Cast film comprising polypropylene composition with improved mechanical, optical and barrier properties

Abstract

The present invention relates to a cast film comprising a polypropylene composition comprising: a) a base polymer comprising a propylene homopolymer in an amount of from 95 to 100 wt.-% based on the total weight of the polypropylene composition, and b) optionally, additives selected from the group consisting of antioxidants, acid scavengers, stabilizers, fillers, colorants, nucleating agents, slip agents, anti-blocking agents and antistatic agents, in an amount of from 0 to 5 wt.-% based on the total weight of the polypropylene composition; wherein the polypropylene composition has: - a melt flow rate MFR2, as determined in accordance with ISO 1133 at 230 °C under a load of 2.16 kg, of from 6.0 to 10.0 g / 10 min; - a xylene cold soluble (XCS) content, as determined in accordance with ISO 16152, of from 1.0 to 2.0 wt.-%; - a melting temperature Tm, as determined in accordance with ISO 11357 / part 3 / method C2, of from 155 to 175 °C; and - a crystallization temperature Tc, as determined in accordance with ISO 11357 / part 3 / method C2, of from 105 to 130 °C - a pentad regularity [mmmm], as determined by 13C-NMR spectroscopy, of from 90 to 99.9 mol-%.

Description

[0001] CAST FILM COMPRISING POLYPROPYLENE COMPOSITION WITH IMPROVED MECHANICAL, OPTICAL AND BARRIER PROPERTIES

[0002] Field of Invention

[0003] The present invention pertains to a cast film comprising a polypropylene composition comprising a propylene homopolymer and optionally additives selected from the group consisting of antioxidants, acid scavengers, stabilizers, fillers, colorants, nucleating agents, slip agents, anti-blocking agents and antistatic agents. The present invention further pertains to the use of such a cast film in a pharmaceutical packaging.

[0004] Background of Invention

[0005] Following the current industry needs and trends, packaging in pharmaceutical industry is also heavily focused on providing easily recyclable packaging for products. In particular, pharmaceutical blister packaging has gained a special attention in the recent years in Europe, as in many of them the material on the blister side is polyvinyl chloride (PVC), polyvinylidene chloride (PvDC) or fluoropolymers, while the push-through closure is made of aluminum; which essentially prevents them from being mechanically recycled. Being on the market for many years, these structures do not really have an ideal design; for instance the aluminum layer has issues with sealing with the PVC-based layer. An additional sealant layer must be present between those two layers in order to strengthen the sealing; which in the end causes the recycling to be even more complicated, and increases costs for production. In addition, the high moisture penetration capability of PVC makes it also a less-attractive material for pharmaceutical blister packaging, since it becomes challenging to preserve the content in the packaging free from any contamination.

[0006] Different solutions for blister packaging focusing on improving different properties have been extensively studied in the art. For instance, US 2020 / 0399037 A1 discloses a multi-layer structure suitable for being used in blister packaging applications. This document aims to solve the moisture penetration-related issues linked to blister packaging materials, and for that purpose discloses the multi-layer structure as comprising, in the following order, a first polymeric layer which can be a metallized polyethylene terephthalate (PET), a first tie layer which can be an adhesive lacquer, a second polymeric layer which can be a cyclic olefin or homopolymer of chlorotrifluoroethylene, a second tie layer which can be an adhesive lacquer, and a third polymeric layer which can comprise polypropylene or PVC. However, such a structure will definitely have issues when mechanically recycled, and it requires a lamination step in production making the final product significantly more expensive. Document EP 0570188 B2, on the other hand, discloses use of a sheet as a blister package or a press-through pack (PTP) and aims at solving the moisture-barrier related issues. However, the blister package or PTP comprises a layer made of at least one non-crystalline polyolefin resin and possible a crystalline polyolefin resin with a crystallinity as determined according to X-ray diffraction method higher than 10%. While the respective sheets have a high moisture barrier, their thermal stability is limited by the low glass transition temperature of the employed non-crystalline polyolefin.

[0007] Hence, the need to obtain a film based on a polymer exhibiting improved mechanical, optical and barrier properties still remains. The present invention solves the above-indicated problems and achieves the mentioned improved properties thanks to the polymer composition disclosed herein.

[0008] Summary of Invention

[0009] The present invention relates to a cast film comprising a polypropylene composition comprising: a) a base polymer comprising a propylene homopolymer in an amount of from 95 to 100 wt.- % based on the total weight of the polypropylene composition, and b) optionally, at least one additive selected from the group consisting of antioxidants, acid scavengers, stabilizers, fillers, colorants, nucleating agents, slip agents, anti-blocking agents and antistatic agents, in an amount of from 0 to 5 wt.-% based on the total weight of the polypropylene composition; wherein the polypropylene composition has:

[0010] - a melt flow rate MFR2, as determined in accordance with ISO 1133 at 230 °C under a load of 2.16 kg, of from 6.0 to 10.0 g / 10 min;

[0011] - a xylene cold soluble (XCS) content, as determined in accordance with ISO 16152, of from 1.0 to 2.0 wt.-%;

[0012] - a melting temperature Tm, as determined in accordance with ISO 11357 I part 3 I method C2, of from 155 to 175 °C; and

[0013] - a crystallization temperature Tc, as determined in accordance with ISO 11357 I part 3 I method C2, of from 105 to 130 °C

[0014] - a pentad regularity [mmmm], as determined by13C-NMR spectroscopy, of from 90 to 99.9 mol-%. The present invention further relates to a cast film wherein the polypropylene composition as described herein, is obtained in a multi-stage polymerization process comprising the steps of: aO) optionally, modifying a Ziegler-Natta catalyst, preferably with a polymeric nucleating agent, more preferably with a vinyl polymer, and pre-polymerizing propylene in a pre-polymerization reactor; a) polymerizing propylene in the presence of a Ziegler-Natta catalyst, in a first polymerization reactor (R1) and obtaining a first polymerization product; b) transferring the first polymerization product to a second polymerization reactor (R2) and obtaining a final polymerization product; and c) optionally, compounding the final polymerization product obtained in step b) with additives.

[0015] The present invention further relates to use of an article as described herein in a pharmaceutical packaging.

[0016] Detailed Description

[0017] All the terms used herein are to be understood in their general meaning known to the skilled person in the art.

[0018] Polypropylene composition

[0019] The polypropylene composition, comprises a homopolymer of polypropylene in an amount of from 95 to 100 wt.-%, preferably from 97 to 100 wt.-%, more preferably from 98.5 to 100 wt.-% and optionally at least one additive, selected from the group consisting of antioxidants, acid scavengers, stabilizers, fillers, colorants, nucleating agents, slip agents, anti-blocking agents and antistatic agents, in an amount of from 0 to 5 wt.-%, preferably from 0 to 3 wt.-%, more preferably from 0 to 1 .5 wt.-%, both based on the total weight of the polypropylene composition.

[0020] The polypropylene composition in the cast film according to the present invention has a melt flow rate MFR2, as determined in accordance with ISO 1133 at 230 °C under a load of 2.16 kg, of from 3.0 to 15.0 g / 10 min. The preferred melt flow rate MFR2, as determined in accordance with ISO 1133 at 230 °C under a load of 2.16 kg, of the polypropylene composition ranges from 4.5 to 12.0 g / 10 min, more preferably from 6.0 to 10.0 g / 10 min.

