Copolyamides and compositions based on same
The invention concerns copolyamides obtained by using multifunctional monomers. It consists in using a multifunctional monomer comprising at least three reactive functions and at least another multifunctional monomer, in amounts such that the terminal group concentrations are balanced. The copolyamides are particularly high viscosity copolyamides. The invention also concerns compositions based on said copolyamides.
1. A copolyamide, comprising macromolecular units derived from the following monomers:
(I) at least one difunctional monomer represented by the abbreviation AB
(II) at least one multifunctional monomer represented by the abbreviation AaBb in which A represents a carboxylic acid function and B represents an amine function, a and b being numbers that satisfy the following relationships:
a≧1
b≧1
a+b≧3
(III) at least one multifunctional monomer represented by the abbreviation AcBd in which A represents a carboxylic acid function and B represents an amine function, c and d being numbers that satisfy the following relationships:
c≧0
d≧0
c+d≧2, the pair (c,d) being different than the pair (1,1)
the monomers (II) and (III) being chosen such that
d>c if a>b
d<c if a<b
the ratio
ax
+
cy
ax
+
cy
+
bx
+
dy
being between 0.4 and 0.6,
in which x represents the number of moles of monomer (II) and y represents the number of moles of monomer (III)
the ratio
ax
+
cy
+
bx
+
dy
(
a
+
c
+
b
+
d
)
*
(
x
+
y
+
0.9
*
z
)
is less than 0.05,
in which z represents the number of moles of monomer (I).
2. The copolyamide as claimed in claim 1 , wherein the ratio
ax
+
cy
+
bx
+
dy
(
a
+
c
+
b
+
d
)
*
(
x
+
y
+
0.9
*
z
)
is less than 0.01,
in which z represents the number of moles of monomer (I).
3. The copolyamide as claimed in claim 2 , wherein the ratio
ax
+
cy
+
bx
+
dy
(
a
+
c
+
b
+
d
)
*
(
x
+
y
+
0.9
*
z
)
is less than 0.002.
4. The copolyamide as claimed in claim 1 , wherein the ratio
χ
=
x
+
y
x
+
y
+
0.9
*
z
is less than 0.25%.
5. The copolyamide as claimed in claim 1 , wherein integers a, b, c and d are chosen so as to satisfy one of the following series of relationships:
a>b, c=0, d≧3
a>b, d=0, c≧3.
6. The copolyamide as claimed in claim 1 , wherein a=1, b=2, c=4 and d=0.
7. The copolyamide as claimed in claim 1 , wherein the melt flow index, measured at 275° C. under a 5 kg load, is less than 10 g/10 minutes.
8. The copolyamide as claimed in claim 1 , wherein the monomer (I) is a lactam, an amino acid or a mixture of these compounds.
9. The copolyamide as claimed in claim 1 , wherein the monomer (I) is elected from the group consisting of caprolactam and aminocaproic acid, and mixtures thereof.
10. The copolyamide as claimed in claim 1 , wherein monomer (II) is represented by formula (b): (XR 1 )—R—(R 2 Y) n (b)
in which:
n is an integer greater than or equal to 2, limits included,
R 1 and R 2 may 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 optionally comprising several aromatic nuclei and/or hetero ketones
X represents an amine or amine salt function, or an acid, ester, acid halide or amide function
Y represents an amine or amine salt function when X represents an acid, ester, acid halide or amide function, and an acid, ester, acid halide or amide function when Y represents an amine or amine salt function.
11. The copolyamide as claimed in claim 1 , wherein the monomer (III) is represented by formula (a)
in which
C is a covalent bond or an aliphatic hydrocarbon radical optionally comprising hetero atoms, and containing from 1 to 20 carbon atoms,
X is a radical
R 4 is a linear or cyclic, aromatic or aliphatic hydrocarbon radical containing at least two carbon atoms and optionally comprising hetero atoms,
m is an integer between 3 and 8, limits included.
12. The copolyamide as claimed in claim 11 , wherein the multifunctional compound is selected from the group consisting of 2,2,6,6-tetrakis(β-carboxyethyl)cyclo-hexanone, trimesic acid, 2,4,6-tris(aminocaproic acid)-1,3,5-triazine and 4-aminoethyl-1,8-octanediamine.
13. The copolyamide as claimed in claim 1 , which is obtained by mixing, in an extrusion device, at least the following three compounds:
compound (I): a polyamide containing repeating units of formula (c) below: —(NH—R 3 —CO]— (c)
compound (II): monomer (II) as defined above
compound (III): monomer (III) as defined above
the ratio α,
α
=
ax
+
cy
ax
+
cy
+
bx
+
dy
,
being between 0.4 and 0.6,
in which x represents the number of moles of compound (II) and y represents the number of moles of compound (III)
the ratio β,
β
=
ax
+
cy
+
bx
+
dy
(
a
+
c
+
b
+
d
)
*
(
x
+
y
+
z
)
being less than 1%,
in which z represents the number of moles of repeating units in compound (I)
the radical R 1 being a hydrocarbon radical optionally comprising hetero atoms.
14. A composition comprising a copolyamide matrix and a reinforcing filler, wherein the matrix comprises a copolyamide as claimed in claim 1 .
15. A yarn, fiber, filament, molded or injection-molded article, or film comprising a copolyamide or a composition as claimed in claim 1 .
16. An article obtained by extrusion blowmolding of a polyamide or a composition as claimed in claim 1 .
17. The copolyamide as claimed in claim 10 , wherein n is an integer between 2 and 10 (limits included).
18. The copolyamide as claimed in claim 10 , wherein n is equal to 2.
19. The copolyamide as claimed in claim 11 , wherein C is an aliphatic hydrocarbon radical optionally comprising heteroatoms and containing 1-6 carbon atoms.