Fireproofing polyamide powders and their use in a sintering process

Abstract

A subject-matter of the invention is the use of a polyamide powder possessing a fireproofing property in a process for the manufacture of an object made of polyamide by sintering this powder using radiation, the said powder comprising, by weight, 2 to 40% of at least one flame retardant for respectively 98 to 60% of at least one polyamide, the flame retardant being a blend of at least one organic phosphinate of a metal and of at least ammonium polyphosphate.

1 . A process for the manufacture of an object made of polyamide comprising sintering a polyamide powder using radiation, said polyamide powder comprising, by weight, 2 to 40% of at least one flame retardant for respectively 98 to 60% by weight of at least one polyamide, the flame retardant being a blend of at least one organic phosphinate of a metal and of at least ammonium polyphosphate.  
   
   
       2 . The process according to  claim 1 , wherein the powder comprises, by weight, of (the total forming 100%): 
 2 to 40% of at least one flame retardant, the flame retardant being a blend of at least one organic phosphinate of a metal and of at least ammonium polyphosphate;    98 to 60% of at least one polyamide; and    at least one agent selected from the group consisting of UV stabilizers, antioxidants, dyes, pigments, bactericides and rheological agents.    
   
   
       3 . The process according to  claim 1 , wherein the phosphinate is selected from the group consisting of phosphinic salts of formula (I) and diphosphinic salts of formula (II):  
     
       
         
         
             
             
         
       
     
     in which R 1  and R 2  are identical or different and are linear or branched C 1  to C 6  alkyl groups and/or aryl groups; 
 R 3  is a linear or branched C 2  to C 10  alkylene group, a C 6  to C 10  arylene group, a C 6  to C 10  alkylarylene group or a C 6  to C 10  arylalkylene group;  
 M is a calcium, aluminium and/or zinc ion;  
 m is 2 or 3;  
 n is 1 or 3;  
 x is 1 or 2.  
 
   
   
       4 . The process according to  claim 1 , in which the polyamide is chosen from PA 11, PA 12, aliphatic polyamides resulting from the condensation of an aliphatic diamine having from 6 to 12 carbon atoms and of an aliphatic diacid having from 9 to 18 carbon atoms, and copolyamides 11/12 having either more than 90% of 11 units or more than 90% of 12 units.  
   
   
       5 . An article comprising a polyamide powder possessing a fireproofing property, said powder comprising, by weight, 2 to 40% of at least one flame retardant for respectively 98 to 60% of at least one polyamide, the flame retardant being a blend of at least one organic phosphinate of a metal and of at least ammonium polyphosphate, the said powder being sintered using radiation.  
   
   
       6 . (canceled)  
   
   
       7 . The process according to  claim 1 , in which the radiation originates from a laser beam.