Water and oil repellent porous particles and methods for making the same

Abstract

This invention relates to a hydrophobic and oleophobic porous materials and processes for making the same. In a first process of the invention, a thermoplastic substrate is at least partially coated and/or impregnated with a surface treatment material. In a second process of the invention, thermoplastic particles which comprise a surface treatment material are sintered together. Preferred surface treatment materials are fluorochemicals.

What is claimed is:  
     
         1 . A porous hydrophobic and/or oleophobic material having a surface energy of from about 5 dynes/cm 2  to about 30 dynes/cm 2  which comprises a sintered porous thermoplastic substrate having a surface at least part of which is coated with a high molecular weight fluorochemical.  
     
     
         2 . The material of  claim 1  wherein the porous thermoplastic substrate is made of a thermoplastic selected from the group consisting of: ethylene vinyl acetate; ethylene methyl acrylate; polyethylenes; polypropylenes; ethylene-propylene rubbers; ethylene-propylene-diene rubbers; poly(1-butene); polystyrene; poly(2-butene); poly(1-pentene); poly(2-pentene); poly(3-methyl-1-pentene); poly(4-methyl-1-pentene); 1,2-poly-1,3-butadiene; 1,4-poly-1,3-butadiene; polyisoprene; polychloroprene; poly(vinyl acetate); poly(vinylidene chloride); and mixtures and derivatives thereof.  
     
     
         3 . The material of  claim 2  wherein thermoplastic is polyethylene.  
     
     
         4 . The material of  claim 3  wherein the polyethylene is ultra-high molecular weight polyethylene.  
     
     
         5 . The material of  claim 1  wherein the high molecular weight fluorochemical is selected from the group consisting of fluorinated acrylates, methacrylates, acrylic esters, and mixtures thereof.  
     
     
         6 . The material of  claim 5  wherein the high molecular weight fluorochemical is polymerized from a compound selected from the group consisting of:  
       
         
           
           
               
               
           
         
       
       and mixtures thereof, wherein R f  is —CF 3 (CF 2 ) n , n is an integer of from about 1 to about 18, preferably of from 1 to 4, and R is hydrogen or substituted or unsubstituted alkyl, aryl, or aralkyl.  
     
     
         7 . The material of  claim 6  wherein the high molecular weight fluorochemical is polymerized from a compound selected from the group consisting of:  
       
         
           
           
               
               
           
         
       
       wherein R f  is —CF 3 (CF 2 ) n , and n is an integer of from about 1 to about 18.  
     
     
         8 . A porous hydrophobic and/or oleophobic material which comprises a sintered porous thermoplastic substrate and a surface treatment material disposed throughout at least part of the substrate.  
     
     
         9 . The material of  claim 8  wherein the porous thermoplastic substrate is made of a thermoplastic selected from the group consisting of: ethylene vinyl acetate; ethylene methyl acrylate; polyethylenes; polypropylenes; ethylene-propylene rubbers; ethylene-propylene-diene rubbers; poly(1-butene); polystyrene; poly(2-butene); poly(1-pentene); poly(2-pentene); poly(3-methyl-1-pentene); poly(4-methyl-1-pentene); 1,2-poly-1,3-butadiene; 1,4-poly-1,3-butadiene; polyisoprene; polychloroprene; poly(vinyl acetate); poly(vinylidene chloride); and mixtures and derivatives thereof.  
     
     
         10 . The material of  claim 9  wherein the porous thermoplastic substrate is made of polyethylene.  
     
     
         11 . The material of  claim 8  wherein the surface treatment material is a low molecular weight fluorochemical.  
     
     
         12 . The material of  claim 11  wherein the low molecular weight fluorochemical is selected from the group consisting of: fluorinated urethanes, allophanates, oxazolidones, piperazines, and mixtures thereof.  
     
     
         13 . The material of  claim 11  wherein the low molecular weight fluorochemical is of the formula:  
       
         
           
           
               
               
           
         
       
       wherein each R f  is independently —CF 3 (CF 2 ) n , n is an integer of from about 1 to about 18, and R′ is selected from the group consisting of:  
       
         
           
           
               
               
           
         
       
       and derivatives thereof, wherein m is an integer of from about 1 to about 20.  
     
     
         14 . The material of  claim 13  wherein the low molecular weight fluorochemical is of the formula:  
       
         
           
           
               
               
           
         
       
       wherein each R f  is independently —CF 3 (CF 2 ) n , and n is an integer of from about 1 to about 18.  
     
     
         15 . A particle comprised of surface treatment material disposed about a thermoplastic core.  
     
     
         16 . The particle of  claim 15  wherein the surface treatment material is a low molecular weight fluorochemical.  
     
     
         17 . The particle of  claim 15  wherein the thermoplastic core is made of polyethylene.  
     
     
         18 . A particle which comprises a surface treatment material of the formula:  
       
         
           
           
               
               
           
         
       
       disposed about a polyethylene core, wherein each R f  is independently —CF 3 (CF 2 ) n , and n is an integer of from about 1 to about 18.  
     
     
         19 . The particle of  claim 18  wherein said particle has a diameter of from about 5 μM to about 1000 μM.  
     
     
         20 . A process for making a porous hydrophobic and/or oleophobic material which comprises contacting a sintered porous thermoplastic substrate with a high molecular weight fluorochemical, wherein the substrate is made of polyethylene.  
     
     
         21 . The product of the process of  claim 20 .  
     
     
         22 . A process for making a particle which comprises cooling a molten pre-particle, wherein the pre-particle is comprised of a thermoplastic and a surface treatment material.  
     
     
         23 . The process of  claim 22  wherein the surface treatment material is a low molecular weight fluorochemical.  
     
     
         24 . The product of the process of  claim 22 .  
     
     
         25 . A process for making a porous hydrophobic and/or oleophobic material which comprises sintering particles which are comprised of a surface treatment material disposed about a thermoplastic core.  
     
     
         26 . The process of  claim 25  wherein the surface treatment material is a low molecular weight fluorochemical and the thermoplastic core is polyethylene.  
     
     
         27 . The product of the process of  claim 25 .