Polypropylene film

Abstract

The present application relates to a film comprising a polypropylene composition, which has a melt flow rate MFR2 of from 0.1 to 5.0 g / 10 min and comprisesma propylene-ethylene random copolymer (A) having a total content of ethylene comonomer units of from 4.0 to 15.0 mol%, a non-detectable content of 2,1-regiodefects, and a relative content of isolated to block ethylene sequences, I(E), of from 62.0 to 70.0%; and a particulate alpha-nucleating agent (B), which comprises a compound selected from compounds having the structure [(Ar1O)(Ar2O)(O=)P-O]nX with n being 1 and X being selected from Li, Na and K, compounds that comprise a dicarboxylic acid derivative or combinations thereof.

Description

[0001] Polypropylene film

[0002] The present application relates to a film comprising a polypropylene composition, which has a melt flow rate MFR2 of from 0.1 to 5.0 g / 10 min and comprises a propyleneethylene random copolymer (A) having a total content of ethylene comonomer units of from 4.0 to 15.0 mol%, a non-detectable content of 2,1 -regiodefects, and a relative content of isolated to block ethylene sequences, l(E), of from 62.0 to 70.0%; and a particulate alpha-nucleating agent (B), which comprises a compound selected from compounds having the structure [(Ar1O)(Ar2O)(O=)P-O]nX with n being 1 and X being selected from Li, Na and K, compounds that comprise a dicarboxylic acid derivative or combinations thereof.

[0003] Background to the Invention

[0004] Plastic packaging is widely used in daily life due to a favorable cost / performance ratio. Polyolefins are easy and economical to produce with good properties and are widely used in plastic packaging.

[0005] Conflicting properties are often required in the packing industry. For example, high stiffness and toughness as well as excellent sealing behavior and good optical properties are required in parallel for plastic films. Different types of polyolefin, for example polypropylene and polyethylene, are routinely combined in blends and / or used in different layers of multilayer films to achieve desired properties. However, use of more than one polymer type, such as combinations of polyethylene terephthalate) (PET) or polyamide(s) with polyolefins, complicates the task of recycling the resulting plastic packaging.

[0006] One approach to enabling recycling is a ‘single material solution’, where only one type of polymer material is used. This simplifies recycling of both post-consumer waste and manufacturing waste but limits the range of properties that are available. As such, there is still a need for plastic packaging that may be formed from a single polymer type though comprising various different polymer grades within that polymer type, optimizing the mechanical, optical and sealing properties required for packaging materials, whilst also being straightforward to mechanically recycle with the resultant recyclate also having a good balance of properties.

[0007] In general, it is known that standard nucleating / clarifying agents, such as sorbitol- and nonitol-derivatives can contribute to the improvement of mechanical properties of films; however, the same increased crystallization typically leads to higher sealing initiation temperatures, which is undesirable.

[0008] WO 2024 / 042070 A1 provides an alpha-nucleated polypropylene composition, based on a propylene-ethylene-1 -butene terpolymer and a particulate nucleating agent, which shows an improved balance of properties in regard of mechanical properties, impact properties and sealing properties.

[0009] It has been found that the results of W02024 / 042070 A1 cannot be transferred to polypropylene compositions based in propylene-ethylene copolymers instead of propylene-ethylene-1 -butene terpolymers. When using propylene-ethylene copolymers, it has been found that a careful selection of the propylene-ethylene copolymer and the particulate alpha-nucleating agent is needed to obtain a film which shows an improved balance of properties in behalf of mechanical properties and impact properties.

[0010] Summary of the invention

[0011] The present invention relates to a film comprising a polypropylene composition, wherein the polypropylene composition comprises

[0012] (A) from 15.00 to 99.99 wt.-%, preferably from 20.00 to 99.98 wt.-%, more preferably from 25.00 wt.-% to 99.95 wt.-%, based on the total weight of the polypropylene composition, of a propylene-ethylene random copolymer having

[0013] • a total content of ethylene comonomer units of from 4.0 to 15.0 mol%, preferably from 5.0 to 12.5 mol%, more preferably from 6.0 to 10.0 mol%, still more preferably from 6.5 to 8.5 mol%, based on the total mol-content of the propylene-ethylene copolymer (A) and determined by quantitative13C- NMR spectroscopy;

[0014] • a non-detectable content of 2,1 -regiodefects, determined by13C-NMR spectroscopy; and

[0015] • a relative content of isolated to block ethylene sequences, l(E), of from 62.0 to 70.0%, preferably 62.5 to 69.0%, more preferably 63.0 to 68.0%, still more preferably 64.0 to 67.0%, wherein the l(E) content is defined by equation (I): 100 (I) wherein

[0016] 1(E) is the relative content of isolated to block ethylene sequences [in %]; fPEP is the mol fraction of propylene / ethylene / propylene sequences (PEP) in the sample; fPEE is the mol fraction of propylene / ethylene / ethylene sequences (PEE) and of ethylene / ethylene / propylene sequences (EEP) in the sample; fEEE is the mol fraction of ethylene / ethylene / ethylene sequences (EEE) in the sample, wherein all sequence concentrations being based on a statistical triad analysis of13C-NMR data; and

[0017] (B) from 0.01 to 1 .00 wt.-%, preferably from 0.02 to 0.50 wt.-%, more preferably from 0.05 to 0.25 wt.-%, based on the total weight of the polypropylene composition, of a particulate alpha-nucleating agent, which comprises a compound selected from

[0018] • compounds having the structure [(Ar1O)(Ar2O)(O=)P-O]nX, wherein Ar1and Ar2are each independently selected from phenyl groups substituted by one or more Ci to C& linear or branched alkyl groups, wherein Ar1and Ar2may also be linked by a direct single bond, an O, or a Ci to C& alkylene group n = 1 , and

[0019] X is selected from the group consisting of Li, Na and K;

[0020] • compounds that comprise a dicarboxylic acid derivative, such as compounds having a structure according to formula (II) wherein each independently selected from hydrogen and a Ci to C10 hydrocarbyl group; whereby two of R3to R10located on adjacent carbon atoms may be fused to form a cyclic hydrocarbyl structure; whereby two of R3to R10located on non-adjacent carbon atoms may be fused to form a bicyclic hydrocarbyl structure;

[0021] M is selected from the groups consisting of sodium, potassium, calcium, strontium, lithium, zinc, magnesium and monobasic aluminium; n is 1 or 2; z is 1 or 2; the sum of n+z is 3; and

[0022] • combinations thereof; and the polypropylene composition has a melt flow rate MFR2 of from 0.1 to 5.0 g / 10 min, preferably from 0.2 to 4.0 g / 10 min, more preferably from 0.5 to 3.0 g / 10 min, still more preferably from 1 .0 to 2.5 g / 10 min, determined according to ISO 1133 at 230°C and 2.16 kg.

[0023] Definitions

[0024] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although, any methods and materials similar or equivalent to those described herein can be used in practice for testing of the present invention, the preferred materials and methods are described herein. In describing and claiming the present invention, the following terminology will be used in accordance with the definitions set out below.

[0025] Unless clearly indicated otherwise, use of the terms “a”, “an”, and the like refers to one or more.

[0026] In the following amounts are given in % by weight (wt.-%) unless it is stated otherwise.

[0027] A propylene homopolymer is a polymer that essentially consists of propylene monomer units. Due to impurities especially during commercial polymerization processes, a propylene homopolymer can comprise up to 0.1 mol% comonomer units, preferably up to 0.05 mol% comonomer units and most preferably up to 0.01 mol% comonomer units.

[0028] A propylene copolymer in the sense of this invention is a polymer with a molar majority of propylene monomer units and a molar minority of comonomer units of a single comonomer selected from ethylene and alpha-olefin monomers having from 4 to 10 carbon atoms. A propylene-ethylene copolymer in this sense is a polymer essentially consisting of a molar majority of propylene monomer units and a molar minority of ethylene comonomer units.

[0029] Due to impurities especially during commercial polymerization processes, the propyleneethylene copolymer can comprise up to 0.1 mol% comonomer units different from propylene and ethylene, preferably up to 0.05 mol% comonomer units different from propylene and ethylene and most preferably up to 0.01 mol% comonomer units different from propylene and ethylene.

[0030] A propylene terpolymer is a polymer with a molar majority of propylene monomer units and a molar minority of comonomer units of two different comonomers selected from ethylene and alpha-olefin monomers having from 4 to 10 carbon atoms.

[0031] A random copolymer is a copolymer, in which the comonomer units are distributed randomly over the polymer chain.

[0032] A propylene-ethylene random copolymer is a copolymer with a molar majority of propylene monomer units, in which the ethylene comonomer units are distributed randomly over the polymer chain.

[0033] Typical for monophasic propylene homopolymers and monophasic propylene random copolymers (including monophasic propylene random terpolymers) is the presence of only one glass transition temperature.

[0034] Particulate nucleating agents are a family of nucleating agents having very high melting temperature. During the processing of the polymer, they remain in the solid state and do not melt and dissolve, instead being dispersed into the polymer melt. This is different from soluble nucleating agents, which dissolve into the polymer melt during processing.

