Foam layer produced of a biodegradable polyester mixture

1. A foam ply based on a biodegradable polyester mixture, comprising

i) from 70 to 5% by weight, based on the total weight of components i) to ii), of at least one polyester based on aliphatic and aromatic dicarboxylic acids and on aliphatic dihydroxy compounds, and

from 30 to 95% by weight, based on the total weight of components i) to ii), of polylactide, and

iii) from 0.1 to 5% by weight, based on the total weight of components i) to ii), of a copolymer which comprises epoxy groups and is based on styrene, acrylates, and/or methacrylates, wherein the content of said epoxy groups in said copolymer is more than 30%, and

iv) from 0.5 to 3% by weight, based on the total weight of components i) to ii), of a nucleating agent, and

v) from 0 to 50% by weight of inorganic or organic filler.

2. The foam ply according to claim 1 , where component i) is composed of:

A) an acid component composed of

a1) from 30 to 99 mol % of at least one aliphatic, or at least one cycloaliphatic, dicarboxylic acid, or its ester-forming derivatives, or a mixture of these

a2) from 1 to 70 mol % of at least one aromatic dicarboxylic acid, or its ester-forming derivative, or a mixture of these, and

a3) from 0 to 5 mol % of a compound comprising sulfonate groups,

where the molar percentages of components a1) to a3) together give 100%, and

B) a diol component composed of at least one C 2 -C 12 alkanediol or one C 5 -C 10 cycloalkanediol, or a mixture of these,

and

D) a component selected from

d1) at least one compound having at least three groups capable of ester formation,

d2) at least one isocyanate,

d3) at least one divinyl ether,

or a mixture composed of d1) to d3).

3. The foam ply according to claim 2 , where, in component i),

the aliphatic or cycloaliphatic dicarboxylic acid (component a1)) is succinic acid, adipic acid, or sebacic acid, ester-forming derivatives thereof, or a mixture of these;

the aromatic dicarboxylic acid (component a2)) is terephthalic acid or ester-forming derivatives thereof, and

the diol component (component B) is 1,4-butanediol or 1,3-propanediol.

4. The foam ply according to claim 1 , where component ii) is a polylactide whose melt volume rate (MVR for 190° C. and 2.16 kg to ISO 1133) is from 2 to 9 ml/10 minutes.

5. The foam ply according to claim 1 whose density is smaller than 50 g/l.

6. The foam ply according to claim 1 whose content of closed cells is greater than 70%.

7. The foam ply according to claim 1 whose maximum water absorption for 23° C. and 4 hours is smaller than 10% by weight.

8. The foam ply according to claim 1 comprising

from 10 to 30% by weight of component i), and

from 70 to 90% by weight of component ii),

based in each case on the total weight of components i) to ii).

9. The foam ply according to claim 1 , where component ii) forms a continuous or cocontinuous phase.

10. The foam ply according to claim 1 having a layer thickness of from 0.5 to 100 cm.

11. The foam ply according to claim 1 , comprising from 0.1 to 2% by weight of component iii), based on the total weight of components i) to ii).

12. The foam ply according to claim 1 , comprising, as filler v), from 5 to 50% by weight, based on components i) and ii), of a renewable polymer.