Multi-layer composite comprising an EVOH layer and a protective layer

1. A multilayer composite comprising the following layers:

I. an interior layer I selected from the group consisting of a fluoropolymer molding composition and a polyolefin molding composition;

II. a bonding agent layer II that has the following composition:

a) from 0 to 80 parts by weight of a graft copolymer prepared using the following monomers:

from 0.5 to 25% by weight, based on the graft copolymer, of a polyamine having at least 4 nitrogen atoms and

polyamide-forming monomers selected from the group consisting of lactams, ω-aminocarboxylic acids and equimolar combinations of diamine and dicarboxylic acid;

b) from 0 to 100 parts by weight of polyamide, and

c) from 0 to 75 parts by weight of a polymer selected from the group consisting of fluoropolymers and polyolefins,

with the sum of the parts by weight of a), b) and c) being 100,

and, in addition,

the sum of the components a) and b) comprising at least 20 parts by weight of monomer units based on 100 parts by weight of a), b) and c), derived from caprolactam and/or the combination hexamethylenediamine/adipic acid, hexamethylenediamine/suberic acid, hexamethylenediamine/sebacic acid, hexamethylenediamine/dodecanedioic acid, hexamethylenediamine/isophthalic acid or hexamethylenediamine/terephthalic acid and

d) not more than 50 parts by weight of additives selected from the group consisting of impact-modifying rubber and auxiliaries and additives; and

III. a layer III comprising an EVOH molding composition,

wherein layer II is between layer I and layer III.

2. The multilayer composite as claimed in claim 1 , wherein

the component II.a) is present in an amount of from 1 to 60 parts by weight and/or

the component II.b) is present in an amount of from 10 to 75 parts by weight.

3. The multilayer composite as claimed in claim 1 , wherein

the component II.a) is present in an amount of from 3 to 40 parts by weight and/or

the component II.b) is present in an amount of from 25 to 65 parts by weight.

4. The multilayer composite as claimed in claim 1 , wherein from 5 to 75 parts by weight of the component II.c) are present.

5. The multilayer composite as claimed in claim 4 , wherein from 10 to 65 parts by weight of the component II.c) are present.

6. The multilayer composite as claimed in claim 4 , wherein from 20 to 55 parts by weight of the component II.c) are present.

7. The multilayer composite as claimed in claim 1 , wherein interior layer I comprises the fluoropolymer molding composition, which comprises a fluoropolymer selected from the group consisting of PVDF, ETFE, ETFE modified by a third component, E-CTFE, PCTFE, THV, FEP and PFA.

8. The multilayer composite as claimed in claim 1 , wherein interior layer I comprises the polyolefin molding composition, which comprises polyethylene or isotactic polypropylene.

9. The multilayer composite as claimed in claim 1 , wherein the fluoropolymer or the polyolefin is adhesion-modified.

10. The multilayer composite as claimed in claim 1 , wherein component II.b, is present and the polyamide of the component II.b, comprises PA6, PA66, PA6/66, PA68, PA610, PA612, a polyamide derived from hexamethylenediamine together with isophthalic acid and/or terephthalic acid or mixtures thereof.

11. The multilayer composite as claimed in claim 1 , further comprising a layer comprising a polyamide molding composition or a polyolefin molding composition and is joined to the layer III by a suitable bonding agent.

12. The multilayer composite as claimed in claim 1 that is a pipe or a hollow body.

13. The multilayer composite as claimed in claim 1 that is a pipe corrugated in its entirety or in subregions.

14. The multilayer composite as claimed in claim 1 that is a fuel line, a brake fluid line, a coolant line, a hydraulic fluid line, a filling station line, an air conditioner line, a vapor line, a container or a filling port.

15. The multilayer composite as claimed in claim 1 , wherein one of the layers of which the composite is composed or an additional interior layer has been made electrically conductive.

16. The multilayer composite as claimed in claim 1 produced by coextrusion, coating, multicomponent injection molding or coextrusion blow molding.

17. The multilayer composite as claimed in claim 1 , wherein interior layer I comprises the fluoropolymer molding composition.

18. The multilayer composite as claimed in claim 1 , wherein interior layer I comprises the polyolefin molding composition.

19. The multilayer composite as claimed in claim 1 , wherein the EVOH of the EVOH molding composition has an ethylene content of 25 to 60 mol %.

20. The multilayer composite as claimed in claim 1 , wherein bonding agent layer II comprises PA6.