Monoaxially oriented multilayer cast film

1. A multilayer cast film oriented in machine direction, the multilayer cast film comprises at least three layers A, B and C, wherein

a) layer A is an outer layer comprising a heterophasic propylene copolymer, wherein the heterophasic propylene copolymer of layer A comprises

a-a) 75 to 95 wt % of a polypropylene matrix (PP-M) with an MFR 2 (ISO 1133, 230° C., 2.16 kg) of 0.5 to 30.0 g/10 min being a homopolymer or a copolymer which has a comonomer content of less than 10.0 wt %,

a-b) 5 to 25 wt % of a propylene/alpha-olefin rubber (EPR) with at least 50 wt % propylene having an intrinsic viscosity (IV) of 0.8 to 2.5 dl/g, and

a-c) 0.0001 to 1 wt % of an alpha-nucleating agent (NA);

b) layer B is a core layer comprising a high isotacticity polypropylene homopolymer, wherein the high isotacticity polypropylene homopolymer of layer B is characterized by

(b-i) an isotacticity expressed in mmmm pentads of at least 96 mol %, measured by means of 13 C-NMR,

(b-ii) a decaline soluble content of 2.0 wt % or below, and

(b-iii) polydispersity index (PI) of at least 5.5;

and

c) layer C is a sealing layer comprising a propylene based random copolymer or a propylene based terpolymer, optionally in combination with a heterophasic propylene copolymer, wherein the propylene based random copolymer or terpolymer of layer C comprises

(c-i) 80.0 to 98.0 wt % of propylene,

(c-ii) up to 5.0 wt % of ethylene, and

(c-iii) 1.5 to 20.0 wt % of an alpha-olefin having 4 to 20 carbon atoms,

wherein the sum of (c-i), (c-ii), (c-iii) is 100 wt % and the amount of ethylene (c-ii), if present, is lower than the amount of alpha-olefin (c-iii),

wherein the machine direction oriented multilayer cast film has

(i) a tensile modulus measured according to ISO 527-3 on a 50 μm film in machine direction of at least 2600 MPa and in transverse direction of at least 1200 MPa,

(ii) a haze value measured according to ASTM D1003 on a 50 μm film of at most 5.5%, and

(iii) a shrinkage measured according to the method as described in the experimental parton a 50 μm film after 10 minutes at 100° C. in machine direction of at most −3.0%.

2. The multilayer cast film oriented in machine direction according to claim 1 , wherein

the copolymer or terpolymer of layer C has been visbroken.

3. The multilayer cast film oriented in machine direction according to claim 2 , wherein

A: the propylene/alpha-olefin rubber (EPR) of the heterophasic propylene copolymer of layer A is a propylene/ethylene rubber and the heterophasic propylene copolymer is alpha nucleated by a reactor technique, and wherein a catalyst used for preparing the heterophasic propylene copolymer is prepolymerized with at least one vinyl compound,

B: the high isotacticity polypropylene homopolymer of layer B has a melting point of at least 162° C., and

C: the propylene based random copolymer is a propylene-1-butene random copolymer and the propylene based terpolymer is a propylene-ethylene-1-butene terpolymer with an ethylene content of 0.5 to 5.0 wt %.

4. The multilayer cast film oriented in machine direction according claim 1 , wherein the multilayer case film has a thickness of 100 to 600 microns before orientation and after being stretched in machine direction with a draw ratio of 1:3 up to 1:12 has a thickness of 15 to 150 microns.

5. The multilayer cast film oriented in machine direction according claim 1 , wherein the multilayer cast film is suitable for being treated with a steam sterilization step at a temperature of above 110° C.

6. A laminate comprising a multilayer case film oriented in machine direction, wherein the multilayer cast film comprises at least three layers A, B and C, wherein

a) layer A is an outer layer comprising a heterophasic propylene copolymer, wherein the heterophasic propylene copolymer of layer A comprises

a-a) 75 to 95 wt % of a polypropylene matrix (PP-M) with an MFR 2 (ISO 1133, 230° C., 2.16 kg) of 0.5 to 30.0 g/10 min being a homopolymer or a copolymer which has a comonomer content of less than 10.0 wt %,

a-b) 5 to 25 wt % of a propylene/alpha-olefin rubber (EPR) with at least 50 wt % propylene having an intrinsic viscosity (IV) of 0.8 to 2.5 dl/g, and

a-c) 0.0001 to 1 wt % of an alpha-nucleating agent (NA);

b) layer B is a core layer comprising a high isotacticity polypropylene homopolymer, wherein the high isotacticity polypropylene homopolymer of layer B is characterized by

(b-i) an isotacticity expressed in mmmm pentads of at least 96 mol%, measured by means of 13C-NMR,

(b-ii) a decaline soluble content of 2.0 wt % or below, and

(b-iii) polydispersity index (PI) of at least 5.5;

and

c) layer C is a sealing layer comprising a propylene based random copolymer or a propylene based terpolymer, optionally in combination with a heterophasic propylene copolymer, wherein the propylene based random copolymer or terpolymer of layer C comprises