[0035] Detailed description

[0036] The present invention relates to a film comprising a polypropylene composition, wherein the polypropylene composition comprises

[0037] (A) from 15.00 to 99.99 wt.-%, preferably from 20.00 to 99.98 wt.-%, more preferably from 25.00 wt.-% to 99.95 wt.-%, based on the total weight of the polypropylene composition, of a propylene-ethylene random copolymer having • a total content of ethylene comonomer units of from 4.0 to 15.0 mol%, preferably from 5.0 to 12.5 mol%, more preferably from 6.0 to 10.0 mol%, still more preferably from 6.5 to 8.5 mol%, based on the total mol-content of the propylene-ethylene copolymer (A) and determined by quantitative13C- NMR spectroscopy;

[0038] • a non-detectable content of 2,1 -regiodefects, determined by13C-NMR spectroscopy; and

[0039] • a relative content of isolated to block ethylene sequences, 1(E), of from 62.0 to 70.0%, preferably 62.5 to 69.0%, more preferably 63.0 to 68.0%, still more preferably 64.0 to 67.0%, wherein the l(E) content is defined by equation (I): 100 (I) wherein

[0040] 1(E) is the relative content of isolated to block ethylene sequences [in %]; fPEP is the mol fraction of propylene / ethylene / propylene sequences (PEP) in the sample; fPEE is the mol fraction of propylene / ethylene / ethylene sequences (PEE) and of ethylene / ethylene / propylene sequences (EEP) in the sample; fEEE is the mol fraction of ethylene / ethylene / ethylene sequences (EEE) in the sample, wherein all sequence concentrations being based on a statistical triad analysis of13C-NMR data; and

[0041] (B) from 0.01 to 1 .00 wt.-%, preferably from 0.02 to 0.50 wt.-%, more preferably from 0.05 to 0.25 wt.-%, based on the total weight of the polypropylene composition, of a particulate alpha-nucleating agent, which comprises a compound selected from

[0042] • compounds having the structure [(Ar1O)(Ar2O)(O=)P-O]nX, wherein Ar1and Ar2are each independently selected from phenyl groups substituted by one or more Ci to C& linear or branched alkyl groups, wherein Ar1and Ar2may also be linked by a direct single bond, an O, or a Ci to C& alkylene group n = 1 , and

[0043] X is selected from the group consisting of Li, Na and K; • compounds that comprise a dicarboxylic acid derivative, such as compounds having a structure according to formula (II) wherein each independently selected from hydrogen and a Ci to C10 hydrocarbyl group; whereby two of R3to R10located on adjacent carbon atoms may be fused to form a cyclic hydrocarbyl structure; whereby two of R3to R10located on non-adjacent carbon atoms may be fused to form a bicyclic hydrocarbyl structure;

[0044] M is selected from the groups consisting of sodium, potassium, calcium, strontium, lithium, zinc, magnesium and monobasic aluminium; n is 1 or 2; z is 1 or 2; the sum of n+z is 3; and

[0045] • combinations thereof; and the polypropylene composition has a melt flow rate MFR2 of from 0.1 to 5.0 g / 10 min, preferably from 0.2 to 4.0 g / 10 min, more preferably from 0.5 to 3.0 g / 10 min, still more preferably from 1 .0 to 2.5 g / 10 min, determined according to ISO 1133 at 230°C and 2.16 kg.

[0046] Film

[0047] The film preferably can be a monolayer film or a multilayer film.

[0048] In one embodiment the film is a monolayer film.

[0049] In said embodiment the film, being a monolayer film, preferably comprises from 90.0 to 100 wt.-%, preferably from 95.0 to 100 wt.-%, more preferably from 97.5 wt.-% to 100 wt.-% of the polypropylene composition, based on the total weight of the film. It is especially preferred that the film consists of the polypropylene composition.

[0050] In said embodiment, the polypropylene composition preferably comprises from 95.00 to 99.99 wt.-%, preferably from 97.50 to 99.98 wt.-%, more preferably from 98.50 wt.-% to 99.95 wt.-% of the propylene-ethylene random copolymer (A), based on the total weight of the polypropylene composition.

[0051] It is preferred that the propylene-ethylene random copolymer (A) is the only polymeric component of the polypropylene composition.

[0052] The polypropylene composition further comprises 0.01 to 1 .00 wt.-%, preferably from 0.02 to 0.50 wt.-%, more preferably from 0.05 to 0.25 wt.-% of the particulate alphanucleating agent (B) as described above or below, based on the total weight of the polypropylene composition.

[0053] The polypropylene composition can further comprise from 0 to 5.0 wt.-% of additives, based on the total weight of the polypropylene composition. The additives are usually selected from pigments, antioxidants, UV-stabilizers, mold release agents, acid scavengers, lubricants, anti-static agents, and mixtures thereof. The additives are well known in the art.

[0054] In said embodiment the film preferably has a film thickness of from 10 to 100 pm, preferably 20 to 75 pm, more preferably from 30 to 65 pm.

[0055] The monolayer film can be a blown film or a cast film.

[0056] The monolayer film shows a superior balance of properties in regard of mechanical properties (i.e. stiffness in form of tensile modulus) and impact strength (in form of dart drop impact).

[0057] The monolayer film preferably has a tensile modulus in machine direction (TM-MD) of from 900 to 1200 MPa, more preferably from 925 to 1100 MPa, still more preferably from 950 to 1050 MPa, determined according to ISO 527-3 at 23 °C on monolayer blown films of 50 pm thickness.

[0058] Further, the monolayer film preferably has a tensile modulus in transverse direction (TM-

[0059] TD) of from 900 to 1200 MPa, more preferably from 925 to 1100 MPa, still more preferably from 950 to 1050 MPa, determined according to ISO 527-3 at 23 °C on monolayer blown films of 50 pm thickness.

[0060] Still further, the monolayer film preferably has a dart drop impact (DDI) strength of from 42 to 200 g, more preferably from 46 to 150 g, more preferably from 48 to 100 g, determined according to ISO 7765-1 , method A on monolayer blown films of 50 pm thickness.

[0061] In another embodiment, the film is a multilayer film.

[0062] In said embodiment at least one layer, such as from one to all layers of the multilayer film, preferably one layer, comprises the polypropylene composition.

[0063] It is preferred that each of the at least one layer, such as from one to all layers of the multilayer film, preferably one layer, independently comprises from 90.0 to 100 wt.-%, preferably from 95.0 to 100 wt.-%, more preferably from 97.5 wt.-% to 100 wt.-% of the polypropylene composition, based on the total weight of the layer.

[0064] The at least one layer, preferably the one layer, of the multilayer film, which comprises the polypropylene composition, preferably has a film thickness of from 1 to 50 pm, more preferably 2 to 25 pm, more preferably from 5 to 20 pm.

[0065] The multilayer film preferably comprises at least three layers, more preferably a skin layer, a core layer and a sealing layer.

[0066] Although other layers may be present, it is preferred that any further layers, if present, are between the skin layer and the core layer or between the core layer and between the sealing layer, most preferably between the skin layer and the core layer.

[0067] It is particularly preferred that no further layers are present, i.e. that the multilayer film is a 3-layer film, consisting of the skin layer, the core layer and the sealing layer.

[0068] It is preferred that the multilayer film has a thickness in the range from 20 to 250 pm, more preferably 40 to 200 pm, most preferably 50 to 150 pm. It is preferred that: a) the skin layer has a thickness in the range from 8 to 30%, preferably in the range from 10 to 25%, more preferably in the range from 12 to 20% of the total thickness of the multilayer film; b) the core layer has a thickness in the range from 40 to 84%, preferably in the range from 50 to 80%, more preferably in the range from 60 to 76% of the total thickness of the multilayer film; and c) the sealing layer has a thickness in the range from 8 to 30%, preferably in the range from 10 to 25%, more preferably in the range from 12 to 20% of the total thickness of the multilayer film.

[0069] The core layer is preferably sandwiched between the skin layer and the sealing layer, whereby the skin layer and the sealing layer are the outer surface layers of the multilayer film.

[0070] The core layer preferably comprises at least 90 wt.-%, more preferably at least 95 wt.-%, yet more preferably at least 97 wt.-%, based on the total weight of the core layer, of a core-layer polypropylene composition. Most preferably, the core layer consists of the core-layer polypropylene composition.

[0071] The core-layer polypropylene composition preferably comprises from 80.0 to 99.0 wt.-% of a heterophasic propylene copolymer or a mixture of two or more, such as two or three heterophasic propylene copolymers and from 1 .0 to 20.0 wt.-% of a low density polyethylene or a or a mixture of two or more, such as two or three low density polyethylenes, all based on the total weight of the core layer polypropylene composition,.

[0072] The heterophasic propylene copolymer(s) and the low density polyethylene(s) preferably make up from 95.0 to 100 wt.-% of the core-layer polypropylene composition.

[0073] The core-layer polypropylene composition can further comprise from 0 to 5.0 wt.-% of additives, based on the total weight of the core-layer polypropylene composition. The additives are usually selected from pigments, antioxidants, UV-stabilizers, nucleating agents, mold release agents, acid scavengers, lubricants, anti-static agents, and mixtures thereof. The additives are well known in the art. The skin layer preferably comprises at least 90 wt.-%, more preferably at least 95 wt.-%, most preferably at least 97 wt.-%, based on the total weight of the skin layer, of a skinlayer polypropylene composition. Most preferably, the skin layer consists of the skinlayer polypropylene composition.

[0074] The skin-layer polypropylene composition preferably comprises from 90.0 to 100 wt.-% of a propylene-based random copolymer or a mixture of two or more, such as two or three propylene-based random copolymers, based on the total weight of the polypropylene composition. The one or more propylene-based random copolymers are preferably propylene-ethylene random copolymers.

[0075] The skin-layer polypropylene composition can further comprise from 0 to 10.0 wt.-% of a polar modified polypropylene, such as a maleic anhydride-grafted polypropylene, based on the total weight of the skin-layer polypropylene composition.

[0076] The skin-layer polypropylene composition can further comprise from 0 to 5.0 wt.-% of additives, based on the total weight of the skin-layer polypropylene composition. The additives are usually selected from pigments, antioxidants, UV-stabilizers, mold release agents, acid scavengers, lubricants, anti-static agents, and mixtures thereof. The additives are well known in the art.

[0077] The sealing layer preferably comprises at least 90 wt.-%, more preferably at least 95 wt.-%, yet more preferably at least 97 wt.-%, based on the total weight of the sealing layer, of a sealing-layer polypropylene composition. Most preferably, the sealing layer consists of the sealing-layer polypropylene composition.

[0078] The sealing-layer polypropylene composition preferably represents the polypropylene composition as described above or below.

[0079] It is preferred that from 15.00 to 49.99 wt.-%, more preferably from 20.00 to 44.98 wt.-%, still more preferably from 25.00 wt.-% to 39.95 wt.-% of the propylene-ethylene random copolymer (A) as described above or below, based on the total weight of the sealinglayer polypropylene composition.

