Surface-modified plexifilamentary structures, and compositions therefor

Abstract

The present invention is concerned with flash-spinning a surface-modified structure such as a plexifilimentary yarn or a microcellular foam.

1 . A process for flash spinning comprising 
 (a) forming a spin mixture that comprises a spin agent and a polymer mixture,    (b) pressurizing the spin mixture to a first pressure that is greater than the autogenous pressure thereof, and    (c) extruding the spin mixture through an aperture into a region at a pressure that is less than the autogenous pressure of the spin mixture, and at a temperature such that the spin agent vaporizes upon exposure to the region, to form a flash-spun structure;    wherein the polymer mixture comprises 0 to 95% by weight of a first polymer and 5 to 100% by weight of a second polymer;    wherein the first polymer is selected from the group consisting of polyolefins, copolymers thereof with ethylenically unsaturated monomers, polyesters, and mixtures thereof; and    wherein the second polymer is selected from the group consisting of polyolefins, copolymers thereof with ethylenically unsaturated monomers, polyesters, and mixtures thereof, and the second polymer comprises 1 to 25 mol % of pendant functional groups.    
     
     
         2 . The process of  claim 1  further comprising subjecting the pressurized spin mixture to a second pressure that is less than the first pressure but is greater than the autogenous pressure of the spin mixture prior to extruding the mixture into the region.  
     
     
         3 . The process of  claim 1  or  claim 2  wherein forming the flash spun structure comprises forming a plexifilamentary yarn.  
     
     
         4 . The process of  claim 1  or  claim 2  wherein forming the flash spun structure comprises forming a microcellular foam.  
     
     
         5 . The process of  claim 1  or  claim 2  wherein the polymer mixture comprises 70 to 95 percent by weight of the first polymer and 30 to 5 percent by weight of the second polymer.  
     
     
         6 . The process of  claim 1  or  claim 2  wherein the first polymer is polyethylene terephthalate.  
     
     
         7 . The process of  claim 1  or  claim 2  wherein the first polymer is polyethylene.  
     
     
         8 . The process of  claim 1  or  claim 2  wherein the second polymer is polyethylene terephthalate.  
     
     
         9 . The process of  claim 1  or  claim 2  wherein the second polymer is polyethylene.  
     
     
         10 . The process of  claim 1  or  claim 2  wherein the pendant group is a fluoro-olefin radical.  
     
     
         11 . The process of  claim 8  wherein the second polymer is polyethylene terephthalate grafted with fluoro-olefin radical.  
     
     
         12 . The process of  claim 9  wherein the second polymer is polyethylene grafted with fluoro-olefin radical.  
     
     
         13 . The process of  claim 1  or  claim 2  wherein the pendant group is oxyethylene trimer.  
     
     
         14 . The process of  claim 8  wherein the second polymer is polyethylene terephthalate grafted with oxyethylene trimer.  
     
     
         15 . The process of  claim 9  wherein the second polymer is polyethylene grafted oxyethylene trimer.  
     
     
         16 . The process of  claim 1  or  claim 2  wherein the pendant group is a perfluorovinyl ether.  
     
     
         17 . The process of  claim 8  wherein the second polymer is polyethylene terephthalate grafted with perfluorovinyl ether.  
     
     
         18 . The process of  claim 9  wherein the second polymer is polyethylene grafted perfluorovinyl ether.  
     
     
         19 . The process of  claim 1  or  claim 2  wherein the pendant group is a vinyl silane.  
     
     
         20 . The process of  claim 8  wherein the second polymer is polyethylene terephthalate grafted with vinyl silane.  
     
     
         21 . The process of  claim 9  wherein the second polymer is polyethylene grafted vinyl silane.  
     
     
         22 . The process of  claim 1  or  claim 2  further comprising adjusting the first pressure to an amount that is greater than the cloud point pressure of any individual polymer in the spin mixture.  
     
     
         23 . The process of  claim 1  or  claim 2  further comprising heating the flash-spun structure thereby formed to a temperature of at least 100° C.  
     
     
         24 . The process of  claim 3  further comprising heating the plexifilimentary yarn thereby formed to a temperature of at least 100° C.  
     
