Propylene copolymer composition having excellent optical and mechanical properties

Abstract

The present invention relates to a polypropylene composition (P) comprising: a copolymer (C) of propylene and 1-hexene, the copolymer (C) comprising a first random propylene copolymer (A) of propylene and 1-hexene, and a second random propylene copolymer (B) of propylene and 1-hexene having a higher 1-hexene content than the first random propylene copolymer (A); and a plastomer (PL) which is an elastomeric copolymer of ethylene and at least one C4 to C10 alpha-olefin. Furthermore, the invention relates to an article comprising said polypropylene composition (P), and the use of said polypropylene composition (P) as a sealant layer in a multilayer film.

Description

[0001] This application is a divisional application of the patent application with application number 201980056582.6 filed on August 7, 2019 and invention name “Propylene copolymer composition with excellent optical and mechanical properties”. Technical Field

[0002] The present invention relates to a polypropylene composition (P) comprising: a copolymer (C) of propylene and 1-hexene, the copolymer (C) comprising a first random propylene copolymer (A) of propylene and 1-hexene, and a second random propylene copolymer (B) of propylene and 1-hexene having a higher 1-hexene content than the first random propylene copolymer (A); and a plastomer (PL), the plastomer (PL) being ethylene and at least one C 4 To C 10 Elastomeric copolymers of alpha-olefins. Furthermore, the present invention is directed to an article comprising the polypropylene composition (P) and to the use of the polypropylene composition (P) as a sealant layer in a multilayer film. Background Art

[0003] As is well known in the art, copolymers of propylene and high alpha-olefins (particularly 1-hexene) prepared in the presence of metallocene catalysts are characterized by excellent sealing properties. Compared with current solutions, such as random copolymers with high ethylene content or terpolymers of ethylene, propylene and butene based on Ziegler-Natta, the sealing window (i.e. the difference between the melting temperature (Tm) and the sealing initiation temperature (SIT)) of such propylene / 1-hexene copolymers is significantly wider. For example, EP2386 603A1 and WO 2011 / 131639 A1 describe propylene / 1-hexene copolymers with wide sealing windows. In addition, metallocene-based propylene / 1-hexene copolymers are also appreciated for their excellent optical properties.

[0004] However, the toughness of propylene polymers prepared in the presence of metallocene catalysts is generally unsatisfactory.Therefore, there is a need in the art to combine the above benefits of metallocene-based propylene / 1-hexene copolymers with a good balance between stiffness and impact properties. Summary of the invention

[0005] It is therefore an object of the present invention to provide a metallocene based propylene polymer characterized by excellent impact strength while the stiffness remains at a high level. Good optical properties, especially the haze before and after sterilization are also highly appreciated.

[0006] Accordingly, the present invention relates to a polypropylene composition (P) comprising:

[0007] a) 80.0 to 99.0 wt.-%, based on the total weight of the polypropylene composition (P), of a copolymer of propylene and 1-hexene (C) comprising:

[0008] i) a first random propylene copolymer (A) of propylene and 1-hexene, and

[0009] ii) a second random propylene copolymer of propylene and 1-hexene (B) having a higher 1-hexene content than the first random propylene copolymer (A),

[0010] wherein copolymer (C) has a xylene soluble content (XCS) of at least 8.0 wt.-%, and

[0011] b) 1.0 to 20.0 wt.-%, based on the total weight of the polypropylene composition (P), of a plastomer (PL), the plastomer (PL) being ethylene and at least one C 4 To C 10 Elastomeric copolymer of alpha-olefins characterized by a density of 0.860 to 0.930 g / cm 3 within the range.

[0012] According to one embodiment of the present invention, copolymer (C) has 2,1 erythro regio defects in an amount of at least 0.4 mol %.

[0013] According to another embodiment of the present invention, the melt flow rate MFR of copolymer (C) measured according to ISO 1133 is 2 (230°C, 2.16 kg) in the range of 0.4 to 12.0 g / 10 min.

[0014] According to another embodiment of the present invention the weight ratio of the first random propylene copolymer (A) to the second random propylene copolymer (B) in copolymer (C) is in the range of 30:70 to 70:30.

[0015] According to another embodiment of the present invention, copolymer (C) satisfies inequality (1)

[0016] MFR(C) / MFR(A) ≤ 1.0 (1)

[0017] wherein MFR(A) is the melt flow rate MFR in [g / 10 min] determined according to ISO 1133 of the first random propylene copolymer (A) 2 (230° C., 2.16 kg), and MFR(C) is the melt flow rate MFR of copolymer (C) measured in [g / 10 min] according to ISO 1133 2 (230°C, 2.16kg).

[0018] According to another embodiment of the present invention, the 1-hexene content of the xylene soluble fraction C6 (XCS) of the copolymer (C) is in the range of 2.0 to 8.0 wt.-%.

[0019] According to one embodiment of the present invention the first random propylene copolymer (A) has a melt flow rate MFR determined according to ISO 1133 2 (230°C, 2.16 kg) in the range of 0.3 to 12.0 g / 10 min, and / or the melt flow rate MFR of the second random propylene copolymer (B) measured according to ISO 1133 2 (230°C, 2.16 kg) in the range of 0.5 to 14.0 g / 10 min.

[0020] According to another embodiment of the present invention, copolymer (C) satisfies inequality (2)

[0021]

[0022] in

[0023] C6(A) is the 1-hexene content [in wt. %] of the first random propylene copolymer (A), based on the total weight of the first random propylene copolymer (A);

[0024] C6(C) is the 1-hexene content [in % by weight] of copolymer (C), based on the total weight of copolymer (C); and

[0025] [A] / [C] is the weight ratio [in g / g] between the first random propylene copolymer (A) and the copolymer (C).

[0026] According to another embodiment of the present invention, the density of the plastomer (PL) is between 0.865 and 0.920 g / cm 3 within the range.

[0027] Especially preferably, the plastomer (PL) is a copolymer of ethylene and 1-octene.

[0028] The present invention is also directed to an article comprising at least 90.0 wt.-% of the polypropylene composition (P) as defined above.

[0029] Preferably, the article is a film, more preferably a blown film.

[0030] Furthermore, preferably, the film has

[0031] i) less than 10.0% haze before steam sterilization as determined by measurement on 50 μm blown films according to ASTM D 1003-00, and

[0032] ii) less than 12.0% haze after steam sterilization as determined in accordance with ASTM D 1003-00 measured on 50 μm blown films.

[0033] The invention also relates to the use of an article as defined above as a sealing layer in a multilayer film.

[0034] Furthermore, the present invention relates to a process for the preparation of a polypropylene composition (P) as described above, wherein the process is a sequential polymerization process comprising at least two reactors connected in series, wherein the process comprises the following steps:

[0035] (A) polymerizing propylene and 1-hexene in a first reactor (R-1) to obtain a first random propylene copolymer (A), the first reactor (R-1) being a slurry reactor (SR), preferably a loop reactor (LR),

[0036] (B) transferring the first random propylene copolymer (A) and the unreacted comonomer of the first reactor (R-1) to a second reactor (R-2), the second reactor (R-2) being a gas phase reactor (GPR-1),

[0037] (C) feeding propylene and 1-hexene into the second reactor (R-2),

[0038] (D) polymerizing propylene and 1-hexene in the presence of the first random propylene copolymer (A) in the second reactor (R-2) to obtain a second random propylene copolymer (B), the first random propylene copolymer (A) and the second random propylene copolymer (B) forming a copolymer (C), and

[0039] (E) blending the copolymer (C) with a plastomer (PL) to obtain a polypropylene composition (P),

[0040] Among them further

[0041] In the first reactor (R-1) and the second reactor (R-2), the polymerization is carried out in the presence of a solid catalyst system (SCS) comprising a transition metal compound of formula (I)

[0042] R n (Cp) 2 MX 2 (I)

[0043] in

[0044] Each Cp is independently an unsubstituted or substituted and / or fused cyclopentadienyl ligand, a substituted or unsubstituted indenyl or a substituted or unsubstituted fluorenyl ligand; the optional one or more substituents are independently preferably selected from halogen, hydrocarbon groups (e.g. C1-C20-alkyl, C2-C20-alkenyl, C2-C20-alkynyl, C3-C12-cycloalkyl, C6-C20-aryl or C7-C20-aralkyl), C3-C12-cycloalkyl containing 1, 2, 3 or 4 heteroatoms in the ring part, C6-C20-heteroaryl, C1-C20 haloalkyl, -SiR" 3 ,-OSiR" 3 , -SR", -PR 2 , OR" or -NR" 2 ,

[0045] Each R" is independently hydrogen or a hydrocarbon group selected from C1-C20-alkyl, C2-C20-alkenyl, C2-C20-alkynyl, C3-C12-cycloalkyl or C6-C20-aryl; or in -NR" 2 In the case of, the two substituents R" may form a five-membered or six-membered ring together with the nitrogen atom to which they are attached;

[0046] R is a bridge of 1-2 C atoms and 0-2 heteroatoms, wherein the heteroatoms may be Si, Ge and / or O atoms, wherein each bridge atom may independently carry a substituent selected from C1-C20-alkyl, tri(C1-C20-alkyl)silyl, tri(C1-C20-alkyl)siloxy or C6-C20-aryl substituents); or a bridge of one or two heteroatoms selected from silicon, germanium and / or oxygen atoms,

[0047] M is a Group 4 transition metal selected from Zr or Hf, especially Zr;

[0048] Each X is independently a sigma-ligand selected from the group consisting of H, halogen, C1-C20-alkyl, C1-C20-alkoxy, C2-C20-alkenyl, C2-C20-alkynyl, C3-C12-cycloalkyl, C6-C20-aryl, C6-C20-aryloxy, C7-C20-aralkyl, C7-C20-aralkenyl, -SR", -PR" 3 、-SiR" 3 、-OSiR" 3 、-NR" 2 or -CH 2 -Y, wherein Y is C6-C20-aryl, C6-C20-heteroaryl, C1-C20-alkoxy, C6-C20-aryloxy, NR" 2 、-SR"、-PR" 3 、-SiR" 3 or -OSiR"3 ;

[0049] Each of the above mentioned ring parts, alone or as part of another part of Cp, X, R" or a substituent of R, may be further substituted by C1-C20-alkyl, which may contain Si and / or O atoms; and

[0050] n is 1 or 2.

[0051] Particularly preferably, the transition metal compound of the formula (I) is an organozirconium compound of the formula (II) or (II′).