[0021] The polypropylene composition in the cast film according to the present invention further has a xylene cold soluble (XCS) content, as determined in accordance with ISO 16152, of from 0.1 to 3.0 wt.-%, preferably from 0.5 to 2.5 wt.-%, more preferably from 1.0 to 2.0 wt.-%. It is particularly preferred when the polypropylene composition has a melt flow rate MFR2, as determined in accordance with ISO 1133 at 230 °C under a load of 2.16 kg, of from 4.5 to 12.0 g / 10 min, more preferably from 6.0 to 10.0 g / 10 min and a xylene cold soluble (XCS) content, as determined in accordance with ISO 16152, of from 0.5 to 2.5 wt.-%, more preferably from 1.0 to 2.0 wt.-%.

[0022] Further, the polypropylene composition in the cast film according to the present invention has an ethylene content, as determined by13C-NMR spectroscopy, of from 0 to 0.5 wt.-%, preferably from 0 to 0.3 wt.-%, more preferably from 0 to 0.1 wt.-%.

[0023] The polypropylene composition in the cast film of the present invention as described herein has a melting temperature Tm, as determined in accordance with ISO 113571 part 31 method C2, of from 155 to 175 °C, preferably from 160 to 170 °C. In addition, the polypropylene composition has a crystallization temperature Tc, as determined in accordance with ISO 11357 I part 31 method C2, of from 105 to 130 °C, preferably from 110 to 122 °C.

[0024] The polypropylene composition in the cast film according to the present invention is characterized as being highly isotactic, with a pentad regularity [mmmm], as determined by13C-NMR spectroscopy, of from 90 to 99.9 mol-%, preferably from 95 to 99.9 mol-%.

[0025] It is preferred when the polypropylene composition in the cast film according to the present invention has:

[0026] - a tensile modulus in machine direction, as determined in accordance with ISO 527-3 on a 300 pm cast film, of from 500 to 1200 MPa, more preferably from 650 to 1000 MPa, and most preferably from 700 to 850 MPa; and / or

[0027] - a tensile modulus in transverse direction, as determined in accordance with ISO 527-3 on a 300 pm cast film, of from 500 to 1300 MPa, more preferably from 650 to 1100 MPa, and most preferably from 700 to 1000 MPa.

[0028] It is also preferred when the polypropylene composition has a dart drop impact (DDI), as determined on a 300 pm cast film at 23 °C in accordance with ISO 7765-1 :19881 Method A of from 350 to 1500 g, more preferably from 400 to 1300 g, and most preferably from 700 to 1200 g.

[0029] It is also preferred when the polypropylene composition has a haze value, as determined in accordance with ASTM D1003 on a 300 pm cast film, of from 0 to 60%, more preferably from 0 to 50%, and most preferably from 0 to 40%; and / or a clarity value, as determined in accordance with ASTM D1003 on a 300 pm cast film, of from 20 to 100%, more preferably from 40 to 85%, and most preferably from 55 to 80%. Such haze and clarity values are particularly preferred, since a more transparent film will allow the content of the blister packaging to be more visible, hence such a polypropylene composition is beneficial to be used in a blister packaging. It is further preferred when the polypropylene composition in the cast film according to present invention, has an optomechanical ability (OMA) of from 5 000 to 40 000 MPa g / %, more preferably from 10 000 to 35 000 MPa g / %, and most preferably from 20 000 to 30 000 MPa g / %. Optomechanical ability (OMA) is the ratio of mechanical behavior to optical performance of a polymer, wherein the mechanical behavior is targeted as high as possible and optical properties such as haze is targeted as low as possible. Optomechanical ability (OMA) is calculated according to the following formula:

[0030] TM x DD1 OMA = — - - haze wherein

[0031] TM is tensile modulus in machine direction, as determined in accordance with ISO 527-3 on a 300 pm cast film, in MPa;

[0032] DDI is dart drop impact, as determined on a 300 pm cast film at 23 °C in accordance with ISO 7765-1 :19881 Method A, in g; and haze is determined in accordance with ASTM D1003 on a 300 pm cast film, in %.

[0033] It is further preferred when the polypropylene composition in the cast film according to the present invention has a water vapor transmission rate (WVTR), as determined in accordance with ISO 15106-3:2003 on a 300 pm cast film, of from 0 to 1.0 g / m2day, more preferably from 0.10 to 0.85 g / m2day, and most preferably from 0.20 to 0.75 g / m2day.

[0034] Process

[0035] The polypropylene composition as described herein is preferably obtained in a multi-stage polymerization process comprising the steps of: aO) optionally, modifying a Ziegler-Natta catalyst, preferably with a polymeric nucleating agent, more preferably with a vinyl polymer, and pre-polymerizing propylene in a pre-polymerization reactor; a) polymerizing propylene in the presence of a Ziegler-Natta catalyst, in a first polymerization reactor (R1) and obtaining a first polymerization product; b) transferring the first polymerization product to a second polymerization reactor (R2) and obtaining a final polymerization product; and c) optionally, compounding the final polymerization product obtained in step b) with additives.

[0036] The polymerization process of the polypropylene composition is conducted in a multi-stage polymerization as described hereinabove, preferably in a sequential polymerization process. The term “sequential polymerization” indicates that the propylene homopolymer is produced in at least two reactors connected in series. Accordingly, the present polymerization system comprises at least a first polymerization reactor (R1) described in step a) and a second polymerization reactor (R2) as described in step b). The term “polymerization reactor” shall indicate that the main polymerization takes place. Thus, in case the process consists of two polymerization reactors, this definition does not exclude the option that the overall system comprises for instance a pre-polymerization step in a pre-polymerization reactor. The term “consist of” is only a closing formulation in view of the main polymerization reactors.

[0037] Preferably, at least one of the two polymerization reactors (R1) and (R2) is a gas phase reactor (GPR). It is more preferred that the second polymerization reactor (R2) is a gas phase reactor (GPR). A gas phase reactor (GPR) according to this invention is preferably a fluidized bed reactor, a fast fluidized bed reactor or a settled bed reactor or any combination thereof. Accordingly, the first polymerization reactor (R1) is preferably a slurry reactor (SR) and can be any continuous or simple stirred batch tank reactor or loop reactor operating in bulk or slurry. Bulk means a polymerization in a reaction medium that comprises of at least 60 % (w / w) monomer. According to the present invention the slurry reactor (SR) is preferably a (bulk) loop reactor (LR).

[0038] Preferably, the propylene homopolymer of the first polymerization reactor (R1), i.e. fraction produced in the first polymerization reactor (R 1 ) , more preferably in the polymer slurry of the loop reactor (LR), is directly fed into the second polymerization reactor (R2), i.e. into the (first) gas phase reactor (GPR1), without a flash step between the stages. This kind of direct feed is described in EP 887379 A, EP 887380 A, EP 887381 A and EP 991684 A. By "direct feed" is meant a process wherein the content of the first polymerization reactor (R1), i.e. of the loop reactor (LR), the polymer slurry comprising the the first propylene homopolymer fraction (H- PP1), is led directly to the next stage gas phase reactor.

[0039] Alternatively, the propylene homopolymer of the first polymerization reactor (R1), i.e. fraction produced in the first polymerization reactor (R1), may be also directed into a flash step or through a further concentration step before fed into the second polymerization reactor (R2), i.e. into the gas phase reactor (GPR). Accordingly, this "indirect feed" refers to a process wherein the content of the first polymerization reactor (R1), of the loop reactor (LR), i.e. the polymer slurry, is fed into the second polymerization reactor (R2), into the (first) gas phase reactor (GPR1), via a reaction medium separation unit and the reaction medium as a gas from the separation unit.

