MULTILAYER FILM WITH OXYGEN PERMEATION BARRIER FOR THE PRODUCTION OF PHOTOVOLTAIC MODULES

1 . A multilayer film, comprising, in the order listed:

a) a layer of a moulding composition which comprises at least 70% by weight, based on the overall layer moulding composition, of an ethylene-vinyl alcohol (EVOH) copolymer;

b) an adhesion promoter layer;

c) a layer of a moulding composition which comprises a thermoplastic polymer;

d) optionally, an adhesion promoter layer; and

e) a layer comprising at least 35% by weight, based on the overall moulding composition, of polyamide.

2 . The multilayer film according to claim 1 , wherein

when the layer c) comprises a thermoplastic polymer selected from the group consisting of a polyamide, a polyester and a polyolefin, the adhesion promoter layer b) comprises at least 35% by weight of a polyolefin having 0.1 to 5% by weight of acid anhydride groups, or

when the layer c) comprises a thermoplastic polymer selected from the group consisting of a polyamide and a polyester, the adhesion promoter layer b) comprises a polyamine-polyamide graft copolymer

3 . The multilayer film according to claim 1 , wherein

a thickness of the layer a) is from 50 to 250 μm.

4 . The multilayer film according to claim 3 , wherein

a thickness of the layer b) is from 15 to 100 μm,

a thickness of the layer c) is from 100 to 500 μm, and

a thickness of the layer e) is from 15 to 100 μm.

5 . The multilayer film according to claim 4 , which comprises a layer d) and a thickness of the layer d) is from 3 to 100 μm.

6 . The multilayer film according to claim 1 , wherein

an ethylene content of the EVOH is from 25 to 60 mol %.

7 . The multilayer film according to claim 1 , wherein at least the polyamide of layer e) comprises at least one selected from the group consisting of a partly crystalline polyamide having an enthalpy of fusion of more than 25 J/g, a semicrystalline polyamide having an enthalpy of fusion of from 4 to 25 J/g and an amorphous polyamide having an enthalpy of fusion of less than 4 J/g.

8 . The multilayer film according to claim 1 , wherein the polyolefin is selected from the group consisting of polyethylene, anisotactic or atactic homopolypropylene, a random copolymer of propene with ethene, a random copolymer of propene, ethene and 1-butene, and an ethylene-propylene block copolymer any of which optionally comprising an impact-modifying component.

9 . The multilayer film according to claim 1 wherein at least one of the layer a), the layer b) and the layer c) further comprises titanium dioxide.

10 . A photovoltaic module, comprising;

a solar cell embedded in a sealing layer; and

the multilayer film according to claim 1 as a back cover;

wherein the layer a) of the laminate film is bonded to the sealing layer.

11 . The photovoltaic module according to claim 10 ,

wherein a thickness of the layer a) is from 50 to 250 μm.

12 . The photovoltaic module according to claim 11 , wherein

a thickness of the layer b) is from 15 to 100 μm,

a thickness of the layer c) is from 100 to 500 μm, and

a thickness of the layer e) is from 15 to 100 μm.

13 . The photovoltaic module according to claim 12 ,

which comprises a layer d) and a thickness of the layer d) is from 3 to 100 μm.

14 . The photovoltaic module according to claim 12 , wherein an ethylene content of the EVOH is from 25 to 60 mol %.

15 . The photovoltaic module according to claim 10 , wherein

the layer a) comprises ethylene vinyl alcohol and titanium dioxide,

the layer b) comprises a polyamine-polyamide graft copolymer and a EVOH compatible polyamide,

the layer c) comprises a polyolefin,

the layer d) is present and comprises a polyamide and polyolefin, and

the layer e) further comprises titanium dioxide.