Processing aids for use in manufacturing extruded polystyrene foams using low global warming potential blowing agents

Abstract

A foamable polymeric mixture is provided that includes a polymer composition and at least one blowing agent. The blowing agent may comprise any blowing agents known not to deplete the ozone or increase the prevalence of global warming, such as CO 2 , HFO, HFC and mixtures thereof. The foamable polymeric mixture may further includes at least one processing aid comprising an organic phase changing material. The inventive foamable mixture is capable of processing at a pressure range of 800 to 1200 psi (5.5 to 8.3 MPa).

1 . A foamable polymeric mixture comprising:
 a polymer composition;   at least one blowing agent, said blowing agent comprising at least one of carbon dioxide, hydrofluoroolefins, and hydrofluorocarbons, and mixtures thereof; and   at least one processing aid comprising an organic phase changing material, wherein said foamable mixture is capable of processing at a pressure range of 800 to 1200 psi (5.5 to 8.3 MPa).   
     
     
         2 . The foamable polymeric mixture of  claim 1 , wherein said polymer composition comprises an alkenyl aromatic polymer. 
     
     
         3 . The foamable polymeric mixture of  claim 2 , wherein said polymer composition comprises a polystyrene. 
     
     
         4 . The foamable polymeric mixture of  claim 1 , wherein said foamable polymeric mixture comprises at least 0.05 to 5.0 weight percent CO 2 . 
     
     
         5 . The foamable polymeric mixture of  claim 1 , wherein said processing aid comprises at least one of a fatty acid ester and a wax. 
     
     
         6 . The foamable polymeric mixture of  claim 5 , wherein said processing aid comprises a synthetic beeswax. 
     
     
         7 . The foamable polymeric mixture of  claim 1 , wherein said processing aid comprises between 0.05 and 10.0 weight percent of the total foamable polymeric mixture. 
     
     
         8 . The foamable polymeric mixture of  claim 1 , wherein said processing aid is microencapsulated. 
     
     
         9 . The foamable polymeric mixture of  claim 1 , further including at least one infrared attenuating agent. 
     
     
         10 . A method of manufacturing extruded polymeric foam comprising:
 introducing a polymer composition into a screw extruder to form a polymer melt;   injecting at least one organic phase changing processing aid and at least one blowing agent into said polymer melt to form an foamable polymeric material, said blowing agent comprising one or more of carbon dioxide, hydrofluorocarbon, and hydrofluoroolefin; and   extruding said extrusion composition through a die under a processing temperature between 800 and 1200° F. to produce a polymeric foam.   
     
     
         11 . The method of  claim 10 , further including the step of microencapsulating said processing aid into a powder prior to injection into said polymer melt. 
     
     
         12 . The method of  claim 10 , further including the step of compounding said processing aid into said polymeric composition forming a masterbatch. 
     
     
         13 . The method of  claim 10 , wherein said processing aid comprises at least one of a fatty acid ester and a wax. 
     
     
         14 . The method of  claim 10 , wherein said polymeric foam is a substantially closed cell foam. 
     
     
         15 . The method of  claim 10 , wherein said polymeric foam has an R value between about 4.0 and 7.0. 
     
     
         16 . An extruded polymeric foam comprising:
 a foamable polymeric material, said material comprising:
 a polymer composition; 
 at least one blowing agent, said blowing agent comprising at least one of carbon dioxide, hydrofluoroolefins, and hydrofluorocarbons, and mixtures thereof; and 
 at least one processing aid comprising an organic phase changing material, wherein said foam has an R-value between 4 and 7. 
   
     
     
         17 . The extruded polymeric foam of  claim 16 , wherein said polymer composition comprises a polystyrene. 
     
     
         18 . The processing aid of  claim 17 , wherein said processing aid is compounded into said polystyrene forming a masterbatch. 
     
     
         19 . The extruded polymeric foam of  claim 16 , wherein said processing aid is a fatty acid ester. 
     
     
         20 . The extruded polymeric foam of  claim 16 , wherein said processing aid is a synthetic beeswax. 
     
     
         21 . The extruded polymeric foam of  claim 16 , wherein said processing aid is microencapsulated by a polymer material comprising one or more of melamine formaldehyde, urea formaldehyde, and acrylate copolymer resins. 
     
     
         22 . A foamable polymeric mixture comprising:
 a polymer composition;   at least one blowing agent, said blowing agent comprising at least one of carbon dioxide, hydrofluoroolefins, and hydrofluorocarbons, and mixtures thereof; and   at least one processing aid comprising an organic phase changing material, wherein said foamable polymeric mixture is capable of forming an extruded polymeric foam, said foam having:
 an R-value between 4 and 7 per inch; 
 an average cell size between 0.005 and 0.6 mm; 
 a compressive strength between 6 and 80 psi; 
 a density between 1.3-4 pcf; and 
 an open cell content of less than 30 percent. 
   
     
     
         23 . The foamable polymeric mixture of  claim 22 , wherein said extruded polymeric foam has a an open cell content of less than 10 percent. 
     
     
         24 . The foamable polymeric mixture of  claim 22 , wherein said foamable mixture is capable of forming said extruded polymeric foam at a pressure range of 800 to 1200 psi (5.5 to 8.3 MPa).