[0080] The sealing-layer polypropylene composition preferably further comprises from 15.00 to 50.00 wt.-%, more preferably from 20.00 to 45.00 wt.-%, still more preferably from 25.00 to 40.00 wt.-% of a second propylene-based random copolymer, preferably a second propylene-ethylene random copolymer, based on the total weight of the sealing-layer polypropylene composition. The sealing-layer polypropylene composition preferably further comprises from 20.00 to 60.00 wt.-%, more preferably from 25.00 to 55.00 wt.-%, still more preferably from 30.00 to 50.00 wt.-% of a heterophasic propylene copolymer, based on the total weight of the sealing-layer polypropylene composition.

[0081] The propylene-ethylene random copolymer (A) as described above or below preferably differs from the second propylene-based random copolymer in a lower melt flow rate MFR2 and a lower amount of xylene cold solubles (XCS) fraction.

[0082] The propylene-ethylene random copolymer (A) and the second propylene-based random copolymer are generally monophasic whereas the heterophasic propylene copolymer is generally heterophasic.

[0083] The sealing-layer polypropylene composition preferably further comprises from 0.01 to 1 .00 wt.-%, preferably from 0.02 to 0.50 wt.-%, more preferably from 0.05 to 0.25 wt.-% of the particulate alpha-nucleating agent (B) as described above or below, based on the total weight of the sealing layer polypropylene composition.

[0084] The sealing-layer polypropylene composition can further comprise from 0 to 5.0 wt.-% of additives, based on the total weight of the sealing-layer polypropylene composition. The additives are usually selected from pigments, antioxidants, UV-stabilizers, mold release agents, acid scavengers, lubricants, anti-static agents, and mixtures thereof. The additives are well known in the art.

[0085] The multilayer film can be produced by coextruding at least part of the layers or all layers.

[0086] The multilayer film can also be produced by extruding single layers or coextruding part of the layers and laminating the single layers or coextruded part of the layers.

[0087] These techniques are well known in the art.

[0088] The layers can be cast film layers or blown film layers.

[0089] Preferably the film is fully recyclable.

[0090] For being fully recyclable, the polymeric components of the film are preferably all polyolefin components, such as polypropylene-based components and optionally polyethylene-based components. This allows the film to be recycled in the same recycling process.

[0091] The polypropylene composition as described above or below comprises from 15.00 to 99.99 wt.-%, preferably from 20.00 to 99.98 wt.-%, more preferably from 25.00 wt.-% to 99.95 wt.-%, based on the total weight of the polypropylene composition, of the propylene-ethylene random copolymer (A) and from 0.01 to 1 .00 wt.-%, preferably from 0.02 to 0.50 wt.-%, more preferably from 0.05 to 0.25 wt.-%, based on the total weight of the polypropylene composition, of the particulate alpha-nucleating agent (B).

[0092] In one embodiment, the propylene-ethylene random copolymer (A) is the only polymeric component of the polypropylene composition.

[0093] In said embodiment, the polypropylene composition preferably comprises from 95.00 to

[0094] 99.99 wt.-%, preferably from 97.50 to 99.98 wt.-%, more preferably from 98.50 wt.-% to

[0095] 99.95 wt.-% of the propylene-ethylene random copolymer (A), based on the total weight of the polypropylene composition.

[0096] In another embodiment, the propylene-ethylene random copolymer (A) is one of several polymeric components of the polypropylene composition.

[0097] In said embodiment, the polypropylene composition preferably comprises from 15.00 to

[0098] 49.99 wt.-%, preferably from 20.00 to 44.98 wt.-%, more preferably from 25.00 wt.-% to

[0099] 39.95 wt.-% of the propylene-ethylene random copolymer (A), based on the total weight of the polypropylene composition.

[0100] In said embodiment, the polypropylene composition preferably further comprises from 15.00 to 50.00 wt.-%, more preferably from 20.00 to 45.00 wt.-%, still more preferably from 25.00 to 40.00 wt.-% of a second propylene-based random copolymer, preferably a second propylene-ethylene random copolymer, based on the total weight of the polypropylene composition.

[0101] The polypropylene composition preferably further comprises from 20.00 to 60.00 wt.-%, more preferably from 25.00 to 55.00 wt.-%, still more preferably from 30.00 to 50.00 wt.- % of a heterophasic propylene copolymer, based on the total weight of the polypropylene composition.

[0102] The propylene-ethylene random copolymer (A) as described above or below preferably differs from the second propylene-based random copolymer in a lower melt flow rate MFR2 and a lower amount of xylene cold solubles (XCS) fraction. The propylene-ethylene random copolymer (A) and the second propylene-based random copolymer are generally monophasic whereas the heterophasic propylene copolymer is generally heterophasic.

[0103] The polypropylene composition can further comprise from 0 to 5.0 wt.-% of additives, based on the total weight of the polypropylene composition. The additives are usually selected from pigments, antioxidants, UV-stabilizers, mold release agents, acid scavengers, lubricants, anti-static agents, and mixtures thereof. The additives are well known in the art.

[0104] The polypropylene composition has a melt flow rate MFR2 of from 0.1 to 5.0 g / 10 min, preferably from 0.2 to 4.0 g / 10 min, more preferably from 0.5 to 3.0 g / 10 min, still more preferably from 1 .0 to 2.5 g / 10 min, determined according to ISO 1133 at 230°C and 2.16 kg.

[0105] The polypropylene composition is preferably not visbroken.

[0106] As is well understood by the skilled person, the process of visbreaking involves treating a precursor polymer with a visbreaking agent, i.e. a free-radical generator. The polymeric chains of the precursor polymer may undergo beta-scission process and / or crosslinking, although in the absence of specific crosslinking agents, typically small molecules with multiple positions of unsaturation (e.g. bis- or tris-olefins), beta-scission processes tend to dominate. The effect of visbreaking is that the high molecular weight fractions of the molecular weight distribution are cleaved to form lower molecular weight polymer chains. Since these high molecular weight fractions contribute disproportionally to the MFR2 of the overall polymer, visbreaking serves to increase the MFR2 of polymers.

[0107] As would be clear to the person skilled in the art, it is possible to determine whether a polymer has been visbroken or not, not only by evaluating the shape of the resultant molecular weight distribution curve, but also by the presence of decomposition products of the visbreaking agent, e.g. peroxide decomposition products.

[0108] The polypropylene composition preferably has a total content of ethylene comonomer units of from 4.0 to 15.0 mol%, more preferably from 5.0 to 12.5 mol%, even more preferably from 6.0 to 10.0 mol%, still more preferably from 6.5 to 8.5 mol%, based on the total mol-content of the polypropylene composition and determined by quantitative13C-NMR spectroscopy.

[0109] Further, the polypropylene composition preferably has a relative content of isolated to block ethylene sequences, l(E), of from 62.0 to 70.0%, more preferably 62.5 to 69.0%, even more preferably 63.0 to 68.0%, still more preferably 64.0 to 67.0%, wherein the l(E) content is defined by equation (I): wherein l(E) is the relative content of isolated to block ethylene sequences [in %]; fPEP is the mol fraction of propylene / ethylene / propylene sequences (PEP) in the sample; fPEE is the mol fraction of propylene / ethylene / ethylene sequences (PEE) and of ethylene / ethylene / propylene sequences (EEP) in the sample; fEEE is the mol fraction of ethylene / ethylene / ethylene sequences (EEE) in the sample, wherein all sequence concentrations being based on a statistical triad analysis of13C- NMR data

[0110] Still further, the polypropylene composition preferably has a non-detectable content of 2,1 -regiodefects, determined by13C-NMR spectroscopy.

[0111] “Non-detectable” in this context means that the content of 2,1 -regiodefects of the polypropylene composition is below the detection limit of the13C-NMR spectroscopy as described below in the determination methods.

[0112] Thereby, the total content of 2,1 -regiodefects is preferably from 0.00 to less than 0.05 mol%, more preferably from 0.00 to less than 0.03 mol%, still more preferably from 0.00 to less than 0.01 mol%, most preferably 0.00 mol%, based on the total mol-content of the polypropylene composition.

[0113] Additionally, the polypropylene composition preferably has a melting temperature Tm of from 135 to 155°C, more preferably from 137 to 152°C, even more preferably from 140 to 150°C, still more preferably from 142 to 148°C, determined by differential scanning calorimetry (DSC) according to ISO 11357 / part 3 / method C2. Furthermore, the polypropylene composition preferably has a crystallization temperature Tc of from 105 to 125°C, more preferably from 108 to 122°C, even more preferably from 112 to 120°C, still more preferably from 114 to 118°C, determined by differential scanning calorimetry (DSC) according to ISO 113571 part 3 / method C2.

[0114] Further, the polypropylene composition preferably has a xylene cold solubles (XCS) content of from 5.0 to 15.0 wt.-%, more preferably from 5.5 to 12.5 wt.-%, even more preferably from 6.0 to 11 .0 wt.-%, still more preferably from 7.0 to 10.0 wt.-%, based on the total weight of the propylene-ethylene random copolymer (A) and determined according to ISO 16152.

[0115] Still further, the polypropylene composition preferably has a polydispersity index PDI, being the ratio of weight average molecular weight and number average molecular weight Mw / Mn, both determined by GPC measurement, of from 5.0 to 20.0, more preferably from 5.5 to 15.0, even more preferably from 6.0 to 12.5, still more preferably from 7.2 to 10.0.

[0116] The polypropylene composition is preferably prepared by melt extruding the propyleneethylene random copolymer (A), the particulate alpha-nucleating agent (B) and optional other components as described above or below, e.g. in a twin screw extruder at conditions as well known in the art.

[0117] Propylene-ethylene random copolymer (A)

[0118] The propylene-ethylene random copolymer (A) preferably essentially consists, more preferably consists of propylene monomer units and ethylene comonomer units. This means that during the polymerization process only propylene monomer units and ethylene comonomer units were introduced into the polymerization reactor(s) for polymerizing the propylene-ethylene random copolymer (A).

