Transparent impact-resistant composition

1. A composition comprising:

(A) an amorphous or quasi-amorphous copolymer containing polyamide blocks and containing polyether blocks, the polyamide blocks comprising cycloaliphatic units;

(B) a semicrystalline polymer comprising amide units or copolymer comprising amide units;

(C) another polymer comprising amide units or copolymer comprising amide units; and

(D) a multilayer polymer comprising at least a layer (D1) and a layer (D2), and

wherein the composition exhibits an impact strength greater than 80 kJ/m 2 at 23° C. and a transmittance greater than 75% at 560 nm over a 2 mm thick plate.

2. The composition as claimed in claim 1 , comprising, by weight:

from 15 to 50% of copolymer (A), relative to the sum of (A)+(B)+(C);

from 20 to 60% of polymer (B), relative to the sum of (A)+(B)+(C);

from 5 to 40% of polymer (C), relative to the sum of (A)+(B)+(C); and

from 1 to 25% of polymer (D), based on the total weight of the composition.

3. The composition as claimed in claim 1 , wherein the polymer (D) is in the form of core-shell particles, the layer (D1) being the core layer and the layer (D2) being a shell layer of the particles.

4. The composition as claimed in claim 1 , wherein:

the layer (D1) of the polymer (D) is a layer of polymer that comprises at least 50% by weight of units derived from isoprene or from butadiene; and/or

the layer (D2) of the polymer (D) is a layer of (meth)acrylic polymer.

5. The composition as claimed in claim 1 , wherein the layer (D1) of the polymer (D) has a glass transition temperature less than or equal to 0° C. and the layer (D2) of the polymer (D) has a glass transition temperature greater than or equal to 60° C.

6. The composition as claimed in claim 1 , wherein the polyamide blocks of the copolymer (A) are formed with a predominance by weight of an equimolar combination of at least one cycloaliphatic diamine and of at least one dicarboxylic acid.

7. The composition as claimed in claim 6 , wherein the cycloaliphatic diamine is selected from bis(3-methyl-4-aminocyclohexyl)methane (BMACM), para-aminodicyclohexylmethane (PACM), isophoronediamine (IPD), bis(4-aminocyclohexyl)methane (BACM), 2,2-bis(3-methyl-4-aminocyclohexyl)propane (BMACP), 2,6-bis(aminomethyl)norbornane (BAMN) and combinations thereof.

8. The composition as claimed in claim 6 , wherein the dicarboxylic acid is selected from aliphatic dicarboxylic acids having from 6 to 36 carbon atoms.

9. The composition as claimed in claim 1 , wherein the polyamide blocks of the copolymer (A) are selected from PA B.6, PA B.9, PA B.10, PA B.12, PA B.14, PA B.16, PA B.18 blocks and mixtures or copolymers thereof.

10. The composition as claimed in claim 1 , wherein the polyamide blocks of the copolymer (A) comprise a number-average molecular weight of 500 to 12 000 g/mol.

11. The composition as claimed in claim 1 , wherein the polyether blocks of the copolymer (A) comprise units derived from at least one polyalkylene ether polyol.

12. The composition as claimed in claim 1 , wherein the polyether blocks of the copolymer (A) comprise a number-average molecular weight of 200 to 4000 g/mol.

13. The composition as claimed in claim 1 , wherein the polymer or copolymer (B) is a copolymer comprising amide units.

14. The composition as claimed in claim 13 , wherein the copolymer (B) comprises polyamide blocks selected from PA 12, PA 11, PA 10.10, PA 10.12, PA 10.14, PA 6.10, PA 6.12, PA 6.14 and PA 6.18 blocks.

15. The composition as claimed in claim 13 , wherein the copolymer (B) comprises polyether blocks comprising units derived from at least one polyalkylene ether polyol.

16. The composition as claimed in claim 1 , wherein the constituent (C) is an amorphous copolyamide or homopolyamide.

17. The composition as claimed in claim 1 , comprising, in addition to the constituents (A) to (D), one or more additives.

18. The composition as claimed in claim 1 , wherein the sum of the constituents (A) to (D) represents at least 90% by weight of the composition.

19. A process for producing a composition as claimed in claim 1 , comprising a step of mixing the constituents (A), (B), (C) and (D) and a step of extrusion or of injection.

20. An article consisting of the composition as claimed in claim 1 or comprising a part consisting of the composition.

21. The article as claimed in claim 20 , selected from a fiber, a fabric, a film, a sheet, a rod, a tube and an injected part.

22. The article as claimed in claim 20 , wherein the article is a sports article, a recreational article, a do-it-yourself article, a highway tool, a piece of equipment, a protective article or a vehicle component.

23. The composition as claimed in claim 1 , wherein the composition exhibits an impact strength below 94 kJ/m 2 at 23° C.