[0052]

[0053] in

[0054] M is Zr;

[0055] Each X is a sigma ligand, preferably each X is independently a hydrogen atom, a halogen atom, a C1-C6 alkoxy group, a C1-C6 alkyl group, a phenyl group or a benzyl group;

[0056] L is selected from -R' 2 C-、-R' 2 C-CR' 2 , -R' 2 Si-、-R' 2 Si-SiR' 2 -、-R' 2 A divalent bridge of Ge-, wherein each R' is independently a hydrogen atom, a C1-C20 alkyl group, a C3-C10 cycloalkyl group, a tri(C1-C20-alkyl)silyl group, a C6-C20-aryl group or a C7-C20 aralkyl group;

[0057] Each R 2 or R 2 ' is a C1-C10 alkyl group;

[0058] R 5 ' is C1-C10 alkyl or Z'R 3 'group;

[0059] R 6 is hydrogen or C1-C10 alkyl;

[0060] R 6 ' is a C1-C10 alkyl group or a C6-C10 aryl group;

[0061] R 7 is hydrogen, C1-C6 alkyl or ZR 3 Group;

[0062] R 7 ' is hydrogen or C1-C10 alkyl;

[0063] Z and Z' are independently O or S;

[0064] R 3 ' is a C1-C10 alkyl group, or a C6-C10 aryl group, which is optionally substituted by one or more halogen groups;

[0065] R 3 is a C1-C10 alkyl group;

[0066] each n is independently 0 to 4;

[0067] And each R 1 are independently C1-C20 hydrocarbon groups. DETAILED DESCRIPTION

[0068] The present invention will be described in more detail below.

[0069] Polypropylene composition (P)

[0070] The polypropylene composition (P) according to the present invention comprises: based on the total weight of the polypropylene composition (P), 80.0 to 99.0 wt.-% of a copolymer of propylene and 1-hexene (C) and 1.0 to 20.0 wt.-% of ethylene and at least one C 4 To C 10 Preferably, the polypropylene composition (P) comprises: based on the total weight of the polypropylene composition (P), 82.0 to 98.0 wt.-%, more preferably 85.0 to 97.0 wt.-%, still more preferably 88.0 to 96.0 wt.-%, such as 90.0 to 95.0 wt.-% of a copolymer of propylene and 1-hexene (C), and 2.0 to 18.0 wt.-%, more preferably 3.0 to 15.0 wt.-%, still more preferably 4.0 to 12.0 wt.-%, such as 5.0 to 10.0 wt.-% of ethylene and at least one C 4 To C 10 Plastomers (PL) of elastomeric copolymers of α-olefins.

[0071] Furthermore, the polypropylene composition (P) may comprise additives (AD).

[0072] Accordingly, preferably the polypropylene composition (P) comprises: 77.0 to 97.99 wt.-%, more preferably 81.0 to 96.9 wt.-%, yet more preferably 85.0 to 95.0 wt.-%, like 87.5 to 93.8 wt.-% of a copolymer of propylene and 1-hexene (C), based on the total weight of the polypropylene composition (P), 2.0 to 18.0 wt.-%, more preferably 3.0 to 15.0 wt.-%, yet more preferably 4.0 to 12.0 wt.-%, like 5.0 to 10.0 wt.-% of ethylene and at least one C 4 To C 10% of an elastomeric copolymer of an alpha-olefin, and 0.01 to 5.0 wt%, more preferably 0.1 to 4.0 wt%, still more preferably 1.0 to 3.0 wt%, such as 1.2 to 2.5 wt% of an additive (AD). Additives (AD) are defined in more detail below.

[0073] As stated above it is appreciated that the polypropylene composition (P) is characterized by excellent sealing properties. Hence, a rather low heat seal initiation temperature (SIT) and a wide sealing window are desired.

[0074] Accordingly, it is preferred that the heat seal initiation temperature (SIT) of the polypropylene composition (P) is equal to or below 115 °C, more preferably in the range of 90 to 112 °C, still more preferably in the range of 95 to 110 °C.

[0075] Not only should the heat seal initiation temperature (SIT) be rather low, but the melting temperature (Tm) should also be rather high. Thus, the difference between the melting temperature (Tm) and the heat seal initiation temperature (SIT) should be rather high. Thus, preferably the polypropylene composition (P) satisfies equation (3), more preferably equation (3a), still more preferably equation (3b):

[0076] Tm - SIT ≥ 20℃ (3)

[0077] Tm-SIT ≥ 22℃ (3a)

[0078] Tm-SIT ≥ 25℃ (3b)

[0079] in

[0080] Tm is the melting temperature of the polypropylene composition (P) given in degrees Celsius [°C],

[0081] SIT is the heat seal initiation temperature of the polypropylene composition (P) given in degrees Celsius [°C].

[0082] The melting temperature (Tm) of the polypropylene composition (P) measured according to ISO 11357-3 is preferably at least 120° C., more preferably at least 125° C. Thus, it is particularly appreciated that the melting temperature (Tm) of the polypropylene composition (P) measured according to ISO 11357-3 is in the range of 125 to 145° C., more preferably in the range of 130 to 140° C.

[0083] The polypropylene composition (P) is preferably obtained by a process which is a sequential polymerization process comprising at least two reactors connected in series, wherein the process comprises the following steps:

[0084] (A) polymerizing propylene and 1-hexene in a first reactor (R-1) to obtain a first random propylene copolymer (A), the first reactor (R-1) being a slurry reactor (SR), preferably a loop reactor (LR),

[0085] (B) transferring the first random propylene copolymer (A) and the unreacted comonomer of the first reactor (R-1) to a second reactor (R-2), the second reactor (R-2) being a gas phase reactor (GPR-1),

[0086] (C) feeding propylene and 1-hexene into the second reactor (R-2),

[0087] (D) polymerizing propylene and 1-hexene in the presence of the first random propylene copolymer (A) in the second reactor (R-2) to obtain a second random propylene copolymer (B), the first random propylene copolymer (A) and the second random propylene copolymer (B) forming a copolymer (C), and

[0088] (E) blending the copolymer (C) with a plastomer (PL) as defined in claims 1, 10 and 11, thereby obtaining a polypropylene composition (P),

[0089] Among them further

[0090] In the first reactor (R-1) and in the second reactor (R-2), the polymerization is carried out in the presence of a solid catalyst system (SCS).

[0091] The preparation process of the copolymer (C) and the solid catalyst system (SCS) are described in more detail below.

[0092] Copolymer (C) and plastomer (PL) are described in more detail below.

[0093] Copolymer (C)

[0094] The copolymer (C) according to the invention is characterized by a rather high comonomer content, i.e. a 1-hexene content. Due to the fact that the copolymer (C) according to the invention comprises two propylene copolymer fractions as defined herein, a rather high comonomer content is achieved. A "comonomer" according to the invention is a polymerizable unit different from propylene. Thus, the 1-hexene content of the copolymer (C) according to the invention should be in the range of 2.0 to 8.0 wt.-%, more preferably in the range of 3.0 to 7.5 wt.-%, still more preferably in the range of 3.5 to 7.2 wt.-%, for example in the range of 4.0 to 7.0 wt.-%.

[0095] Copolymer (C) comprises a first random propylene copolymer (A) and a second random propylene copolymer (B). The term "random copolymer" is preferably understood according to IUPAC (Pure Appl. Chem., Vol. 68, No. 8, pp. 1591 to 1595, 1996). Preferably, the molar concentration of the comonomer diad (e.g. 1-hexene diad) obeys the following relationship:

[0096] [HH]<[H] 2

[0097] in

[0098] [HH] is the mole fraction of adjacent comonomer units (e.g., adjacent 1-hexene units), and

[0099] [H] is the mole fraction of the total comonomer units (eg, total 1-hexene units) in the polymer.

[0100] Furthermore, it is preferred that the copolymer (C) of the present invention has a melt flow rate (MFR) given in a specific range. The melt flow rate measured at 230° C. under a load of 2.16 kg (ISO 1133) is denoted as MFR 2 (230°C, 2.16 kg). Therefore, in the present invention, preferably the melt flow rate MFR of the copolymer (C) measured according to ISO 1133 is 2 (230°C, 2.16 kg) is in the range of 0.4 to 12.0 g / 10 min, more preferably in the range of 0.6 to 9.0 g / 10 min, more preferably in the range of 0.8 to 6.0 g / 10 min, such as in the range of 1.0 to 3.5 g / 10 min.

[0101] Additionally, copolymer (C) is defined by the xylene cold soluble (XCS) content measured according to ISO 16152 (25° C.). Accordingly, copolymer (C) is characterized by a xylene cold soluble (XCS) content of at least 8.0 wt.-%, preferably in the range of 8.0 to 30.0 wt.-%, more preferably in the range of 10.0 to 28.0 wt.-%, such as in the range of 10.0 to 26.0 wt.-%.

[0102] The amount of xylene cold solubles (XCS) also shows that copolymer (C) preferably does not contain any elastomeric polymer component, such as ethylene-propylene rubber. In other words, copolymer (C) should not be a heterophasic polypropylene, i.e. a system consisting of a polypropylene matrix in which an elastomeric phase is dispersed. Such a system is characterized by a fairly high xylene cold soluble content. Therefore, in a preferred embodiment, copolymer (C) comprises the first random propylene copolymer (A) and the second random propylene copolymer (B) as the only polymer components.

[0103] Furthermore, preferably, the 1-hexene content of the xylene soluble fraction C6 (XCS) of the copolymer (C) is in the range of 2.0 to 15.0 wt%, more preferably in the range of 2.5 to 12.0 wt%, more preferably in the range of 3.0 to 10.0 wt%.

[0104] Similar to xylene cold solubles (XCS), hexane hot solubles (HHS) represent the polymer fraction having low isotacticity and crystallinity and being soluble in hexane at 50°C.

[0105] Therefore, preferably, the copolymer (C) of the present invention has an amount of hexane hot solubles (HHS) measured according to FDA 177.1520 equal to or lower than 1.5 wt.-%, more preferably equal to or lower than 1.2 wt.-%, still more preferably equal to or lower than 1.0 wt.-%, such as equal to or lower than 0.8 wt.-%.

[0106] The copolymer (C) of the present invention is further defined by the polymer fractions it is present in. Accordingly, the copolymer (C) of the present invention comprises (preferably consists of) at least two fractions, namely a first random propylene copolymer (A) and a second random propylene copolymer (B).

