28 . The method of  claim 24 , wherein the particles are comprised of a titanium oxide or an iron oxide. 
     
     
         29 . The method of  claim 14 , wherein the thermochromic compound is at least one selected from the group consisting of: liquid crystals, microencapsulated liquid crystals, leuco dyes, microencapsulated leuco dyes, spirolactones, spiropyrans, fluorans, cholesteryl nonanoates, cyanobiphenyls and inorganic pigments. 
     
     
         30 . The method of  claim 14 , wherein the first layer is applied to the substrate by spraying a mixture of the thermochromic compound and the polyurea resin at a temperature of from 5° C. to 50° C. and an aerosol pressure of from 1 psi to 50 psi. 
     
     
         31 . The method of  claim 14 , wherein the first layer is applied to the substrate by painting a mixture of the thermochromic compound and the polyurea resin onto the substrate. 
     
     
         32 . The method of  claim 14 , wherein the first layer is applied to the substrate on a roll to roll coater using coating application methods selected from the group comprising: slot die coating, knife over roll coating, rod coating, extrusion coating and roll coating. 
     
     
         33 . The method of  claim 19 , further comprising a step: d) forming a fourth layer on the substrate, wherein the fourth layer comprises a thermochromic compound and a polyurea resin.