Foam of polymers comprising an ethylene-vinyl acetate (EVA) copolymer and/or a copolymer of ethylene and of alkyl (meth)acrylate and a copolymer containing polyamide blocks and polyether blocks
The present invention relates to a foam of polymers comprising an ethylene-vinyl acetate (EVA) copolymer and/or a copolymer of ethylene and of alkyl (meth)acrylate and a copolymer containing polyamide blocks and polyether blocks (PEBA). The present invention also relates to a process for producing such a foam and also to the use of said foam, in particular in shoes.
1 . Crosslinked foam comprising:
from 30% to 99.9%, typically from 50% to 99.9%, by weight of a copolymer (a) chosen from an ethylene-vinyl acetate (EVA) copolymer, a copolymer of ethylene and of alkyl (meth)acrylate and/or mixtures thereof,
from 0.1% to 40% by weight of a copolymer (b) containing polyamide blocks and polyether blocks (PEBA copolymer),
from 0% to 50% by weight of a polyolefin (c) and/or a thermoplastic elastomeric polymer (d);
the total amounting to 100% by weight of the foam;
said foam having a density of less than or equal to 200 kg/m 3 , and/or a rebound resilience, according to the standard ISO 8307:2007, of greater than or equal to 50%.
2 . Foam according to claim 1 , wherein the mass ratio of the polyamide blocks relative to the polyether blocks of the copolymer (b) is from 0.3 to 5.
3 . Foam according to claim 1 , comprising from 0.1% to 20% by weight of additives, relative to the total weight of the foam.
4 . Foam according to claim 1 , wherein the polyolefin (c) is a functionalized polyolefin (c1).
5 . Foam according to claim 4 , comprising from 0.1% to by weight, relative to the total weight of the foam, of the polyolefin (c).
6 . Foam according to wherein claim 1 , the thermoplastic elastomeric polymer (d) is chosen from a copolymer containing polyester blocks and polyether blocks, a thermoplastic polyurethane, an olefinic thermoplastic elastomer or an olefinic block copolymer, a styrene-diene block copolymer, and/or mixtures thereof.
7 . Foam according to claim 1 , wherein the polyamide blocks of the copolymer (b) comprise polyamide blocks chosen from PA 6, PA 11, PA 12, PA 5.4, PA 5.9, PA 5.10, PA 5.12, PA 5.13, PA 5.14, PA 5.16, PA 5.18, PA 5.36, PA 6.4, PA 6.9, PA 6.10, PA 6.12, PA 6.13, PA 6.14, PA 6.16, PA 6.18, PA 6.36, PA 10.4, PA 10.9, PA 10.10, PA 10.12, PA 10.13, PA 10.14, PA 10.16, PA 10.18, PA 10.36, PA 10.T, PA 12.4, PA 12.9, PA 12.10, PA 12.12, PA 12.13, PA 12.14, PA 12.16, PA 12.18, PA 12.36, PA 12.T, PA 6/12, PA 11/12, PA11/10.10, or mixtures or copolymers thereof.
8 . Foam according to claim 1 , wherein the polyether blocks of the copolymer (b) are chosen from PEG blocks, and/or PPG blocks, and/or PO3G (polytrimethylene glycol) blocks and/or PTMG blocks.
9 . Foam according to claim 1 , wherein the number-average molecular mass Mn of the polyamide blocks is between 400 and 13,000 g/mol, and the number-average molecular mass Mn of the polyether blocks is between 100 and 3000 g/mol.
10 . Process for preparing a foam according to claim 1 , comprising:
(i) a step of providing a mixture comprising:
from 30% to 99.9% by weight of a copolymer (a),
from 0.1% to 40% by weight of a copolymer (b),
from 0.01% to 2% by weight of a crosslinking agent,
from 0.5% to 10% by weight of a foaming agent,
from 0% to 50% by weight of a polyolefin (c) and/or a thermoplastic elastomeric polymer (d), and from 0% to 20% by weight of at least one additive,
the total amounting to 100% by weight of the mixture;
(ii) a step of shaping the mixture by injection moulding, compression/moulding or extrusion; and
(iii) a step of foaming the mixture.
11 . Foam capable of being obtained according to the process of claim 10 .
12 . Article, comprising at least one element consisting of a foam according to claim 1 .
13 . Article according to claim 12 , which is chosen from shoe soles, large or small balls, gloves, personal protective equipment, rail pads, motor vehicle parts, construction parts and electrical and electronic equipment parts.