[0107] The first random propylene copolymer (A) is a copolymer of propylene and 1-hexene having a 1-hexene content in the range of 0.1 to 4.0 wt%, preferably in the range of 0.5 to 3.5 wt%, more preferably in the range of 0.8 to 3.0 wt%, still more preferably in the range of 1.0 to 2.5 wt%, and the second random propylene copolymer (B) is a copolymer of propylene and 1-hexene having a 1-hexene content in the range of 4.0 to 15.0 wt%, preferably in the range of 5.0 to 13.0 wt%, more preferably in the range of 6.0 to 12.0 wt%, still more preferably in the range of 6.5 to 10.0 wt%.

[0108] Thus, the first random propylene copolymer (A) is the 1-hexene-lean fraction and the second random propylene copolymer (B) is the 1-hexene-rich fraction.

[0109] About melt flow rate MFR 2 , the copolymer (C) satisfies inequality (1), more preferably inequality (1a), and even more preferably inequality (1b),

[0110] MFR(C) / MFR(A) ≤ 1.0 (1)

[0111] 0.5≤MFR(C) / MFR(A)≤1.0(1a)

[0112] 0.6≤MFR(C) / MFR(A)≤0.9(1b)

[0113] wherein MFR(A) is the melt flow rate MFR in [g / 10 min] determined according to ISO 1133 of the first random propylene copolymer (A) 2 (230° C., 2.16 kg), and MFR(C) is the melt flow rate MFR of copolymer (C) measured in [g / 10 min] according to ISO 1133 2 (230°C, 2.16kg).

[0114] Furthermore, it is understood that the melt flow rate MFR of the first random propylene copolymer (A) measured according to ISO 1133 is 2 (230°C, 2.16 kg) is in the range of 0.3 to 12.0 g / 10 min, more preferably in the range of 0.5 to 9.0 g / 10 min, still more preferably in the range of 0.7 to 6.0 g / 10 min, such as in the range of 1.0 to 3.0 g / 10 min.

[0115] Melt flow rate MFR of the second random propylene copolymer (B) measured according to ISO 1133 2 (230°C, 2.16 kg) is preferably in the range of 0.5 to 14.0 g / 10 min, more preferably in the range of 0.7 to 11.0 g / 10 min, still more preferably in the range of 0.9 to 8.0 g / 10 min, such as in the range of 1.1 to 5.0 g / 10 min.

[0116] Preferably, the weight ratio between the first random propylene copolymer (A) and the second random propylene copolymer (B) in copolymer (C) is preferably in the range of 30:70 to 70:30, more preferably in the range of 35:65 to 65:35, still more preferably in the range of 40:60 to 60:40.

[0117] In particular, preferably copolymer (C) comprises 30.0 to 70.0 wt.-%, more preferably 35.0 to 50.0 wt.-%, still more preferably 38.0 to 45.0 wt.-%, such as 39.0 to 43.0 wt.-% of the first random propylene copolymer (A), and 30.0 to 70.0 wt.-%, more preferably 40.0 to 65.0 wt.-%, still more preferably 48.0 to 60.0 wt.-%, such as 52.0 to 55.0 wt.-%, of the second random propylene copolymer (B), based on the total weight of copolymer (C).

[0118] Furthermore, preferably, copolymer (C) has 2,1 erythro regio defects in an amount of at least 0.4 mol%. Without being bound by theory, a large amount of intercalation of propylene and / or 1-hexene within the polymer chain indicates that copolymer (C) is produced in the presence of a single-site catalyst, preferably a metallocene catalyst.

[0119] Copolymers (C) are obtainable, preferably obtained, in particular by the process defined in detail below.

[0120] The process for preparing the copolymer (C) forming the polypropylene composition (P) as defined above is a sequential polymerization process comprising at least two reactors connected in series, wherein the process comprises the following steps:

[0121] (A) polymerizing propylene and 1-hexene, preferably 1-hexene, in a first reactor (R-1) to obtain the first random propylene copolymer (A) as defined in the present invention, the first reactor (R-1) being a slurry reactor (SR), preferably a loop reactor (LR),

[0122] (B) transferring the first random propylene copolymer (A) and the unreacted comonomer of the first reactor (R-1) to a second reactor (R-2), the second reactor (R-2) being a gas phase reactor (GPR-1),

[0123] (C) feeding propylene and 1-hexene into the second reactor (R-2),

[0124] (D) polymerizing propylene and 1-hexene in the presence of the first random propylene copolymer (A) in the second reactor (R-2) to obtain the second random propylene copolymer (B) as defined in the present invention, the first random propylene copolymer (A) and the second random propylene copolymer (B) forming the copolymer (C) as defined in the present invention, wherein further

[0125] In the first reactor (R-1) and the second reactor (R-2), the polymerization is carried out in the presence of a solid catalyst system (SCS), said solid catalyst system (SCS) comprising

[0126] (i) Transition metal compound of formula (I)

[0127] R n (Cp) 2 MX 2 (I)

[0128] in

[0129] "M" is zirconium (Zr) or hafnium (Hf),

[0130] Each "X" is independently a monovalent anionic sigma-ligand,

[0131] each "Cp" is a cyclopentadienyl-type organic ligand independently selected from unsubstituted or substituted and / or fused cyclopentadienyl, substituted or unsubstituted indenyl or substituted or unsubstituted fluorenyl, said organic ligand being coordinated to the transition metal (M),

[0132] "R" is a divalent bridging group connecting the organic ligand (Cp),

[0133] "n" is 1 or 2, preferably 1, and

[0134] (ii) Optionally, a promoter (Co) comprising an element (E) of Group 13 of the Periodic Table (IUPAC), preferably a promoter (Co) comprising a compound of Al and / or B.

[0135] Concerning the definition of copolymer (C), the first random propylene copolymer (A) and the second random propylene copolymer (B), reference is made to the definitions given above.

[0136] The solid catalyst system (SCS) is defined in more detail below.

[0137] Due to the use of a solid catalyst system (SCS) in a sequential polymerization process, the copolymer (C) defined above can be produced. In particular, due to the preparation of a propylene copolymer, i.e. a first random propylene copolymer (A), in a first reactor (R-1) and the transfer of said propylene copolymer and in particular the transfer of unreacted comonomers to a second reactor (R-2), a copolymer (C) with a high comonomer content can be produced in a sequential polymerization process. Typically, the preparation of propylene copolymers with a high comonomer content in a sequential polymerization process leads to fouling or, in severe cases, to blockages in the transport line, since unreacted comonomers typically condense at the transport line. However, with the new process, the conversion of the comonomer is increased and thereby a better incorporation into the polymer chain is achieved, leading to a higher comonomer content and reduced viscosity problems.

[0138] The term "sequential polymerization process" means that the copolymer (C) is produced in at least two reactors connected in series. More precisely, the term "sequential polymerization process" means in the present application that the polymer of the first reactor (R-1) and the unreacted comonomer are directly conveyed to the second reactor (R-2). Therefore, a decisive aspect of the present process is the preparation of the copolymer (C) in two different reactors, wherein the reaction mass of the first reactor (R-1) is directly conveyed to the second reactor (R-2). Therefore, the present process comprises at least a first reactor (R-1) and a second reactor (R-2). In a particular embodiment, the present process consists of two polymerization reactors (R-1) and (R-2). The term "polymerization reactor" shall mean that the main polymerization takes place here. Therefore, in the case where the process consists of two polymerization reactors, this definition does not exclude the option that the entire process includes a prepolymerization step, for example in a prepolymerization reactor. The term "consisting of..." is a closed expression only with respect to the main polymerization reactor.

[0139] The first reactor (R-1) is a slurry reactor (SR) and can be any continuous or simple stirred batch tank reactor or loop reactor operating in slurry. According to the present invention, the slurry reactor (SR) is preferably a loop reactor (LR).

[0140] The second reactor (R-2) and any subsequent reactors are gas phase reactors (GPR). Such a gas phase reactor (GPR) may be any mechanically mixed or fluidized bed reactor. Preferably, the gas phase reactor (GPR) comprises a mechanically agitated fluidized bed reactor having a gas velocity of at least 0.2 m / s. Thus, it is understood that the gas phase reactor (GPR) is a fluidized bed type reactor preferably with a mechanical agitator.

[0141] The conditions in each reactor (temperature, pressure, reaction time, monomer feed) depend on the desired product, as is known to those skilled in the art. As described above, the first reactor (R-1) is a slurry reactor (SR), such as a loop reactor (LR), and the second reactor (R-2) is a gas phase reactor (GPR-1). Subsequent reactors (if present) are also gas phase reactors (GPR).

[0142] A preferred multistage process is the "loop-gas phase" process, for example as developed by Borealis A / S of Denmark (known as Methods developed by the invention (Technology) are described in the patent literature, for example in EP 0 887 379 or WO 92 / 12182.

[0143] Multimodal polymers can be produced according to a number of processes as described in, for example, WO 92 / 12182, EP 0 887 379 and WO 98 / 58976. The contents of these documents are incorporated herein by reference.

[0144] Preferably, in the present process for producing the copolymer (C) as defined above, the conditions in the first reactor (R-1) of step (A), i.e. the slurry reactor (SR), such as the loop reactor (LR), are as follows:

[0145] - the temperature is in the range of 40°C to 110°C, preferably between 60°C to 100°C, more preferably in the range of 65°C to 90°C,

[0146] - a pressure in the range of 20 to 80 bar, preferably between 40 and 70 bar,

[0147] - Hydrogen can be added in a manner known per se to control the molar mass.

[0148] The reaction mixture from step (A) is subsequently transferred to the second reactor (R-2), i.e. the gas phase reactor (GPR-1), i.e. to step (D), wherein the conditions in step (D) are preferably as follows:

[0149] - a temperature in the range of 50°C to 130°C, preferably between 60°C and 100°C,

[0150] - a pressure in the range of 5 to 50 bar, preferably between 15 and 40 bar,

[0151] - Hydrogen can be added in a manner known per se to control the molar mass.

[0152] The residence time in the two reactor zones can vary.

[0153] In one embodiment of the process for producing copolymer (C), the residence time in the slurry reactor (SR), e.g. loop reactor (LR), is in the range of 0.2 to 4.0 hours, e.g. 0.3 to 1.5 hours, and the residence time in the gas phase reactor (GPR) is typically 0.2 to 6.0 hours, such as 0.5 to 4.0 hours.

[0154] In the first reactor (R-1), ie in the slurry reactor (SR), such as in the loop reactor (LR), the polymerization can, if desired, be carried out in a known manner under supercritical conditions.

[0155] The conditions in the other gas phase reactor (GPR), if present, are similar to the second reactor (R-2).

[0156] The process may also comprise a prepolymerization prior to the polymerization in the first reactor (R-1). The prepolymerization may be carried out in the first reactor (R-1), but preferably, the prepolymerization is carried out in a separate reactor, the so-called prepolymerization reactor.