[0040] More specifically, the second polymerization reactor (R2) can be any mechanically mixed or fluid bed reactors. Preferably the gas phase reactors (GPRs) comprise a mechanically agitated fluid bed reactor with gas velocities of at least 0.2 m / sec. Thus it is appreciated that the gas phase reactor is a fluidized bed type reactor preferably with a mechanical stirrer.

[0041] Thus, in a preferred embodiment the first polymerization reactor (R1) is a slurry reactor (SR), like loop reactor (LR), whereas the second polymerization reactor (R2) is gas phase reactor (GPR). Accordingly for the instant process two polymerization reactors (R1) and (R2), namely a slurry reactor (SR), like loop reactor (LR) and a (first) gas phase reactor (GPR1), connected in series are used. If needed prior to the slurry reactor (SR) a pre-polymerization reactor is placed.

[0042] The Ziegler-Natta catalyst (ZN-C) is fed into the first polymerization reactor (R1) and is transferred with the polymer (slurry) obtained in the first polymerization reactor (R1) into the subsequent reactors. If the process covers also a pre-polymerization step it is preferred that all of the Ziegler-Natta catalyst (ZN-C) is fed in the pre-polymerization reactor. Subsequently the pre-polymerization product containing the Ziegler-Natta catalyst (ZN-C) is transferred into the first polymerization reactor (R1).

[0043] A preferred multistage process is a “loop-gas phase”-process, such as developed by Borealis A / S, Denmark (known as BORSTAR® technology) described e.g. in patent literature, such as in EP 0 887 379, WO 92 / 12182 WO 2004 / 000899, WO 2004 / 111095, WO 99 / 24478, WO 99 / 24479 or in WO 00 / 68315. A further suitable slurry-gas phase process is the Spheripol® process of Basell.

[0044] Especially good results are achieved in case the temperature in the reactors is carefully chosen.

[0045] Accordingly it is preferred that the operating temperature in the first polymerization reactor (R1) is in the range of 62 to 90 °C, more preferably in the range of 70 to 88 °C, still more preferably in the range of 75 to 85 °C.

[0046] Alternatively or additionally to the previous paragraph it is preferred that the operating temperature in the second polymerization reactor (R2) is in the range of 62 to 90 °C, more preferably in the range of 70 to 88 °C, still more preferably in the range of 75 to 85 °C.

[0047] Typically the pressure in the first polymerization reactor (R1), preferably in the loop reactor (LR), is in the range from 2000 to 8000 kPa, preferably 3000 to 7000 kPa, like 3500 to 6500 kPa, whereas the pressure in the second polymerization reactor (R2), i.e. in the (first) gas phase reactor (GPR1), is in the range from 500 to 5000 kPa, preferably 1500 to 4000 kPa. Preferably hydrogen is added in each polymerization reactor in order to control the molecular weight, i.e. the melt flow rate MFR2.

[0048] Preferably the average residence time is rather long in the polymerization reactors (R1) and (R2). In general, the average residence time (T) is defined as the ratio of the reaction volume (VR) to the volumetric outflow rate from the reactor (Qo) (i.e. VR / Q0), i.e T = VR / Q0[tau = VR / Q0], In case of a loop reactor the reaction volume (VR) equals to the reactor volume.

[0049] Accordingly the average residence time (T) in the first polymerization reactor (R1) is preferably at least 15 min, more preferably in the range of 15 to 80 min, still more preferably in the range of 20 to 60 min, like in the range of 24 to 50 min, and / or the average residence time (T) in the second polymerization reactor (R2) is preferably at least 70 min, more preferably in the range of 70 to 220 min, still more preferably in the range of 80 to 210 min, yet more preferably in the range of 90 to 200 min, like in the range of 90 to 190 min.

[0050] In the pre-polymerization reactor (PR) a polypropylene (Pre-PP) is produced. The prepolymerization is conducted in the presence of the Ziegler-Natta catalyst (ZN-C). According to this embodiment the Ziegler-Natta catalyst (ZN-C), the co-catalyst (Co), and the external donor (ED) are all introduced to the pre-polymerization step. However, this shall not exclude the option that at a later stage for instance further co-catalyst (Co) and / or external donor (ED) is added in the polymerization process, for instance in the first reactor (R1). In one embodiment the Ziegler-Natta catalyst (ZN-C), the co-catalyst (Co), and the external donor (ED) are only added in the pre-polymerization reactor (PR), if a pre-polymerization is applied.

[0051] 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.

[0052] 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 2000 to 8000 kPa, for example 3000 to 7000 kPa.

[0053] 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.

[0054] 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 (Pre-PP) 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. The precise control of the pre-polymerization conditions and reaction parameters is within the skill of the art.

[0055] Due to the above defined process conditions in the pre-polymerization, preferably a mixture (Ml) of the Ziegler-Natta catalyst (ZN-C) and the polypropylene (Pre-PP) produced in the pre- polymerization reactor (PR) is obtained. Preferably the Ziegler-Natta catalyst (ZN-C) is (finely) dispersed in the polypropylene (Pre-PP). In other words, the Ziegler-Natta catalyst (ZN-C) particles introduced in the pre-polymerization reactor (PR) split into smaller fragments which are evenly distributed within the growing polypropylene (Pre-PP). The sizes of the introduced Ziegler-Natta catalyst (ZN-C) particles as well as of the obtained fragments are not of essential relevance for the instant invention and is within the skilled knowledge.

[0056] As mentioned above, if a pre-polymerization is used, subsequent to said pre-polymerization, the mixture (Ml) of the Ziegler-Natta catalyst (ZN-C) and the polypropylene (Pre-PP) produced in the pre-polymerization reactor (PR) is transferred to the first reactor (R1). Typically the total amount of the polypropylene (Pre-PP) in the final propylene copolymer (R-PP) is rather low and typically not more than 5.0 wt.-%, more preferably not more than 4.0 wt.-%, still more preferably in the range of 0.5 to 4.0 wt.-%, like in the range 1 .0 of to 3.0 wt.-%.

[0057] As mentioned hereinabove, the Ziegler-Natta catalyst (ZN-C) may be modified in pre- polymerization step aO). The details of such modification are provided below.

[0058] Catalyst

[0059] In a preferred embodiment, the catalyst is a solid Ziegler-Natta catalyst comprising: a) compounds of a transition metal of Group 4 to 6 of IIIPAC; b) a Group 2 of IIIPAC metal compound; c) an internal donor, that is a non-phthalic compound, preferably a non-phthalic ester; d) a co-catalyst; and e) optionally, an external donor.

[0060] The catalyst comprises compounds (TC) of a transition metal of Group 4 to 6 of IIIPAC, like titanium, a Group 2 metal compound (MC), like a magnesium, and an internal donor (ID) being a non-phthalic compound, preferably a non-phthalic acid ester, still more preferably being a diester of non-phthalic dicarboxylic acids as described in more detail below. Thus, the catalyst is in a preferred embodiment fully free of undesired phthalic compounds. Further, the solid catalyst is free of any external support material, like silica or MgCh, but the catalyst is selfsupported. 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 a monohydric 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 monohydric 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 (MC) and the monohydric alcohol (B), optionally in an organic liquid reaction medium; or

[0061] 34) providing a solution of Group 2 alkoxide of formula M(ORi)n(OR2)mX2-n-m or mixture of Group 2 alkoxides M(0Ri)nX2-n’ and M(OR2)mX2-m’, where M is Group 2 metal, X is halogen, R1 and R2 are different alkyl groups of C2 to C16 carbon atoms, and 0 < n < 2, 0 < m < 2 and n+m+(2-n-m) = 2, provided that both n and m 0, 0 < n’ < 2 and 0 < m’ < 2; 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 an internal electron donor (ID), preferably a non-phthalic internal donor (ID), at any step prior to step c).

