High-viscosity polyamide composition

1. A composition obtained by blending at least:

a) one copolyamide having a random tree structure, which results from a reaction between at least:

one polyfunctional monomer corresponding to a general formula I:

(AR 1 )—R—(R 2 B) n   (I)

in which: n is an integer between 2 and 10 (limits included), R 1 and R 2 can be identical or different and represent a covalent bond or an aliphatic, arylaliphatic, aromatic or alkylaromatic hydrocarbon radical, R is a linear or branched aliphatic radical, a substituted or unsubstituted cycloaliphatic radical, a substituted or unsubstituted aromatic radical which can comprise several aromatic rings and/or heteroketones, A represents an amine or amine salt functional group or an acid, ester, acid halide or amide functional group, and B represents another amine or amine salt functional group, when A represents an acid, ester, acid halide or amide functional group, and an acid, ester, acid halide or amide functional group, when A represents an amine or amine salt functional group,

at least one bifunctional monomer of following formula II to IV:

A 1 -R 3 -A 1   (II)

B 1 -R 4 -B 1   (III)

and

A 1 -R 5 -B 1 or the corresponding lactams  (IV)

with optionally at least one monofunctional monomer of formula V or formula VI:

R 6 -B 1   (V),

and

R 7 -A 1   (VI)

in which: A 1 and B 1 respectively represent an acid, ester or acid chloride functional group and an amine or amine salt functional group and R 3 , R 4 , R 5 , R 6 and R 7 represent linear or branched alkyl hydrocarbon radicals, substituted or unsubstituted aromatic hydrocarbon radicals or alkylaryl, arylalkyl or cycloaliphatic hydrocarbon radicals which can comprise unsaturations; and

b) one chain extender.

2. The composition as described by claim 1 , wherein R is an aromatic radical.

3. The composition as described by claim 1 , wherein the monomer of formula (I) is a compound in which A represents the amine functional group, B represents the acid functional group, n is equal to 2, R represents an aromatic radical and R 1 and R 2 represent a covalent bond.

4. The composition as described by claim 1 , wherein the monomer of formula (I) is 5-aminoisophthalic acid.

5. The composition as described by claim 1 , wherein the monomer of formula (I) is 6-aminoundecanedioic acid.

6. The composition as described by claim 1 , wherein the copolyamide exhibits a melt flow index of less than 5 g/10 min, measured at 275° C. under a load of 2160 g.

7. The composition as described by claim 1 , wherein the copolyamide exhibits a distribution index D of the molecular weights of greater than 2.

8. The composition as described by claim 1 , wherein the chain extender is selected from the group consisting of: a dialcohol, a bis-epoxide, a polymer carrying epoxide functional group, a polymer carrying anhydride functional group, a bis-N-acyl bis-caprolactam, a diphenyl carbonate, a bisoxazoline, an oxazolinone, a diisocyanate, an organic phosphite.

9. The composition as described by claim 1 , wherein the composition comprises from 0.01% to 5% by weight of chain extenders for the polyamide, with respect to the total weight of the composition.

10. The composition as described by claim 1 , wherein the composition comprises an impact modifier.

11. The composition as described by claim 8 , wherein the dialcohol is selected from the group consisting of ethylene glycol, propanediol, butanediol, hexanediol and hydroquinone bis(hydroxyethyl) ether.

12. The composition as described by claim 8 , wherein the bis-epoxide is bisphenol A diglycidyl ether.

13. The composition as described by claim 8 , wherein the bis-N-acyl bis-caprolactams is selected from the group consisting of isophthaloyl bis-caprolactam, adipoyl bis-caprolactam and terephthaloy bis-caprolactam.

14. The composition as described by claim 8 , wherein the organic phosphite is a triphenyl phosphite or a caprolactam phosphite.