[0157] The copolymers (C) according to the present invention are prepared in the presence of a solid catalyst system (SCS) comprising a transition metal compound.

[0158] The transition metal compound has the formula (I)

[0159] R n (Cp) 2 MX 2 (I)

[0160] in

[0161] Each Cp is independently an unsubstituted or substituted and / or fused cyclopentadienyl ligand, such as a substituted or unsubstituted cyclopentadienyl, a substituted or unsubstituted indenyl or a substituted or unsubstituted fluorenyl ligand; the optional one or more substituents are independently preferably selected from halogen, hydrocarbon groups (e.g. C1-C20-alkyl, C2-C20-alkenyl, C2-C20-alkynyl, C3-C12-cycloalkyl, C6-C20-aryl or C7-C20-aralkyl), C3-C12-cycloalkyl containing 1, 2, 3 or 4 heteroatoms in the ring part, C6-C20-heteroaryl, C1-C20 haloalkyl, -SiR" 3 ,-OSiR" 3 , -SR", -PR 2 , OR" or -NR" 2 ,

[0162] Each R" is independently hydrogen or a hydrocarbon group, such as C1-C20-alkyl, C2-C20-alkenyl, C2-C20-alkynyl, C3-C12-cycloalkyl or C6-C20-aryl; or, for example, in -NR" 2 In the case of, the two substituents R" may form a ring together with the nitrogen atom to which they are attached, such as a five-membered or six-membered ring;

[0163] R is a bridge of 1-3 atoms, for example a bridge of 1-2 C atoms and 0-2 heteroatoms, wherein the heteroatoms may be, for example, Si, Ge and / or O atoms, wherein the individual bridge atoms may independently carry substituents, for example C1-C20-alkyl, tri(C1-C20-alkyl)silyl, tri(C1-C20-alkyl)siloxy or C6-C20-aryl substituents); or a bridge of 1-3, for example one or two heteroatoms (for example silicon, germanium and / or oxygen atoms), for example -SiR 10 2 , where each R 10 are independently C1-C20-alkyl, C3-12-cycloalkyl, C6-C20-aryl or tri(C1-C20-alkyl)silyl residues, for example trimethylsilyl;

[0164] M is a transition metal of Group 4, such as Zr or Hf, especially Zr;

[0165] Each X is independently a sigma-ligand, such as H, halogen, C1-C20-alkyl, C1-C20-alkoxy, C2-C20-alkenyl, C2-C20-alkynyl, C3-C12-cycloalkyl, C6-C20-aryl, C6-C20-aryloxy, C7-C20-aralkyl, C7-C20-aralkenyl, -SR", -PR" 3 、-SiR" 3 、-OSiR" 3、-NR" 2 or -CH 2 -Y, wherein Y is C6-C20-aryl, C6-C20-heteroaryl, C1-C20-alkoxy, C6-C20-aryloxy, NR" 2 、-SR"、-PR" 3 、-SiR" 3 or -OSiR" 3 ;

[0166] Each of the above mentioned ring parts, alone or as part of another part of Cp, X, R" or a substituent of R, may be further substituted, for example, by C1-C20-alkyl, which may contain Si and / or O atoms;

[0167] n is 1 or 2.

[0168] Appropriately, in as-CH 2 -Y, each Y is independently selected from C6-C20-aryl, NR" 2 、-SiR" 3 or -OSiR" 3 Most preferably, as -CH 2 -Y X is benzyl. 2 Each X other than -Y is independently halogen, C1-C20-alkyl, C1-C20-alkoxy, C6-C20-aryl, C7-C20-arylalkenyl or -NR" as defined above 2 , for example -N(C1-C20-alkyl) 2 .

[0169] Preferably, each X is halogen, methyl, phenyl or -CH 2 -Y, and each Y is independently as defined above.

[0170] Cp is preferably cyclopentadienyl, indenyl or fluorenyl, optionally substituted as defined above. Ideally, Cp is cyclopentadienyl or indenyl.

[0171] In a suitable subgroup of compounds of formula (I), each Cp independently carries 1, 2, 3 or 4 substituents as defined above, preferably 1, 2 or 3, for example 1 or 2 substituents, said substituents being preferably selected from C1-C20-alkyl, C6-C20-aryl, C7-C20-aralkyl (wherein the aryl ring, alone or as part of another moiety, may be further substituted as described above), -OSiR" 3 , wherein R" is as described above, preferably C1-C20-alkyl.

[0172] R is preferably a methylene, ethylene or silyl bridge, wherein the silyl group may be substituted as defined above, for example (dimethyl)Si=, (methylphenyl)Si=, (methylcyclohexyl)silyl=((methylccylcohexyl)silyl=) or (trimethylsilylmethyl)Si=; n is 0 or 1. Preferably, R" is not hydrogen.

[0173] A specific subgroup includes the well-known metallocenes of Zr and Hf with two η5-ligands, bridged with a cyclopentadienyl ligand optionally substituted with a silanoxy or alkyl group (e.g. C1-6-alkyl) as defined above, or with two bridged indenyl ligands optionally substituted with a silanoxy or alkyl group (e.g. C1-6-alkyl) at any ring part (e.g. 2-, 3-, 4- and / or 7-position). Preferred bridges are ethylene or -SiMe 2 .

[0174] The preparation of metallocenes can be carried out according to or in analogy to methods known in the literature and is within the capabilities of a person skilled in the art. For the preparation, see, for example, EP-A-129368, in which the metal atom carries -NR" 2 Examples of compounds of the ligands are described in, for example, WO-A-985683 1 and WO-A-0034341. For the preparation, see, for example, EP-A-260 130, WO-A-9728170, WO-A-9846616, WO-A-9849208, WO-A-9912981, WO-A-9919335, WO-A-9856831, WO-A-00 34341, EP-A-423 101 and EP-A-537 130.

[0175] Complex of the present invention is preferably asymmetric. This simply means that the two indenyl ligands forming the metallocene are different, that is, each indenyl ligand carries a set of substituents that are chemically different or positioned at different positions relative to another indenyl ligand. More specifically, they are chiral, racemic bridged bis-indenyl metallocenes. Although complex of the present invention can be in its cis configuration under ideal circumstances, they are in its trans configuration. For purposes of the present invention, racemic-trans means that two indenyl ligands are oriented in opposite directions relative to the cyclopentadienyl-metal-cyclopentadienyl plane, while racemic-cis means that two indenyl ligands are oriented in the same direction relative to the cyclopentadienyl-metal-cyclopentadienyl plane.

[0176] Preferred complexes of the present invention have the formula (II') or (II)

[0177]

[0178] in

[0179] M is Zr;

[0180] Each X is a sigma ligand, preferably each X is independently a hydrogen atom, a halogen atom, a C1-C6 alkoxy group, a C1-C6 alkyl group, a phenyl group or a benzyl group;

[0181] L is selected from -R' 2 C-、-R' 2 C-CR' 2 , -R' 2 Si-、-R' 2 Si-SiR' 2 -、-R' 2 A divalent bridge of Ge-, wherein each R' is independently a hydrogen atom, a C1-C20-alkyl group, a C3-C10 cycloalkyl group, a tri(C1-C20-alkyl)silyl group, a C6-C20-aryl group, or a C7-C20 aralkyl group;

[0182] Each R 2 or R 2 ' is a C1-C10 alkyl group;

[0183] R 5 ' is C1-C10 alkyl or Z'R 3 'group;

[0184] R 6 is hydrogen or C1-C10 alkyl;

[0185] R 6 ' is a C1-C10 alkyl group or a C6-C10 aryl group;

[0186] R 7 is hydrogen, C1-C6 alkyl or ZR 3 Group;

[0187] R 7 ' is hydrogen or C1-C10 alkyl;

[0188] Z and Z' are independently O or S;

[0189] R 3 ' is a C1-C10 alkyl group, or a C6-C10 aryl group, which is optionally substituted by one or more halogen groups;

[0190] R 3 is a C1-C10 alkyl group;

[0191] each n is independently 0 to 4, such as 0, 1 or 2;

[0192] And each R 1 are independently C1-C20 hydrocarbon groups, such as C1-C10 alkyl groups.

[0193] Particularly preferred compounds of the present invention include:

[0194] Racemic-dimethylsilylenebis[2-methyl-4-(4-tert-butylphenyl)-1,5,6,7-tetrahydro-s-inden-l-yl]zirconium dichloride

[0195] Racemic-dimethylsilylenebis(2-methyl-4-phenyl-5-methoxy-6-tert-butylinden-1-yl)zirconium dichloride

[0196] Racemic-trans-Me 2 Si(2-Me-4-Ph-6-tBu-Ind)(2-Me-4-Ph-5-OMe-6-tBu-Ind)ZrCl 2

[0197] Racemic-trans-Me 2 Si(2-Me-4-(p-tBuPh)-Ind)(2-Me-4-Ph-5-OMe-6-tBu-Ind)ZrCl 2

[0198] Racemic-trans-Me 2 Si(2-Me-4-(3,5-di-tBuPh)-6-tBu-Ind)(2-Me-4-Ph-5-OMe-6-tBu-Ind)ZrCl 2

[0199] Racemic-trans-Me 2 Si(2-Me-4-(p-tBuPh)-Ind)(2-Me-4-Ph-5-OC 6 F 5 )-6-iPr-Ind)ZrCl 2

[0200] Racemic-trans-Me(CyHex)Si(2-Me-4-Ph-6-tBu-Ind)(2-Me-4-Ph-5-OMe-6-tBu-Ind)ZrCl 2

[0201] Racemic-trans-Me 2 Si(2-Me-4-(3,5-di-tBuPh)-7-Me-Ind)(2-Me-4-Ph-5-OMe-6-tBu-Ind)ZrCl 2

[0202] Racemic-trans-Me 2Si(2-Me-4-(3,5-di-tBuPh)-7-OMe-Ind)(2-Me-4-Ph-5-OMe-6-tBu-Ind)ZrCl 2 Racemic-trans-Me 2 Si(2-Me-4-(p-tBuPh)-6-tBu-Ind)(2-Me-4-Ph-5-OMe-6-tBu-Ind)ZrCl 2

[0203] Racemic-trans-Me 2 Si(2-Me-4-(p-tBuPh)-Ind)(2-Me-4-(4-tBuPh)-5-OMe-6-tBu-Ind)ZrCl 2

[0204] Racemic-trans-Me 2 Si(2-Me-4-(p-tBuPh)-Ind)(2-Me-4-(3,5-tBu2Ph)-5-OMe-6-tBu-Ind)ZrCl 2

[0205] Racemic-trans-Me 2 Si(2-Me-4-(p-tBuPh)-Ind)(2-Me-4-Ph-5-OtBu-6-tBu-Ind)ZrCl 2

[0206] The most preferred metallocene complex (procatalyst) is rac-trans-dimethylsilylene(2-methyl-4-phenyl-5-methoxy-6-tert-butyl-indenyl)(2-methyl-4-(4-tert-butylphenyl)indenyl)zirconium dichloride.

