Multilayer film, use of a multilayer film and process for producing a multilayer film

1. A multilayer film for medical purposes comprising two external layers, and a further layer arranged between said two external layers,

wherein each of said two external layers contains:

a first polyalphaolefin;

a first thermoplastic elastomer with a melt viscosity of a melt flow index according to ISO 1133 of 0.001 to 6 g/10 min at 230° C., 2.16 kg; and

a second thermoplastic elastomer with a high melt viscosity not measurable according to ISO 1133 which is higher than the melt viscosity of the first thermoplastic elastomer; and

wherein said further layer contains:

a second polyalphaolefin; and

a third thermoplastic elastomer with a melt viscosity of a melt flow index according to ISO 1133 of from 0.001 to 6 g/10 min at 230° C., 2.16 kg; and

wherein

the content of the first thermoplastic elastomer in each of said two external layers is 20 to 50 wt.-%, or

the content of said second thermoplastic elastomer in each of said two external layers is 2 to 20 wt.-%, or

the content of said first thermoplastic elastomer in each of said two external layers is 20 to 50 wt.-% and the content of said second thermoplastic elastomer in each of said two external layers is 2 to 20 wt.-%; and

wherein the compositions of said two external layers are identical.

2. The multilayer film according to claim 1 , wherein the content of the first thermoplastic elastomer in each of said two external layers is 20 to 50 wt.-%.

3. The multilayer film according to claim 1 , wherein said first polyalphaolefin is selected from: polypropylene, polypropylene copolymer, polypropylene random copolymer, and heterophase polypropylene random copolymer.

4. The multilayer film according to claim 1 , wherein said first polyalphaolefin comprises a heterophase polypropylene random.

5. The multilayer film according to claim 1 , wherein each of said external layers has a thickness of 5 to 20 μm and said the further layer has a thickness of approximately 50 to 500 μm.

6. The multilayer film according to claim 1 , wherein the content of said third thermoplastic elastomer in said further layer is 40 to 90 wt; and/or the content of said second polyalphaolefin in said further layer is 10 to 60 wt.

7. The multilayer film according to claim 1 , wherein

the third thermoplastic elastomer is selected from: styrene block copolymers, hydrogenated styrene block copolymers, styrene-isoprene-styrene copolymer, styrene-ethylene-butylene-styrene copolymer, styrene-ethylene-propylene copolymer, styrene-ethylene-propylene-styrene copolymer, and styrene-ethylene-ethylene-propylene-styrene copolymer; and/or

said second polyalphaolefin is selected from polypropylene, polypropylene copolymer, polypropylene random copolymer, and polypropylene homopolymer, and/or said second polyalphaolefin comprises an ethylene comonomer.

8. The multilayer film according to claim 1 , wherein

said third thermoplastic elastomer comprises a styrene-ethylene-butylene-styrene copolymer, and/or

said second polyalphaolefin comprises a polypropylene random copolymer or a polypropylene random copolymer with ethylene as comonomer.

9. The multilayer film according to claim 1 , wherein

each of said two external layers has a thickness of from 5 to 20 μm; and/or

said further layer has a thickness of from 50 to 500 μm; and/or

the multilayer film has at least one element selected from:

an elongation at tear in longitudinal direction of an extrusion of the multilayer film of from 300% to 750%;

an elongation at tear in transverse direction of the extrusion of the multilayer film of from 300% to 750%;

a tear strength in longitudinal direction of the extrusion of the multilayer film of from 20 N/mm 2 to 50 N/mm 2 , and

a tear strength in transverse direction of the extrusion of the multilayer film of from 10 N/mm 2 to 40 N/mm 2 .

10. The multilayer film according to claim 1 , wherein said two external layers and/or said further layer have an additives content of less than 5000 ppm.

11. The multilayer film according to claim 1 , wherein the content of the second thermoplastic elastomer in each of said two external layers is 2 to 20 wt.-%.

12. The multilayer film according to claim 1 , wherein said first thermoplastic elastomer and/or said second thermoplastic elastomer is selected from: styrene block copolymers, hydrogenated styrene block copolymers, styrene-butadiene-styrene copolymer, styrene-isoprene-styrene copolymer, styrene-ethylene-butylene-styrene copolymer, styrene-ethylene-propylene copolymer, styrene-ethylene-propylene-styrene copolymer, styrene-ethylene-ethylene-propylene-styrene copolymer and styrene-ethylene-butylene copolymer.

13. The multilayer film according to claim 1 , wherein said first thermoplastic elastomer comprises a styrene-ethylene-butylene-styrene copolymer.

14. The multilayer film according to claim 1 , wherein said second thermoplastic elastomer is selected from: styrene-ethylene-propylene-styrene copolymer and styrene-ethylene-ethylene-propylene-styrene copolymer.

15. The multilayer film according to claim 1 , wherein the content of the third thermoplastic elastomer in said further layer is 55 to 75 wt.-%; and/or the content of said second polyalphaolefin in said further layer is 25 to 45 wt.-%.

16. A bag for accommodating blood or blood components or medical solutions, wherein said bag is made from a multilayer film according to claim 1 , and wherein the thickness of said further layer of said multilayer film is in a range of from 100 to 500 μm.

17. A medical pump comprising a multilayer film according to claim 1 , wherein the thickness of said further layer of said multilayer film is in a range of from 50 to 150 μm.

18. A multi-chamber bag for use in hemodialysis or peritoneal dialysis or in a hemodialysis or peritoneal dialysis device, wherein said bag is made from a multilayer film according to claim 1 .

19. A process for producing a multilayer film according to claim 1 , wherein said multilayer film is produced by coextrusion.