Polyamide-based compositions that are rigid and ductile at low temperature for the preparation of sports articles obtained by injection molding

1. A composition comprising, by weight, the total being equal to 100%:

(A) 65% to 93% of a polyamide mixture comprising from:

40% to 70% by weight of at least one semicrystalline polyamide, of which the mean number of carbon atoms relative to the nitrogen atom is greater than 9, said semicrystalline polyamide being of formula A/Z wherein,

A is an aliphatic repeating unit chosen from a unit obtained from the polycondensation of at least one amino acid, a unit obtained from the polycondensation of at least one lactam and a unit X.Y obtained from the polycondensation:

of at least one diamine, said diamine being a linear or branched aliphatic diamine, or a mixture thereof, and

of at least one dicarboxylic acid, said diacid being a linear or branched aliphatic diacid,

said diamine and said diacid comprising from 4 to 36 carbon atoms, and

Z represents another aliphatic repeating unit different from A and is included from 0 to 20%;

30% to 60% by weight of at least one amorphous polyamide,

(B) 7% to 30% of one or more impact modifier(s),

(C) 0 to 5% of at least one additive chosen from stabilizers, dyes, plasticizers, fibers, fillers, processing aids or a mixture thereof,

said amorphous polyamide being in a sufficient proportion so that the composition is sufficiently ductile at low temperature, and rigid, and has a ductile-brittle transition temperature (T BD )<0° C. as determined according to the standard ISO 179 1 eA and a flexural modulus of greater than 900 MPa as determined according to the standard ISO 178: 2010, and said composition being free of polyethylene-block-amide (PEBA).

2. The composition as claimed in claim 1 , wherein in that said semicrystalline PA is compatible with said amorphous PA.

3. The composition as claimed in either of claim 1 , wherein said composition is substantially devoid of transparency.

4. The composition as claimed in claim 1 , wherein said impact (B) comprises a core-shell impact modifier, and said composition is transparent.

5. The composition as claimed in claim 1 , wherein the semicrystalline polyamide is an aliphatic semicrystalline polyamide.

6. The composition as claimed in claim 5 , wherein the aliphatic semicrystalline polyamide is chosen from PA11, PA12, PA1010, and PA1012.

7. The composition as claimed in claim 5 , wherein the aliphatic semicrystalline polyamide is PA11 and the amorphous polyamide is 11/B10.

8. The composition as claimed in claim 1 , wherein the amorphous polyamide is a polyamide of formula B/X 1 Y 1 wherein:

B is an aliphatic repeating unit chosen from a unit obtained from the polycondensation of at least one amino acid, a unit obtained from the polycondensation of at least one lactam and a unit obtained from the polycondensation of at least one aliphatic diamine and of at least one aliphatic diacid,

X 1 is a cycloaliphatic diamine, and

Y 1 is a dicarboxylic acid, said diacid being chosen from an aliphatic diacid, a cycloaliphatic diacid and an aromatic diacid,

said diamine X 1 and said diacid Y 1 comprising from 4 to 36 carbon atoms.

9. The composition as claimed in claim 8 , wherein the amorphous polyamide is chosen from 12/B10, and 11/B10.

10. The composition as claimed in claim 1 , wherein the impact modifier is chosen from a polyolefin or a mixture of several polyolefins.

11. The composition as claimed in claim 10 , wherein the polyolefin or the mixture of polyolefins is selected from the group consisting of polyolefins that bear a function chosen from maleic anhydride, carboxylic acid, carboxylic anhydride and epoxide functions; ethylene/octene copolymers, ethylene/butene copolymers, ethylene/propylene elastomers (EPRs), ethylene-propylene-diene copolymers of elastomeric nature (EPDMs) and ethylene/alkyl (meth)acrylate copolymers.

12. The composition as claimed in claim 1 , wherein Z=0.

13. The composition as claimed in claim 12 , wherein said impact modifier (B) is in a proportion of from 10% to 20%.

14. The composition as claimed in claim 12 , comprising:

(A) 75% to 89.9%,

(B) 10% to 20%,

(C) 0.1% to 5%,

the sum A+B+C being equal to 100%.

15. The composition as claimed in claim 14 , wherein the semicrystalline polyamide and/or the amorphous polyamide is (are) partially or completely biobased.

16. A process for preparing a composition as defined in claim 1 , and an article from that composition of claim 1 , comprising a step of melt blending the constituents (A), (B) and (C), in an extruder, at a temperature between 230° C. and 330° C., in order to obtain granules, followed by a step of injecting said granules at a temperature of between 230° C. and 330° C., into an injection-molding machine to obtain the desired article.

17. A fashioned article, comprising the composition as defined in claim 1 , wherein said article is selected from the group consisting of fiber, fabric, film, sheet, rod, tube or injection-molded part.

18. The article as claimed in claim 17 , which is a sports article.

19. The article as claimed in claim 17 , which is an optical article.

20. A method of producing an article, comprising extruding, injection molding, molding or thermoforming the composition as claimed in claim 1 .

21. The method of claim 20 , wherein the article is a sports article or an optical article.

22. The method as claimed in claim 20 , wherein the article is a ski boot, a part of a ski boot or a rigid boot with studs, a running shoe, a golf ball, a part of a golf ball, a lacrosse stick, a helmet, gloves, shoulder pads, elbow pads, knee pads or shin pads.

23. The method as claimed in claim 20 , wherein the article is glasses or googles.