[0207] In addition to the metallocene complex (main catalyst), the metallocene catalyst also contains a cocatalyst as defined in WO 2015 / 011135 A1. Therefore, the preferred cocatalyst is methylaluminoxane (MAO) and / or a borate, preferably triphenylcarbonium tetrakis(pentafluorophenyl)borate (or triphenylcarbonium tetrakis(pentafluorophenyl)borate).

[0208] Particularly preferably, the metallocene catalyst is unsupported, ie no external support is used. With regard to the preparation of such metallocene complexes, reference is again made to WO 2015 / 011135 A1.

[0209] Plastic body (PL)

[0210] The polypropylene composition (P) according to the present invention further comprises ethylene and at least one C 4 To C 10 Plastomers (PL) of elastomeric copolymers of α-olefins.

[0211] Preferably, the plastomer (PL) is a very low density polyolefin, more preferably a very low density polyolefin polymerized using single-site catalysis.

[0212] The density of the plastomer (PL) is between 0.860 and 0.930 g / cm 3 Preferably, the density of the plastomer (PL) is between 0.865 and 0.920 g / cm 3 In the range of 0.868 to 0.910 g / cm 3 within the range.

[0213] Preferably, the melt flow rate MFR of the plastomer (PL) is 2 (190°C, 2.16 kg) is in the range of 0.1 to 40.0 g / 10 min, more preferably in the range of 0.3 to 35.0 g / 10 min, still more preferably in the range of 0.4 to 32.0 g / 10 min, such as in the range of 0.5 to 30.0 g / 10 min.

[0214] Preferably, the plastomer (PL) comprises 4 To C 10 α-olefin units.

[0215] The plastomer (PL) comprises, preferably consists of: a polyol derivable from (i) ethylene and (ii) at least one other C 4 To C 10 The plastomer (PL) comprises at least units derivable from (i) ethylene and (ii) at least one other α-olefin selected from the group consisting of 1-butene, 1-pentene, 1-hexene, 1-heptene and 1-octene. In particular, the plastomer (PL) comprises at least units derivable from (i) ethylene and (ii) 1-butene or 1-octene.

[0216] In a particularly preferred embodiment, the plastomer (PL) consists of units derivable from (i) ethylene and (ii) 1-butene or 1-octene. In particular, it is preferred that the plastomer (PL) is a copolymer of ethylene and 1-octene.

[0217] The ethylene content of the plastomer (PL) is in the range of 60.0 to 95.0 wt. %, preferably in the range of 65.0 to 90.0 wt. %, more preferably in the range of 70.0 to 85.0 wt. %.

[0218] In addition, preferably, the melting temperature Tm of the plastomer (PL) is lower than 100°C, more preferably in the range of 50°C to 90°C, still more preferably in the range of 55°C to 85°C.

[0219] As an alternative or supplement to the previous paragraph, preferably, the glass transition temperature of the plastomer (PL) is below -25°C, more preferably in the range of -65°C to -30°C, still more preferably in the range of -60°C to -35°C.

[0220] In a preferred embodiment, the plastomer (PL) is prepared with at least one single-site catalyst. The plastomer (PL) may also be prepared with more than one single-site catalyst, or may be a mixture of multiple plastomers prepared with different single-site catalysts. In some embodiments, the plastomer (PL) is a substantially linear ethylene polymer (SLEP). SLEP and other single-site catalyzed plastomers (PL) are known in the art, for example in US 5,272,236. These resins are also commercially available, for example Queo TM Plastomers, available from Dow Chemical Co. as ENGAGE TM Plastomers, available from Exxon as EXACT TM The polymer may be obtained from Mitsui's TAFMER TM polymers, Lucene polymers available from LG, Fortify polymers available from Sabic, or Solumer polymers available from SK Chemicals.

[0221] According to step (E) of the process of the present invention, the plastomer (PL) is blended with the copolymer (C) to obtain the polypropylene composition (P). Preferably, the plastomer (PL) is blended with the copolymer (C) by melt blending. Particularly preferably, the plastomer (PL) is melt blended with the copolymer (C) in an extruder, more preferably in a co-rotating twin-screw extruder.

[0222] Additives (AD)

[0223] As stated above the polypropylene composition (P) may comprise additives (AD).

[0224] Typical additives are acid scavengers, antioxidants, colorants, light stabilizers, plasticizers, slip agents, anti-scratch agents, dispersants, processing aids, lubricants, pigments, and the like.

[0225] Such additives are commercially available and are described, for example, in the "Plastic Additives Handbook", 6th edition, 2009 by Hans Zweifel (pages 1141 to 1190).

[0226] Furthermore, the term "additive (AD)" according to the present invention also comprises carrier materials, in particular polymeric carrier materials.

[0227] Polymer carrier materials

[0228] Preferably, the polypropylene composition (P) of the present invention does not comprise other polymers different from the first random propylene copolymer (A) and the second random propylene copolymer (B) forming the copolymer (C) and the plastomer (PL) in an amount of more than 15 wt.-%, preferably in an amount of more than 10 wt.-%, more preferably in an amount of more than 9 wt.-%, based on the weight of the polypropylene composition (P). Any polymer acting as a carrier material for the additive (AD) is not counted in the amount of polymer compound as indicated in the present invention but in the amount of the respective additive.

[0229] The polymer carrier material of the additive (AD) is a carrier polymer to ensure uniform distribution in the polypropylene composition (P) of the present invention. The polymer carrier material is not limited to a specific polymer. The polymer carrier material can be an ethylene homopolymer, a copolymer of ethylene and an α-olefin comonomer (e.g. C 3 To C 8 α-olefin comonomers), ethylene copolymers obtained from propylene homopolymers and / or copolymers of propylene and α-olefin comonomers (e.g. ethylene and / or C 4 To C 8 Preferably, the polymeric carrier material does not comprise monomer units derivable from styrene or its derivatives.

[0230] Products

[0231] The present invention also relates to an article comprising at least 90.0 wt.-% of the polypropylene composition (P) as defined above.

[0232] Preferably, the article comprises at least 95.0 wt.-% of the polypropylene composition (P), more preferably at least 97.0 wt.-%, still more preferably at least 98.0 wt.-%, like at least 99.9 wt.-%. In particular preferably, the article consists of the polypropylene composition (P).

[0233] Preferably the article is a film, more preferably a blown film. The film according to the invention can be obtained by conventional means, for example by cast film technology or extrusion blown film technology. The thickness of the film is generally in the range of 15 to 300 μm, preferably in the range of 20 to 250 μm, for example in the range of 30 to 200 μm.

[0234] Preferably, the film has a haze before steam sterilization measured on a 50 μm blown film according to ASTM D 1003-00 of less than 10.0%, more preferably less than 8.0%, still more preferably less than 7.5%, such as less than 6.5%, and a haze after steam sterilization measured on a 50 μm blown film according to ASTM D 1003-00 of less than 12.0%, more preferably less than 10.0%, still more preferably less than 9.0%, such as less than 8.5%.

[0235] Furthermore, preferably, the film has a tensile modulus measured according to ISO 527-3 on a 50 μm film in the machine direction (MD) and / or transverse direction (TD) of at least 300 MPa, more preferably in the range of 350 to 1000 MPa, still more preferably in the range of 400 to 800 MPa, such as in the range of 450 to 700 MPa.

[0236] In addition, preferably, the film has a dart-drop strength (DDI) of at least 200 g, more preferably at least 250 g, and even more preferably at least 300 g, as measured on a 50 μm blown film according to ASTM D1709, Method A. The upper limit of the method is 1700 g.

[0237] Further preferably, the film is characterized by a hot tack greater than 2.0N, more preferably greater than 2.5N.

[0238] use

[0239] The present invention is also directed to the use of an article, preferably a film, comprising the polypropylene composition (P) according to the present invention as a sealant layer in a multilayer film.

[0240] Such multilayer film is usually prepared by multilayer blown film coextrusion. Coextrusion process can be carried out using conventional blown film technology. Therefore, the polypropylene composition (P) obtained from the polymerization process defined above is usually fed into the extrusion device forming a part of the multilayer blown film unit in the form of pellets (optionally comprising additives). The polymer melt preferably arrives at the annular die of the blown film unit from the extruder through a distributor, forming one of the outermost layers of the multilayer film produced. The other layer of the multilayer film can include other types of polypropylene or polyethylene homopolymers and copolymers.

[0241] The present invention is described below by way of examples.

[0242] Example

[0243] A. Measurement Method

[0244] Unless defined otherwise, the following definitions of terms and assay methods apply to the above general description of the invention as well as to the following examples.

[0245] Comonomer content of 1-hexene in propylene 1-hexene copolymer

[0246] Quantitative analysis was recorded in the melt using a Bruker Avance III 500 NMR spectrometer. 13 C{ 1 H}NMR spectrum, for 1 H and 13 C operates at 500.13 and 125.76 MHz respectively. 13All spectra were recorded at 180°C using nitrogen for all pneumatics using a C optimized 7 mm magic angle spinning (MAS) probe. Approximately 200 mg of material was loaded into a 7 mm outer diameter zirconium oxide MAS rotor and spun at 4 kHz. This setup was chosen primarily for the high sensitivity required for rapid identification and accurate quantification. (Klimke, K., Parkinson, M., Piel, C., Kaminsky, W., Spiess, H. W., Wilhelm, M., Macromol. Chem. Phys. 2006; 207: 382., Parkinson, M., Klimke, K., Spiess, H. W., Wilhelm, M., Macromol. Chem. Phys. 2007; 208: 2128., Castignolles, P., Graf, R., Parkinson, M., Wilhelm, M., Gaborieau, M., Polymer 50 (2009) 2373). The NOE was used with a short recycle delay of 3 s (Klimke, K., Parkinson, M., Piel, C., Kaminsky, W., Spiess, H. W., Wilhelm, M., Macromol. Chem. Phys. 2006; 207: 382., Pollard, M., Klimke, K., Graf, R., Spiess, H. W., Wilhelm, M., Sperber, O., Piel, C., Kaminsky, W., Macromolecules 2004; 37: 813.) and the RS-HEPT decoupling scheme (Filip, X., Tripon, C., Filip, C., J. Mag. Resn. 2005, 176, 239., Griffin, J. M., Tripon, C., Samoson, A., Filip, C., and Brown, S. P., Mag. Res. in Chem. 2007; 37: 813.). 45, S1, S198) using standard single pulse excitation. A total of 16384 (16k) transient signals were collected for each spectrum.