[0119] As discussed above in the definitions section, due to impurities especially during commercial polymerization processes, the propylene-ethylene random copolymer (A) can comprise up to 0.1 mol% comonomer units different from propylene and ethylene, preferably up to 0.05 mol% comonomer units different from propylene and ethylene and most preferably up to 0.01 mol% comonomer units different from propylene and ethylene. Thereby, the total content of ethylene comonomer units of from 4.0 to 15.0 mol%, preferably from 5.0 to 12.5 mol%, more preferably from 6.0 to 10.0 mol%, still more preferably from 6.5 to 8.5 mol%, based on the total mol-content of the propyleneethylene copolymer (A) and determined by quantitative13C-NMR spectroscopy.

[0120] Consequently, the total content of propylene monomer units is from 85.0 to 96.0 mol%, preferably from 87.5 to 95.0 mol%, more preferably from 90.0 to 94.0 mol%, still more preferably from 91 .5 to 95.5 mol%, based on the total mol-content of the propyleneethylene copolymer (A) and determined by quantitative13C-NMR spectroscopy.

[0121] Further, the propylene-ethylene random copolymer (A) has a relative content of isolated to block ethylene sequences, l(E), of from 62.0 to 70.0%, preferably 62.5 to 69.0%, more preferably 63.0 to 68.0%, still more preferably 64.0 to 67.0%, wherein the l(E) content is defined by equation (I): 100 (I) wherein

[0122] 1(E) is the relative content of isolated to block ethylene sequences [in %]; fPEP is the mol fraction of propylene / ethylene / propylene sequences (PEP) in the sample; fPEE is the mol fraction of propylene / ethylene / ethylene sequences (PEE) and of ethylene / ethylene / propylene sequences (EEP) in the sample; fEEE is the mol fraction of ethylene / ethylene / ethylene sequences (EEE) in the sample, wherein all sequence concentrations being based on a statistical triad analysis of13C- NMR data.

[0123] The propylene-ethylene random copolymer (A) preferably has a melt flow rate MFR2 of from 0.1 to 5.0 g / 10 min, more preferably from 0.2 to 4.0 g / 10 min, even more preferably from 0.5 to 3.0 g / 10 min, still more preferably from 1 .0 to 2.5 g / 10 min, determined according to ISO 1133 at 230°C and 2.16 kg.

[0124] Further, the propylene-ethylene random copolymer (A) preferably has a xylene cold solubles (XCS) content of from 5.0 to 15.0 wt.-%, more preferably from 5.5 to 13.5 wt.- %, even more preferably from 6.5 to 12.5 wt.-%, still more preferably from 7.5 to 11 .5 wt.-%, based on the total weight of the propylene-ethylene random copolymer (A) and determined according to ISO 16152.

[0125] Still further, the propylene-ethylene random copolymer (A) preferably has a polydispersity index PDI, being the ratio of weight average molecular weight and number average molecular weight Mw / Mn, both determined by GPC measurement, of from 5.0 to 20.0, more preferably from 5.5 to 15.0, even more preferably from 6.0 to 12.5, still more preferably from 7.2 to 10.0.

[0126] Furthermore, the propylene-ethylene random copolymer (A) preferably has a flexural modulus of from 500 to 1000 MPa, more preferably from 550 to 900 MPa, even more preferably from 600 to 850 MPa, still more preferably from 625 to 800 MPa, determined according to ISO 178 method A (3-point bending test) on 80 mm x 10 mm x 4 mm specimens.

[0127] Additionally, the propylene-ethylene random copolymer (A) has a non-detectable content of 2,1 -regiodefects, determined by13C-NMR spectroscopy.

[0128] “Non-detectable” in this context means that the content of 2,1 -regiodefects of the propylene-ethylene random copolymer (A) is below the detection limit of the13C-NMR spectroscopy as described below in the determination methods.

[0129] Thereby, the total content of 2,1 -regiodefects is preferably from 0.00 to less than 0.05 mol%, more preferably from 0.00 to less than 0.03 mol%, still more preferably from 0.00 to less than 0.01 mol%, most preferably 0.00 mol%, based on the total mol-content of the propylene-ethylene random copolymer (A).

[0130] A non-detectable content of 2,1 -regiodefects, preferably 0.00 mol% 2,1 -regiodefects, is an indication that the propylene-ethylene random copolymer (A) has been polymerized in the presence of a Ziegler-Natta catalyst.

[0131] Therefore, it is further preferred that the propylene-ethylene random copolymer (A) has been polymerized in the presence of a Ziegler-Natta catalyst system.

[0132] The Ziegler-Natta catalyst system preferably comprises a) a Ziegler-Natta catalyst comprising compounds (TC) of a transition metal of Group 4 to 6 of IUPAC, a Group 2 metal compound and an internal donor, wherein said internal donor is a non-phthalic compound, preferably a non-phthalic acid ester; b) a co-catalyst (Co), and c) optionally an external donor (ED), wherein the molar ratio of co-catalyst (Co) to external donor (ED) [Co / ED] is preferably in the range of 5 to 45, and the molar ratio of co-catalyst (Co) to titanium compound (TC) [Co / TC] is preferably in the range of above 80 to 500.

[0133] The internal donor is preferably selected from

[0134] - optionally substituted malonates,

[0135] - maleates,

[0136] - succinates,

[0137] - glutarates,

[0138] - cyclohexene-1 ,2-dicarboxylates,

[0139] - benzoates and derivatives and / or mixtures thereof,

[0140] - citraconate.

[0141] Preferably, the internal donor (ID) is a citraconate.

[0142] The Ziegler-Natta catalyst can be further defined by the way as obtained. Accordingly, the Ziegler-Natta catalyst is preferably obtained by a process comprising the steps of a) ai) providing a solution of at least a Group 2 metal alkoxy compound (Ax) being the reaction product of a Group 2 metal compound (MC) and an alcohol (A) comprising in addition to the hydroxyl moiety at least one ether moiety optionally in an organic liquid reaction medium; or a2) a solution of at least a Group 2 metal alkoxy compound (Ax’) being the reaction product of a Group 2 metal compound (MC) and an alcohol mixture of the alcohol (A) and a monohydric alcohol (B) of formula ROH, optionally in an organic liquid reaction medium; or as) providing a solution of a mixture of the Group 2 alkoxy compound (Ax) and a Group 2 metal alkoxy compound (Bx) being the reaction product of a Group 2 metal compound (MG) and the monohydric alcohol (B), optionally in an organic liquid reaction medium; and b) adding said solution from step a) to at least one compound (TC) of a transition metal of Group 4 to 6 and c) obtaining the solid catalyst component particles, and adding a non-phthalic internal electron donor (ID) at any step prior to step c).

[0143] The internal donor (ID) or precursor thereof is added preferably to the solution of step a).

[0144] According to the procedure above the Ziegler-Natta catalyst can be obtained via precipitation method or via emulsion (liquid / liquid two-phase system) - solidification method depending on the physical conditions, especially temperature used in steps b) and c).

[0145] In both methods (precipitation or emulsion-solidification) the catalyst chemistry is the same.

[0146] In precipitation method combination of the solution of step a) with at least one transition metal compound (TC) in step b) is carried out and the whole reaction mixture is kept at least at 50 °C, more preferably in the temperature range of 55 to 110 °C, more preferably in the range of 70 to 100 °C, to secure full precipitation of the catalyst component in form of a solid particles (step c).

[0147] In emulsion - solidification method in step b) the solution of step a) is typically added to the at least one transition metal compound (TC) at a lower temperature, such as from - 10 to below 50 °C, preferably from -5 to 30 °C. During agitation of the emulsion the temperature is typically kept at -10 to below 40 °C, preferably from -5 to 30 °C. Droplets of the dispersed phase of the emulsion form the active catalyst composition. Solidification (step c) of the droplets is suitably carried out by heating the emulsion to a temperature of 70 to 150 °C, preferably to 80 to 110 °C.

[0148] The catalyst prepared by emulsion - solidification method is preferably used in the present invention. In a preferred embodiment in step a) the solution of a2) or as) are used, i.e. a solution of (Ax’) or a solution of a mixture of (Ax) and (Bx).

[0149] Preferably the Group 2 metal (MG) is magnesium.

[0150] The magnesium alkoxy compounds (Ax), (Ax’) and (Bx) can be prepared in situ in the first step of the catalyst preparation process, step a), by reacting the magnesium compound with the alcohol(s) as described above, or said magnesium alkoxy compounds can be separately prepared magnesium alkoxy compounds or they can be even commercially available as ready magnesium alkoxy compounds and used as such in the catalyst preparation process of the invention.

[0151] Illustrative examples of alcohols (A) are monoethers of dihydric alcohols (glycol monoethers). Preferred alcohols (A) are C2 to C4 glycol monoethers, wherein the ether moieties comprise from 2 to 18 carbon atoms, preferably from 4 to 12 carbon atoms. Preferred examples are 2-(2-ethylhexyloxy)ethanol, 2-butyloxy ethanol, 2-hexyloxy ethanol and 1 ,3-propylene-glycol-monobutyl ether, 3-butoxy-2-propanol, with 2-(2- ethylhexyloxy)ethanol and 1 ,3-propylene-glycol-monobutyl ether, 3-butoxy-2-propanol being particularly preferred.

[0152] Illustrative monohydric alcohols (B) are of formula ROH, with R being straight-chain or branched Ce-C alkyl residue. The most preferred monohydric alcohol is 2-ethyl-1 - hexanol or octanol.

[0153] Preferably a mixture of Mg alkoxy compounds (Ax) and (Bx) or mixture of alcohols (A) and (B), respectively, are used and employed in a mole ratio of Bx:Ax or B:A from 8:1 to 2:1 , more preferably 5:1 to 3:1 .

[0154] Magnesium alkoxy compound may be a reaction product of alcohol(s), as defined above, and a magnesium compound selected from dialkyl magnesiums, alkyl magnesium alkoxides, magnesium dialkoxides, alkoxy magnesium halides and alkyl magnesium halides. Alkyl groups can be a similar or different C1-C20 alkyl, preferably C2- C10 alkyl. Typical alkyl-alkoxy magnesium compounds, when used, are ethyl magnesium butoxide, butyl magnesium pentoxide, octyl magnesium butoxide and octyl magnesium - l - octoxide. Preferably the dialkyl magnesiums are used. Most preferred dialkyl magnesiums are butyl octyl magnesium or butyl ethyl magnesium.

