High-flow polyamides
A polyamide modified by a multi-functional compound, and a method for producing said polyamide and compositions comprising same are described. A method for the production of a polyamide comprising linear macromolecular chains and star-shaped macromolecular chains is also described. A resulting polyamide having optimal mechanical and rheological properties in order to (i) improve mould filling speed and quality, and (ii) produce moldable compositions with high filler contents is also described.
1. A polyamide obtained by the polycondensation of a mixture of:
a) monomers of the following general formula (I):
b) monomers of the following general formulae (IIa) and (IIb):
and
c) monomers of the following general formula (III):
Z—R 3 —Z (III)
in which:
R 1 is a linear or cyclic, aromatic or aliphatic, hydrocarbon radical which comprises at least two carbon atoms and which can comprise heteroatoms,
A is a covalent bond or an aliphatic hydrocarbon radical comprising 1 to 6 carbon atoms,
Z is a primary amine radical or a carboxyl group,
R 2 and R 3 , which are identical or different, are each aliphatic, cycloaliphatic or aromatic hydrocarbon radicals which comprise from 2 to 20 carbon atoms and which can comprise heteroatoms,
X is a carboxyl radical or a primary amine radical; and Y is a primary amine radical when X is a carboxyl radical, or Y is a carboxyl radical when X is a primary amine radical,
m is an integer ranging from 3 to 8,
the molar concentration of the monomers of formula (I) in the mixture of monomers of general formulae (I), (IIa) and (IIb) being from 0.01% to 1%, and
the molar ratio of the monomers of formula (I) to the monomers of formula (III) being from 0.01 to 0.4, and
the molar concentration of monomers of formula (III) is from 0.1% to 2% in the mixture of monomers (III), (IIa), and (IIb).
2. The polyamide as defined by claim 1 , wherein the concentration by number of polyamide chains of star is from 0.5% to 35%, with respect to the total number of polyamide chains.
3. The polyamide as defined by claim 1 , wherein the radical R 1 is a cyclohexanoyl radical.
4. The polyamide as defined by claim 1 , wherein R 3 is a polymethylene radical comprising from 2 to 36 carbon atoms.
5. The polyamide as defined by claim 1 , wherein the compound of formula (III) is selected from the group consisting of: succinic acid, adipic acid, terephthalic acid, isophthalic acid, sebacic acid, azelaic acid, dodecanoic acid, di(β-carboxyethyl)cyclohexanone, hexamethylenediamine, 5-methylpentamethylendiamine, meta-xylylenediamine, isophoronediamine and 1,4-diaminocyclohexane.
6. The polyamide as defined by claim 1 , wherein the monomer of formula (IIb) is ε-caprolactam.
7. A composition comprising at least one polyamide as defined by claim 1 .
8. A composition comprising from 20% to 95% by weight of a polyamide as defined by claim 1 , with respect to the total weight of the composition.
9. The composition as defined by claim 7 , further comprising reinforcing or bulking fillers.
10. An article obtained by shaping the composition as defined by claim 7 .