Method for making a conductive coating containing graphene on natural or synthetic leather, and natural or synthetic leather thus obtained

Abstract

Method for making a thermally and electrically conductive coating on natural or synthetic leather comprising the deposition of several layers based on aliphatic polyurethanes, with an intermediate layer, having a thickness from 10 to 50 μm, comprising graphene nano-platelets, wherein at least 90% has a lateral dimension (x, y) from 50 to 50000 μm and a thickness (z) from 0.34 to 50 nm, and wherein the C/O ratio is ≥100:1.

1 - 10 . (canceled) 
     
     
         11 . A method for making a thermally and electrically conductive coating containing graphene on a leather substrate, the method comprising:
 a) formation of an internal layer, comprising one or more aliphatic polyurethanes, having a thickness from 10 to 50 μm, and applied on the substrate;   b) formation of one or more intermediate layers, each of the one or more intermediate layers comprising a thickness from 10 to 50 μm and one or more aliphatic polyurethanes and graphene nano-platelets, wherein at least 90% of the graphene nano-platelets have a lateral dimension from 50 to 50000 nm and a thickness from 0.34 to 50 nm, and wherein a carbon-oxygen (C/O) ratio is ≥100:1; and   c) formation of an external layer comprising one or more aliphatic polyurethanes, the external layer having a thickness from 2 to 10 μm and applied on one of the one or more intermediate layers.   
     
     
         12 . The method of  claim 11 , wherein the substrate is a natural leather substrate or a textile substrate for production of synthetic leather. 
     
     
         13 . The method of  claim 11 , wherein in each of steps a), b), and c), the aliphatic polyurethanes are applied in the form of an aqueous dispersion. 
     
     
         14 . The method of  claim 13 , wherein the aqueous dispersion further comprises one or more components selected from a group consisting of: leveling agents; cross-linking agents; and thickening agents. 
     
     
         15 . The method of  claim 11 , further comprising a heating treatment at a temperature between 70 and 100° C. after each of steps a) and b), and a heating treatment at a temperature between 100 and 160° C. after step c), wherein each of the heating treatments are carried out for a time between 1 minute and 10 minutes. 
     
     
         16 . The method of  claim 11 , wherein:
 steps a), b), and c) are carried out in sequential order;   a deposition of the respective layers is carried out in reverse order with respect to the sequential order on an external support; and   the layers thus deposited are then coupled to the substrate, wherein the internal layer is in contact with the substrate, and the external support is detached, exposing the external layer.   
     
     
         17 . A leather substrate comprising a coating, wherein the coating comprises:
 an internal adhesive layer comprising one or more aliphatic polyurethanes, having a thickness from 10 to 50 μm, in contact with the substrate;   one or more intermediate layers, each of the one or more intermediate layers having a thickness from 10 to 50 μm, superimposed on the internal adhesive layer, each of the one or more intermediate layers comprising one or more aliphatic polyurethanes and nano-platelets of graphene, wherein at least 90% of the graphene nano-platelets have a lateral dimension from 50 to 50000 nm and a thickness (z) from 0.34 to 50 nm, and wherein a carbon-oxygen (C/O) ratio is ≥100:1; and   an outer layer comprising one or more aliphatic polyurethanes, having a thickness from 2 to 10 μm, and superimposed on one of the intermediate layers.   
     
     
         18 . The leather substrate of  claim 17 , comprising natural leather or a textile substrate for production of synthetic leather. 
     
     
         19 . The leather substrate of  claim 17 , wherein each of the internal adhesive layer, the one or more intermediate layers, and the external layer respectively comprises as its main component one or more aliphatic polyurethanes, present in amounts of at least 80% by weight of each individual layer. 
     
     
         20 . The leather substrate of  claim 19 , wherein each of the internal adhesive layer, the one or more intermediate layers, and the external layer respectively comprises as its main component one or more aliphatic polyurethanes, present in amounts of at least 90% by weight of each individual layer. 
     
     
         21 . The leather substrate of  claim 17 , wherein the graphene is present in each of the one or more intermediate layers in an amount from 0.5 to 15% by weight on a total weight of the respective layer. 
     
     
         22 . The leather substrate of  claim 21 , wherein the graphene is present in each of the one or more intermediate layers in an amount between 1.5 and 10% by weight. 
     
     
         23 . The leather substrate of  claim 22 , wherein the graphene is present in each of the one or more intermediate layers in an amount between 2 and 8% by weight. 
     
     
         24 . The leather substrate of  claim 17 , wherein the graphene comprises graphene nano-platelets, and wherein at least 90% of the graphene nano-platelets have a lateral dimension from 100 to 10000 nm and a thickness from 0.34 to 10 nm. 
     
     
         25 . The leather substrate of  claim 24 , wherein the at least 90% of the graphene nano-platelets have a lateral dimension from 200 to 8000 nm. 
     
     
         26 . The leather substrate of  claim 25 , wherein the at least 90% of the graphene nano-platelets have a lateral dimension between 500 and 5000 nm. 
     
     
         27 . The leather substrate of  claim 24 , wherein the at least 90% of the graphene nano-platelets have a thickness from 0.34 to 8 nm. 
     
     
         28 . The leather substrate of  claim 27 , wherein the at least 90% of the graphene nano-platelets have a thickness from 0.34 to 5 nm. 
     
     
         29 . The leather substrate of  claim 17 , wherein the graphene comprises graphene nano-platelets having a CIO ratio ≥100:1. 
     
     
         30 . The leather substrate of  claim 29 , wherein the graphene comprises graphene nano-platelets having a CIO ratio ≥200:1.