[0155] It is also possible that magnesium compound can react in addition to the alcohol (A) and alcohol (B) also with a polyhydric alcohol (C) of formula R” (OH)mto obtain said magnesium alkoxide compounds. Preferred polyhydric alcohols, if used, are alcohols, wherein R” is a straight-chain, cyclic or branched C2 to C10 hydrocarbon residue, and m is an integer of 2 to 6.

[0156] The magnesium alkoxy compounds of step a) are thus selected from the group consisting of magnesium dialkoxides, diaryloxy magnesiums, alkyloxy magnesium halides, aryloxy magnesium halides, alkyl magnesium alkoxides, aryl magnesium alkoxides and alkyl magnesium aryloxides. In addition a mixture of magnesium dihalide and a magnesium dialkoxide can be used.

[0157] The solvents to be employed for the preparation of the present catalyst may be selected among aromatic and aliphatic straight chain, branched and cyclic hydrocarbons with 5 to 20 carbon atoms, more preferably 5 to 12 carbon atoms, or mixtures thereof. Suitable solvents include benzene, toluene, cumene, xylene, pentane, hexane, heptane, octane and nonane. Hexanes and pentanes are particular preferred.

[0158] Mg compound is typically provided as a 10 to 50 wt.-% solution in a solvent as indicated above. Typical commercially available Mg compound, especially dialkyl magnesium solutions are 20 - 40 wt.-% solutions in toluene or heptanes.

[0159] The reaction for the preparation of the magnesium alkoxy compound may be carried out at a temperature of 40 °C to 70 °C. Most suitable temperature is selected depending on the Mg compound and alcohol(s) used.

[0160] The transition metal compound of Group 4 to 6 is preferably a titanium compound, most preferably a titanium halide, like TiCk. The internal donor (ID) used in the preparation of the catalyst used in the present invention is preferably selected from substituted maleates and citraconates. Most preferably the internal donoer is citraconate.

[0161] In emulsion method, the two phase liquid-liquid system may be formed by simple stirring and optionally adding (further) solvent(s) and additives, such as the turbulence minimizing agent (TMA) and / or the emulsifying agents and / or emulsion stabilizers, like surfactants, which are used in a manner known in the art for facilitating the formation of and / or stabilize the emulsion. Preferably, surfactants are acrylic or methacrylic polymers. Particular preferred are unbranched C12 to C20 (meth)acrylates such as poly(hexadecyl)- methacrylate and poly(octadecyl)-methacrylate and mixtures thereof. Turbulence minimizing agent (TMA), if used, is preferably selected from a-olefin polymers of a-olefin monomers with 6 to 20 carbon atoms, like polyoctene, polynonene, polydecene, polyundecene or polydodecene or mixtures thereof. Most preferable it is polydecene.

[0162] The solid particulate product obtained by precipitation or emulsion - solidification method may be washed at least once, preferably at least twice, most preferably at least three times with aromatic and / or aliphatic hydrocarbons, preferably with toluene, heptane or pentane. The catalyst can further be dried, as by evaporation or flushing with nitrogen, or it can be slurried to an oily liquid without any drying step.

[0163] The finally obtained Ziegler-Natta catalyst is desirably in the form of particles having generally an average particle size range of 5 to 200 pm, preferably 10 to 100. Particles are compact with low porosity and have surface area below 20 g / m2, more preferably below 10 g / m2. Typically the amount of Ti is 1 to 6 wt.-%, Mg 10 to 20 wt.-% and donor 10 to 40 wt.-% of the catalyst composition.

[0164] Detailed description of preparation of catalysts is disclosed in WO 2012 / 007430, EP 2 415 790, EP 2 610 270, EP 2 610 271 and EP 2 610 272 which are incorporated here by reference.

[0165] The Ziegler-Natta catalyst is preferably used in association with an alkyl aluminum cocatalyst and optionally external donors. As further component in the instant polymerization process an external donor (ED) is preferably present. Suitable external donors (ED) include certain silanes, ethers, esters, amines, ketones, heterocyclic compounds and blends of these. It is especially preferred to use a silane. It is most preferred to use silanes of the general formula

[0166] RapRbqSi(ORc)(4-p-q) wherein Ra, Rband Rcdenote a hydrocarbon radical, in particular an alkyl or cycloalkyl group, and wherein p and q are numbers ranging from 0 to 3 with their sum p + q being equal to or less than 3. Ra, Rband Rccan be chosen independently from one another and can be the same or different. Specific examples of such silanes are (tert- butyl)2Si(OCHs)2, (cyclohexyl)(methyl)Si(OCH3)2, (phenyl)2Si(OCH3)2 and (cyclopentyl)2Si(OCHs)2, or of general formula

[0167] Si(OCH2CH3)3(NR3R4) wherein R3and R4can be the same or different a represent a hydrocarbon group having 1 to 12 carbon atoms.

[0168] R3and R4are independently selected from the group consisting of linear aliphatic hydrocarbon group having 1 to 12 carbon atoms, branched aliphatic hydrocarbon group having 1 to 12 carbon atoms and cyclic aliphatic hydrocarbon group having 3 to 12 carbon atoms. It is in particular preferred that R3and R4are independently selected from the group consisting of methyl, ethyl, n-propyl, n-butyl, octyl, decanyl, iso-propyl, isobutyl, iso-pentyl, tert. -butyl, tert. -amyl, neopentyl, cyclopentyl, cyclohexyl, methylcyclopentyl and cycloheptyl.

[0169] More preferably both R3and R4are the same, yet more preferably both R3and R4are an ethyl group.

[0170] Especially preferred external donors (ED) are the pentyl dimethoxy silane donor (D- donor) or the cyclohexylmethyl dimethoxy silane donor (C-Donor), the latter especially preferred.

[0171] In addition to the Ziegler-Natta catalyst and the optional external donor (ED) a cocatalyst can be used. The co-catalyst is preferably a compound of group 13 of the periodic table (IUPAC), e.g. organo aluminum, such as an aluminum compound, like aluminum alkyl, aluminum halide or aluminum alkyl halide compound. Accordingly, in one specific embodiment the co-catalyst (Co) is a trialkylaluminium, like triethylaluminium (TEAL), dialkyl aluminium chloride or alkyl aluminium dichloride or mixtures thereof. In one specific embodiment the co-catalyst (Co) is triethylaluminium (TEAL).

[0172] Advantageously, the triethyl aluminium (TEAL) has a hydride content, expressed as AIH3, of less than 1 .0 wt.-% with respect to the triethyl aluminium (TEAL). More preferably, the hydride content is less than 0.5 wt.-%, and most preferably the hydride content is less than 0.1 wt.-%.

[0173] Preferably the ratio between the co-catalyst (Co) and the external donor (ED) [Co / ED] and / or the ratio between the co-catalyst (Co) and the transition metal (TM) [Co / TM] should be carefully chosen.

[0174] Accordingly,

[0175] (a) the mol-ratio of co-catalyst (Co) to external donor (ED) [Co / ED] preferably is in the range of 5 to 45, preferably is in the range of 5 to 35, more preferably is in the range of 5 to 25; and optionally

[0176] (b) the mol-ratio of co-catalyst (Co) to titanium compound (TC) [Co / TC] preferably is in the range of above 80 to 500, preferably is in the range of 100 to 450, still more preferably is in the range of 120 to 350.

[0177] The propylene-ethylene random copolymer (A) is preferably polymerized in a polymerization process, which comprises the following steps: a) polymerizing propylene monomer units and ethylene comonomer units in a first polymerization reactor in the presence of a Ziegler-Natta catalyst system to produce a first polymerization mixture comprising a first random copolymer fraction and the Ziegler-Natta catalyst system, wherein the first polymerization reactor is preferably a slurry reactor, more preferably a loop reactor; b) withdrawing said first polymerization mixture from the first polymerization reactor and optionally carrying out steps c1 ) through c3) prior to step d) c1 ) transferring the first polymerization mixture into a second polymerization reactor, preferably a gas phase reactor; c2) polymerizing propylene monomer units and ethylene comonomer units in said second polymerization reactor in the presence of said Ziegler-Natta catalyst system to produce a second polymerization mixture comprising the first random copolymer fraction, a second random copolymer fraction and the Ziegler-Natta catalyst system; c3) withdrawing said second polymerization mixture from said second polymerization reactor; and d) compounding the first polymerization mixture if steps c1 ) to c3) are not present, or the second polymerization mixture if steps c1 ) to c3) are present, with the alpha nucleating agent (B), and optionally with the addition of further additives to form the polypropylene composition.

[0178] It is preferred that the operating temperature in the first polymerization reactor is in the range from 62 to 85 °C, more preferably in the range from 65 to 82 °C, still more preferably in the range from 67 to 80 °C.

[0179] Alternatively or additionally to the previous paragraph it is preferred that the operating temperature in the second polymerization reactor is in the range from 75 to 95 °C, more preferably in the range from 78 to 92 °C.

[0180] Typically, the pressure in the first polymerization reactor, preferably in the loop reactor (LR), is in the range from 20 to 80 bar, preferably 30 to 70 bar, like 35 to 65 bar, whereas the pressure in the second polymerization reactor, i.e. in the gas phase reactor (GPR), is in the range from 5 to 50 bar, preferably 15 to 40 bar.

[0181] Preferably hydrogen is added in each polymerization reactor in order to control the molecular weight, i.e. the melt flow rate MFR2.

[0182] The preparation of the propylene-ethylene random copolymer (A) can comprise in addition to the (main) polymerization of the propylene-ethylene random copolymer (A) in the at two polymerization reactors prior thereto a pre-polymerization in a prepolymerization reactor upstream to the first polymerization reactor.

[0183] In the pre-polymerization reactor a polypropylene is produced. The pre-polymerization is conducted in the presence of the Ziegler-Natta catalyst system. According to this embodiment, the Ziegler-Natta catalyst system is introduced to the pre-polymerization step. However, this shall not exclude the option that at a later stage for instance further co-catalyst is added in the polymerization process, for instance in the first reactor. In one embodiment, all components of the Ziegler-Natta catalyst system are only added in the pre-polymerization reactor, if a pre-polymerization is applied.