[0247] Quantitative 13 C{ 1 H} NMR spectra were processed, integrated and relevant quantitative properties determined from the integrals. All chemical shifts were internally referenced to the methyl isotactic pentad (mmmm) at 21.85 ppm.

[0248] A characteristic signal corresponding to the incorporation of 1-hexene was observed and the comonomer content was quantified in the following manner.

[0249] The amount of 1-hexene incorporated into the PHP isolate was quantified using the integration of the αB4 site at 44.2 ppm, taking into account the number of reported sites for each comonomer:

[0250] H=IαB4 / 2

[0251] The amount of 1-hexene incorporated into the PHHP double continuous sequence was quantified using the integration of the ααB4 site at 41.7 ppm, taking into account the number of reported sites for each comonomer:

[0252] HH=2*IααB4

[0253] When a double continuous incorporation is observed, the amount of 1-hexene introduced in the PHP isolation sequence needs to be compensated due to the overlap of the signals αB4 and αB4B4 at 44.4 ppm:

[0254] H=(IαB4-2*IααB4) / 2

[0255] The total 1-hexene content was calculated based on the sum of isolated and continuously introduced 1-hexene:

[0256] H total = H + HH

[0257] When no sites indicative of continuous incorporation were observed, the total 1-hexene comonomer content was calculated based solely on this amount:

[0258] Htotal=H

[0259] Characteristic signals indicative of regional 2,1-erythro defects were observed (Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem. Rev. 2000, 100, 1253).

[0260] The presence of 2,1-erythro regio defects is indicated by the presence of Pαβ (21e8) and Pαγ (21e6) methyl sites at 17.7 and 17.2 ppm and confirmed by other characteristic signals.

[0261] The total amount of minor (2,1-erythro) inserted propene was quantified based on the αα21e9 methylene site at 42.4 ppm:

[0262] P21=Iαα21e9

[0263] The total amount of primarily (1,2) inserted propene is quantified based on the relative amounts of the primary Sαα methylene site at 46.7 ppm and compensating for the unaccounted 2,1-erythro, αB4, and ααB4B4 methylene units of propene (note that H and HH are counts of hexene monomers per sequence, not the number of sequences):

[0264] P12=I S αα+2*P21+H+HH / 2

[0265] The total amount of propene was quantified as the sum of the major (1,2) and minor (2,1-erythro) insertions of propene:

[0266] Ptotal=P12+P21=I S αα+3*Iαα21e9+(IαB4-2*IααB4) / 2+IααB4

[0267] This simplifies to:

[0268] Ptotal=I S αα+3*Iαα21e9+0.5*IαB4

[0269] The total mole fraction of 1-hexene in the polymer was then calculated as:

[0270] fH=Htotal / (Htotal+Ptotal)

[0271] The complete integrated equation for the mole fraction of 1-hexene in the polymer is:

[0272] fH=(((IαΒ4-2*IααΒ4) / 2)+(2*IααΒ4)) / ((I S αα+3*Iαα21e9+0.5*IαB4)+((IαΒ4-2

[0273] *IααΒ4) / 2)+(2*IααΒ4))

[0274] This simplifies to:

[0275] fH=(IαΒ4 / 2+IααΒ4) / (I S αα+3*Iαα21e9+IαB4+IααB4)

[0276] The total comonomer incorporation of 1-hexene in mole percent was calculated from the mole fractions in the conventional manner:

[0277] H [mol %] = 100 * fH

[0278] The total comonomer incorporation of 1-hexene in weight percent was calculated from the mole fractions in the standard manner:

[0279] H [weight %] = 100 * (fH * 84.16) / ((fH * 84.16) + ((1-fH) * 42.08))

[0280] Calculate the comonomer content of the second random propylene copolymer (B):

[0281]

[0282] in

[0283] w(A) is the weight fraction of the first random propylene copolymer (A),

[0284] w(B) is the weight fraction of the second random propylene copolymer (B),

[0285] C(A) is the first random propylene copolymer (A), i.e. the product of the first reactor (R1) 13 Comonomer content [in wt. %] measured by C NMR spectroscopy,

[0286] C(CPP) is the product obtained in the second reactor (R2), i.e. a mixture of the first random propylene copolymer (A) and the second random propylene copolymer (B) [of the propylene copolymer (C-PP)] 13 Comonomer content [in wt. %] measured by C NMR spectroscopy,

[0287] C(B) is the calculated comonomer content [in wt. %] of the second random propylene copolymer (B).

[0288] 1-Octene Comonomer Content of Linear Low Density Polyethylene Plastomer (PL)

[0289] Quantitative nuclear magnetic resonance (NMR) spectroscopy was used to quantify the comonomer content of the polymers.

[0290] Quantitative analysis was recorded in the melt using a Bruker Avance III 500 NMR spectrometer. 13 C{ 1 H}NMR spectrum, for 1 H and 13 C operates at 500.13 and 125.76 MHz respectively. 13All spectra were recorded with a C-optimized 7 mm magic angle spinning (MAS) probe at 150°C using nitrogen for all pneumatics. Approximately 200 mg of material was loaded into a 7 mm outer diameter zirconium oxide MAS rotor and spun at 4 kHz. This setup was chosen primarily for the high sensitivity required for rapid identification and accurate quantification. (Klimke, K., Parkinson, M., Piel, C., Kaminsky, W., Spiess, HW, Wilhelm, M., Macromol. Chem. Phys. 2006; 207:382.; Parkinson, M., Klimke, K., S piess,HW,Wilhelm,M.,Macromol.Chem.Phys.2007;208:2128.;Castignolles,P.,Graf,R.,Parkinson,M.,Wilhelm,M.,Gaborieau,M.,Polymer 50 (2009) 2373; NMR Spectroscopy of Polymers: Innovative Strategies for Complex Macromolecules, Chapter 24, 401 (2011)). Transient NOE with a short recycle delay of 3 s (Pollard, M., Klimke, K., Graf, R., Spiess, H. W., Wilhelm, M., Sperber, O., Piel, C., Kaminsky, W., Macromolecules 2004; 37:813.; Klimke, K., Parkinson, M., Piel, C., Kaminsky, W., Spiess, H. W., Wilhelm, M., Macromol. Chem. Phys. 2006; 207:382.) and the RS-HEPT decoupling scheme (Filip, X., Tripon, C., Filip, C., J. Mag. Resn. 2005, 176, 239.; Griffin, J. M., Tripon, C., Samoson, A., Filip, C., and Brown, S. P., Mag. Res. in Chem. Phys. 2006; 207:382.) were used. Chem. 2007 45, S1, S198) with standard single pulse excitation. A total of 1024 (1k) transients were collected for each spectrum. This setting was chosen because of its high sensitivity to low comonomer content.

[0291] A custom-made automated spectroscopic analysis program was used to quantify 13 C{ 1H} NMR spectra were processed, integrated, and quantitative properties determined. All chemical shifts were internally referenced to the bulk methylene signal (δ+) at 30.00 ppm (J. Randall, Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201).

[0292] A characteristic signal corresponding to the incorporation of 1-octene was observed (J. Randall, Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201.; Liu, W., Rinaldi, P., McIntosh, L., Quirk, P., Macromolecules 2001, 34, 4757; Qiu, X., Redwine, D., Gobbi, G., Nuamthanom, A., Rinaldi, P., Macromolecules 2007, 40, 6879), and all comonomer contents were calculated relative to all other monomers present in the polymer.

[0293] Characteristic signals generated by isolated 1-octene introduction (i.e., EEOEE comonomer sequence) were observed. The integration of the signal at 38.37ppm was used to quantify the isolated 1-octene introduction. The integration was attributed to the unresolved signals corresponding to both the *B6 and *βB6B6 sites of the isolated (EEOEE) and isolated dual non-continuous (EEOEOEE) 1-octene sequences, respectively. In order to compensate for the influence of the two *βB6B6 sites, the integration of the ββB6B6 site at 24.7ppm was used:

[0294] O=I *B6+*βB6B6 -2*I ββB6B6

[0295] Characteristic signals resulting from continuous 1-octene incorporation (i.e., EEOOEE comonomer sequences) were also observed. Such continuous 1-octene incorporation was quantified using the integration of the signal at 40.57 ppm assigned to the ααB6B6 site, taking into account the number of reported sites for each comonomer:

[0296] OO=2*I ααB6B6

[0297] Characteristic signals arising from isolated discontinuous 1-octene incorporation (i.e., EEOEOEE comonomer sequences) were also observed. Such isolated discontinuous 1-octene incorporation was quantified using the integration of the signal at 24.7 ppm assigned to the ββB6B6 site, taking into account the number of reported sites for each comonomer:

[0298] OEO=2*I ββB6B6

[0299] Characteristic signals arising from isolated triple continuous 1-octene incorporation (i.e., EEOOOEE comonomer sequence) were also observed. Such isolated triple continuous 1-octene incorporation was quantified using the integration of the signal at 41.2 ppm assigned to the ααγB6B6B6 site, taking into account the number of reported sites for each comonomer:

[0300] OOO=3 / 2*I ααγB6B6B6

[0301] In the absence of other observed signals indicative of other comonomer sequences, the total 1-octene comonomer content was calculated based solely on the amounts of isolated (EEOEE), isolated doubly continuous (EEOOEE), isolated non-continuous (EEOEOEE), and isolated triply continuous (EEOOOEE) 1-octene comonomer sequences:

[0302] O 总 =O+OO+OEO+OOO

[0303] Characteristic signals generated by saturated end groups were observed. The average integral of the two resolved signals at 22.84 and 32.23 ppm was used to quantify this saturated end group. The 22.84 ppm integral was attributed to the unresolved signals corresponding to the 2B6 and 2S sites of 1-octene and saturated chain ends, respectively. The 32.23 ppm integral was attributed to the unresolved signals corresponding to the 3B6 and 3S sites of 1-octene and saturated chain ends, respectively. In order to compensate for the effects of the 2B6 and 3B6 l-octene sites, the total l-octene content was used:

[0304] S=(1 / 2)*(I 2S+2B6 +I 3S+3B6 -2*O 总 )

[0305] The integration of the bulk methylene (bulk) signal at 30.00 ppm was used to quantify the ethylene comonomer content. This integral includes the γ and 4B6 sites from 1-octene as well as the δ + The total ethylene comonomer content is calculated based on the total integral and compensated for the observed 1-octene sequences and end groups:

[0306] E 总 =(1 / 2)*[I 本体 +2*O+1*OO+3*OEO+0*OOO+3*S]

[0307] It should be noted that since the number of under- and over-calculated ethylene units is equal, no bulk integral is required to compensate for the presence of the isolated triply introduced (EEOOOEE) 1-octene sequence.

