Multi-layer blown film

1. A multi-layer blown polymer film comprising:

(a) a core layer (CL) selected from the group consisting of polyvinyl alcohols, polyacrylates, polyamides, poly(ethylene terephthalate), polyolefins (PO) and mixtures thereof, and

(b) a sealing layer (SL), said sealing layer (SL) comprises a propylene copolymer composition (P), said propylene copolymer composition (P),

(c1) has a comonomer content in the range of 3.0 to 8.0 wt. %, the comonomer—is C 6 α-olefin,

(c2) comprises a polypropylene (A) and a polypropylene (B) in the weight ratio [(A)/(B)] of 35/65 to 50/50, wherein said polypropylene (A) is a propylene homopolymer (H-PP) or a propylene copolymer (C-A) having a comonomer content of below 4.0 wt. %, the comonomer is C 6 α-olefin, said propylene copolymer (B) has a comonomer content of 4.0 to 20.0 wt. %, the comonomer is C 6 α-olefin,

(c3) fulfils the ratio

MFR( A )/MFR( P )≤1.0

wherein MFR (A) is the melt flow rate MFR2 (230° C.) [g/10 min] measured according to ISO 1133 of the polypropylene (A), MFR (P) is the melt flow rate MFR2 (230° C.) [g/10 min] measured according to ISO 1133 of the propylene copolymer composition (P),

(c4) has a xylene soluble content (XCS) determined at 25° C. according to ISO 16152 of below 16.0 wt. %,

(c5) has a melting temperature Tm determined by differential scanning calorimetry (DSC) of at least 135° C.,

(c6) has a heat sealing initiation temperature (SIT) of equal or below 115° C., and

(c7) is free of any elastomeric polymer component, and wherein the film is not subjected to a stretching step.

2. A multi-layer blown polymer film according to claim 1 , wherein the sealing layer (SL) and/or the propylene copolymer composition (P) has/have a melt flow rate MFR2 (230° C.) measured according to ISO 1133 in the range of 2.0 to 50.0 g/10 min.

3. A multi-layer blown polymer film according to claim 1 , wherein the sealing layer (SL) and/or the propylene copolymer composition (P) has/have:

a molecular weight distribution (MWD) measured by gel permeation chromatography (GPC) of at least 2.5.

4. A multi-layer blown polymer film according to claim 1 , wherein:

(a) the comonomer content in the polypropylene (A) is lower compared to the comonomer content in the propylene copolymer (B), and/or

(b) com (P)-com (A) is at least 1.0 wherein com (A) is the comonomer content of the polypropylene (A) given in weight percent [wt. %], com (P) is the comonomer content of the propylene copolymer composition (P) given in weight percent [wt. %].

5. A multi-layer blown polymer film according to claim 1 , wherein the sealing layer (SL) and/or the propylene copolymer composition (P) fulfill(s) the equation (I):

Tm −SIT≥22° C.  (I)

wherein Tm is the melting temperature of the sealing layer (SL) and/or of the propylene copolymer composition (P) determined by differential scanning calorimetry (DSC) and given in centigrade [° C.], SIT is the heat sealing initiation temperature (SIT) given in centigrade [° C.] of the sealing layer (SL) and/or of the propylene copolymer composition (P).

6. A multi-layer blown polymer film according to— claim 1 , wherein the polypropylene (A) of the propylene copolymer composition (P):

(a) is a propylene copolymer (C-A) with a comonomer content in the range of 0.5 to equal or below 4.0 wt. %, and/or

(b) has a melt flow rate MFR2 (230° C.) measured according to ISO 1133 of at least 1.5 g/10 min, and/or

(c) has a xylene soluble content (XCS) of below 2.5 wt. %.

7. A multi-layer blown polymer film according to claim 1 , wherein said core layer (CL) is a polypropylene (PP) or a propylene homopolymer (H-PP), having:

(a) a melt flow rate MFR2 (230° C.) measured according to ISO 1133 in the range of 1.0 to 15.0 g/10 min, and/or

(b) a melting temperature Tm determined by differential scanning calorimetry (DSC) of at least 155° C.

8. A multi-layer blown polymer film according to claim 1 , wherein:

(a) core layer (CL) has a thickness in the range of 5 to 500 μm, and/or

(b) the sealing layer (SL) has a thickness in the range of 0.5 to 40 μm.

9. A multi-layer blown polymer film according to claim 1 , wherein said multi-layer blown polymer film comprises three layers, namely a core layer (CL), a sealing layer (SL) and at least one of:

(a) an outer layer (OL) being a polyolefin (PO), or

(b) a further sealing layers (SL), or

(c) a metal layer (ML),

wherein the multi-layer blown polymer film has the stacking order

(a1) sealing layer (SL)-core layer (CL)-outer layer (OL), or

(b1) sealing layer (SL)-core layer (CL)-sealing layer (SL), or

(c1) sealing layer (SL)-core layer (CL)-a metal layer (ML).