[0062] The internal donor (ID) or precursor thereof is thus added preferably to the solution of step a) or to the transition metal compound before adding the solution of step a).

[0063] According to the procedure above the Ziegler-Natta catalyst (ZN-C) can be obtained via precipitation method or via emulsion- solidification method depending on the physical conditions, especially temperature used in steps b) and c). Emulsion is also called in this application liquid / liquid two-phase system.

[0064] In both methods (precipitation or emulsion-solidification) the catalyst chemistry is the same.

[0065] 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).

[0066] 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.

[0067] The catalyst prepared by emulsion - solidification method is preferably used in the present invention.

[0068] 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), especially the solution of 82).

[0069] Preferably the Group 2 metal (MC) is magnesium.

[0070] The magnesium alkoxy compounds as defined above 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.

[0071] Illustrative examples of alcohols (A) are 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.

[0072] Illustrative monohydric alcohols (B) are of formula ROH, with R being straight-chain or branched C2-C16 alkyl residue, preferably 0 0 C10, more preferably C6 to Cs alkyl residue. The most preferred monohydric alcohol is 2-ethyl-1 -hexanol or octanol.

[0073] 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 10:1 to 1 :10, more preferably 6:1 to 1 :6, most preferably 4.1 to 1 :4.

[0074] Magnesium alkoxy compound may be a reaction product of alcohol(s), as defined above, and a magnesium compound selected from dialkyl magnesium, alkyl magnesium alkoxides, magnesium dialkoxides, alkoxy magnesium halides and alkyl magnesium halides. Further, magnesium dialkoxides, magnesium diaryloxides, magnesium aryloxyhalides, magnesium aryloxides and magnesium alkyl aryloxides can be used. 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 octoxide. Preferably the dialkyl magnesium are used. Most preferred dialkyl magnesium are butyl octyl magnesium or butyl ethyl magnesium.

[0075] 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.

[0076] The magnesium alkoxy compounds of step a) are thus selected from the group consisting of magnesium dialkoxides, diaryloxy magnesium, 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.

[0077] 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.

[0078] 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.

[0079] The transition metal compound of Group 4 to 6 is preferably a titanium compound, most preferably a titanium halide, like TiCk

[0080] The internal donor (ID) used in the preparation of the catalyst used in the present invention is preferably selected from (di)esters of non-phthalic carboxylic (di)acids, 1 ,3-diethers, derivatives and mixtures thereof. Especially preferred donors are diesters of mono-unsaturated dicarboxylic acids, in particular esters belonging to a group comprising malonates, maleates, succinates, citraconates, glutarates, cyclohexene-1 ,2-dicarboxylates and benzoates, and any derivatives and / or mixtures thereof. Preferred examples are e.g. substituted maleates and citraconates, most preferably citraconates. 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 stabilisers, like surfactants, which are used in a manner known in the art for facilitating the formation of and / or stabilise 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.

[0081] 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 an aromatic and / or aliphatic hydrocarbons, preferably with toluene, heptane or pentane and or with TiCU. Washing solutions can also contain donors and / or compounds of Group 13, like trialkyl aluminum, halogenated alky aluminum compounds or alkoxy aluminum compounds. Aluminum compounds can also be added during the catalyst synthesis. 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.

[0082] 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.

[0083] Detailed description of preparation of catalysts is disclosed in WO 2012 / 007430, EP2610271 , EP 2610270 and EP2610272.

[0084] The Ziegler-Natta catalyst (ZN-C) is preferably used in association with an alkyl aluminum cocatalyst and optionally external donors.

[0085] 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

[0086] 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(OCH3)2, (cyclohexyl)(methyl)Si(OCH3)2, (phenyl)2Si(OCH3)2 and (cyclopentyl)2Si(OCH3)2, or of general formula

[0087] Si(OCH2CH3)3(NR3R4) wherein R3and R4can be the same or different a represent a hydrocarbon group having 1 to 12 carbon atoms.

[0088] 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 1 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, iso-butyl, iso-pentyl, tert.-butyl, tert.- amyl, neopentyl, cyclopentyl, cyclohexyl, methylcyclopentyl and cycloheptyl.

[0089] More preferably both R3and R4are the same, yet more preferably both R3and R4are an ethyl group.

[0090] Especially preferred external donors (ED) are the pentyl dimethoxy silane donor (D-donor) or the cyclohexylmethyl dimethoxy silane donor (C-Donor).

[0091] In addition to the Ziegler-Natta catalyst (ZN-C) 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 (IIIPAC), 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).

[0092] 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.-%.

[0093] 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.

[0094] Accordingly, the mole ratio of co-catalyst (Co) to external donor (ED) [Co / ED] must be 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 the mole ratio of co-catalyst (Co) to titanium compound (TC) [Co / TC] must be in the range of above 80 to 500, preferably is in the range of 100 to 350, still more preferably is in the range of 120 to 300.

[0095] As mentioned above the Ziegler-Natta catalyst (ZN-C) is preferably modified during the above described pre-polymerization step in order to introduce the polymeric nucleating agent. Details of such a modification can further be found in EP 1183307, EP 2 960 279 and EP 3 184 587.

[0096] Such a polymeric nucleating agent may be as described above a vinyl polymer, such as a vinyl polymer derived from monomers of the formula

[0097] CH2 = CH-CHR1 R2 wherein R1 and R2, together with the carbon atom they are attached to, form an optionally substituted saturated or unsaturated or aromatic ring or a fused ring system, wherein the ring or fused ring moiety contains four to 20 carbon atoms, preferably 5 to 12 membered saturated or unsaturated or aromatic ring or a fused ring system or independently represent a linear or branched C4-C30 alkane, C4- C20 cycloalkane or C4-C20 aromatic ring. Preferably R1 and R2, together with the C-atom wherein they are attached to, form a five- or six-membered saturated or unsaturated or aromatic ring or independently represent a lower alkyl group comprising from 1 to 4 carbon atoms. Preferred vinyl compounds for the preparation of a polymeric nucleating agent to be used in accordance with the present invention are in particular vinyl cycloalkanes, in particular vinyl cyclohexane (VCH), vinyl cyclopentane, and vinyl-2- methyl cyclohexane, 3-methyl-1 -butene, 3-ethyl-1 -hexene, 3-methyl-1 -pentene, 4-methyl-1- pentene or mixtures thereof. VCH is a particularly preferred monomer.

[0098] The weight ratio of vinyl compound to polymerization catalyst in the modification step of the polymerization catalyst preferably is 0.3 or more up to 40, such as 0.4 to 20 or more preferably 0.5 to 15, like 0.5 to 2.0.

[0099] The polymerization of the vinyl compound, e. g. VCH, can be done in any inert fluid that does not dissolve the polymer formed (e. g. polyVCH). It is important to make sure that the viscosity of the final catalyst / polymerized vinyl compound / inert fluid mixture is sufficiently high to prevent the catalyst particles from settling during storage and transport.

[0100] The adjustment of the viscosity of the mixture can be done either before or after the polymerization of the vinyl compound. It is, e. g., possible to carry out the polymerization in a low viscosity oil and after the polymerization of the vinyl compound the viscosity can be adjusted by addition of a highly viscous substance. Such highly viscous substance can be a "wax", such as an oil or a mixture of an oil with a solid or highly viscous substance (oil-grease). The viscosity of such a viscous substance is usually 1 ,000 to 15,000 cP at room temperature. The advantage of using wax is that the catalyst storing and feeding into the process is improved. Since no washing, drying, sieving and transferring are needed, the catalyst activity is maintained.