(c-i) 80.0 to 98.0 wt % of propylene,

(c-ii) up to 5.0 wt % of ethylene, and

(c-iii) 1.5 to 20.0 wt % of an alpha-olefin having 4 to 20 carbon atoms,

wherein the sum of (c-i), (c-ii) and (c-iii) is 100 wt % and the amount of ethylene (c-ii), if present, is lower than the amount of alpha-olefin (c-iii),

wherein the machine direction oriented multilayer cast film has

(i) a tensile modulus measured according to ISO 527-3 on a 50 μm film in machine direction of at least 2600 MPa and in transverse direction of at least 1200 MPa,

(ii) a haze value measured according to ASTM D1003 on a 50 μm film of at most 5.5%, and

(iii) a shrinkage measured in analogy to ISO 11501 on a 50 μm film after 10 minutes at 100° C. in machine direction of at most −3.0%, wherein the shrinkage is measured by putting 10 pieces of film on a talcum bed in an oven with the selected temperature.

7. A retortable stand up pouch comprising a multilayer case film oriented in machine direction, wherein the multilayer cast film comprises at least three layers A, B and C, wherein

a) layer A is an outer layer comprising a heterophasic propylene copolymer, wherein the heterophasic propylene copolymer of layer A comprises

a-a) 75 to 95 wt % of a polypropylene matrix (PP-M) with an MFR 2 (ISO 1133, 230° C., 2.16 kg) of 0.5 to 30.0 g/10 min being a homopolymer or a copolymer which has a comonomer content of less than 10.0 wt %,

a-b) 5 to 25 wt % of a propylene/alpha-olefin rubber (EPR) with at least 50 wt % propylene having an intrinsic viscosity (IV) of 0.8 to 2.5 dl/g, and

a-c) 0.0001 to 1 wt % of an alpha-nucleating agent (NA);

b) layer B is a core layer comprising a high isotacticity polypropylene homopolymer wherein the high isotacticity polypropylene homopolymer of layer B is characterized by

(b-i) an isotacticity expressed in mmmm pentads of at least 96 mol %, measured by means of 13C-NMR,

(b-ii) a decaline soluble content of 2.0 wt % or below, and

b-iii) polydispersity index (PI) of at least 5.5;

and

c) layer C is a sealing layer comprising a propylene based random copolymer or a propylene based terpolymer, optionally in combination with a heterophasic propylene copolymer, wherein the propylene based random copolymer or terpolymer of layer C comprises

(c-i) 80.0 to 98.0 wt % of propylene,

(c-ii) up to 5.0 wt % of ethylene, and

(c-iii) 1.5 to 20.0 wt % of an alpha-olefin having 4 to 20 carbon atoms,

wherein the sum of (c-i), (c-ii) and (c-iii) is 100 wt % and the amount of ethylene (c-ii), if present, is lower than the amount of alpha-olefin (c-iii),

wherein the machine direction oriented multilayer cast film has

(i) a tensile modulus measured according to ISO 527-3 on a 50 μm film in machine direction of at least 2600 MPa and in transverse direction of at least 1200 MPa,

(ii) a haze value measured according to ASTM D1003 on a 50 μm film of at most 5.5%, and

(iii) a shrinkage measured in analogy to ISO 11501 on a 50 μm film after 10 minutes at 100° C. in machine direction of at most −3.0%, wherein the shrinkage is measured by putting 10 pieces of film on a talcum bed in an oven with the selected temperature.

8. The multilayer cast film oriented in machine direction according to claim 1 , having a seal strength of at least 40 N/15 mm before and after steam sterilization at 121° C. for 30 min, between the multilayer cast film and a further layer comprising Al-foil-layer, wherein the laminate structure is 12μm oriented polyester (PET)/9μm Al-layer 50 μm machine direction oriented multilayer cast film, and the laminate has been sealed at 170° C.

9. The multilayer cast film oriented in machine direction according to claim 1 having a seal strength of at least 45 N/15 mm before steam sterilization at 121° C. for 30 min and at least 32 N/15 mm after steam sterilization at 121° C. for 30 min between the multilayer cast film and a further layer comprising oriented polyamide, wherein the laminate structure of 12μm oriented polyester (PET)/15μm oriented polyamide layer (OPA)/50 μm machine direction oriented multilayer cast film, and the laminate has been sealed at 200° C.

10. The multilayer cast film oriented in machine direction according to claim 8 , having a seal strength between the multilayer cast film and the further layer of at least 45 N/15 mm before and after steam sterilization at 121° C. for 30 min.

11. The multilayer cast film oriented in machine direction according to claim 9 , having a seal strength between the multilayer cast film and the further layer of at least 50 N/15 mm before steam sterilization at 121° C. for 30 minutes.

12. The multilayer cast film oriented in machine direction according to claim 9 , having a seal strength between the multilayer cast film and the further layer of at least 35 N/15 mm after steam sterilization at 121° C. for 30 minutes.

13. The multilayer cast film oriented in machine direction according to claim 9 , having a seal strength between the multilayer cast film and the further layer of at least 50 N/15 mm before steam sterilization at 121° C. for 30 minutes and at least 35 N/15 mm after steam sterilization at 121° C. for 30 minutes.