[0184] The pre-polymerization reaction is typically conducted at a temperature of 0 to 60 °C, preferably from 15 to 50 °C, and more preferably from 20 to 45 °C.

[0185] The pressure in the pre-polymerization reactor is not critical but must be sufficiently high to maintain the reaction mixture in liquid phase. Thus, the pressure may be from 20 to 100 bar, for example 30 to 70 bar.

[0186] In a preferred embodiment, the pre-polymerization is conducted as bulk slurry polymerization in liquid propylene, i.e. the liquid phase mainly comprises propylene, with optionally inert components dissolved therein. Furthermore, according to the present invention, an ethylene feed is employed during pre-polymerization as mentioned above.

[0187] It is possible to add other components also to the pre-polymerization stage. Thus, hydrogen may be added into the pre-polymerization stage to control the molecular weight of the polypropylene as is known in the art. Further, antistatic additive may be used to prevent the particles from adhering to each other or to the walls of the reactor.

[0188] The precise control of the pre-polymerization conditions and reaction parameters is within the skill of the art.

[0189] Particulate alpha-nucleating agent (B)

[0190] The particulate alpha-nucleating agent, which comprises a compound, which is selected from compounds having a phosphate moiety, compounds that comprise a dicarboxylic acid derivative and combinations thereof.

[0191] The compounds having a phosphate moiety are compounds having the structure [(Ar1O)(Ar2O)(O=)P-O]nX, wherein Ar1and Ar2are each independently selected from phenyl groups substituted by one or more Ci to Ce linear or branched alkyl groups, wherein Ar1and Ar2may also be linked by a direct single bond, an O, or a Ci to Ce alkylene group n = 1 , and

[0192] X is selected from the group consisting of Li, Na and K, preferably Li and Na, more preferably Li.

[0193] Said compounds are preferably selected from the group consisting of sodium di(4-tert- butylphenyl)phosphate, sodium 2, 2’-methylene-bis-(4,6-di-tert. butylphenyl) phosphate, potassium 2, 2’-methylene-bis-(4,6-di-tert. butylphenyl) phosphate, and lithium 2,2’- methylene-bis-(4,6-di-tert. butylphenyl) phosphate, more preferably from the group consisting of sodium di(4-tert-butylphenyl)phosphate, sodium 2,2’-methylene-bis-(4,6-di- tert. butylphenyl) phosphate, lithium 2, 2’-methylene-bis-(4,6-di-tert. butylphenyl) phosphate and mixtures thereof.

[0194] Most preferably the compound is lithium 2, 2’-methylene-bis-(4,6-di-tert. butylphenyl) phosphate.

[0195] As would be understood by the person skilled in the art, such particulate alpha nucleating agents may be present either as a single compound or as a particulate blend. One such particulate blend that contains lithium 2,2’-methylene-bis-(4,6-di- tert. butylphenyl) phosphate as the major component is ADK STAB NA-71 , commercially available from Adeka Corp.

[0196] The compounds that comprise a dicarboxylic acid derivative preferably have a structure according to formula (II) wherein each of R1, R2, R3, R4, R5, R6, R7, R8, R9and R10is independently selected from hydrogen and a Ci to C10 hydrocarbyl group; whereby two of R3to R10located on adjacent carbon atoms may be fused to form a cyclic hydrocarbyl structure; whereby two of R3to R10located on non-adjacent carbon atoms may be fused to form a bicyclic hydrocarbyl structure;

[0197] M is selected from the groups consisting of sodium, potassium, calcium, strontium, lithium, zinc, magnesium and monobasic aluminium; n is 1 or 2; z is 1 or 2; the sum of n+z is 3.

[0198] More preferably, each of R1, R2, R3, R4, R5, R6, R7, R8, R9and R10is independently selected from hydrogen and a Ci to C4 alkyl group, even more preferably from hydrogen, methyl or ethyl. In one particularly preferred embodiment, each of R1, R2, R3, R4, R5, R6, R7, R8, R9and R10is hydrogen.

[0199] M is preferably sodium or calcium, more preferably calcium.

[0200] It is particularly preferred that the compound is selected from bicyclo (2.2.1 ) heptane- 2,3-dicarboxylic acid, disodium salt and calcium 1 ,2-cyclohexane dicarboxylate, most preferably calcium (1 R, 2S)-cyclohexane dicarboxylate and mixtures thereof.

[0201] As would be understood by the person skilled in the art, such particulate alpha nucleating agents may be present either as a single compound or as a particulate blend. One such particulate blend that contains calcium (1 R, 2S)-cyclohexane dicarboxylate as the major component is Hyperform HPN-20E, commercially available from Milliken Chemical.

[0202] Examples

[0203] 1. Measuring methods

[0204] The following definitions of terms and determination methods apply for the above general description of the invention including the claims as well as to the below examples unless otherwise defined.

[0205] Quantification of microstructure by NMR spectroscopy Quantitative nuclear-magnetic resonance (NMR) spectroscopy was used to quantify the isotacticity and regio-regularity of the polymers.

[0206] Quantitative13C{1H} NMR spectra were recorded in the solution-state using a Bruker Advance III 400 NMR spectrometer operating at 400.15 and 100.62 MHz for1H and13C respectively. All spectra were recorded using a13C optimised 10 mm extended temperature probehead at 125°C using nitrogen gas for all pneumatics.

[0207] For polymers approximately 200 mg of material was dissolved in 7,2-tetrachloroethane- dz (TCE-cfe). To ensure a homogenous solution, after initial sample preparation in a heat block, the NMR tube was further heated in a rotatary oven for at least 1 hour. Upon insertion into the magnet the tube was spun at 10 Hz. This setup was chosen primarily for the high resolution needed for tacticity distribution quantification (Busico, V., Cipullo, R., Prog. Polym. Sci. 26 (2001 ) 443; Busico, V.; Cipullo, R., Monaco, G., Vacatello, M., Segre, A.L., Macromolecules 30 (1997) 6251 ). Standard single-pulse excitation was employed utilising the NOE and bi-level WALTZ16 decoupling scheme (Zhou, Z., Kuemmerle, R., Qiu, X., Redwine, D., Cong, R., Taha, A., Baugh, D. Winniford, B., J. Mag. Reson. 187 (2007) 225; Busico, V., Carbonniere, P., Cipullo, R., Pellecchia, R., Severn, J., Talarico, G., Macromol. Rapid Commun. 2007, 28, 11289). A total of 8192 (8k) transients were acquired per spectra.

[0208] Quantitative13C{1H} NMR spectra were processed, integrated and relevant quantitative properties determined from the integrals using proprietary computer programs.

[0209] For propylene homopolymers all chemical shifts are internally referenced to the methyl isotactic pentad (mmmm) at 21 .85 ppm.

[0210] Characteristic signals corresponding to regio defects (Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem. Rev. 2000, 100, 1253; Wang, W-J., Zhu, S., Macromolecules 33 (2000), 1157; Cheng, H. N., Macromolecules 17 (1984), 1950) or comonomer were observed.

[0211] The tacticity distribution was quantified through integration of the methyl region between 23.6-19.7 ppm correcting for any sites not related to the stereo sequences of interest (Busico, V., Cipullo, R., Prog. Polym. Sci. 26 (2001 ) 443; Busico, V., Cipullo, R., Monaco, G., Vacatello, M., Segre, A.L., Macromolecules 30 (1997) 6251 ).

[0212] Specifically the influence of regio-defects and comonomer on the quantification of the tacticity distribution was corrected for by subtraction of representative regio-defect and comonomer integrals from the specific integral regions of the stereo sequences. The isotacticity was determined at the pentad level and reported as the percentage of isotactic pentad (mmmm) sequences with respect to all pentad sequences: [mmmm] % = 100 * (mmmm / sum of all pentads)

[0213] The presence of 2,1 erythro regio-defects was indicated by the presence of the two methyl sites at 17.7 and 17.2 ppm and confirmed by other characteristic sites. Characteristic signals corresponding to other types of regio-defects were not observed (Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem. Rev. 2000, 100, 1253).

[0214] The amount of 2,1 erythro regio-defects was quantified using the average integral of the two characteristic methyl sites at 17.7 and 17.2 ppm:

[0215] P21e = (Ie6 + les) / 2

[0216] The amount of 1 ,2 primary inserted propylene was quantified based on the methyl region with correction undertaken for sites included in this region not related to primary insertion and for primary insertion sites excluded from this region: Pl2 = lcH3 + Pl2e

[0217] The total amount of propylene was quantified as the sum of primary inserted propylene and all other present regio-defects:

[0218] Ptotal = P12 + P2le

[0219] The mole percent of 2,1 erythro regio-defects was quantified with respect to all propylene:

[0220] [21 e] mol% = 100 * (P2ie / Ptotai)

[0221] The comonomer fraction was quantified using the method of Wang et. al. (Wang, W-J., Zhu, S., Macromolecules 33 (2000), 1157) through integration of multiple signals across the whole spectral region in the13C{1H} spectra. This method was chosen for its robust nature and ability to account for the presence of regio-defects when needed. Integral regions were slightly adjusted to increase applicability across the whole range of encountered comonomer contents.

[0222] For systems where only isolated ethylene in PPEPP sequences was observed the method of Wang et. al. was modified to reduce the influence of non-zero integrals of sites that are known to not be present. This approach reduced the overestimation of ethylene content for such systems and was achieved by reduction of the number of sites used to determine the absolute ethylene content to:

[0223] E = O.5(S P + Spy + Sp6 + O.5(Sa + Say))

[0224] Through the use of this set of sites the corresponding integral equation becomes: E = 0.5(IH +IG + 0.5(lc + ID)) using the same notation used in the article of Wang et. al. (Wang, W-J., Zhu, S., Macromolecules 33 (2000), 1157). Equations used for absolute propylene content were not modified.

