High temperature non-crosslinked polyethylene-based foam and method of making the same

Abstract

A linear low density polyethylene (LLDPE) foam and methods of making the same are described. The LLDPE foam has a maximum operating temperature of about 220° F. The LLDPE foam can also have a density in the range of from 0.6 to 10.0 lbs/ft3. The LLDPE foam can be manufactured in part by processing an LLDPE resin in order to create a long branch molecular structure in the LLDPE resin without crosslinking or otherwise adversely affecting the thermoplastic properties of the LLDPE resin.

I/We claim: 
     
         1 . A high-temperature linear low density polyethylene-based foam comprising linear low density polyethylene foam, wherein the high-temperature linear low density polyethylene-based foam has a maximum operating temperature of about 220° F., wherein the low density polyethylene-based foam is formed from an linear low density polyethylene-based resin that is irradiated such that a melt index of the linear low density polyethylene-based resin is reduced from between 15 and 25 at 190° C. to between 0.7 and 5.0 at 190° C. 
     
     
         2 . The high-temperature linear low density polyethylene-based foam as claimed in  claim 1 , wherein the linear low density polyethylene-based foam has a density in the range of from 0.6 to 10.0 lbs/ft 3 . 
     
     
         3 . The high-temperature linear low density polyethylene-based foam as claimed in  claim 2 , wherein the high-temperature linear low density-based foam has density has a density in the range of from 1.0 to 2.0 lbs/ft 3 . 
     
     
         4 . The high-temperature linear low density polyethylene-based foam as claimed in  claim 1 , wherein the linear low density polyethylene includes a long chain branch molecular structure. 
     
     
         5 . The high-temperature linear low density polyethylene-based foam as claimed in  claim 1 , wherein the high temperature linear low density polyethylene-based foam is a non-crosslinked foam. 
     
     
         6 . The high-temperature linear low density polyethylene-based foam as claimed in  claim 1 , further comprising one or more additives selected from the consisting of flame retardants, color pigments, nucleating agents, diffusion blockers, and blowing agents. 
     
     
         7 . The high-temperature linear low density polyethylene-based foam as claimed in  claim 1 , wherein the high-temperature linear low density polyethylene-based foam meets the ASTM C411 standard for hot-surface performance of high-temperature thermal insulation when tested at temperatures up to about 220° F. 
     
     
         8 . A method of manufacturing a high-temperature linear low density polyethylene-based foam comprising:
 processing a linear low density polyethylene resin to produce a long branch molecular structure in the linear low density polyethylene resin, wherein the linear low density polyethylene resin has a melt index of between 15 and 25 at 190° C. and is irradiated until the melt index of the linear low density polyethylene resin is reduced to between 0.7 and 5.0 at 190° C.; and   manufacturing a high-temperature linear low density polyethylene-based foam from the processed linear low density polyethylene resin.   
     
     
         9 . The method of  claim 8 , wherein processing the linear low density polyethylene resin comprises irradiating the linear low density polyethylene resin. 
     
     
         10 . The method of  claim 9 , wherein the irradiation is carried out without eliminating the thermoplastic property of the linear low density polyethylene resin. 
     
     
         11 . The method of  claim 8 , wherein the linear low density polyethylene resin is a linear low density polyethylene resin having a melt temperature of about 255° F. 
     
     
         12 . The method of  claim 8 , wherein manufacturing a high temperature linear low density polyethylene-based foam from the processed linear low density polyethylene comprises a step of melting the processed linear low density polyethylene resin. 
     
     
         13 . The method of claim  112 , wherein manufacturing a high temperature linear low density polyethylene-based foam from the processed linear low density polyethylene further comprises the steps of:
 injecting a blowing agent into the melted linear low density polyethylene resin;   extruding the melted linear low density polyethylene resin; and   passing the melted linear low density polyethylene resin through a die.   
     
     
         14 . The method of  claim 12 , wherein manufacturing the high-temperature linear low density polyethylene-based foam from the processed polyethylene resin comprises using manufacturing equipment configured to manufacture low density polyethylene foam.