Foam compositions and uses thereof

Abstract

Components for articles of footwear and athletic equipment including a foam are provided. The foam portion of the components and articles include a composition which includes a thermoplastic copolyester, the composition having a foam structure. A polymer layer is provided on at least on surface of the foam portion. The polymer layer can control or reduce the water uptake of the foam portion. Methods of making the compositions, foams, and components are provided, as well as methods of making an article of footwear including one of the foam components. In some aspects, the foams and foam components can be made by injection molding, or injection molding followed by compression molding.

What is claimed: 
     
         1 . A cushioning element for an article of footwear, the cushioning element comprising:
 a first foam, wherein the first foam is a thermoplastic multicellular foam having an open cell foam microstructure, an average cell size of from about 50 micrometers to about 500 micrometers, and a specific gravity of about 0.15 to about 0.25;   wherein the first foam compositionally comprises a first thermoplastic composition comprising one or more copolyesters;   wherein the first foam is the physically foamed product of a single-phase solution of a supercritical fluid and the first thermoplastic composition in a molten state; and   wherein the first thermoplastic composition of the first foam is free or essentially free of nucleating agents, or is free or essentially free of fillers, or is free or essentially free of both nucleating agents and fillers.   
     
     
         2 . The cushioning element of  claim 1 , wherein the cushioning element is produced by the method comprising:
 forming a single-phase solution of the first thermoplastic composition comprising the one or more thermoplastic copolyesters and the supercritical fluid, wherein the first thermoplastic composition is molten in the single-phase solution;   injecting the single-phase solution into a mold cavity, the single-phase solution having an injection temperature during the injecting;   reducing pressure in the mold cavity and foaming the molten first thermoplastic composition, the single-phase solution having a foaming temperature during the foaming, thereby forming a first foam, wherein the first foam is a thermoplastic multicellular foam having an open cell foam microstructure;   solidifying the first foam; and   removing the solidified first foam from the mold cavity, forming the cushioning element.   
     
     
         3 . The cushioning element of  claim 1 , wherein the supercritical fluid comprises supercritical carbon dioxide or supercritical nitrogen. 
     
     
         4 . The cushioning element of  claim 1 , wherein the supercritical fluid is present in the single-phase solution in an amount of about 1 percent to about 3 percent by weight based on upon a total weight of the single-phase solution. 
     
     
         5 . The cushioning element of  claim 1 , wherein the foaming temperature is from about the melting temperature of the thermoplastic copolyester as determined by dynamic scanning calorimetry to about 50 degrees centigrade above the tail temperature of the thermoplastic copolyester as determined by dynamic scanning calorimetry. 
     
     
         6 . The cushioning element of  claim 1 , wherein the first foam has a split tear greater than or equal to about 2.0 kg/cm, or an energy efficiency greater than or equal to about 60 percent, or both. 
     
     
         7 . The cushioning element of  claim 1 , wherein the first thermoplastic composition of the first foam comprises less than 5 weight percent of dyes or pigments. 
     
     
         8 . The cushioning element of  claim 1 , wherein the first thermoplastic composition of the first foam further comprises a non-polymeric component comprising all non-polymeric ingredients present in the first thermoplastic composition, and the non-polymeric component makes up less than one weight percent of the first thermoplastic composition based on a total weight of the first thermoplastic composition. 
     
     
         9 . The cushioning element of  claim 1 , wherein the first thermoplastic composition of the first foam comprises a polymeric component comprising all polymers present in the first thermoplastic composition, and the polymeric component makes up at least 95 weight percent of the first thermoplastic composition based on a total weight of the first thermoplastic composition. 
     
     
         10 . The cushioning element of  claim 1 , wherein the first thermoplastic composition of the first foam comprises a polymeric component comprising all polymers present in the first thermoplastic composition, and, in addition to the one or more copolyesters, the polymeric component further comprises a polyester, a polyolefin, or both. 
     
     
         11 . The cushioning element of  claim 1 , wherein the first thermoplastic composition of the first foam comprises a polymeric component comprising all polymers present in the first thermoplastic composition, and the polymeric component consists essentially of the one or more copolyesters. 
     
     
         12 . The cushioning element of  claim 1 , wherein the thermoplastic copolyester comprises
 (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.   
     
     
         13 . The cushioning element of  claim 1 , wherein the open cell foam microstructure of the first foam comprises less than 10 percent of cells having a closed cell foam microstructure. 
     
     
         14 . The cushioning element of  claim 1 , wherein the open cell foam microstructure of the first foam comprises less than 5 percent of cells having a closed cell foam microstructure. 
     
     
         15 . The cushioning element of  claim 1 , wherein the open cell foam microstructure of the first foam comprises less than 1 percent of cells having a closed cell foam microstructure. 
     
     
         16 . The cushioning element of  claim 1 , wherein up to 80% of the open cells in the first foam have an average diameter of from about 50 micrometers to about 200 micrometers. 
     
     
         17 . The cushioning element of  claim 1 , wherein the thermoplastic copolyester comprises,
 (a) a plurality of first copolyester units, each first copolyester unit of the plurality comprising the first segment derived from a dihydroxy-terminated polydiol and the third segment derived from an aromatic dicarboxylic acid, wherein the first copolyester unit has a structure represented by a formula 1:   
       
         
           
           
               
               
           
         
          wherein R 1  is a group remaining after removal of terminal hydroxyl groups from the poly(alkylene oxide) diol of the first segment, wherein the poly(alkylene oxide) diol 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 the second segment derived from a diol and the third segment derived from an aromatic dicarboxylic acid, wherein the second copolyester unit 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 derived from a diol, wherein the diol 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. 
       
     
     
         18 . The cushioning element of  claim 1 , wherein the one or more thermoplastic copolyesters comprise at least one thermoplastic copolyester elastomer. 
     
     
         19 . The cushioning element of  claim 1 , wherein the cushioning element is a midsole or a heel cushion. 
     
     
         20 . An article of footwear comprising the cushioning element of  claim 1 .