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

Abstract

The invention relates to a process for producing a shaped article having improved optical properties compared to a polyamide 12/polytetramethylene block copolymer. The article is made from a block copolymer PAX.Y/PE where polyamide (PA) blocks are selected from PA 10,12; PA 6,18; PA 10,14; and PA 12.12; alternating with polyether (PP blocks, selected front the group consisting of: PE blocks comprising hydroxyl ends, and PE blocks comprising NH 2 ends; 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 polyether other than PO3G or PEG. The formed article is a fabric, film, sheet, rod, pipe, injection-molded component, or a shoe sole.

What is claimed is: 
     
         1 . A process for producing a shaped article having excellent optical properties, 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 acid having Y carbon atoms in the presence of a chain-limiting agent chosen from dicarboxyilic acids, wherein said PAX.Y is selected from the group consisting of PA 10,12; PA 6,18; PA 10,14; and PA 12.12,   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 polyether other than PO3G or PEG (% 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 copolymer PAX.Y/PE has an increase in optical transmission of at least 24% in comparison with a copolymer polyamide 12/polytetramethylene measured at 460 nm, at 560 nm and at 700 nm (a) with the same size of PA block and with the same size of PE block respectively or (b) 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 process as claimed in  claim 1 , wherein the 100 to 61% of polyether in said PE block are chosen from PTMG, polypropylene glycol PPG, their blends and their copolymers. 
     
     
         3 . The process as claimed in  claim 1 , wherein the number-average molecular weight of said PA blocks is between 500 and 10,000 g/mol. 
     
     
         4 . The process as claimed in  claim 1 , wherein the number-average molecular weight of said PE blocks is between 250 and 5,000 g/mol. 
     
     
         5 . The process as claimed in  claim 1 , wherein the number-average molecular weight of said copolymer is between 5000 and 50,000 g/mol. 
     
     
         6 . The process as claimed in  claim 1 , wherein the PA blocks represent between 5 and 95% by weight of the sum of the PA blocks and PE blocks of said copolymer.