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

1. A process for producing a shaped article, said article comprising a block copolymer PAX.Y/PE comprising polyamide (PA) blocks alternating with polyether (PE) blocks, wherein said process comprises the steps of:

a) preparing homopolyamide blocks PAX.Y by polycondensation of linear aliphatic diamines having X carbon atoms and dicarboxylic acids having Y carbon atoms, the dicarboxylic acids introduced in excess with respect to the stoichiometry, wherein said PAX.Y is selected from the group consisting of PA 6.18 and PA 10.14,

b) reacting said homopolyamide blocks with polyether PE blocks in the presence of a catalyst to produce a block copolymer PAX.Y/PE, wherein said PE blocks are selected from the group consisting of:

(i) 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; and

(ii) 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;

wherein said PE blocks 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 polytetramethylene glycol PTMG (% by weight, expressed with respect to the total weight of the PE blocks);

c) forming said block copolymer PAX.Y/PE into a fabric, film, sheet, rod, pipe, injection-molded component, or a shoe sole;

wherein the crystallinity of the PAX.Y block is greater than the crystallinity of a PA12 block of the same size and/or the PA/PE phase separation of said copolymer PAX.Y/PE is greater than that of a copolymer PA12/PTMG composed of PA12 blocks of the same size as the PAX.Y blocks of said copolymer PAX.Y/PE and of polytetramethylene glycol PTMG blocks of the same size as the PE blocks of the PAX.Y/PE copolymer; wherein the copolymer PAX.Y/PE has an improved flexural modulus of at least 300 MPa greater than a copolymer PA12/PTMG with the same size of PA block and with the same size of PE block respectively, after conditioning at 23° C. and 50% relative humidity for 14 days, wherein said copolymer PAX.Y/PE does not break after 150,000 cycles during a flex fatigue test at −10° C. (Ross Flex test); and

wherein step a) and step b) are carried out as a single step.

2. The process as claimed in claim 1 , wherein the number-average molecular weight of the PA blocks is between 500 and 10 000.

3. The process as claimed in claim 1 , wherein the number-average molecular weight of the PE blocks is between 250 and 5000.

4. The process as claimed in claim 1 , wherein the number-average molecular weight of said copolymer is between 5000 and 50 000.

5. The process 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.

6. The process as claimed in claim 1 , wherein said catalyst comprises a derivative of a metal chosen from the group consisting of titanium, zirconium and hafnium, phosphoric acid or boric acid.

7. The process as claimed in claim 1 , wherein the polycondensation at carried out at a temperature from 180 to 300° C.

8. A process for producing a shaped article, said article comprising a block copolymer PAX.Y/PE comprising polyamide (PA) blocks alternating with polyether (PE) blocks, wherein said process comprises the steps of:

a) preparing homopolyamide blocks PAX.Y by polycondensation of linear aliphatic diamines having X carbon atoms and dicarboxylic acids having Y carbon atoms, the dicarboxylic acids introduced in excess with respect to the stoichiometry, wherein said PAX.Y is selected from the group consisting of PA6.18 and PA10.14,

b) reacting said homopolyamide blocks with polyether PE blocks in the presence of a catalyst to produce a block copolymer PAX.Y/PE, wherein said PE blocks are polytetramethylene glycol PTMG,

c) forming said block copolymer PAX.Y/PE into a fabric, film, sheet, rod, pipe, injection -molded component, or a shoe sole;

wherein the crystallinity of the PAX.Y block is greater than the crystallinity of a PA12 block of the same size and/or the PA/PE phase separation of said copolymer PAX.Y/PE is greater than that of a copolymer PA12/PTMG composed of PA12 blocks of the same size as the PAX.Y blocks of said copolymer PAX.Y/PE and of polytetramethylene glycol PTMG blocks of the same size as the PE blocks of the PAX.Y/PE copolymer; wherein the copolymer PAX.Y/PE has an improved flexural modulus of at least 300 MPa greater than a copolymer PA12/PTMG with the same size of PA block and with the same size of PE block respectively, after conditioning at 23° C. and 50% relative humidity for 14 days, wherein said copolymer PAX.Y/PE does not break after 150,000 cycles during a flex fatigue test at −10° C. (Ross Flex test); and

wherein step a) and step b) are carried out as a single step.