Foams based on thermoplastic polyurethanes

Abstract

Expandable thermoplastic polyurethane comprising blowing agent, wherein the Shore hardness of the thermoplastic polyurethane is from A 44 to A 84.

1 . An expandable thermoplastic polyurethane comprising a blowing agent, wherein the thermoplastic polyurethane exhibits a Shore hardness that ranges from A 44 to A 84. 
   
   
       2 . The expandable thermoplastic polyurethane according to  claim 1 , wherein the thermoplastic polyurethane exhibits a melting range, measured by DSC using a heating rate of 20 K/min, that starts below 130° C., and 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. 
   
   
       3 . The expandable thermoplastic polyurethane according to  claim 1 , wherein the thermoplastic polyurethane is based on a polytetrahydrofuran of a molar mass that ranges from 600 g/mol to 2500 g/mol. 
   
   
       4 . The expandable thermoplastic polyurethane according to  claim 1 , wherein the thermoplastic polyurethane is based on a polyester alcohol of a molar mass that ranges from 600 g/mol to 900 g/mol. 
   
   
       5 . The expandable thermoplastic polyurethane according to  claim 1 , wherein the thermoplastic polyurethane has an average diameter that ranges from 0.2 to 10 mm. 
   
   
       6 . The expandable thermoplastic polyurethane according to  claim 1 , further comprising from 5 to 80% by weight of an organic filler, an inorganic filler, or a combination thereof, based on the total weight of the thermoplastic polyurethane. 
   
   
       7 . A process for producing an expandable thermoplastic polyurethane comprising a blowing agent, which comprises:
 (i) extruding a thermoplastic polyurethane exhibiting a Shore hardness that ranges from A 44 to A 84, if appropriate together with additives, to give pellets with an average diameter that ranges from 0.2 to 10 mm,   (ii) impregnating the pellets with from 0.1 to 40% by weight, based on the total weight of the pellets, of a blowing agent in aqueous suspension under pressure at temperatures in the range from 100 to 150° C.,   (iii) cooling the suspension comprising the thermoplastic polyurethanes to from 20 to 95° C., and   (iv) depressurizing the thermoplastic polyurethane.   
   
   
       8 . A process for producing an expandable thermoplastic polyurethane comprising a blowing agent, which comprises:
 (i) melting a thermoplastic polyurethane exhibiting a Shore hardness that ranges from A 44 to A 84 together with from 0.1 to 40% by weight, based on the total weight of pellets, of a blowing agent and, if appropriate with additives, in an extruder to form a melt, and   (ii) pelletizing the melt under water at a pressure that ranges from 2 bar to 20 bar and a temperature that ranges from 5° C. to 95° C.   
   
   
       9 . A process for producing a foam based on a thermoplastic polyurethane, which comprises foaming the expandable thermoplastic polyurethane according to  claim 1  at a temperature that ranges from 100° C. to 140° C. 
   
   
       10 . A foam based on thermoplastic polyurethane obtained by the process according to  claim 9 . 
   
   
       11 . A process for producing an expanded thermoplastic polyurethane, which comprises:
 (i) extruding a thermoplastic polyurethane exhibiting a Shore hardness that ranges from A 44 to A 84, if appropriate together with additives, to give pellets with an average diameter that ranges from 0.2 to 10 mm,   (ii) impregnating the pellets with from 0.1 to 40% by weight, based on the total weight of the pellets, of a blowing agent, under pressure at temperatures in the range from 100 to 150° C., and   (iii) depressurizing said expandable thermoplastic polyurethane.   
   
   
       12 . A process for producing an expanded thermoplastic polyurethane, which comprises:
 (i) melting a thermoplastic polyurethane exhibiting a Shore hardness that ranges from A 44 to A 84, together with from 0.1 to 40% by weight, based on the total weight of pellets, of a blowing agent, if appropriate with additives, in an extruder to form a melt, and   (ii) pelletizing the melt without devices which inhibit foaming.   
   
   
       13 . An expanded thermoplastic polyurethane obtained by a process according to  claim 11 . 
   
   
       14 . The expanded thermoplastic polyurethane according to  claim 13 , wherein the thermoplastic polyurethane comprises, based on the total weight of the thermoplastic polyurethane, from 5 to 80% by weight of an organic filler, an inorganic filler, or a combination thereof. 
   
   
       15 . A process for production of foam based on thermoplastic polyurethane, which comprises using steam with a temperature of from 100° C. to 140° C. to fuse expanded thermoplastic polyurethane according to  claim 13  to give a molding.