Polyamide composition having high thermal conductivity
The present invention relates to a composition based on a polyamide matrix having a high thermal conductivity and comprising specific proportions of alumina and of graphite and also a flame-retardant system. This composition may in particular be used for producing components for lighting devices comprising light-emitting diodes.
1. A composition comprising:
a) a polyamide matrix;
b) from 2% to 30% by weight of alumina;
c) from 15% to 50% by weight of a natural or artificial graphite having a particle size of from 0.1 to 100 μm; and
d) from 5% to 40% by weight of a flame-retardant system;
wherein the percentages by weight are expressed with respect to the total weight of the composition.
2. The composition as claimed in claim 1 , wherein the composition comprises from 20% to 80% by weight of polyamide, with respect to the total weight of the composition.
3. The composition of claim 1 , wherein the composition comprises from 2% to 20% by weight of alumina.
4. The composition of claim 1 , wherein the composition comprises from 20% to 40% by weight of graphite.
5. The composition of claim 1 , wherein the flame-retardant system comprises at least one flame retardant selected from the group consisting of: phosphorus-comprising flame retardants, flame retardants of nitrogen-comprising organic compound type and flame retardants comprising halogenated derivatives.
6. The composition of claim 1 , wherein the flame-retardant system comprises at least one phosphonic acid or its salt or one phosphinic acid or its salt.
7. The composition of claim 1 , wherein the composition further comprises reinforcing or bulking fillers.
8. The composition of claim 1 , wherein the composition comprises:
from 2% to 15% by weight of the alumina;
from 20% to 35% by weight of the graphite; and
from 5% to 20% by weight of the flame-retardant system.
9. The composition of claim 1 , wherein the composition exhibits a thermal conductivity of from greater than 0.1 W/mK to 3.0 W/mK.
10. The composition of claim 1 , wherein the composition exhibits a thermal conductivity of 3.0 W/mK.