[0101] The weight ratio between the oil and the solid or highly viscous polymer is preferably less than 5: 1.

[0102] In addition to viscous substances, liquid hydrocarbons, such as isobutane, propane, pentane and hexane, can also be used as a medium in the modification step..

[0103] The polypropylenes produced with a catalyst modified with polymerized vinyl compounds contain essentially no free (unreacted) vinyl compounds. This means that the vinyl compounds shall be completely reacted in the catalyst modification step. To that end, the weight ratio of the (added) vinyl compound to the catalyst should be in the range of 0.05 to 10, preferably less than 3, more preferably about 0.1 to 2.0, and in particular about 0.1 to 1.5. It should be noted that no benefits are achieved by using vinyl compounds in excess.

[0104] Further, the reaction time of the catalyst modification by polymerization of a vinyl compound should be sufficient to allow for complete reaction of the vinyl monomer, i. e. the polymerization is continued until the amount of unreacted vinyl compounds in the reaction mixture (including the polymerization medium and the reactants) is less than 0.5 wt.-%, in particular less than 2000 ppm by weight (shown by analysis). Thus, when the prepolymerized catalyst contains a maximum of about 0.1 wt.-% vinyl compound, the final vinyl compound content in the polypropylene will be below the limit of determination using the GC-MS method ( < 0.01 ppm by weight). Generally, when operating on an industrial scale, a polymerization time of at least 30 minutes is required, preferably the polymerization time is at least 1 hour and in particular at least 5 hours. Polymerization times even in the range of 6 to 50 hours can be used. The modification can be done at temperatures of 10 to 70 °C, preferably 35 to 65 °C.

[0105] According to the invention, nucleated high-stiffness propylene polymers are obtained when the modification of the catalyst is carried out in the presence of strongly coordinating external donors.

[0106] General conditions for the modification of the catalyst are also disclosed in WO 00 / 6831 , incorporated herein by reference with respect to the modification of the polymerization catalyst.

[0107] The preferred embodiments as described previously in the present application with respect to the vinyl compound also apply with respect to the polymerization catalyst of the present invention and the preferred polypropylene composition in accordance with the present invention. Suitable media for the modification step include, in addition to oils, also aliphatic inert organic solvents with low viscosity, such as pentane and heptane. Furthermore, small amounts of hydrogen can be used during the modification.

[0108] Additives

[0109] As mentioned hereinabove, the polypropylene composition may comprise at least one additive in an amount of from 0 to 5 wt.-%, more preferably from 0 to 3 wt.-%, and most preferably from 0 to 1.5 wt.-%, based on the total weight of the polypropylene composition. Such an additive may be selected from the group consisting of antioxidants, acid scavengers, stabilizers, fillers, colorants, nucleating agents, slip agents, antiblocking agents and antistatic agents. These additives are generally commercially available and are described, for example, in "Plastic Additives Handbook", pages 871 to 873, 5th edition, 2001 of Hans Zweifel. It is further preferred that the polypropylene composition comprises at least one antioxidant that is selected from the group of primary antioxidants like sterically hindered phenols, for example Pentaerythrityl- tetrakis(3-(3’,5’-di-tert. butyl-4-hydroxyphenyl)-propionate (CAS-No. 6683-19-8, commercially available as Irganox 1010 of BASF SE, Germany) and at least one acid scavenger that is either selected from the group of metal stearates, for example calcium stearate (CAS-No. 1592-23- 0), or selected from the group of layered hydroxycarbonates, like synthetic hydrotalcite (CAS- No. 11097-59-9) as the additives. In a more preferred embodiment, the mentioned acid scavenger is calcium stearate.

[0110] Cast Film

[0111] The cast film may have a thickness of from 100 to 500 pm and be an oriented or non-oriented cast film, non-oriented cast film being preferred. A more preferred thickness of the film ranges from 150 to 450 pm, like from 200 to 400 pm. Said film may be a multilayer film, like a two- layer film or a three-layer film, in which case the layer comprising the polymer composition as described herein is the core layer. According to a preferred embodiment, said film is a monolayer film.

[0112] It is preferred when the film according to the present invention has:

[0113] - a tensile modulus in machine direction, as determined in accordance with ISO 527-3 on a 300 pm cast film, of from 500 to 1200 MPa, more preferably from 650 to 1000 MPa, and most preferably from 700 to 850 MPa; and / or

[0114] - a tensile modulus in transverse direction, as determined in accordance with ISO 527-3 on a 300 pm cast film, of from 500 to 1300 MPa, more preferably from 650 to 1100 MPa, and most preferably from 700 to 1000 MPa. It is also preferred when the film has a dart drop impact (DDI), as determined on a 300 pm cast film at 23 °C in accordance with ISO 7765-1 :1988 I Method A, of from 350 to 1500 g, more preferably from 400 to 1300 g, and most preferably from 700 to 1200 g.

[0115] It is also preferred when the film has a haze value, as determined in accordance with ASTM D1003 on a 300 pm cast film, of from 0 to 60%, more preferably from 0 to 50%, and most preferably from 0 to 40%; and / or a clarity value, as determined in accordance with ASTM D1003 on a 300 pm cast film, of from 20 to 100%, more preferably from 40 to 85%, and most preferably from 55 to 80%. Such a haze and clarity values are particularly preferred, since a more transparent film will allow the content of the blister packaging to be more visible, hence such a film can be beneficially used in a blister packaging.

[0116] It is further preferred when the film according to present invention has an optomechanical ability (OMA) of from 5 000 to 40 000 MPa g / %, more preferably from 10 000 to 35 000 MPa g / %, and most preferably from 20 000 to 30 000 MPa g / %. Optomechanical ability (OMA) is the ratio of mechanical behavior to optical performance of a polymer, wherein the mechanical behavior is targeted as high as possible and optical properties such as haze is targeted as low as possible. Optomechanical ability (OMA) is calculated according to the following formula:

[0117] TM x DDI OMA = — - - haze wherein

[0118] TM is tensile modulus in machine direction, as determined in accordance with ISO 527-3 on a 300 pm cast film, in MPa;

[0119] DDI is dart drop impact, as determined on a 300 pm cast film at 23 °C in accordance with ISO 7765-1 :19881 Method A, in g; and haze is determined in accordance with ASTM D1003 on a 300 pm cast film, in %.

[0120] The film according to the present invention preferably has a water vapor transmission rate (WVTR), as determined in accordance with ISO 15106-3:2003 on a 300 pm cast film, of from 0 to 1.0 g / m2day, more preferably from 0.10 to 0.85 g / m2day, and most preferably from 0.20 to 0.75 g / m2day.

[0121] Use

[0122] The present invention further pertains to a use of the cast film as described herein, in a blister packaging like a pharmaceutical packaging, a food packaging or a non-food packaging, like a detergent or personal care packaging. Such blister packaging comprises a thermoformed element formed from the film according to the present invention, being the recipient for the packaged goods like tablets or capsules, and an aluminum-based sheet for the push-through part. The respective blister package is closed by sealing the flat parts of said thermoformed element formed from the film according to the present invention, to the aluminum-based sheet.

[0123] Disclosure of Further Aspects

[0124] Further aspects (1) to (14) are also disclosed.

