Reflective conductive composite film

Abstract

A reflective conductive film includes (i) a reflective polymeric substrate having a polymeric base layer and a polymeric binding layer, wherein the polymeric material of the base layer has a softening temperature T S-B , and the polymeric material of the binding layer has a softening temperature T S-HS ; and (ii) a conductive layer that includes a plurality of nanowires, wherein the nanowires are bound by the polymeric matrix of the binding layer such that the nanowires are dispersed at least partially in the polymeric matrix of the binding layer, wherein the polymeric substrate is a biaxially oriented substrate, and wherein the polymeric binding layer is a copolyester.

1 . A reflective conductive film comprising:
 (i) a reflective polymeric substrate comprising a polymeric base layer and a polymeric binding layer, wherein the polymeric material of the base layer has a softening temperature T S-B , and the polymeric material of the binding layer has a softening temperature T S-HS ; and   (ii) a conductive layer comprising a plurality of nanowires,   wherein said nanowires are bound by the polymeric matrix of the binding layer such that the nanowires are dispersed at least partially in the polymeric matrix of the binding layer,   
       wherein the polymeric substrate is a biaxially oriented substrate, and wherein the polymeric binding layer is a copolyester. 
     
     
         2 . The reflective conductive film according to  claim 1  obtained by a process comprising the steps of providing a reflective polymeric substrate comprising a polymeric base layer and a polymeric binding layer; disposing said nanowires on the exposed surface of the binding layer; and heating the composite film to a temperature T 1  wherein T 1  is equal to or greater than T S-HS , and T 1  is at least about 5° C. below T S-B . 
     
     
         3 . The reflective conductive film according to  claim 2  wherein said nanowires are disposed on the exposed surface of the binding layer by dispersing said nanowires in a liquid vehicle and coating the nanowire-containing liquid onto the exposed surface of the binding layer. 
     
     
         4 . The reflective conductive film according to  claim 1  wherein the reflective polymeric substrate exhibits a reflectance at 540 nm of at least 80%. 
     
     
         5 . The reflective conductive film according to  claim 1  wherein the reflective conductive film exhibits a reflectance at 540 nm of at least 60%, and in one embodiment at least 70%. 
     
     
         6 . The reflective conductive film according to  claim 1  wherein the polymeric substrate is a polyester substrate. 
     
     
         7 . The reflective conductive film according to  claim 1  wherein the polyester of the base layer is selected from poly(ethylene terephthalate) and poly(ethylene 2,6-naphthalate). 
     
     
         8 . The reflective conductive film according to  claim 1  wherein the copolyester is selected from:
 (i) a copolyester derived from ethylene glycol, terephthalic acid and isophthalic acid; 
 (ii) a copolyester derived from terephthalic acid, an aliphatic dicarboxylic acid and a glycol; and 
 (iii) a copolyester derived from terephthalic acid, ethylene glycol and 1,4-cyclohexanedimethanol. 
 
     
     
         9 . The reflective conductive film according to  claim 8  wherein the copolyester is a copolyester derived from ethylene glycol, terephthalic acid and isophthalic acid which exhibits a molar ratio of the terephthalic acid component to the isophthalic acid component in the range from 25:75 to 85:15. 
     
     
         10 . The reflective conductive film according to  claim 8  wherein the copolyester is a copolyester derived from terephthalic acid, an aliphatic dicarboxylic acid and ethylene glycol which exhibits a molar ratio of the terephthalic acid component to the aliphatic dicarboxylic acid component about 50:50 to about 70:30. 
     
     
         11 . The reflective conductive film according to  claim 8  wherein the copolyester is derived from terephthalic acid, azelaic acid and ethylene glycol. 
     
     
         12 . The reflective conductive film according to  claim 10  wherein the copolyester is derived from terephthalic acid, azelaic acid and ethylene glycol. 
     
     
         13 . The reflective conductive film according to  claim 1  wherein the binding layer and base layer are coextruded. 
     
     
         14 . The reflective conductive film according to  claim 1  wherein the total thickness of the substrate is no more than 350 μm. 
     
     
         15 . The reflective conductive film according to  claim 1  wherein the polymeric substrate comprises one or more reflecting agent(s) selected from particulate inorganic filler(s), incompatible resin filler(s) and mixtures thereof, wherein the amount of reflecting agent incorporated into the substrate is in the range of from 5% to 60% by weight, based on the weight of the polymeric material of a given layer. 
     
     
         16 . The reflective conductive film according to  claim 1  wherein the polymeric substrate comprises a reflecting agent selected from titanium dioxide, barium sulphate and mixtures thereof. 
     
     
         17 . The reflective conductive film according to  claim 1  wherein the sheet resistance of the transparent conductive film is less than 100,000 ohms per square. 
     
     
         18 . The reflective conductive film according to  claim 1  wherein the nanowires are metal nanowires, and in one embodiment wherein the nanowires are silver nanowires. 
     
     
         19 . The reflective conductive film according to  claim 1  wherein the nanowires are carbon nanotubes. 
     
     
         20 . The reflective conductive film according to  claim 1  wherein the conductive layer is applied to the surface of the binding layer of the substrate after the film manufacture process has been completed, wherein following deposition of the nanowires, the film is heated to temperature T 1 . 
     
     
         21 . The reflective conductive film according to  claim 1  wherein the conductive layer is applied to the surface of the binding layer of the substrate during the film manufacturing process, wherein following deposition of the nanowires, the film is heated to temperature T 1 . 
     
     
         22 . The reflective conductive film according to  claim 21  wherein the conductive layer is applied to the surface of the binding layer of the substrate prior to the heat-setting step. 
     
     
         23 . The reflective conductive film according to  claim 22  wherein the conductive layer is applied to the surface of the binding layer of the substrate between the two stages (longitudinal and transverse) of a biaxial stretching operation. 
     
     
         24 . The reflective conductive film according to  claim 2  wherein the temperature T 1  is in the range of from about 50° C. to about 240° C. 
     
     
         25 . The reflective conductive film according to  claim 21  wherein the temperature T 1  is in the range of from about 50° C. to about 240° C. 
     
     
         26 . The reflective conductive film according to  claim 1  wherein said polymeric binding layer is a heat-sealable layer. 
     
     
         27 . The reflective conductive film according to  claim 1  wherein T S-HS  is at least about 5° C. below T S-B . 
     
     
         28 . The reflective conductive film according to  claim 1  wherein T S-HS  is in the range of from about 30 to about 250° C. 
     
     
         29 . The reflective conductive film according to  claim 1  wherein T S-HS  is greater than or equal to T g-HS  wherein T g-HS  is the glass transition temperature of the polymeric material of the binding layer. 
     
     
         30 . An electronic device comprising a reflective conductive film as defined in  claim 1 .