Foamable polyamide composition and foam obtained therefrom

1. A foamable composition consisting essentially of:

a) 21.0 to 99.6 wt % of a polyamide 6,6 comprising at least one carboxylic group;

b) 1.0 to 4.5 wt % of a styrene-ethylene/butylene-styrene thermoplastic elastomer;

c) 0.1 to 3.0 wt % of hexamethylene diisocyanate biuret;

d) 0 to 65.0 wt % of at least one filler selected from the group consisting of glass fibers, glass beads, calcium carbonate, silicates, talc, kaolin, mica, carbon black, graphite, wood powders, and synthetic fibers; and

e) 0 to 2.0 wt % of at least one additive;

wherein the sum of wt % of the components a) to e) is 100 wt % of the composition.

2. The foamable composition according to claim 1 , wherein the at least one additive is selected from the group consisting of an antioxidant, a pore-forming agent, a surfactant, a nucleating agent, a plasticizer, a matting agent, a pigment, a colorant, a heat stabilizer, a light stabilizer, a bioactive agent, an antisoiling agent, an antistatic agent, flame retardant, and a catalyst to accelerate decarboxylation by reaction of the carboxylic acid functional groups with isocyanate functional groups.

3. The foamable composition according to claim 1 , wherein the composition includes about 5 to 65.0 wt % of the at least one filler.

4. The foamable composition according to claim 1 , wherein the at least one filler is selected from the group consisting of glass fibers, glass beads, calcium carbonate, silicates, talc, kaolin, mica, carbon black, graphite, and wood powders.

5. The foamable composition according to claim 1 , wherein the at least one filler is glass fibers.

6. The foamable composition according to claim 1 , wherein the composition consists essentially of:

a) 40.0 to 98.7 wt % of the polyamide 6,6 comprising at least one carboxylic group;

b) 1.0 to 4.5 wt % of the styrene-ethylene/butylene-styrene thermoplastic elastomer;

c) 0.3 to 1.5 wt % of the hexamethylene diisocyanate biuret;

d) 15 to 45.0 wt % of the at least one filler selected from the group consisting of glass fibers, glass beads, calcium carbonate, silicates, talc, kaolin, mica, carbon black, graphite, wood powders, and synthetic fibers; and

e) 0.1 to 2.0 wt % of the at least one additive.

7. A method for producing the foamable composition according to claim 1 , comprising:

i) preparing a master-batch comprising a mixture of the styrene-ethylene/butylene-styrene thermoplastic elastomer and the hexamethylene diisocyanate biuret;

ii) heating the polyamide 6,6; and optionally the at least one filler at a temperature equal to or greater than a melting point of the polyamide to obtain a molten polyamide matrix; and

iii) adding at least a portion of the master-batch to the molten polyamide matrix.

8. A foam obtained from the foamable composition according to claim 1 .

9. An aeronautical vehicle, a motor vehicle, packaging, or sound insulation comprising the foam according to claim 8 .

10. A motor vehicle comprising the foam according to claim 8 .