[0125] (1) Polypropylene composition comprising: a) a base polymer comprising a propylene homopolymer in an amount of from 95 to 100 wt.- % based on the total weight of the polypropylene composition, and b) optionally, at least one additive selected from the group consisting of antioxidants, acid scavengers, stabilizers, fillers, colorants, nucleating agents, slip agents, anti-blocking agents and antistatic agents, in an amount of from 0 to 5 wt.-% based on the total weight of the polypropylene composition; wherein the polypropylene composition has:

[0126] - a melt flow rate MFR2, as determined in accordance with ISO 1133 at 230 °C under a load of 2.16 kg, of from 3.0 to 15.0 g / 10 min;

[0127] - a xylene cold soluble (XCS) content, as determined in accordance with ISO 16152, of from 0.1 to 3.0 wt.-%;

[0128] - a melting temperature Tm, as determined in accordance with ISO 11357 I part 3 1 method C2, of from 155 to 175 °C; and

[0129] - a crystallization temperature Tc, as determined in accordance with ISO 11357 I part 3 I method C2, of from 105 to 130 °C

[0130] - a pentad regularity [mmmm], as determined by13C-NMR spectroscopy, of from 90 to 99.9 mol-%.

[0131] (2) Polypropylene composition according to aspect (1), comprising at least one antioxidant selected from the group consisting of primary antioxidants such as sterically hindered phenols and at least one acid scavenger that is either selected from the group of metal stearates or selected from the group of layered hydroxycarbonates, such as synthetic hydrotalcite.

[0132] (3) Polypropylene composition according to any of the preceding aspects, having: a) a melt flow rate MFR2, as determined in accordance with ISO 1133 at 230 °C under a load of 2.16 kg, of from 4.5 to 12.0 g / 10 min, more preferably from 6.0 to 10.0 g / 10 min; and / or b) a xylene cold soluble (XCS) content, as determined in accordance with ISO 16152, of from 0.5 to 2.5 wt.-%, more preferably from 1 .0 to 2.0 wt.-%. (4) Polypropylene composition according to any of the preceding aspects, having an ethylene content, as determined in accordance with13C-NMR spectroscopy, of from 0 to 0.5 wt.-%, more preferably from 0 to 0.3 wt.-%, and most preferably from 0 to 0.1 wt.-%.

[0133] (5) Polypropylene composition according to any of the preceding aspects, having: a) a tensile modulus in machine direction, as determined in accordance with ISO 527-3 on a 300 pm cast film, of from 500 to 1200 MPa, more preferably from 650 to 1000 MPa, and most preferably from 700 to 850 MPa; and / or b) a tensile modulus in transverse direction, as determined in accordance with ISO 527-3 on a 300 pm cast film, of from 500 to 1300 MPa, more preferably from 650 to 1100 MPa, and most preferably from 700 to 1000 MPa.

[0134] (6) Polypropylene composition according to any of the preceding aspects, having a dart drop impact (DDI), as determined on a 300 pm cast film at 23 °C in accordance with ISO 7765- 1 :1988 I Method A, of from 350 to 1500 g, more preferably from 400 to 1300 g, and most preferably from 700 to 1200 g.

[0135] (7) Polypropylene composition according to any of the preceding aspects, having: a) a haze value, as determined in accordance with ASTM D1003 on a 300 pm cast film, of from 0 to 60%, more preferably from 0 to 50%, and most preferably from 0 to 40%; and / or b) a clarity value, as determined in accordance with ASTM D1003 on a 300 pm cast film, of from 20 to 100%, more preferably from 40 to 85%, and most preferably from 55 to 80%.

[0136] (8) Polypropylene composition according to any of the preceding aspects, having an optomechanical ability (OMA) of from 5000 to 40 000 MPa g / %, more preferably from 10 000 to 35 000 MPa g / %, and most preferably from 20 000 to 30 000 MPa g / %, wherein optomechanical ability (OMA) is calculated according to the formula:

[0137] TM x DDI OMA = — - - haze wherein

[0138] TM is tensile modulus in machine direction, as determined in accordance with ISO 527-3 on a 300 pm cast film, in MPa;

[0139] DDI is dart drop impact, as determined on a 300 pm cast film at 23 °C in accordance with ISO 7765-1 :19881 Method A, in g; and haze is determined in accordance with ASTM D1003 on a 300 pm cast film, in %. (9) Polypropylene composition according to any of the preceding aspects, having a water vapor transmission rate (WVTR), as determined in accordance with ISO 15106-3:2003 on a 300 pm cast film, of from 0 to 1.0 g / m2day, more preferably from 0.10 to 0.85 g / m2day, and most preferably from 0.20 to 0.75 g / m2day.

[0140] (10) A process for obtaining a polypropylene composition according to aspects (1)-(9), in a multi-stage polymerization process comprising the steps of: aO) optionally, modifying a Ziegler-Natta catalyst, preferably with a polymeric nucleating agent, more preferably with a vinyl polymer, and pre-polymerizing propylene in a pre-polymerization reactor; a) polymerizing propylene in the presence of a Ziegler-Natta catalyst, in a first polymerization reactor (R1) and obtaining a first polymerization product; b) transferring the first polymerization product to a second polymerization reactor (R2) and obtaining a final polymerization product; and c) optionally, compounding the final polymerization product obtained in step b) with additives.

[0141] (11) Process according to aspect (10), wherein the Ziegler-Natta catalyst comprises: a) compounds of a transition metal of Group 4 to 6 of IIIPAC; b) a Group 2 of IIIPAC metal compound; c) an internal donor, that is a non-phthalic compound, preferably a non-phthalic ester; d) a co-catalyst; and e) optionally, an external donor.

[0142] (12) An article, preferably a film, comprising or consisting essentially of a polypropylene composition according to aspects (1)-(9).

[0143] (13) Article according to aspect (12), wherein the article is a blown or a cast film with a thickness of from 100 to 500 pm.

[0144] (14) Use of an article according to aspects (12)-(13) in a pharmaceutical packaging. A. MEASUREMENT METHODS

[0145] The properties of the polymers made in accordance with the present invention have been characterized according to the methods described herein, unless otherwise stated.

[0146] Melt Flow Rate

[0147] The melt flow rate (MFR) was 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 was determined at a temperature of 230 °C and a load of 2.16 kg.

[0148] Calculation of melt flow rate MFR2 (230 °C) of the polymer fraction produced in the second polymerization reactor is carried out using the formula below: wherein w(A) is the weight fraction in [wt.-%] and MFR(A) is melt flow rate MFR2 (230 °C) in [g / 10 min] of the first polymer fraction (A) obtained in the first polymerization reactor, w(B) is the weight fraction in [wt.-%] and MFR(B) is melt flow rate MFR2 (230 °C) in [g / 10 min] of second polymer fraction (B) obtained in the second polymerization reactor,

[0149] MFR(C) is melt flow rate MFR2 (230 °C) in [g / 10 min] of the polymer obtained as a result of the second polymerization step (the final polymer, which comprises both fractions (A) and (B)).

[0150] Xylene Cold Soluble (XCS) Content

[0151] The amount of the polymer soluble in xylene was determined at 25 °C according to ISO 16152; 5th edition; 2005-07-01.

