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

Abstract

Copolymer comprising polyamide PA blocks alternating with polyether PE blocks, the PA blocks comprising or being composed of polyamide PA X,Y blocks, optionally PA X,Y/{Z} blocks, obtained by polycondensation of at least one linear aliphatic diamine having X carbon atoms; of at least one dicarboxylic acid having Y carbon atoms; and, if appropriate, of at least one comonomer {Z} chosen from lactams and α,ω-aminocarboxylic acids having Z carbon atoms and equimolar mixtures of at least one diamine having X1 carbon atoms and of at least one dicarboxylic acid having Y1 carbon atoms, (X1, Y1) being different from (X, Y), the said comonomer or comonomers {Z} having being introduced in a proportion by weight ranging up to 50%, preferably up to 20%, more advantageously still up to 10%, with respect to the combined polyamide precursor monomers; the said copolymer being characterized in that the said PA blocks comprise carboxyl ends; X is at least equal to 2; Y is at least equal to 6; the said PE blocks 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; or, in the case where Y has a number of carbon atoms of greater than 14, PE blocks comprising NH 2 ends, so that the bonds between the PA blocks comprising carboxyl ends and the PE blocks comprising NH 2 ends are amide bonds.

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 the copolymer PAX.Y/PE has improved optical transmission properties at 460 nm, at 560 nm and at 700 nm in comparison with a copolymer polyamide 12/polytetramethylene glycol PA12/PTMG (iv) with the same size of PA block and with the same size of PE block respectively or (v) with the same stiffness, defined either by a flexural modulus (in MPa) or by a tensile modulus (in MPa) or by a Shore D hardness. 
   
   
       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≧22. 
   
   
       4 . The copolymer as claimed in  claim 3 , wherein X+Y≧24. 
   
   
       5 . The copolymer as claimed in  claim 3 , wherein X+Y=22 and the PA block is a PA10.12 block. 
   
   
       6 . The copolymer as claimed in  claim 4 , wherein X+Y=24 and the PA block is a PA6.18. 
   
   
       7 . The copolymer as claimed in  claim 4 , wherein the PA block is PA10.14. 
   
   
       8 . The copolymer as claimed in  claim 4 , wherein X+Y=26 and the PA block is a PA12.14 block. 
   
   
       9 . The copolymer as claimed in  claim 4 , wherein X+Y=28 and the PA block is a PA10.18 block. 
   
   
       10 . The copolymer as claimed in  claim 4 , wherein X+Y=30 and the PA block is a PA12.18 block. 
   
   
       11 . The copolymer as claimed in  claim 1 , wherein the dicarboxylic acid having Y carbon atoms is chosen from linear aliphatic diacids. 
   
   
       12 . The copolymer as claimed in  claim 1 , wherein Y is between 12 and 20, limits included. 
   
   
       13 . The copolymer as claimed in  claim 1 , wherein X is between 6 and 20, limits included, preferably between 6 and 14, limits included. 
   
   
       14 . The copolymer as claimed in  claim 1 , wherein the number-average molecular weight of its PA blocks is between 500 and 10 000. 
   
   
       15 . The copolymer as claimed in  claim 1 , wherein the number-average molecular weight of its PE blocks is between 250 and 5000. 
   
   
       16 . The copolymer as claimed in  claim 1 , wherein the number-average molecular weight of said copolymer is between 5000 and 50 000. 
   
   
       17 . 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. 
   
   
       18 . 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 acids having Y carbon atoms; and   in the presence of a chain-limiting agent chosen from dicarboxylic acids; then   reacting in the second stage, the polyamide PA blocks obtained with polyether PE blocks in the presence of a catalyst.   
   
   
       19 . 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.   
   
   
       20 . The process as claimed in  claim 18 , 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. 
   
   
       21 . The process as claimed in  claim 18 , 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. 
   
   
       22 . The process as claimed in  claim 18 , wherein the polycondensation at carried out at a temperature from 180 to 300° C. 
   
   
       23 . 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, 
   
   
       24 . (canceled) 
   
   
       25 . The copolymer of  claim 1 , wherein X is at least 4, and Y is at least 12. 
   
   
       26 . 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.