Process for Foaming Polyolefin Compositions Using a Fluororesin/Azodicarbonamide Mixture as a Nucleating Agent

Abstract

The process of foaming a polyolefin, e.g., polyethylene, composition using as a nucleator a combination an azodicarbonamide (ADCA) and a fluororesin at a ADCA:fluororesin weight ratio of 60:40 to 20:80. The synergic effect between these two nucleating agents results in a higher nuclei density and a foamed product with a smaller cell size as compared to processes using and products produced by the use of neat PTFE or neat ADCA alone as the nucleating agent.

1 - 12 . (canceled) 
     
     
         13 . A composition, comprising:
 (a) a polyolefin; and   (b) a nucleator comprising:
 (i) azodicarbonamide (ADCA); and 
 (ii) a fluororesin; 
   wherein an ADCA:fluororesin weight ratio is from 60:40 to 20:80, further wherein the fluororesin is composed of agglomerates and particles with the fluororesin comprising 80% or more of particles or agglomerates of less than 1 micron in size based on the total number of agglomerates and particles of the fluororesin.   
     
     
         14 . The composition of  claim 13 , wherein the polyolefin comprises low density polyethylene (LDPE). 
     
     
         15 . The composition of  claim 14 , wherein the polyolefin consists of LDPE. 
     
     
         16 . The composition of  claim 13 , wherein the fluororesin comprises polytetrafluoroethylene (PTFE). 
     
     
         17 . The composition of  claim 16 , wherein the fluororesin consists of PTFE. 
     
     
         18 . The composition of  claim 13 , wherein the nucleator is present in the composition in an amount from 2 wt % to 10 wt %, based on the weight of the composition. 
     
     
         19 . The composition of claim  1 , wherein the composition comprises high-density polyethylene. 
     
     
         20 . The composition of  claim 19 , wherein the nucleator is present in the composition in an amount from 0.01 wt % to 1 wt %, based on the weight of the composition. 
     
     
         21 . The composition of  claim 13 , wherein the composition further comprises at least one of an antioxidant and a cell stabilizer.