[0152] Ethylene (C2) Content and Pentad Regularity

[0153] Quantitative nuclear-magnetic resonance (NMR) spectroscopy was used to quantify the comonomer content and comonomer distribution of the copolymers, specifically propene-co- ethylene copolymers. Quantitative13C{1H} NMR spectra 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 selective excitation probe head at 125°C using nitrogen gas for all pneumatics. Approximately 200 mg of material was dissolved in 1 ,2-tetrachloroethane-d2 (TCE-cfe) with chromium-(lll)-acetylacetonate (Cr(acac)3) resulting in a 65 mM solution of relaxation agent in solvent (Singh, G., Kothari, A., Gupta, V., Polymer Testing 28 5 (2009), 475). This setup was chosen primarily for the high resolution and quantitative spectra needed for accurate ethylene content determination. Standard singlepulse excitation was employed without NOE, using an optimised tip angle, 1 s recycle delay 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 6144 (6k) transients were acquired per spectra. Quantitative13C{1H} NMR spectra were processed, integrated and relevant quantitative properties determined from the integrals using proprietary computer programs. All chemical shifts were indirectly referenced to the central methylene group of the ethylene block (EEE) at 30.00 ppm using the chemical shift of the solvent. This approach allowed comparable referencing even when this structural unit was not present.

[0154] Characteristic signals corresponding to regio-irregular propene insertion were observed (Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem. Rev. 2000, 100, 1253).].

[0155] Characteristic signals corresponding to the incorporation of ethylene were observed (Cheng, H. N., Macromolecules 17, 1984, 1950). The comonomer content was calculated as the mole fraction or percent of incorporated ethylene with respect to all monomer in the copolymer using the method of Wang et. al. (Wang, W-J., Zhu, S., Macromolecules 33, 2000, 1157) through integration of multiple signals spanning the whole spectral13C spectra. This analyze method was chosen for its robust nature and ability to account for the presence of regio irregular propene insertion when needed. Integral regions were slightly adjusted to increase applicability across the whole range of encountered comonomer contents.

[0156] For systems where only isolated ethylene incorporation (PPEPP) was observed the method of Wang et. al. was modified to reduce the influence of non-zero integrals used to quantify higher order comonomer sequences. In such cases the term for the absolute ethylene content was determined based upon only

[0157] E = 0.5( Spp + Spy + Sp8 + 0.5( Sap + Say)) or

[0158] E = 0.5( lH+IG + 0.5( lc + ID )) using the same notation as Wang et. al. (Wang, W-J., Zhu, S., Macromolecules 33, 2000, 1157). The term used for absolute propylene content (P) was not modified and the mole fraction of ethylene calculated as

[0159] [E] = E / (E + P).

[0160] The comonomer content in weight percent was calculated from the mole fraction in the usual way i.e. [E wt.-%] = 100 * ( [E] * 28.06) I ([E] * 28.06) + ((1-[E]) * 42.08) ).

[0161] 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). 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.

[0162] The isotacticity was determined at the pentad level and reported as the percentage of isotactic pentad (mmmm) sequences with respect to all pentad sequences:

[0163] [mmmm] % = 100 * (mmmm I sum of all pentads )

[0164] Melting Temperature Tm and Crystallization Temperature Tc

[0165] Melting temperature Tm and crystallization temperature Tc were measured using a TA Instrument Q2000 differential scanning calorimetry (DSC) on 5 to 7 mg samples. DSC is run according to ISO 113571 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.

[0166] Crystallization temperature Tc was determined from the cooling step, while melting temperature Tm was determined from the second heating step.

[0167] Molecular weight distribution

[0168] Molar mass averages (Mw and Mn) and molecularweight distribution (MWD), 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).

[0169] 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 at 160 °C under continuous gentle shaking in the autosampler of the GPC instrument. Tensile Modulus

[0170] Tensile modulus in machine and transverse directions were determined in accordance with ISO 527-3 on 300 pm cast films.

[0171] Dart Drop Impact Dart drop impact (DDI) was determined on 300 pm cast films at 23 °C in accordance with ISO 7765-1:1988 / Method A.

[0172] Haze and Clarity

[0173] Haze and clarity were determined in accordance with ASTM D1003 on 300 pm cast films.

[0174] Water Vapor Transmission Rate (WVTR) Water vapour transmission rate (WVTR) was measured on 300 pm cast films in accordance with ISO 15106-3:2003.

[0175] Device: Mocon Aquatran

[0176] Temperature: 38° C ± 0.3°C.

[0177] Relative Humidity: 0 / 100% Area sample: 5 cm2

[0178] B. EXAMPLES

[0179] Base polymer used for producing polypropylene compositions IE1 and IE2 was the same, PP-1. It was produced using a Ziegler-Natta catalyst (description is provided below), and the polymerization conditions are presented in Table 1. It was produced in a Borstar pilot plant with a pre-polymerization reactor, one slurry loop reactor and one gas phase reactor. The solid catalyst was used along with triethyl-aluminium (TEAL) as cocatalyst and dicyclo pentyl dimethoxy silane (D-donor) as donor.

[0180] 1a) Catalyst preparation

[0181] 3.4 liter of 2-ethylhexanol and 810 ml of propylene glycol butyl monoether ( in a molar ratio 4 / 1) were added to a 20 I reactor. Then 7.8 liter of a 20 % solution in toluene of BEM (butyl ethyl magnesium) provided by Crompton GmbH was slowly added to the well stirred alcohol mixture. During the addition the temperature was kept at 10 °C. After addition the temperature of the reaction mixture was raised to 60 °C and mixing was continued at this temperature for 30 minutes. Finally, after cooling to room temperature the obtained Mg-alkoxide was transferred to storage vessel.

[0182] 21.2 g of Mg alkoxide prepared above was mixed with 4,0 ml bis(2-ethylhexyl) citraconate for 5 min. After mixing the obtained Mg complex was used immediately in the preparation of catalyst component.

[0183] 19.5 ml titanium tetrachloride was placed in a 300 ml reactor equipped with a mechanical stirrer at 25 °C. Mixing speed was adjusted to 170 rpm. 26.0 of Mg-complex prepared above was added within 30 minutes keeping the temperature at 25 °C . 3.0 ml of Viscoplex 1-254 and 24.0 ml of heptane were added to form an emulsion. Mixing was continued for 30 minutes at 25 °C. Then the reactor temperature was raised to 90 °C within 30 minutes. The reaction mixture was stirred for further 30 minutes at 90°C. Afterwards stirring was stopped and the reaction mixture was allowed to settle for 15 minutes at 90 °C.

[0184] The solid material was washed with 100 ml of toluene, with of 30 ml of TiCI4, with 100 ml of toluene and two times with 60 ml of heptane. I ml of donor was added to the two first washings. Washings were made at 80 °C under stirring 30 min with 170 rpm. After stirring was stopped the reaction mixture was allowed to settle for 20-30 minutes and followed by siphoning.

[0185] The solid material was washed 5 times: Washings were made at 80 °C under stirring 30 min with 170 rpm. After stirring was stopped the reaction mixture was allowed to settle for 20-30 minutes and followed by siphoning.

[0186] Wash 1 : Washing was made with a mixture of 100 ml of toluene and 1 ml donor Wash 2: Washing was made with a mixture of 30 ml of TiCI4 and 1 ml of donor. Wash 3: Washing was made with 100 ml toluene.

[0187] Wash 4: Washing was made with 60 ml of heptane.

[0188] Wash 5. Washing was made with 60 ml of heptane under 10 minutes stirring.

[0189] Afterwards stirring was stopped and the reaction mixture was allowed to settle for 10 minutes decreasing the temperature to 70 °C with subsequent siphoning, and followed by N2 sparging for 20 minutes to yield an air sensitive powder.

