Foams based on thermoplastic polyurethanes

Abstract

A process can be used for recycling foams based on thermoplastic polyurethane.

1 - 15 . (canceled) 
     
     
         16 : A process for recycling of foams based on thermoplastic polyurethane, comprising:
 (i) extruding foamed thermoplastic polyurethane using a vented extruder to produce thermoplastic polyurethane pellets,   (ii) impregnating the thermoplastic polyurethane pellets with a blowing agent, to produce impregnated pellets, and   (iii) expanding said impregnated pellets to produce expanded thermoplastic polyurethane beads,   wherein a melting range of the thermoplastic polyurethane starts below 130° C. when measured by differential scanning calorimetry (DSC) with a heating rate of 20 K/min.   
     
     
         17 : The process according to  claim 16 , wherein the thermoplastic polyurethane has at most a melt flow rate of 250 g/10 min at 190° C. with an applied weight of 21.6 kg to DIN EN ISO 1133. 
     
     
         18 : The process according to  claim 16 , wherein the thermoplastic polyurethane in (i) is based on a polyether alcohol. 
     
     
         19 : The process according to  claim 16 , wherein the thermoplastic polyurethane in (i) is based on a polytetrahydrofuran of a molar mass that ranges from 600 g/mol to 2500 g/mol. 
     
     
         20 : The process according to  claim 16 , wherein the shore hardness of the thermoplastic polyurethane is from A 44 to A 84. 
     
     
         21 : The process according to  claim 16 , wherein prior to extrusion in (i), the foamed thermoplastic polyurethane is mechanically comminuted. 
     
     
         22 : The process according to  claim 23 , wherein the thermoplastic polyurethane pellets are impregnated in (ii) with from 0.1 to 40% by weight, based on the total weight of the thermoplastic polyurethane pellets, of a blowing agent. 
     
     
         23 : The process according to  claim 16 , wherein the expanded thermoplastic polyurethane beads have a diameter from 0.2 mm to 20 mm. 
     
     
         24 : The process according to  claim 16 , wherein the expanded thermoplastic polyurethane beads are spherical or cylindrical or elongate. 
     
     
         25 : The process according to  claim 16 , wherein after (iii) the expanded thermoplastic polyurethane beads are fused in a mold to give a molding. 
     
     
         26 : The process according to  claim 25 , wherein the expanded thermoplastic polyurethane beads are fused with steam at a temperature of from 100° C. to 140° C. 
     
     
         27 : The process according to  claim 25 , wherein the molding comprises a density in the range from 8 g/l to 600 g/l. 
     
     
         28 : The process according to  claim 16 , further comprising:
 forming the expanded thermoplastic polyurethane beads into energy-absorbing moldings, moldings for automotive interiors, foams for helmet shells, foams for knee protectors, foams for elbow protectors, foams for shoe soles, foams for midsoles, foams for insoles, foams for steering wheel parts, foams for door side parts, or foams for foot well parts.