Composite materials comprising a reinforcing material and a star polyamide as a thermoplastic matrix, the precursor compound article of said materials and the products obtained using same

1. A precursor article of a composite material comprising a polymeric matrix and at least one reinforcing yarn and/or reinforcing fibers, said article comprising at least one reinforcing yarn and/or reinforcing fibers and at least one polymeric matrix yarn and/or polymeric matrix fibers, wherein:

said reinforcing yarn and/or said reinforcing fibers are made of reinforcing material and optionally comprise a part made of thermoplastic polyamide,

said polymeric matrix yarn and/or said polymeric matrix fibers are made of thermoplastic polyamide, and wherein:

said thermoplastic polyamide of said reinforcing yarn and/or of said reinforcing fibers and/or of said polymeric matrix yarn and/or of said polymeric matrix fibers comprises at least one polyamide possessing a star structure comprising:

star macromolecular chains comprising one or more cores and at least three polyamide branches or three polyamide segments bonded to a core, and

optionally, linear polyamide macromolecular chains.

2. The article as claimed in claim 1 , wherein the ratio by weight of the star macromolecular chains to the sum of the star macromolecular chains and linear chains in the polyamide possessing a star structure is between 0.1 and 1.

3. The article as claimed in claim 1 , wherein said polyamide possessing a star structure is obtained by copolymerization of a mixture of monomers comprising at least:

a) monomers of following general formula (I):

b) monomers of following general formulae (IIa) and (IIb):

c) and, optionally, monomers of following general formula (III):

Z-R 3 -Z  (III)

 wherein:

R 1 is an aliphatic or aromatic, cyclic or linear, hydrocarbonaceous radical comprising at least 2 carbon atoms which can comprise heteroatoms,

A is a covalent bond or an aliphatic hydrocarbonaceous radical which can comprise heteroatoms and which comprises from 1 to 20 carbon atoms,

Z represents a primary amine functional group or a carboxylic acid functional group, and

Y is a primary amine functional group when X represents a carboxylic acid functional group, or

Y is a carboxylic acid functional group when X represents a primary amine functional group,

R 2 and R 3 , which are identical or different, represent substituted or unsubstituted, aromatic, cycloaliphatic or aliphatic hydrocarbonaceous radicals comprising from 2 to 20 carbon atoms which can comprise heteroatoms, and

m represents an integer between 3 and 8.

4. The article as claimed in claim 1 , wherein said polyamide possessing a star structure is obtained by extrusion of a polyamide obtained by polymerization of lactams and/or amino acids with the compound of formula (I).

5. The article as claimed in claim 3 , wherein A represents a methylene, polymethylene or polyoxyalkylene radical.

6. The article as claimed in claim 3 , wherein the compound of formula (I) is 2,2,6,6-tetra(β-carboxyethyl)cyclohexanone, trimesic acid, 2,4,6-tri(aminocaproic acid)-1,3,5-triazine or 4-aminoethyl-1,8-octanediamine.

7. The article as claimed in claim 1 , wherein the polyamide possessing a star structure has a number-average molecular mass of at least equal to 15 000.

8. The article as claimed in claim 1 , wherein the matrix yarn and/or matrix fibers are obtained from a blend of the polyamide possessing a star structure and of a linear polyamide.

9. The article as claimed in claim 1 , further comprising at least one matrix yarn and/or matrix fibers made of linear polyamide.

10. The article as claimed in claim 8 , wherein the linear polyamide is an aliphatic and/or semicrystalline polyamide or copolyamide is PA-4,6, PA-6, PA-6,6, PA-6,9, PA-6,10, PA-6,12, PA-6,36, PA-11, PA-12, a semicrystalline semiaromatic polyamide or a semicrystalline semiaromatic copolyamide chosen from the group consisting of polyphthalamides, and the blends of these polymers and of their copolymers.

11. The article as claimed in claim 1 , wherein the polyamide possessing a star structure has a ratio by weight in the matrix yarn and/or matrix fibers of between 0.4 and 1.

12. The article as claimed in claim 11 , wherein the ratio by weight is at least equal to 0.6.

13. The article as claimed in claim 1 , wherein the matrix yarn and/or matrix fibers further comprise additives, selected from the group consisting of flame-retardants, plasticizers, heat and light stabilizers, waxes, pigments, nucleating agents, antioxidants, and impact-strength modifiers.

14. The article as claimed in claim 1 , wherein the reinforcing yarn and/or reinforcing fibers are carbon, glass, aramid or polyimide yarns and/or fibers.

15. The article as claimed in claim 1 , wherein the reinforcing yarn and/or reinforcing fibers are sisal, hemp or flax yarns and/or fibers.

16. The article as claimed in claim 1 , further comprising a powdered material which is the matrix precursor.

17. The article as claimed in claim 16 , wherein said powdered material is a polyamide.

18. The article as claimed in claim 1 , being in the form of continuous or cut yams, slivers, mats, braids, woven fabrics, knitted fabrics, sheets, multiaxials or nonwovens.

19. A composite material, obtained from an article as claimed in claim 1 , by at least partial melting of the matrix yarn and/or matrix fibers of said article.

20. The composite material as claimed in claim 19 , wherein exhibiting a level of reinforcing material by weight of between 25 and 80%.

21. A semi-finished product, obtained by the process comprising the steps of thermoforming or of calendering the article as claimed in claim 1 , during which the matrix yarn and/or matrix fibers is/are at least partially melted in order to impregnate the reinforcing yarn and/or reinforcing fibers.

22. The semi-finished product as claimed in claim 21 , being in the form of panels or of tapes.

23. A finished product, obtained by the process comprising the step of thermoforming the article as claimed in claim 1 to a final form, wherein the matrix yarn and/or matrix fibers is/are at least partially melted in order to impregnate the reinforcing yarn and/or reinforcing fibers.