Method of Making Foam

Abstract

A method of making a foam from a polymerizable resin includes the following steps. A thermally-activated initiator having a temperature below the initiation temperature is combined with an elevated-temperature solution having the polymerizable resin and carbon dioxide at a temperature above a promoted temperature to create a resulting mixture having a temperature above the promoted temperature. The resulting mixture is expanded by decreasing the pressure of the mixture to create a froth having a plurality of cells formed by carbon dioxide that expanded out of solution. The polymerizable resin within the froth is cured to create a foam.

1 - 20 . (canceled) 
     
     
         21 . A method of making a foam, the method comprising:
 (i) providing a solution comprising:
 a polymerizable resin; 
 a thermally-activated initiator having a given promoted temperature; 
 carbon dioxide; and 
 optionally a promoter, wherein the temperature of the solution is below the promoted temperature of the initiator; 
   (ii) expanding the solution to create a froth comprising a plurality of cells formed by carbon dioxide that expanded out of solution; and   (iii) exposing the froth to microwave radiation to heat the froth above the promoted temperature of the initiator; and   (iv) curing the polymerizable resin to create a foam having a solidified matrix encasing the plurality of cells.   
     
     
         22 . The method of  claim 21 , wherein:
 the solution is provided by mixing the polymerizable resin, the initiator, and carbon dioxide in a mixing chamber at a pressure of at least 100 psig, preferably any one of at least 200, 300, 350, 500, and 800 psig; and   the expanding step (ii) occurs in a dispensing chamber having a pressure less than 100 psig.   
     
     
         23 . The method of  claim 21 , further comprising dispensing the froth from the dispensing chamber to create the foam of step (iv) outside of the dispenser chamber. 
     
     
         24 . The method of  claim 21 , wherein the method is conducted continuously. 
     
     
         25 . The method of  claim 21 , wherein the expanding step (ii) occurs intermittently. 
     
     
         26 . The method of  claim 21 , wherein the polymerizable resin comprises triglyceride having acrylate functionality. 
     
     
         27 . The method of  claim 21 , wherein the solution further comprises co-reactant. 
     
     
         28 . The method of  claim 27 , wherein the co-reactant comprises an acrylate. 
     
     
         29 . The method of  claim 21 , wherein the temperature of the solution of the providing step (i) is at most 45° C., preferably at most any one of 40, 35, 25, and 20° C. 
     
     
         30 . The method of  claim 21 , wherein the exposing step (iii) comprises directing microwave radiation toward a stream of the froth as the stream passes through the bore of a housing. 
     
     
         31 . The method of  claim 21 , wherein the solution of step (i) comprises one or more promoters.