Heat/light-stabilized polyamide compositions
Heat and light-stabilized polyamide compositions containing a stabilization system that includes copper oxide and KBr, and have an excellent preservation of color and of the mechanical properties thereof after exposure to heat or to light; these compositions are especially useful for producing shaped articles in the automotive field.
1. An admixture comprising at least one polyamide having an apparent viscosity in the molten state ranging from 30 to 1200 Pa.s, measured according to ISO 11443 and a heat- and light-stabilizing amount of Cu 2 O and KBr, wherein said at least one polyamide comprises at least one PA-6 polyamide or PA-6,6 polyamide, wherein the concentration of Cu 2 O is from 0.001% to 2% by weight relative to the total weight of said at least one polyamide, wherein the concentration of KBr is from 0.1% to 1.2% by weight relative to the total weight of said at least one polyamide, and wherein the admixture comprises a branched polyamide or a star polyamide.
2. The admixture as defined in claim 1 , wherein said admixture comprises a blend of polyamides.
3. The admixture as defined in claim 1 , wherein said admixture comprises at least one (co)polyamide and/or star polyamide.
4. The admixture as defined in claim 1 , wherein said admixture comprises between 20 and 80% by weight of said at least one polyamide, relative to the total weight of the composition.
5. The admixture as defined in claim 1 , wherein said admixture comprises from 0.009% to 1.2% by weight of Cu 2 O.
6. The admixture as defined in claim 1 , further comprising at least one other heat and/or light stabilizer selected from the group consisting of KI, hindered phenols, stabilizers having at least one hindered amine structural unit, organic phosphorus-containing stabilizers, inorganic phosphorus-containing stabilizers, sodium hypophosphite and manganese hypophosphite.
7. The admixture as defined in claim 1 , further comprising fibrous and/or non-fibrous reinforcing fillers.
8. The admixture as defined in claim 7 , wherein said fibrous fillers comprise glass fibers.
9. The admixture as defined in claim 1 , further comprising impact modifiers.
10. An admixture comprising at least one polyamide and a heat- and light-stabilizing amount of at least one copper oxide and KBr, wherein the at least one polyamide comprises linkages of isophthalic acid or benzoic acid and said isophthalic acid or benzoic acid is present in an amount from 0.2% wt % to 1 wt % of the composition.
11. The admixture as defined in claim 1 , wherein said at least one polyamide is:
(a) a PA-6 polyamide having an apparent viscosity in a molten state ranging from 30 to 1200 Pa·s or 30 to 700 Pa·s, measured according to ISO 11443, or
(b) a PA-6,6 polyamide having an apparent melt viscosity ranging from 30 to 700 Pa·s, measured according to the ISO 11443 standard at a shear rate of 1000 s −1 and a temperature of 280° C.
12. The admixture as defined in claim 1 , said branched polyamide or star polyamide having an apparent viscosity in a molten state ranging from 30 to 700 Pa·s, measured according to ISO 11443.
13. An admixture comprising at least one polyamide and a heat- and light-stabilizing amount of at least one copper oxide and KBr, wherein the at least one polyamide comprises linkages of isophthalic acid or benzoic acid, said at least one polyamide having an apparent viscosity in a molten state ranging from 30 to 1200 Pa·s or 30 to 700 Pa·s, measured according to ISO 11443, and said isophthalic acid or benzoic acid is present in an amount from 0.2% wt % to 1 wt % of the composition.
14. The admixture as defined in claim 13 , wherein said at least one oxide of copper comprises Cu 2 O.
15. The admixture of claim 1 , wherein said admixture, upon being extruded to form granules and the granules are molded into a article, provides said article, after aging for 31 days in ambient air at 200° C. followed by 7 days of aging at 220° C., with a Charpy unnotched impact strength as measured according to ISO 179-1/1 Fu standard that is greater than that of a similar article made from the admixture comprising comparable amounts of (a) Cu 2 O without KBr or (b) CuI and KI.
16. The admixture of claim 10 , wherein the copper oxide comprises Cu 2 O, wherein the concentration of Cu 2 O is from 0.009% to 1.2% by weight relative to the total weight of said at least one polyamide and wherein the concentration of KBr is from 0.1% to 1.2% by weight relative to the total weight of said at least one polyamide.
17. The admixture of claim 14 , wherein the concentration of Cu 2 O is from 0.009% to 1.2% by weight relative to the total weight of said at least one polyamide and wherein the concentration of KBr is from 0.1% to 1.2% by weight relative to the total weight of said at least one polyamide.