[0308] Then, the total mole fraction of 1-octene in the polymer was calculated as:

[0309] fO=(O 总 / (E 总 +O 总 )

[0310] The total comonomer incorporation of 1-octene in mole percent was calculated from the mole fractions in the standard manner:

[0311] O [mol%] = 100 * fO

[0312] The molar percentage of ethylene incorporation was calculated by the following formula:

[0313] E [mol %] = 100 - O [mol %].

[0314] Melt flow rate (MFR)

[0315] The melt flow rate MFR was measured at 230°C with a load of 2.16 kg for propylene copolymers and at 190°C with a load of 2.16 kg for ethylene copolymers. 2 The melt flow rate is the amount of polymer in grams which a test apparatus conforming to ISO 1133 extrudes within 10 minutes under a load of 2.16 kg at temperatures of 230° C. and 190° C., respectively.

[0316] Melt flow rate MFR of the second random propylene copolymer (B) 2 Calculation of (230°C, 2.16kg):

[0317]

[0318] in

[0319] w(A) is the weight fraction of the first random propylene copolymer (A),

[0320] w(B) is the weight fraction of the second random propylene copolymer (B),

[0321] MFR(A) is the melt flow rate MFR of the first random propylene copolymer (A) measured according to ISO 1133 2 (230°C, 2.16 kg) [g / 10 min],

[0322] MFR(C) is the melt flow rate MFR of the polypropylene composition (P) measured according to ISO 1133 2 (230°C, 2.16 kg) [g / 10 min],

[0323] MFR(B) is the calculated melt flow rate MFR of the second random propylene copolymer (B)2 (230°C, 2.16 kg) [g / 10 min].

[0324] Xylene cold solubles (XCS, wt. %): The content of xylene cold solubles (XCS) is determined according to ISO 16152; 1st edition; 2005-07-01 at 25°C.

[0325] Hexane soluble matter (wt%)

[0326] FDA Section 177.1520

[0327] 1 g of a polymer film having a thickness of 100 μm was added to 400 ml of hexane at 50° C. for 2 hours while stirring with a reflux cooler.

[0328] After 2 hours, the mixture was immediately filtered on N° 41 filter paper.

[0329] The precipitate was collected in an aluminum container and 2 Evaporate the remaining hexane under running water on a steam bath.

[0330] The amount of hexane solubles is determined by the following formula:

[0331] ((sample weight + crucible weight) - (crucible weight)) / (sample weight) · 100

[0332] Melting temperature T m , crystallization temperature T c Mettler TA820 differential scanning calorimetry (DSC) was used for the measurement on 5-10 mg samples. Crystallization and melting curves were obtained during 10°C / min cooling and heating scans between 30°C and 225°C. Melting and crystallization temperatures were obtained as the peaks of the endotherms and exotherms.

[0333] Haze was measured according to ASTM D 1003-00 on blown films of 50 μm thickness.

[0334] Steam sterilization was performed in a Systec D series machine (Systec Inc., USA). The samples were heated starting from 23°C at a heating rate of 5°C / min. After 30 minutes at 121°C, they were immediately removed from the steam sterilizer and stored at room temperature until further processing.

[0335] Sealing start temperature (SIT); Sealing end temperature (SET), Sealing range:

[0336] This method determines the sealing temperature range (sealing range) of polypropylene films, in particular blown films or cast films. The sealing temperature range is the temperature range within which the film can be sealed according to the conditions given below.

[0337] The lower limit (heat seal initiation temperature (SIT)) is the sealing temperature at which a seal strength of >3 N is achieved. The upper limit (seal end temperature (SET)) is reached when the film adheres to the sealing device.

[0338] The sealing range was determined on a J&B Universal Sealing Machine Type 3000 with a film thickness of 50 μm using the following additional parameters:

[0339] Sample width: 25.4mm

[0340] Sealing pressure: 0.1N / mm 2

[0341] Sealing time: 0.1 seconds

[0342] Cooldown: 99 seconds

[0343] Peeling speed: 10 mm / s

[0344] Starting temperature: 80℃

[0345] End temperature: 150℃

[0346] Increment: 10℃

[0347] At each seal bar temperature, the test specimens were sealed from A to A and the seal strength (force) was measured at each step.

[0348] The temperature was measured when the sealing strength reached 3N.

[0349] Hot tack:

[0350] The hot tack was determined on a J&B Hot Tack Tester with a film thickness of 50 μm using the following additional parameters:

[0351] Sample width: 25.4mm

[0352] Sealing pressure: 0.3N / mm2

[0353] Sealing time: 0.5 seconds

[0354] Cooldown: 99 seconds

[0355] Peeling speed: 200 mm / s

[0356] Starting temperature: 90℃

[0357] End temperature: 140℃

[0358] Increment: 10℃

[0359] Determine and report the maximum hot tack force, which is the maximum value of the force / temperature graph.

[0360] The tensile modulus was determined in accordance with ISO 527-3 at a crosshead speed of 1 mm / min on 50 μm blown films in the machine and transverse directions.

[0361] Dart Drop Intensity (DDI) is measured from film samples using ASTM D1709, Method A (alternative test technique). A dart with a 38 mm diameter hemispherical head is dropped from a height of 0.66 m onto the film clamped over a hole. Successive groups of twenty specimens are tested. One weight is used per group, and the weight is increased (or decreased) from group to group in uniform increments. The weight that causes 50% of the specimens to fail is calculated and reported.

[0362] 2. Example

[0363] Catalyst preparation

[0364] The catalyst used in the examples of the present invention was prepared as described in detail in WO 2015 / 011135 A1 (metallocene complex MC1 with methylaluminoxane (MAO) and borate to produce catalyst 3 described in WO 2015 / 011135 A1), with the proviso that the surfactant was 2,3,3,3-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy)-1-propanol. The metallocene complex (MC1 in WO 2015 / 011135 A1) was prepared as described in WO 2013 / 007650 A1 (metallocene E2 in WO 2013 / 007650 A1).

[0365] Preparation of copolymer (C)

[0366] Copolymer (C) was prepared in a sequential process involving a loop reactor and a gas phase reactor. The reaction conditions are summarized in Table 1.

[0367] Table 1: Preparation of polypropylene composition (P)

[0368] C1 C2 Prepolymerization temperature [℃] 20 20 Catalyst feed [g / h] 2.5 2.5 TEAL / C3 [g / t] 0 0 C3 Feed [kg / h] 60.9 60.7 H2 feed [g / h] 0.5 0.5 Dwell time [h] 0.2 0.2 Ring pipe (R1) temperature [℃] 70 70 pressure [kPa] 5297 5292 H2 / C3 Ratio [mol / kmol] 0.08 0.08 C6 / C3 Ratio [mol / kmol] 15.5 14.1 <![CDATA[MFR 2 ]]> [g / 10min] 1.9 1.8 XCS [weight%] 1.9 1.9 C6 [weight%] 1.7 1.7 Dwell time [h] 0.5 0.5 Split ratio [weight%] 42.5 42.0 GPR(R2) temperature [℃] 80 80 pressure [kPa] 2406 2406 H2 / C3 Ratio [mol / kmol] 0.3 0.8 C6 / C3 Ratio [mol / kmol] 8.7 9.2 C6(GPR) [weight%] 6.9 8.2 <![CDATA[MFR 2 (GPR)]]> [g / 10min] 1.1 1.2 Dwell time [h] 2.6 2.6 Split Ratio [weight%] 57.5 58.0 C6 [weight%] 5.0 5.5 XCS [weight%] 13.8 25.0 C6(XCS) [weight%] 6.0 7.2 1,2e [mol %] 0.46 0.47 <![CDATA[MFR 2 (Copolymer)]]> [g / 10min] 1.4 1.4 MFR(C) / MFR(A) [-] 0.74 0.74

[0369] Preparation of polypropylene composition (P)

[0370] The polypropylene composition (P) was obtained by melt blending in a co-rotating twin screw extruder the copolymer (C) and the plastomer (PL) in the amounts indicated in Table 2. Table 2 summarizes the properties of the polypropylene composition (P) and 50 μm blown films made therefrom.

[0371] PL1 is a commercial polymer of ethylene and 1-octene, Queo 8230 from Borealis, with a melt flow rate (190°C, 2.16 kg) of 30.0 g / 10 min, a melting temperature Tm of 76°C, a glass transition temperature Tg of -51°C, and a density of 0.882 g / cm 3 , and the ethylene content was 76.2 wt%.

[0372] PL2 is a commercial polymer of ethylene and 1-octene, Queo 8201 from Borealis, with a melt flow rate (190°C, 2.16 kg) of 1.1 g / 10 min, a melting temperature Tm of 72°C, a glass transition temperature Tg of -52°C, and a density of 0.882 g / cm 3 , and the ethylene content was 75.5 wt%.

[0373] PL3 is a commercial polymer of ethylene and 1-octene, Engage 8100 from Dow, with a melt flow rate (190°C, 2.16 kg) of 1.0 g / 10 min, a melting temperature Tm of 60°C, a glass transition temperature Tg of -52°C, and a density of 0.870 g / cm 3 , and the ethylene content was 74.0 wt%.

[0374] C3 is a commercial nucleated C2 / C3 copolymer, RB709CF from Borealis, having a melt flow rate (230°C, 2.16 kg) of 1.5 g / 10 min, a melting temperature Tm of 141°C, a xylene soluble content of 15.0 wt%, and an ethylene content of 5.5 wt%.

[0375] C4 is a C2 / C3 / C4 terpolymer prepared in the presence of a Ziegler-Natta catalyst, having a melt flow rate (230° C., 2.16 kg) of 1.6 g / 10 min, a melting temperature Tm of 135° C., a xylene soluble content of 10.7 wt %, a 1-butene content of 7.1 wt %, and an ethylene content of 1.6 wt %. It is the same as comparative example CE1 of EP 17186987.