[0190] 1b) VCH modification of catalyst

[0191] 35 ml of mineral oil (Paraffinum Liquidum PL68) was added to a 125 ml stainless steel reactor followed by 0.82 g of triethyl aluminium (TEAL) and 0.33 g of dicyclopentyl dimethoxy silane (donor D) under inert conditions at room temperature. After 10 minutes 5.0 g of the catalyst prepared in 1a (Ti content 1.4 wt.%) was added and after additionally 20 minutes 5.0 g of vinylcyclohexane (VCH) was added.). The temperature was increased to 60 °C during 30 minutes and was kept there for 20 hours. Finally, the temperature was decreased to 20 °C and the concentration of unreacted VCH in the oil / catalyst mixture was analysed and was found to be 120 ppm weight.

[0192] Table 1. Polymerization conditions for base polymer PP-1

[0193] * calculated, **measured

[0194] Base polymer PP-1 produced according to Table 1 was then mixed with different additives in an intensive mixer and IE1 and IE2 were prepared in a co-rotating twin-screw extruder. Recipe and some of the properties measured on pellets are presented in Table 2, where AO1 is an antioxidant (Irganox 1010 supplied by BASF AG, DE), AO2 is an antioxidant (Irgafos 168 supplied by BASF AG, DE), AS1 is an acid scavenger (synthetic hydrotalcite supplied by Kisuma Chemicals, NL) and AS2 is an acid scavenger (calcium stearate Ceasit Fl supplied by Baerlocher, DE).

[0195] Table 2. Recipes and properties of polypropylene compositions IE1 and IE2

[0196] Comparative Example CE1 comprises DM55pharm as base polymer, which is a commercially available polypropylene homopolymer (sold by Borealis AG) with a melt flow rate MFR2 of 2.8 g / 10 min, a density of 905 kg / m3and a melting temperature Tm of 163 °C, a crystallization temperature Tc of 116°C, and a xylene cold soluble (XCS) content, as determined in accordance with ISO 16152, of 3.0 wt.-%.

[0197] Cast films were prepared using IE1 and CE1 on a Collin lab scale cast film line with a melting temperature of 220 °C, chill roll temperature of 20 °C and throughput of 8 kg / h. The obtained thickness of the films was 300 pm. The films were then characterized, which is reported in Table 3 below.

[0198] Table 3. Film properties

[0199] It is evident from Table 3 that films made of both polypropylene compositions IE1 and IE2 exhibit an improved mechanical performance in terms of tensile modulus in machine and transverse directions and dart drop impact, compared to the film made of polypropylene composition CE1. At the same time, it can be seen that the films made of both IE1 and IE2 have lower haze and higher clarity compared to the film made of CE1. As a consequence, optomechanical ability (OMA) of films made of IE1 and IE2 are much higher than for the film made of CE1. In addition, the film made of IE1 has a lower water vapor transmission rate compared to the film made of CE1.

Claims

Claims1. Cast film comprising a polypropylene composition comprising: a) a base polymer comprising a propylene homopolymer in an amount of from 95 to 100 wt.-% based on the total weight of the polypropylene composition, and b) optionally, at least one additive selected from the group consisting of antioxidants, acid scavengers, stabilizers, fillers, colorants, nucleating agents, slip agents, anti-blocking agents and antistatic agents, in an amount of from 0 to 5 wt.-% based on the total weight of the polypropylene composition; wherein the polypropylene composition has:- a melt flow rate MFR2, as determined in accordance with ISO 1133 at 230 °C under a load of 2.16 kg, of from 6.0 to 10.0 g / 10 min;- a xylene cold soluble (XCS) content, as determined in accordance with ISO 16152, of from 1.0 to 2.0 wt.-%;- a melting temperature Tm, as determined in accordance with ISO 11357 I part 3 I method C2, of from 155 to 175 °C; and- a crystallization temperature Tc, as determined in accordance with ISO 11357 I part 3 I method C2, of from 105 to 130 °C- a pentad regularity [mmmm], as determined by13C-NMR spectroscopy, of from 90 to 99.9 mol-%.

2. Cast film according to claim 1 , wherein the polypropylene composition comprises at least one antioxidant selected from the group consisting of primary antioxidants such as sterically hindered phenols and at least one acid scavenger that is either selected from the group of metal stearates or selected from the group of layered hydroxycarbonates, such as synthetic hydrotalcite.

3. Cast film according to any of the preceding claims, wherein the polypropylene composition has an ethylene content, as determined in accordance with13C-NMR spectroscopy, of from 0 to 0.5 wt.-%, more preferably from 0 to 0.3 wt.-%, and most preferably from 0 to 0.1 wt.-%.

4. Cast Film according to any of the preceding claims, wherein the polypropylene composition has: a) a tensile modulus in machine direction, as determined in accordance with ISO 527-3 on a 300 pm cast film, of from 500 to 1200 MPa, more preferably from 650 to 1000 MPa, and most preferably from 700 to 850 MPa; and / orb) a tensile modulus in transverse direction, as determined in accordance with ISO 527-3 on a 300 pm cast film, of from 500 to 1300 MPa, more preferably from 650 to 1100 MPa, and most preferably from 700 to 1000 MPa.

5. Cast film according to any of the preceding claims, wherein the polypropylene composition has a dart drop impact (DDI), as determined on a 300 pm cast film at 23 °C in accordance with ISO 7765-1 :19881 Method A, of from 350 to 1500 g, more preferably from 400 to 1300 g, and most preferably from 700 to 1200 g.

6. Cast film according to any of the preceding claims, wherein the polypropylene composition has: a) a haze value, as determined in accordance with ASTM D1003 on a 300 pm cast film, of from 0 to 60%, more preferably from 0 to 50%, and most preferably from 0 to 40%; and / or b) a clarity value, as determined in accordance with ASTM D1003 on a 300 pm cast film, of from 20 to 100%, more preferably from 40 to 85%, and most preferably from 55 to 80%.

7. Cast film according to any of the preceding claims, wherein the polypropylene composition has an optomechanical ability (OMA) of from 5000 to 40 000 MPa g / %, more preferably from 10 000 to 35 000 MPa g / %, and most preferably from 20 000 to 30 000 MPa g / %, wherein optomechanical ability (OMA) is calculated according to the formula:TM x DDI OMA = — - - haze whereinTM is tensile modulus in machine direction, as determined in accordance with ISO 527-3 on a 300 pm cast film, in MPa;DDI is dart drop impact, as determined on a 300 pm cast film at 23 °C in accordance with ISO 7765-1 :19881 Method A, in g; and haze is determined in accordance with ASTM D1003 on a 300 pm cast film, in %.

8. Cast film according to any of the preceding claims, wherein the polypropylene composition has a water vapor transmission rate (WVTR), as determined in accordance with ISO 15106- 3:2003 on a 300 pm cast film, of from 0 to 1.0 g / m2day, more preferably from 0.10 to 0.85 g / m2day, and most preferably from 0.20 to 0.75 g / m2day.

9. Cast film according to any of the preceding claims, wherein the polypropylene composition is obtained in a multi-stage polymerization process comprising the steps of:aO) optionally, modifying a Ziegler-Natta catalyst, preferably with a polymeric nucleating agent, more preferably with a vinyl polymer, and pre-polymerizing propylene in a pre-polymerization reactor; a) polymerizing propylene in the presence of a Ziegler-Natta catalyst, in a first polymerization reactor (R1) and obtaining a first polymerization product; b) transferring the first polymerization product to a second polymerization reactor (R2) and obtaining a final polymerization product; and c) optionally, compounding the final polymerization product obtained in step b) with additives.

10. Cast film according to any of the preceding claims having a thickness of from 100 to 500 pm.

11. Use of the cast film according to any of the preceding claims in a pharmaceutical packaging.

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