Foam compositions and uses thereof

Abstract

A variety of forms and foam components are provided, including foam components for articles of footwear and athletic equipment. The articles include a composition having a foam structure, wherein the composition includes a thermoplastic copolyester elastomer comprising: (a) a plurality of first segments, each first segment derived from a dihydroxy-terminated polydiol; (b) a plurality of second segments, each second segment derived from a diol; and (c) a plurality of third segments, each third segment derived from an aromatic dicarboxylic acid. Methods of making the compositions and foams are provided, as well as methods of making an article of footwear including at least one of the foam components. In some aspects, the foams and foam components can be made by extrusion or injection molding to foam the polymeric composition, or extrusion or injection molding to foam the polymeric composition followed by compression molding of the foam.

What is claimed: 
     
         1 . A method of making a midsole component, the method comprising:
 forming a single phase solution (SPS) comprising a molten polymeric material and a blowing agent consisting of a supercritical fluid comprising carbon dioxide, wherein the molten polymeric material comprises a thermoplastic elastomer;   injecting the SPS into a pressurized mold cavity;   foaming the molten polymeric material of the SPS in the mold cavity by transitioning the supercritical fluid to a gas by decreasing pressure within the mold cavity, thereby forming a foamed polymeric material;   solidifying the foamed polymeric material in the mold cavity, thereby forming a midsole component including a single solidified thermoplastic foam portion, wherein the single solidified thermoplastic foam portion has a closed skin over its entire exterior surface, the closed skin surrounds an interior region, and the interior region has a multicellular foam structure, wherein the single solidified thermoplastic foam portion has a specific gravity of from about 0.08 to about 0.31; and   removing the midsole component from the mold cavity.   
     
     
         2 . The method of  claim 1 , wherein the thermoplastic elastomer is a thermoplastic copolyester elastomer, and the solidified thermoplastic foam portion is a solidified thermoplastic copolyester foam portion. 
     
     
         3 . The method of  claim 2 , wherein the interior region of the single solidified thermoplastic copolyester foam portion has an open-cell multicellular foam structure. 
     
     
         4 . The method of  claim 2 , wherein the thermoplastic copolyester elastomer comprises:
 (a) a plurality of first segments, each first segment of the plurality derived from a dihydroxy-terminated polydiol;   (b) a plurality of second segments, each second segment of the plurality derived from a diol; and   (c) a plurality of third segments, each third segment of the plurality derived from an aromatic dicarboxylic acid.   
     
     
         5 . The method of  claim 2 , wherein the thermoplastic copolyester elastomer comprises:
 (a) a plurality of first copolyester units, each first copolyester unit of the plurality comprising a segment derived from a dihydroxy-terminated polydiol and an additional segment derived from an aromatic dicarboxylic acid, wherein each first copolyester unit of the plurality has a structure represented by a formula 1:   
       
         
           
           
               
               
           
         
       
       wherein R 1  is a group remaining after removal of terminal hydroxyl groups from the dihydroxy-terminated polydiol of the first segment, wherein the dihydroxy-terminated polydiol of the first segment is a poly(alkylene oxide) diol having a number-average molecular weight of about 400 to about 6000; and wherein R 2  is a group remaining after removal of carboxyl groups from the aromatic dicarboxylic acid of the third segment; and
 (b) a plurality of second copolyester units, each second copolyester unit of the plurality comprising a segment derived from a diol and a further segment derived from an aromatic dicarboxylic acid, wherein each second copolyester unit of the plurality has a structure represented by a formula 2: 
 
       
         
           
           
               
               
           
         
       
       wherein R 3  is a group remaining after removal of hydroxyl groups from the diol of the second segment, wherein the diol of the second segment is a diol having a molecular weight of less than about 250; and wherein R 2  is the group remaining after removal of carboxyl groups from the aromatic dicarboxylic acid of the third segment. 
     
     
         6 . The method of  claim 4 , wherein the thermoplastic copolyester elastomer consists essentially of about 40 weight percent to about 65 weight percent of the plurality of second copolyester units based on total weight of the thermoplastic copolyester elastomer. 
     
     
         7 . The method of  claim 1 , wherein the supercritical fluid consists of carbon dioxide. 
     
     
         8 . The method of  claim 1 , wherein the supercritical fluid is present in the SPS in an amount of from about 1 percent to about 5 percent by weight based upon a total weight of the SPS. 
     
     
         9 . The method of  claim 1 , wherein the pressurized mold cavity has a first pressure greater than atmospheric pressure; and wherein the foaming the molten polymeric material comprises decreasing the first pressure to a second pressure initiating formation of gas bubbles by the supercritical fluid, thereby foaming the molten polymeric material. 
     
     
         10 . The method of  claim 1 , wherein the injecting comprises monitoring an injection pressure of the SPS prior or during the injecting, and controlling the injecting based on the injection pressure of the SPS. 
     
     
         11 . The method of  claim 1 , wherein the SPS has an expansion ratio of 1 as compared to a volume of the mold cavity. 
     
     
         12 . The method of  claim 1 , wherein before the foaming, a gas counter pressure of from about 100 pounds per square inch to about 3,000 pounds per square inch is applied to the mold cavity. 
     
     
         13 . The method of  claim 9 , wherein the second pressure is atmospheric pressure; and wherein decreasing the first pressure to the second pressure comprises venting the pressurized mold cavity to atmospheric pressure. 
     
     
         14 . The method of  claim 9 , wherein the second pressure is atmospheric pressure; and wherein decreasing the first pressure to the second pressure comprises using a controlled rate of pressure decrease until the mold cavity has a pressure essentially equal to atmospheric pressure. 
     
     
         15 . The method of  claim 14 , wherein the controlled rate of pressure decrease is from about 10 pounds per square inch per second to about 600 pounds per square inch per second. 
     
     
         16 . The method of  claim 1 , wherein the interior region of the single solidified thermoplastic foam portion has an average cell size of from about 50 microns to about 5 millimeters. 
     
     
         17 . The method of  claim 1 , wherein the single solidified thermoplastic foam portion has an energy efficiency when determined using a cyclic tensile test of greater than or equal to about 50%. 
     
     
         18 . The method of  claim 1 , wherein the single solidified thermoplastic foam portion has a split tear value of about 1.0 kilogram per centimeter to 4.5 kilogram per centimeter. 
     
     
         19 . The method of  claim 1 , wherein the thermoplastic elastomer does not form crosslinks during the foaming; and wherein the thermoplastic elastomer does not form crosslinks during the solidifying. 
     
     
         20 . The method of  claim 2 , wherein the thermoplastic elastomer is a block copolymer, a segmented copolymer, or a random copolymer.