PEBA-based composition and use thereof for producing a fatigue-resistant transparent object

1. A copolymer with a rigid polyamide (PA) block and a flexible polyether or polyester (PE) block, wherein said polyamide block is semicrystalline and consists of a copolyamide of W/Y.Z type, wherein:

(i) W is a lactam or an alpha,omega-aminocarboxylic acid;

(ii) Y is a cycloaliphatic diamine;

(iii) Z is a first aliphatic and/or aromatic dicarboxylic acid;

and the W/Y.Z molar ratio is between 14/1 and 20/1 limits excluded, wherein the W/Y.Z molar ratio is a comparison of the moles of monomer W to the total moles of monomer Y.Z, and wherein monomer Y.Z is an equimolar combination of units Y and Z.

2. The copolymer as claimed in claim 1 , wherein the W/Y.Z molar ratio is between 14/1 to 15/1 limits excluded.

3. The copolymer as claimed in claim 1 , wherein the percentage by weight of the various components is such that:

(i) the percentage of the monomer W is within the range of 75% and 98% by weight;

(ii) the percentage of the Y.Z monomer is within the range of 2% and 25%;

forming a total of 100% of the polyamide block.

4. The copolymer as claimed in claim 1 , wherein the percentage of polyamide blocks in the copolymer is within the range of from 60% to 97%, and the percentage of polyether blocks in the copolymer is within the range of from 3% to 40%.

5. The copolymer as claimed in claim 1 , wherein W is chosen from: caprolactam, oenantholactam, lauryllactam, aminocaproic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid and 12-aminododecanoic acid.

6. The copolymer as claimed in claim 1 , wherein the cycloaliphatic diamine Y is chosen from: bis(3,5-dialkyl-4-aminocyclohexyl)methane, bis(4-aminocyclohexyl)methane (BACM), bis(3,5-dialkyl-4-aminocyclohexyl)ethane, bis(3,5-dialkyl-4-aminocyclohexyl)propane, 2,2-bis(3-methyl-4-aminocyclohexyl)propane (BMACP), bis(3,5-dialkyl-4-aminocyclohexyl)butane, bis(3-methyl-4-aminocyclohexyl)methane (BMACM or MACM), p-bis(aminocyclohexyl)methane (PACM), isopropylidenedi(cyclohexylamine) (PACP), isophoronediamine (IPD), 2,6-bis(aminomethyl)norbornane (BAMN).

7. The copolymer as claimed in claim 1 , wherein the first aliphatic and/or aromatic dicarboxylic acid is chosen from aliphatic and/or aromatic dicarboxylic acids having from 6 to 36 carbon atoms.

8. The copolymer as claimed in claim 1 , wherein:

the number-average molecular mass of the PA blocks is within the range of from 500 to 18 000 g/mol; and

the number-average molecular mass of the PE blocks is within the range of from 500 to 2000 g/mol.

9. The copolymer as claimed in 1 , wherein the PE blocks are derived from at least one polyalkylene ether polyol.

10. The copolymer as claimed in claim 9 , wherein the polyalkylene ether diol is chosen from polyethylene glycol (PEG), polypropylene glycol (PPG), polytrimethylene glycol (PO3G), polytetramethylene glycol (PTMG) and mixtures thereof.

11. The copolymer as claimed in claim 1 , wherein it has:

a transparency such that the transmittance at 560 nm through a 2-mm thick sheet is at least 80%;

a melting point within the range of from 130° C. to 210° C.; and

a crystallinity such that the enthalpy of fusion (delta Hm(2)) during the second heating is within the range of from 30 to 60 J/g;

the melting point and the enthalpy of fusion being measured according to the ISO 11357-3: 2013 DSC standard.

12. A process for preparing a copolymer as defined in claim 1 , comprising the steps of:

preparing the polyamide PA blocks by polycondensation in a first step, wherein the polyamide PA blocks are prepared from

the lactam or an alpha,omega-aminocarboxylic acid W;

the cycloaliphatic diamine Y and the first aliphatic and/or aromatic dicarboxylic acid Z;

wherein the polyamide PA blocks are optionally prepared in the presence of a chain stopper chosen from a second dicarboxylic acid; and

reacting the polyamide PA blocks W/Y.Z obtained with the polyether PE blocks in a second step, in the presence of a catalyst.

13. A process for preparing a copolymer as defined in claim 1 , wherein the process comprises a one-step polycondensation with:

the lactam or alpha,omega-aminocarboxylic acid W;

the cycloaliphatic diamine Y and the first aliphatic and/or aromatic dicarboxylic acid Z;

optionally a chain stopper chosen from a second dicarboxylic acid;

the polyether PE blocks; and

a catalyst.

14. A shaped article which is transparent, comprising a copolymer as defined in claim 1 .

15. The shaped article as claimed in claim 14 , wherein the article is selected from the group consisting of an article of sports equipment or a component of an article of sports equipment; a motor vehicle component; tanks; an industrial, electrical, an electronic or computer part, a tablet, a telephone, a computer, a safety accessory, a sign, a cornice lighting, an information and advertising panel, a display case, an engraving, a furnishing, a shopfitting, a decoration, a contact ball, a dental prosthesis, an implant, an ophthalmology article, a hemodialysis membrane, optical fibers, a work of art, a sculpture, camera lenses, disposable camera lenses, a printing substrate for direct printing with UV inks for photographic pictures, a glazing, and a sunroof.