     
         25 . A process for flash spinning comprising 
 (a) forming a spin mixture that comprises a spin agent selected from the group consisting of aliphatic hydrocarbons, fluorocarbons, halogenated hydrocarbons, and hydrofluorocarbons, and a polymer mixture,    (b) pressurizing the spin mixture to a first pressure that is greater than the autogenous pressure thereof,    (c) subjecting the pressurized spin mixture to a second pressure that is less than the first pressure but is greater than the autogenous pressure of the spin mixture, and    (d) extruding the spin mixture through an aperture into a region at a third pressure that is less than the autogenous pressure of the spin mixture, and at a temperature such that the spin agent vaporizes upon exposure to the region, to form a flash-spun structure;    wherein the polymer mixture comprises 70 to 95 percent by weight of a first polymer and 5 to 30 percent by weight of a second polymer;    wherein the first polymer is polyethylene or polyethylene terephthalate; and    wherein the second polymer is polyethylene or polyethylene terephthalate, and the second polymer comprises 5 to 15 mol % of pendant fluorocarbon radicals or oxyethylene radicals.    
     
     
         26 . The process of  claim 25  wherein the second polymer is grafted with 5 to 15 mol % fluorocarbon radicals.  
     
     
         27 . The process of  claim 25  wherein the second polymer is grafted with 5 to 15 mol % oxyethylene radicals.  
     
     
         28 . The process of  claim 25  further comprising heating the flash-spun structure thereby formed to a temperature of at least 100° C.  
     
     
         29 . A spin mixture comprising a spin agent and a polymer mixture comprising 0 to 95% by weight of polyethylene or polyethylene terephthalate and 5 to 100% by weight of a functional polymer the functional polymer being polyethylene or polyethylene terephthalate having 1 to 25 mol % of pendant functional groups selected from the group consisting of fluorocarbon radicals and oxyethylene radicals.  
     
     
         30 . A spin mixture comprising a spin agent and a polymer mixture, 
 wherein the polymer mixture comprises 0 to 95% by weight of a first polymer and 5 to 100% by weight of a second polymer;    wherein the first polymer is selected from the group consisting of polyolefins, copolymers thereof with ethylenically unsaturated monomers, polyesters, and mixtures thereof; and    wherein the second polymer is selected from the group consisting of polyolefins, copolymers thereof with ethylenically unsaturated monomers, polyesters, and mixtures thereof, and the second polymer comprises 1 to 25 mol % of pendant functional groups.    
     
     
         31 . The spin mixture of  claim 30  wherein the spin agent is selected from the group consisting of aliphatic hydrocarbons, fluorocarbons, halogenated hydrocarbons, and hydrofluorocarbons  
     
     
         32 . The spin mixture of  claim 30  wherein the polymer mixture comprises 70 to 95 percent by weight of the first polymer and 30 to 5 percent by weight of the second polymer.  
     
     
         33 . The spin mixture of  claim 30  wherein the first polymer is polyethylene terephthalate.  
     
     
         34 . The spin mixture of  claim 30  wherein the first polymer is polyethylene.  
     
     
         35 . The spin mixture of  claim 30  wherein the second polymer is polyethylene terephthalate.  
     
     
         36 . The spin mixture of  claim 30  wherein the second polymer is polyethylene.  
     
     
         37 . The spin mixture of  claim 30  wherein the pendant group is a fluoro-olefin radical.  
     
     
         38 . The spin mixture of  claim 30  wherein the second polymer is grafted with fluoro-olefin radical.  
     
     
         39 . The spin mixture of  claim 30  wherein the pendant group is oxyethylene trimer.  
     
     
         40 . The spin mixture of  claim 30  wherein the second polymer is grafted with oxyethylene trimer.  
     
     
         41 . The spin mixture of  claim 30  wherein the pendant group is a perfluorovinyl ether.  
     
     
         42 . The spin mixture of  claim 30  wherein the second polymer is grafted with perfluorovinyl ether.  
     
     
         43 . The spin mixture of  claim 30  wherein the pendant group is a vinyl silane.  
     
     
         44 . The spin mixture of  claim 30  wherein the second polymer is grafted with vinyl silane.  
     
     
         45 . The spin mixture of  claim 30  wherein the second polymer comprises 5 to 15 mol % of pendant functional groups.  
     
     
         46 . The spin mixture of  claim 30  formed as a plexifilamentary yarn.  
     
     
         47 . The spin mixture of  claim 30  formed as a microcellular foam.  
     
     
         48 . The spin mixture of  claim 30  formed as a non-woven fabric.  
     
     
         49 . The plexifilimentary yarn of  claim 46  formed as a non-woven fabric.