[0225] The mole percent comonomer incorporation was calculated from the mole fraction:

[0226] E [mol%] = 100 * fE

[0227] The weight percent comonomer incorporation was calculated from the mole fraction:

[0228] E [wt.-%] = 100 * (f E * 28.06) / ((f E * 28.06) + ((1 -f E) * 42.08))

[0229] The comonomer sequence distribution at the triad level was determined using the analysis method of Kakugo et al. (Kakugo, M., Naito, Y., Mizunuma, K., Miyatake, T. Macromolecules 15 (1982) 1150). This method was chosen for its robust nature and integration regions slightly adjusted to increase applicability to a wider range of comonomer contents.

[0230] The relative content of isolated to block ethylene incorporation was calculated from the triad sequence distribution using the following relationship (equation (II)): 100 (II) wherein l(E) is the relative content of isolated to block ethylene sequences [in %]; fPEP is the mol fraction of propylene / ethylene / propylene sequences (PEP) in the sample; fPEE is the mol fraction of propylene / ethylene / ethylene sequences (PEE) and of ethylene / ethylene / propylene sequences (EEP) in the sample; fEEE is the mol fraction of ethylene / ethylene / ethylene sequences (EEE) in the sample

[0231] Melt Flow Rate

[0232] The melt flow rate (MFR) is determined according to ISO 1133 and is indicated in g / 10 min. The MFR is an indication of the flowability, and hence the processability, of the polymer. The higher the melt flow rate, the lower the viscosity of the polymer. The MFR2 of polypropylene is determined at a temperature of 230 °C and a load of 2.16 kg.

[0233] The xylene soluble fraction at room temperature (XCS, wt.-%): The amount of the polymer soluble in xylene is determined at 25 °C according to ISO 16152; 5thedition; 2005-07-01 . DSC analysis, melting temperature (Tm) and heat of fusion (Hm), crystallization temperature (Tc) and heat of crystallization (Hc): measured with a TA Instrument Q200 differential scanning calorimetry (DSC) on 5 to 7 mg samples. DSC is run according to ISO 11357 I part 3 / method C2 in a heat I cool I heat cycle with a scan rate of 10 °C / min in the temperature range of -30 to +225 °C. Crystallization temperature (Tc) and heat of crystallization (Hc) are determined from the cooling step, while melting temperature (Tm) and heat of fusion (Hm) are determined from the second heating step.

[0234] Molar mass:

[0235] Molar mass averages (Mz, Mw and Mn) and polydispersity index (PDI), i.e. Mw / Mn, were determined by Gel Permeation Chromatography (GPC) according to ISO 16014- 4:2003 and ASTM D 6474-99 using the following formulas: where Ai and Mi are the chromatographic peak slice area and polyolefin molecular weight (MW).

[0236] A PolymerChar GPC instrument, equipped with infrared (IR) detector was used with 3 x Olexis and 1x Olexis Guard columns from Polymer Laboratories and 1 ,2,4- trichlorobenzene (TCB, stabilized with 250 mg / l 2,6-Di-tert-butyl-4-methyl-phenol) as solvent at 160 °C and at a constant flow rate of 1 ml / min. 200 pL of sample solution were injected per analysis. The column set was calibrated using universal calibration (according to ISO 16014-2:2003) with at least 15 narrow MWD polystyrene (PS) standards in the range of 0.5 kg / mol to 11500 kg / mol. Mark Houwink constants used for PS, PE and PP are as described per ASTM D 6474-99. All samples were prepared by dissolving 5.0 to 9.0 mg of polymer in 8 ml (at 160 °C) of stabilized TCB (same as mobile phase) for 2.5 hours for PP or 3 hours for PE at 160 °C under continuous gentle shaking in the autosampler of the GPC instrument. The Flexural Modulus was determined according to ISO 178 method A (3-point bending test) on 80 mm x 10 mm x 4 mm specimens. Following the standard, a test speed of 2 mm / min and a span length of 16 times the thickness was used. The testing temperature was 23±2 ° C. Injection molding was carried out according to ISO 19069-2 using a melt temperature of 230 °C for all materials irrespective of material melt flow rate.

[0237] Tensile Modulus in both the machine (MD) and transverse (TD) directions was determined according to ISO 527-3 at 23 °C on blown films of 50 pm thickness produced as indicated below.

[0238] Dart drop impact (DDI)

[0239] ISO 7765-1 :1988 / Method A

[0240] This test method covers the determination of the energy that causes films to fail under specified conditions of impact of a free-falling dart from a specified height that would result in failure of 50 % of the specimens tested (Staircase method A). A uniform missile mass increment is employed during the test and the missile weight is decreased or increased by the uniform increment after test of each specimen, depending upon the result (failure or no failure) observed for the specimen.

[0241] Standard conditions:

[0242] Conditioning time: > 96 h

[0243] Test temperature: 23 °C

[0244] Dart head material: phenolic

[0245] Dart diameter: 38 mm

[0246] Drop height: 660 mm

[0247] Results:

[0248] • Impact failure mass [g]

[0249] • Minimum thickness [mm]

[0250] • Maximum thickness [mm]

[0251] Testing according to ISO7765-1 :19881 Method A was carried out on films with a thickness as indicated and produced as described below under “Examples” and reported in gram (g).

[0252] DDI per unit thickness (in g / micron) is calculated by dividing DDI (in gram) to the thickness of film (in micron) 2. Polypropylene Compositions

[0253] 2.1 Synthesis of the propylene-ethylene random copolymers (PP-R1 and PP- R2)

[0254] For the polymerization of the propylene-ethylene random copolymer PP-R1 a Ziegler- Natta type catalyst as used in for the inventive examples of WO 2016 / 066446 A1 was employed (without any vinylcyclohexane prepolymerization). As co-catalyst triethylaluminium (TEAL) and as donor dicyclo pentyl dimethoxy silane (D-donor) was used.

[0255] For the polymerization of the propylene-ethylene random copolymer PP-R2 a Ziegler- Natta type catalyst as described in the example section of WO 2010 / 009827 A1 (see pages 30 and 31 ) was employed. As co-catalyst triethyl-aluminium (TEAL) and as donor dicyclo pentyl dimethoxy silane (D-donor) was used.

[0256] The two propylene-ethylene random copolymers PP-R1 and PP-R2 were both polymerized in a reactor set-up of a prepolymerization loop reactor followed by a loop reactor and a gas phase reactor.

[0257] The subsequent polymerizations have been effected under the conditions as listed in Table 1 .

[0258] The compounding was done on a ZSK 18 twin screw extruder, operated at 210 °C, production rate of 7 kg / h. The properties of the pellets of propylene-ethylene random copolymers PP-R1 and PP-R2 are listed in Table 1.

[0259] Table 1 Polymerization conditions for the propylene-ethylene random copolymers

[0260] 2.2 Blown films of examples IE1 and CE1-CE3

[0261] Blown films IE1 , and CE1 were prepared from PP-R1 and blown films CE2 and CE3 were prepared from PP-R2, all following the recipes given in Table 2. The blown films were prepared on a Collin 30 lab scale blown film line. The melt temperature is 210°C, film thickness is 50 pm, BUR 1 :2.5, uptake speed 7m / min.

[0262] Table 2 Recipes for inventive and comparative examples AS acid scavenger synthetic hydrotalcite (Gas. No 11097-59-9), commercially available as DHT4A from Kisuma Chemicals

[0263] AO1 antioxidant pentaerythrityl-tetrakis(3-(3’,5’-di-tert. butyl-4-hydroxyphenyl)- propionate (Cas. No. 6683-19-8), commercially available as Irganox 1010 from BASF SE

[0264] AO2 antioxidant tris (2,4-di-t-butylphenyl) phosphite (Cas. No. 31570-04-4), commercially available as Irgafos 168 from BASF SE

[0265] NA1 a particulate blend, comprising 2,2’- methylene bis-(2,6-di-tert. butylphenyl) phosphate lithium salt as the major component, commercially available as ADK STAB NA-71 from Adeka Corp.

[0266] NA2 a particulate blend, comprising aluminium hydroxybis[2,2’methylene-bis(4,6-di- tert-butylphenyl)phosphate] as the major component, commercially available as ADK STAB NA-21 from Adeka Corp.

[0267] The properties of the blown films of examples IE1 and CE1 -CE3 are shown in Table 3.

[0268] Table 3 Properties of the compositions and blown films of IE1 and CE1 -CE3 n.m. = not measured

[0269] When comparing the properties of the blown films of IE1 to CE1 , which only differ in their nucleating agent, it can be seen that IE1 shows a higher stiffness (TD-MD, TD-TD) and impact (DDI) compared to CE1 . When comparing the properties of the blown films of IE1 to CE2 and CE3, which only differ in the propylene-ethylene random copolymer, it can be seen that IE1 shows a higher stiffness (TD-MD, TD-TD) and impact (DDI) compared to CE2 and CE3. The loss in stiffness cannot be compensated by the higher amount of nucleating agent used in CE3.

