Polymeric foam containing alumina boehmite

Abstract

Prepare a polymeric foam by expanding a foamable polymer composition comprising alumina boehmite.

1 . A process for producing a polymeric foam comprising the following steps:
 a. providing a foamable polymer composition comprising a blowing agent dispersed in a polymer matrix, the polymer matrix having a softening temperature; and   b. exposing the foamable polymer composition while at a temperature at or above the softening temperature of the polymer matrix to an environment having a pressure low enough to cause the foamable polymer composition to expand into a polymeric foam;   
       wherein the foamable polymer composition further comprises alumina boehmite dispersed in the polymer matrix. 
     
     
         2 . The process of  claim 1 , wherein the process is an extrusion process where the foamable polymer composition is provided in an extruder at an initial temperature that is above the softening temperature of the polymer matrix and at an initial pressure that precludes foaming of the foamable polymer composition and where step (b) occurs by expelling the foamable polymer composition to an environment having a pressure lower than the initial pressure and sufficiently low to cause the foamable polymer composition to expand into an extruded polymeric foam. 
     
     
         3 . The process of  claim 1 , wherein the alumina boehmite is present in the polymer matrix at a concentration in a range of 0.1 to 30 weight-percent based on polymer matrix weight. 
     
     
         4 . The process of  claim 1 , wherein the alumina boehmite has a nitrate concentration of less than 3.0 weight percent. 
     
     
         5 . The process of  claim 1 , wherein 50 weight-percent of all the polymers in the polymer matrix are alkenyl aromatic polymers. 
     
     
         6 . The process of  claim 1 , wherein the blowing agent comprises carbon dioxide. 
     
     
         7 . The process of  claim 1 , wherein the blowing agent comprises carbon dioxide and at least one of iso-butane and water. 
     
     
         8 . A polymeric foam comprising a polymer matrix defining a plurality of cells dispersed therein and further comprising alumina boehmite dispersed within the polymer matrix. 
     
     
         9 . The polymeric foam of  claim 8 , wherein the polymeric foam is extruded polymeric foam that is free of a network of polymer skins defining foam beads. 
     
     
         10 . The polymeric foam of  claim 8 , wherein the alumina boehmite is present at a concentration in a range of 0.1 to 30 weight percent based on total polymer weight in the polymer matrix. 
     
     
         11 . The polymeric foam of  claim 8 , wherein the alumina boehmite is present at a concentration in a range of 0.5 to 5 weight-percent based on polymer composition weight. 
     
     
         12 . The polymeric foam of  claim 8 , wherein the alumina boehmite has a nitrate concentration of less than three weight-percent. 
     
     
         13 . The polymeric foam of  claim 8 , wherein more than 50 weight-percent of all the polymers in the polymer matrix are alkenyl aromatic polymers. 
     
     
         14 . The polymeric foam of  claim 8 , wherein the alkenyl aromatic polymer is selected from polystyrene homopolymer and styrenic copolymers. 
     
     
         15 . The polymeric foam of  claim 8 , wherein the polymeric foam has an open cell content of five percent or less.