Copolymers comprising polyamide blocks and polyether blocks and having improved mechanical properties

Abstract

The invention relates to a copolymer comprising polyamide blocks PA alternated with polyether blocks PE, said PA blocks being formed by homopolyamide blocks PA X.Y obtained by polycondensation of: a linear aliphatic diamine having X carbon atoms, and a carboxylic diacid having Y carbon atoms. Said copolymer is characterized in that the crystallinity of block PA is greater than the crystallinity of a PA block of the same size and/or the PA/PE phase separation is greater than that of a PA12/PTMG copolymer with PA12 blocks of the same size as the PAX.Y blocks and PTMG of the same size as the PE blocks.

1 . A copolymer PAX.Y/PE comprising polyamide PA blocks alternating with polyether PE blocks, the PA blocks being composed of homopolyamide PAX.Y blocks obtained by polycondensation:
 of a linear aliphatic diamine having X carbon atoms;   of a dicarboxylic acid having Y carbon atoms; and   
     said copolymer being wherein:
 said PA blocks comprise carboxyl ends; 
 X is at least equal to 4; 
 Y is at least equal to 10; 
 said PE blocks:
 (i) are either PE blocks comprising hydroxyl ends, otherwise known as PE diol blocks, so that the bonds between the PA blocks comprising carboxyl ends and the PE diol blocks are ester bonds; 
 (ii) or are PE blocks comprising NH 2  ends in the case where Y has a number of carbon atoms of greater than 14, so that the bonds between the PA blocks comprising carboxyl ends and the PE blocks comprising NH 2  ends are amide bonds; 
 (iii) comprise from 0 to 39% by weight of polytrimethylene ether glycol PO3G and/or polyethylene glycol PEG and from 100 to 61% by weight of polyether other than PO3G or PEG (% by weight, expressed with respect to the total weight of the copolymer); 
 
 
     wherein that (iv) the crystallinity of the PAX.Y block is >the crystallinity of a PA 12 block of the same size and/or (v) the PA/PE phase separation of said copolymer PAX.Y/PE is >that of a copolymer PA 12/PTMG composed of PA12 blocks of the same size as the PAX.Y blocks of said copolymer PAX.Y/PE and of PTMG blocks of the same size as the PE blocks of the PAX.Y/PE copolymer. 
   
   
       2 . The copolymer as claimed in  claim 1 , wherein the 100 to 61% of polyether in (iii) are chosen from PTMG, polypropylene glycol PPG, their blends and their copolymers. 
   
   
       3 . The copolymer as claimed in  claim 1 , wherein X+Y≦24. 
   
   
       4 . The copolymer as claimed in  claim 3 , wherein X+Y=24 with PA blocks made of PA10.14. 
   
   
       5 . The copolymer as claimed in  claim 3 , wherein X+Y=24 with PA blocks made of PA6.18. 
   
   
       6 . The copolymer as claimed in  claim 3 , wherein X+Y=22 with PA blocks made of PA 10.12. 
   
   
       7 . The copolymer as claimed in  claim 3 , wherein X+Y=20 with PA blocks made of PA6.14. 
   
   
       8 . The copolymer as claimed in  claim 3 , wherein X+Y=20 with PA blocks made of PA10.10. 
   
   
       9 . The copolymer as claimed in  claim 1 , wherein the dicarboxylic acid having Y carbon atoms is chosen from linear aliphatic diacids. 
   
   
       10 . The copolymer as claimed in  claim 1 , wherein Y is between 10 and 20, limits included. 
   
   
       11 . The copolymer as claimed in  claim 1 , wherein X is between 6 and 20, limits included. 
   
   
       12 . The copolymer as claimed in  claim 1 , wherein the number-average molecular weight of its PA blocks is between 500 and 10 000. 
   
   
       13 . The copolymer as claimed in  claim 1 , wherein the number-average molecular weight of the PE blocks is between 250 and 5000, preferably between 250 and 2000, more advantageously still between 350 and 1000. 
   
   
       14 . The copolymer as claimed in  claim 1 , wherein the number-average molecular weight of said copolymer is between 5000 and 50 000. 
   
   
       15 . The copolymer as claimed in  claim 1 , wherein the PA blocks advantageously represent between 5 and 95% by weight, of the sum of the PA blocks and PE blocks of said copolymer. 
   
   
       16 . A process for the preparation of a copolymer as defined in  claim 1 , comprising:
 preparing in a first stage, the polyamide PA blocks by polycondensation   of the linear aliphatic diamine having X carbon atoms;   of the dicarboxylic acid or acids having Y carbon atoms; and   in the presence of a chain-limiting agent chosen from dicarboxylic acids; then in a second stage, the polyamide PA blocks obtained are reacted with polyether PE blocks in the presence of a catalyst.   
   
   
       17 . The process for the preparation of a copolymer as defined in  claim 1 , wherein a single-stage polycondensation is carried out:
 of the linear aliphatic diamine having X carbon atoms;   in the presence of a chain-limiting agent chosen from dicarboxylic acids;   in the presence of polyether PE blocks; and   in the presence of a catalyst for the reaction between the PE blocks and the PA blocks.   
   
   
       18 . The process as claimed in  claim 16 , wherein use is made, as chain-limiting agent, of the dicarboxylic acid having Y carbon atoms, which is introduced in excess with respect to the stoichiometry of the diamine. 
   
   
       19 . The process as claimed in  claim 16 , wherein use is made, as catalyst, of a derivative of a metal chosen from the group formed by titanium, zirconium and hafnium or a strong acid, such as phosphoric acid or boric acid. 
   
   
       20 . The process as claimed in  claim 16 , wherein the polycondensation at carried out at a temperature from 180 to 300° C. 
   
   
       21 . A shaped article, comprising the copolymer as defined in  claim 1 , wherein said article is a fiber, fabric, film, sheet, rod, pipe, injection-molded component, or a shoe sole, 
   
   
       22 . (canceled) 
   
   
       23 . The copolymer as claimed in  claim 1 , wherein the number-average molecular weight of its PA blocks is between 1500 and 6000, and the number-average molecular weight of its PE blocks is between 350 and 1000.