Claims

1. Claims1 . A film comprising a polypropylene composition, wherein the polypropylene composition comprises(A) from 15.00 to 99.99 wt.-%, preferably from 20.00 to 99.98 wt.-%, more preferably from 25.00 wt.-% to 99.95 wt.-%, based on the total weight of the polypropylene composition, of a propylene-ethylene random copolymer having• a total content of ethylene comonomer units of from 4.0 to 15.0 mol%, preferably from 5.0 to 12.5 mol%, more preferably from 6.0 to 10.0 mol%, still more preferably from 6.5 to 8.5 mol%, based on the total mol-content of the propylene-ethylene copolymer (A) and determined by quantitative 13C-NMR spectroscopy;• a non-detectable content of 2,1 -regiodefects, determined by13C-NMR spectroscopy; and• a relative content of isolated to block ethylene sequences, l(E), of from 62.0 to 70.0%, preferably 62.5 to 69.0%, more preferably 63.0 to 68.0%, still more preferably 64.0 to 67.0%, wherein the l(E) content is defined by equation (I):1( 'E ') = - i -f'EEE+f—f'PEE -+f'PEP -) x 100 ( 'I ') wherein l(E) is the relative content of isolated to block ethylene sequences [in %]; fPEP is the mol fraction of propylene / ethylene / propylene sequences (PEP) in the sample; fPEE is the mol fraction of propylene / ethylene / ethylene sequences (PEE) and of ethylene / ethylene / propylene sequences (EEP) in the sample; fEEE is the mol fraction of ethylene / ethylene / ethylene sequences (EEE) in the sample, wherein all sequence concentrations being based on a statistical triad analysis of13C-NMR data; and(B) from 0.01 to 1 .00 wt.-%, preferably from 0.02 to 0.50 wt.-%, more preferably from 0.05 to 0.25 wt.-%, based on the total weight of the polypropylene composition, of a particulate alpha-nucleating agent, which comprises a compound selected from• compounds having the structure [(Ar1O)(Ar2O)(O=)P-O]nX, wherein Ar1and Ar2are each independently selected from phenyl groups substituted by one or more Ci to C& linear or branched alkyl groups, wherein Ar1and Ar2may also be linked by a direct single bond, an O, or a Ci to C& alkylene group n = 1 , andX is selected from the group consisting of Li, Na and K;• compounds that comprise a dicarboxylic acid derivative, such as compounds having a structure according to formula (II) wherein eachindependently selected from hydrogen and a Ci to C10 hydrocarbyl group; whereby two of R3to R10located on adjacent carbon atoms may be fused to form a cyclic hydrocarbyl structure; whereby two of R3to R10located on non-adjacent carbon atoms may be fused to form a bicyclic hydrocarbyl structure;M is selected from the groups consisting of sodium, potassium, calcium, strontium, lithium, zinc, magnesium and monobasic aluminium; n is 1 or 2; z is 1 or 2; the sum of n+z is 3; and• combinations thereof; and the polypropylene composition has a melt flow rate MFR2 of from 0.1 to 5.0 g / 10 min, preferably from 0.2 to 4.0 g / 10 min, more preferably from 0.5 to 3.0 g / 10 min, still more preferably from 1 .0 to 2.5 g / 10 min, determined according to ISO 1 133 at 230°C and 2.16 kg.

2. The film according to claim 1 , wherein the propylene-ethylene random copolymer(A) has one or more or all of the following properties:• a melt flow rate MFR2 of from 0.1 to 5.0 g / 10 min, preferably from 0.2 to 4.0 g / 10 min, more preferably from 0.5 to 3.0 g / 10 min, still more preferably from 1.0 to 2.5 g / 10 min, determined according to ISO 1133 at 230°C and 2.16 kg;• a xylene cold solubles (XCS) content of from 5.0 to 15.0 wt.-%, preferably from 5.5 to 13.5 wt.-%, more preferably from 6.5 to 12.5 wt.-%, still more preferably from 7.5 to 11 .5 wt.-%, based on the total weight of the propylene-ethylene random copolymer (A) and determined according to ISO 16152;• a polydispersity index PDI, being the ratio of weight average molecular weight and number average molecular weight Mw / Mn, both determined by GPC measurement, of from 5.0 to 20.0, more preferably from 5.5 to 15.0, even more preferably from 6.0 to 12.5, still more preferably from 7.2 to 10.0;• a flexural modulus of from 500 to 1000 MPa, preferably from 550 to 900 MPa, more preferably from 600 to 850 MPa, still more preferably from 625 to 800 MPa, determined according to ISO 178 method A (3-point bending test) on 80 mm x 10 mm x 4 mm specimens.

3. The film according to claims 1 or 2, wherein the propylene-ethylene random copolymer (A) has been polymerized in the presence of a Ziegler Natta catalyst system comprising a) a Ziegler-Natta catalyst comprising compounds (TC) of a transition metal of Group 4 to 6 of IUPAC, a Group 2 metal compound and an internal donor, wherein said internal donor is a non-phthalic compound, preferably a non- phthalic acid ester; b) a co-catalyst (Co), and c) optionally an external donor (ED), wherein the molar ratio of co-catalyst (Co) to external donor (ED) [Co / ED] is preferably in the range of 5 to 45, and the molar ratio of co-catalyst (Co) to titanium compound (TC) [Co / TC] is preferably in the range of above 80 to 500.

4. The film according to any one of claims 1 to 3, wherein the particulate alphanucleating agent (B) comprises a compound selected from the group consisting of sodium di(4-tert-butylphenyl)phosphate, sodium 2,2’-methylene-bis-(4,6-di-tert. butylphenyl) phosphate, potassium 2, 2’-methylene-bis-(4,6-di-tert. butylphenyl) phosphate, and lithium 2, 2’-methylene-bis-(4,6-di-tert. butylphenyl) phosphate, preferably from the group consisting of sodium di(4-tert-butylphenyl)phosphate, sodium 2, 2’-methylene-bis-(4,6-di-tert. butylphenyl) phosphate, lithium 2,2’- methylene-bis-(4,6-di-tert. butylphenyl) phosphate, more preferably lithium 2,2’- methylene-bis-(4,6-di-tert. butylphenyl) phosphate or mixtures thereof.The film according to any one of claims 1 to 4, wherein the particulate alphanucleating agent (B) comprises a compound selected from the group consisting of bicyclo (2.2.1 ) heptane-2,3-dicarboxylic acid, disodium salt and calcium 1 ,2- cyclohexane dicarboxylate, most preferably calcium (1 R, 2S)-cyclohexane dicarboxylate or mixtures thereof.

6. The film according to any one of claims 1 to 5, wherein the polypropylene composition has one or more or all of the following properties:• a total content of ethylene comonomer units of from 4.0 to 15.0 mol%, preferably from 5.0 to 12.5 mol%, more preferably from 6.0 to 10.0 mol%, still more preferably from 6.5 to 8.5 mol%, based on the total mol-content of the polypropylene composition and determined by quantitative13C-NMR spectroscopy; and• a relative content of isolated to block ethylene sequences, l(E), of from 62.0 to 70.0%, preferably 62.5 to 69.0%, more preferably 63.0 to 68.0%, still more preferably 64.0 to 67.0%, wherein the l(E) content is defined by equation (I): 100(I) wherein1(E) is the relative content of isolated to block ethylene sequences [in %]; fPEP is the mol fraction of propylene / ethylene / propylene sequences (PEP) in the sample; fPEE is the mol fraction of propylene / ethylene / ethylene sequences (PEE) and of ethylene / ethylene / propylene sequences (EEP) in the sample; fEEE is the mol fraction of ethylene / ethylene / ethylene sequences (EEE) in the sample,wherein all sequence concentrations being based on a statistical triad analysis of13C-NMR data;• a melting temperature Tm of from 135 to 155°C, preferably from 137 to 152°C, more preferably from 140 to 150°C, still more preferably from 142 to 148°C, determined by differential scanning calorimetry (DSC) according to ISO 113571 part 3 / method C2;• a crystallization temperature Tc of from 105 to 125°C, preferably from 108 to 122°C, more preferably from 112 to 120°C, still more preferably from 114 to 118°C, determined by differential scanning calorimetry (DSC) according to ISO 11357 / part 3 / method C2;• a non-detectable content of 2,1 -regiodefects, determined by13C-NMR spectroscopy;• a xylene cold solubles (XCS) content of from 5.0 to 15.0 wt.-%, preferably from 5.5 to 12.5 wt.-%, more preferably from 6.0 to 11 .0 wt.-%, still more preferably from 7.0 to 10.0 wt.-%, based on the total weight of the propylene-ethylene random copolymer (A) and determined according to ISO 16152;• a polydispersity index PDI, being the ratio of weight average molecular weight and number average molecular weight Mw / Mn, both determined by GPC measurement, of from 5.0 to 20.0, more preferably from 5.5 to 15.0, even more preferably from 6.0 to 12.5, still more preferably from 7.2 to 10.0.

7. The film according to any one of claims 1 to 6 being a monolayer film comprising from 90.0 to 100 wt.-%, preferably from 95.0 to 100 wt.-%, more preferably from 97.5 wt.-% to 100 wt.-% of the polypropylene composition, based on the total weight of the film.

8. The film according to claim 7, wherein the polypropylene composition comprises from 95.00 to 99.99 wt.-%, preferably from 97.50 to 99.98 wt.-%, more preferably from 98.50 wt.-% to 99.95 wt.-% of the propylene-ethylene random copolymer (A), based on the total weight of the polypropylene composition.

9. The film according to claim 7 or 8 having a film thickness of from 10 to 100 pm, preferably 20 to 75 pm, more preferably from 30 to 65 pm.

10. The film according to any one of claims 7 to 9 having one or more or all of the following properties:• a tensile modulus in machine direction (TM-MD) of from 900 to 1200 MPa, preferably from 925 to 1100 MPa, still more preferably from 950 to 1050 MPa, determined according to ISO 527-3 at 23 °C on monolayer blown films of 50 pm thickness;• a tensile modulus in transverse direction (TM-TD) of from 900 to 1200 MPa, preferably from 925 to 1100 MPa, still more preferably from 950 to 1050 MPa, determined according to ISO 527-3 at 23 °C on monolayer blown films of 50 pm thickness;• a dart drop impact (DDI) strength of from 42 to 200 g, preferably from 46 to 150 g, more preferably from 48 to 100 g, determined according to ISO 7765-1 , method A on monolayer blown films of 50 pm thickness.11 . The film according to any one of claims 1 to 6 being a multilayer film, wherein at least one layer, preferably one layer, comprises from 90.0 to 100 wt.-%, preferably from 95.0 to 100 wt.-%, more preferably from 97.5 wt.-% to 100 wt.-% of the polypropylene composition, based on the total weight of the layer.

12. The film according to claim 11 , wherein the polypropylene composition of the at least one layer, preferably one layer, comprises from 15.00 to 49.99 wt.-%, preferably from 20.00 to 44.98 wt.-%, more preferably from 25.00 wt.-% to 39.95 wt.-% of the propylene-ethylene random copolymer (A), based on the total weight of the polypropylene composition.

13. The film according to claims 11 or 12, wherein the at least one layer, preferably the layer, has a film thickness of from 1 to 50 pm, preferably 2 to 25 pm, more preferably from 5 to 20 pm.

14. The film according to any one of claims 1 to 13 being a blown film or a cast film.

15. The film according to any one of claims 1 to 14, wherein the film is fully recyclable.

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