Process for the production of expanded material based on sulfone polymers

Abstract

A process for the production of expanded material based on sulfone polymers includes an extrusion step in an extruder of virgin sulfone polymer with the injection of at least one expanding agent and in the presence of at least one nucleating agent, and a recycling step of part of the expanded material, which provides a recycled product used as raw material fed to the extruder in combination with the virgin sulfone polymer.

The invention claimed is: 
     
         1 . An expanded material from sulfone polymer, comprising:
 an expanded material having a density ranging from 20 to 200 kg/m 3  and a closed-cell structure, the expanded material being produced with a process comprising:   extruding, in an extruder, virgin sulfone polymer by injecting at least one expanding agent in presence of at least one nucleating agent to produce the expanded material; and   recycling a part of the expanded material to produce a recycled product, fed as a raw material to the extruder in combination with the virgin sulfone polymer.   
     
     
         2 . The expanded material according to  claim 1 , wherein the expanded material has over 80% of closed cells. 
     
     
         3 . The expanded material according to  claim 1 , wherein the expanded material has over 95% of closed cells. 
     
     
         4 . The expanded material according to  claim 1 , wherein the recycled product consists of particles of the expanded material having a size ranging from 0.1 mm to 10 mm. 
     
     
         5 . The expanded material according to  claim 1 , wherein the recycled product has the following structural formula: 
       
         
           
           
               
               
           
         
         wherein: 
       
       
         
           
           
               
               
           
         
         wherein: 
         n=60-400, and 
         m=0.1. 
       
     
     
         6 . The expanded material according to  claim 1 , wherein the recycled product has:
 a T g  value of at least 180° C. as measured according to standard DIN EN ISO 11357 with DSC (differential scanning calorimetry), under the following conditions:   equilibrium at 0° C.,   temperature rise at 20° C./min from 0 to 340° C.,   isotherm at 340° C. for 5 minutes,   cooling at 20° C./min from 340° C. to 0° C.,   isotherm 5 minutes,   second temperature rise at 20° C./min from 0 to 340° C., and   an IV value of at least 30 ml/g as measured according to standard DIN EN ISO 1628-1 under the following conditions:   concentration analyzed from 0.008 to 0.013 g/ml,   ratio solvent phenol:tetrachloroethane being (60:40);   using a Uhbbelold IC capillary,   analysis of temperature at 30° C., and   a density of at least 1000 kg/m 3 .   
     
     
         7 . The expanded material according to  claim 1 , wherein the recycled product is a polyethersulfone having:
 an IV=30-50 ml/g as measured according to standard DIN EN ISO 1628-1 under the following conditions:   concentration analyzed from 0.008 to 0.013 g/ml,   a ration of solvent phenol:tetrachloroethane being (60:40),   using a Uhbbelold IC capillary,   an analysis of temperature at 30° C.,   and   T g =223-228° C. as measured according to standard DIN EN ISO 11357 with DSC (differential scanning calorimetry), under the following conditions:   equilibrium at 0° C.,   temperature rise at 20° C./min from 0 to 340° C.,   isotherm at 340° C. for 5 minutes,   cooling at 20° C./min from 340° C. to 0° C.,   isotherm for 5 minutes, and   a second temperature rise at 20° C./min from 0 to 340° C.