Nanofiber Non-Wovens Containing Particles

Abstract

A nano-fiber non-woven comprising a plurality of thermoplastic nano-fibers and a plurality of particles. At least 50% of the particles are positioned adjacent a surface of the nanofibers and at least 70% of the nanofibers are fused to other nanofibers within the nano-fiber non-woven. A process for making the nano-fiber non-woven is also disclosed.

1 . A nanofiber non-woven comprising a plurality of thermoplastic nano-fibers and a plurality of particles, wherein at least 50% of the particles are positioned adjacent a surface of the nanofibers and at least 70% of the nanofibers are fused to other nanofibers within the nanofiber non-woven. 
     
     
         2 . The nanofiber non-woven of  claim 1 , wherein the particles are nano-particles having at least one dimension less than one micron. 
     
     
         3 . The nanofiber non-woven of  claim 1 , wherein the particles are approximately equally distributed throughout the nanofiber non-woven. 
     
     
         4 . The nanofiber non-woven of  claim 1 , further comprising a second type of thermoplastic nanofibers. 
     
     
         5 . The nanofiber non-woven of  claim 1 , further comprising a second type of particles. 
     
     
         6 . The nanofiber non-woven of  claim 1 , further comprising a thermoplastic matrix which at least partially encapsulates a portion of the particles and the nanofibers. 
     
     
         7 . The nanofiber non-woven of  claim 1 , further comprising a plurality of micron-sized fibers. 
     
     
         8 . The nanofiber non-woven of  claim 1 , wherein the average diameter of the nanofibers is less than about 200 nanometers. 
     
     
         9 . The nanofiber non-woven of  claim 1 , wherein at least 80% of the particles are positioned adjacent a surface of the nanofibers. 
     
     
         10 . The nanofiber non-woven of  claim 1 , wherein at least 95% of the nanofibers are fused to at least one other nanofiber. 
     
     
         11 . The nanofiber non-woven of  claim 1 , wherein the thermoplastic nanofibers comprise a thermoplastic selected from the group consisting of polyolefins, polycarbonates, polyesters, and polyamides. 
     
     
         12 . A nanofiber non-woven formed by the process comprising, in order:
 a) mixing a plurality of particles, a first thermoplastic polymer and a second thermoplastic polymer, wherein the first polymer and second polymer are in a softened state, wherein the second polymer is at least partially soluble in a first solvent, and optionally cooling the mixture;   b) subjecting the mixture of step b) to elongational forces and heat forming nanofibers comprising the first polymer;   c) bringing the mixture of step c) to a condition where the temperature is below the softening temperature of the first polymer forming a first intermediate;   d) consolidating the first intermediate with pressure and a temperature greater than the glass transition temperature of the second polymer forming a second intermediate, wherein at least 70% of the nanofibers are fused to other nanofibers, and   e) removing at least a portion of the second polymer from the second intermediate forming the nanofiber non-woven, wherein after step e) at least 50% of the particles are positioned adjacent a surface of the nanofibers.   
     
     
         13 . The nanofiber non-woven of  claim 12 , wherein the particles are nano-particles having at least one dimension less than one micron. 
     
     
         14 . The nanofiber non-woven of  claim 12 , wherein the mixing of step a) is performed at a temperature greater than the softening temperature of the second polymer. 
     
     
         15 . The nanofiber non-woven of  claim 12 , wherein the mixing of step a) is performed at a temperature where both the first and second polymers are in a molten state. 
     
     
         16 . The nanofiber non-woven of  claim 12 , wherein the subjecting the mixture of step a) to elongational forces comprises extruding the particles, the first polymer, and the second polymer in the softened state. 
     
     
         17 . The nanofiber non-woven of  claim 12 , wherein bringing the mixture of step b) to a condition where the temperature is below the softening temperature of the first polymer comprises cooling the mixture of step b) to a temperature is below the softening temperature of the first polymer. 
     
     
         18 . The nanofiber non-woven of  claim 12 , wherein the consolidation of step d) is at a temperature below the softening temperature of the first polymer. 
     
     
         19 . The nanofiber non-woven of  claim 12 , wherein removing at least a portion of the second polymer comprises removing essentially all of the second polymer with the first solvent. 
     
     
         20 . The nanofiber non-woven of  claim 12 , wherein the particles are approximately equally distributed throughout the composite. 
     
     
         21 . The nanofiber non-woven of  claim 12 , wherein at least 80% of the particles are positioned adjacent a surface of the nanofibers in the nanofiber non-woven. 
     
     
         22 . The nanofiber non-woven of  claim 12 , wherein at least 85% of the nanofibers are fused to at least one other nanofiber in the nanofiber non-woven. 
     
     
         23 . The nanofiber non-woven of  claim 12 , wherein the thermoplastic nanofibers comprise a thermoplastic selected from the group consisting of polyolefins, polycarbonates, polyesters, and polyamides.