[0376] All film properties were measured on a single layer blown film with a thickness of 50 μm produced on a Collin blown film line. The line had a screw diameter of 30 millimeters (mm), an L / D of 30, a die diameter of 60 mm, a die gap of 1.5 mm, and a duo-lip cooling ring. The film samples were produced at 90° C. with an average thickness of 50 μm, a blow-up ratio of 2.5, and an output rate of about 8 kilograms per hour (kg / h).

[0377] As can be seen from Table 2, the composition of the present invention comprising the copolymer of propylene and 1-hexene according to the present invention shows excellent haze values ​​before and after sterilization, while the tensile modulus remains at a high level.

[0378] Table 2: Compositions and properties of the examples of the present invention and the comparative examples

[0379] CE1 CE2 IE1 IE2 IE3 IE4 C1 [weight%] 90 95 C2 [weight%] 90 90 C3 [weight%] 100 C4 [weight%] 90 PL1 [weight%] 10 10 5 PL2 [weight%] 10 PL3 [weight%] 10 Tm [℃] 141 135 139 139 135 135 <![CDATA[MFR 2 ]]> [g / 10min] 1.5 2.8 2.7 2.0 1.6 1.5 50μm Blow Mould SIT [℃] 114 105 102 105 107 102 Tm-SIT [℃] 27 30 37 34 28 33 HTF [N] 5.3 5.0 5.3 4.7 2.8 3.3 TM / MD [MPa] 707 438 497 592 663 536 TM / TD [MPa] 700 429 486 592 652 560 DDI [g] 70 97 540 618 301 ＞1700 Fog before sterilization [％] 12.0 8.5 6.0 4.3 3.8 1.9 Fog after sterilization [％] 14.0 9.0 5.6 4.1 2.6 2.6

Claims

1. A polypropylene composition (P) comprising: a) 80.0 to 99.0 wt.-%, based on the total weight of the polypropylene composition (P), of a copolymer of propylene and 1-hexene (C) comprising: i) a first random propylene copolymer (A) of propylene and 1-hexene, and ii) a second random propylene copolymer (B) of propylene and 1-hexene having a higher 1-hexene content than said first random propylene copolymer (A), wherein the copolymer (C) has a xylene soluble content (XCS) of at least 8.0 wt.-%, and b) 1.0 to 20.0 wt.-%, based on the total weight of the polypropylene composition (P), of a plastomer (PL) comprising ethylene and at least one C4 to C 10 Elastomeric copolymer of alpha-olefin, characterized in that Density 0.860 to 0.930 g / cm 3 within the range.

2. The polypropylene composition (P) according to claim 1, wherein the copolymer (C) has 2,1 erythro regio defects in an amount of at least 0.4 mol%.

3. The polypropylene composition (P) according to claim 1 or 2, wherein the copolymer (C) has a melt flow rate MFR2 (230°C, 2.16 kg) determined according to ISO 1133 in the range of 0.4 to 12.0 g / 10 min.

4. The polypropylene composition (P) according to anyone of the preceding claims, wherein the weight ratio of the first random propylene copolymer (A) to the second random propylene copolymer (B) in the copolymer (C) is in the range of 30:70 to 70:

30.

5. The polypropylene composition (P) according to any one of the preceding claims, wherein the copolymer (C) satisfies inequality (1) MFR(C) / MFR(A) ≤ 1.0 (1) wherein MFR(A) is the melt flow rate MFR2 (230°C, 2.16 kg) measured in [g / 10 min] according to ISO 1133 of the first random propylene copolymer (A), and MFR(C) is the melt flow rate MFR2 (230°C, 2.16 kg) measured in [g / 10 min] according to ISO 1133 of the copolymer (C).

6. The polypropylene composition (P) according to anyone of the preceding claims, wherein the xylene soluble fraction C6 (XCS) of the copolymer (C) has a 1-hexene content in the range of 2.0 to 8.0 wt.-%.

7. A polypropylene composition (P) according to any one of the preceding claims, wherein i) the first random propylene copolymer (A) has a melt flow rate MFR2 (230°C, 2.16 kg) determined according to ISO 1133 in the range of 0.3 to 12.0 g / 10 min, and / or ii) the second random propylene copolymer (B) has a melt flow rate MFR2 (230°C, 2.16 kg) determined according to ISO 1133 in the range of 0.1 to 14.0 g / 10 min.

8. The polypropylene composition (P) according to any one of the preceding claims, wherein the copolymer (C) satisfies inequality (2) in C6(A) is the 1-hexene content of the first random propylene copolymer (A) [in wt. %] based on the total weight of the first random propylene copolymer (A); C6(C) is the 1-hexene content of the copolymer (C) [in % by weight], based on the total weight of the copolymer (C); and [A] / [C] is the weight ratio [in g / g] between the first random propylene copolymer (A) and the copolymer (C).

9. The polypropylene composition (P) according to any one of the preceding claims, wherein the density of the plastomer (PL) is in the range of 0.865 to 0.920 g / cm 3 within the range.

10. The polypropylene composition (P) according to anyone of the preceding claims, wherein the plastomer (PL) is a copolymer of ethylene and 1-octene.

11. An article comprising at least 90.0 wt.-% of the polypropylene composition (P) according to any of claims 1 to 10.

12. The article according to claim 11, wherein the article is a film, preferably a blown film.

13. The article of claim 12, wherein the film has i) less than 10.0% haze before steam sterilization as determined by measurement on 50 μm blown films according to ASTM D 1003-00, and ii) less than 12.0% haze after steam sterilization as determined in accordance with ASTM D 1003-00 measured on 50 μm blown films.

14. Use of the article according to any one of claims 12 to 13 as a sealing layer in a multilayer film.

15. A process for the preparation of a polypropylene composition (P) according to any one of the preceding claims 1 to 10, wherein the process is a sequential polymerization process comprising at least two reactors connected in series, wherein the process comprises the following steps: (A) polymerizing propylene and 1-hexene in a first reactor (R-1) to obtain a first random propylene copolymer (A), wherein the first reactor (R-1) is a slurry reactor (SR), preferably a loop reactor (LR), (B) transferring the first random propylene copolymer (A) and the unreacted comonomer of the first reactor (R-1) to a second reactor (R-2), the second reactor (R-2) being a gas phase reactor (GPR-1), (C) feeding propylene and 1-hexene into the second reactor (R-2), (D) polymerizing propylene and 1-hexene in the presence of the first random propylene copolymer (A) in the second reactor (R-2) to obtain a second random propylene copolymer (B), the first random propylene copolymer (A) and the second random propylene copolymer (B) forming a copolymer (C), and (E) blending said copolymer (C) with said plastomer (PL) as defined in claims 1, 9 and 10, thereby obtaining said polypropylene composition (P), Among them further In the first reactor (R-1) and the second reactor (R-2), the polymerization is carried out in the presence of a solid catalyst system (SCS), the solid catalyst system (SCS) comprising Transition metal compound of formula (I) R n (Cp)2MX2(I) in Each Cp is independently an unsubstituted or substituted and / or fused cyclopentadienyl ligand, a substituted or unsubstituted indenyl or a substituted or unsubstituted fluorenyl ligand; the optional one or more substituents are independently preferably selected from halogen, hydrocarbon groups (e.g. C1-C20-alkyl, C2-C20-alkenyl, C2-C20-alkynyl, C3-C12-cycloalkyl, C6-C20-aryl or C7-C20-aralkyl), C3-C12-cycloalkyl containing 1, 2, 3 or 4 heteroatoms in the ring part, C6-C20-heteroaryl, C1-C20 haloalkyl, -SiR"3, -OSiR"3, -SR", -PR"2, OR" or -NR"2, Each R" is independently hydrogen or a hydrocarbon group selected from C1-C20-alkyl, C2-C20-alkenyl, C2-C20-alkynyl, C3-C12-cycloalkyl or C6-C20-aryl; or in the case of -NR"2, the two substituents R" are able to form a five-membered or six-membered ring together with the nitrogen atom to which they are attached; R is a bridge of 1-2 C atoms and 0-2 heteroatoms, wherein the heteroatoms can be Si, Ge and / or O atoms, wherein each bridge atom can independently carry a substituent selected from C1-C20-alkyl, tri(C1-C20-alkyl)silyl, tri(C1-C20-alkyl)siloxy or C6-C20-aryl substituents); or a bridge of one or two heteroatoms selected from silicon, germanium and / or oxygen atoms, M is a Group 4 transition metal selected from Zr or Hf, especially Zr; each X is independently a sigma-ligand selected from the group consisting of H, halogen, C1-C20-alkyl, C1-C20-alkoxy, C2-C20-alkenyl, C2-C20-alkynyl, C3-C12-cycloalkyl, C6-C20-aryl, C6-C20-aryloxy, C7-C20-aralkyl, C7-C20-aralkenyl, -SR", -PR", -SiR", -OSiR", -NR", or -CH2-Y, wherein Y is C6-C20-aryl, C6-C20-heteroaryl, C1-C20-alkoxy, C6-C20-aryloxy, NR", -SR", -PR", -SiR", or -OSiR", Each of the above mentioned ring parts, alone or as part of another part of Cp, X, R" or a substituent of R, can be further substituted by C1-C20-alkyl, which may contain Si and / or O atoms; and n is 1 or 2.

16. The method according to claim 15, wherein the transition metal compound of formula (I) is an organic zirconium compound of formula (II) or (II'): in M is Zr; Each X is a sigma ligand, preferably each X is independently a hydrogen atom, a halogen atom, a C1-C6 alkoxy group, a C1-C6 alkyl group, a phenyl group or a benzyl group; L is a divalent bridge selected from -R'2C-, -R'2C-CR'2, -R'2Si-, -R'2Si-SiR'2-, -R'2Ge-, wherein each R' is independently a hydrogen atom, a C1-C20 alkyl group, a C3-C10 cycloalkyl group, a tri(C1-C20-alkyl)silyl group, a C6-C20-aryl group or a C7-C20 aralkyl group; Each R 2 or R 2 ' is a C1-C10 alkyl group; R 5 ' is C1-C10 alkyl or Z'R 3 'group; R 6 is hydrogen or C1-C10 alkyl; R 6 ' is a C1-C10 alkyl group or a C6-C10 aryl group; R 7 is hydrogen, C1-C6 alkyl or ZR 3 Group; R 7 ' is hydrogen or C1-C10 alkyl; Z and Z' are independently O or S; R 3 ' is a C1-C10 alkyl group, or a C6-C10 aryl group, which is optionally substituted by one or more halogen groups; R 3 is a C1-C10 alkyl group; each n is independently 0 to 4; And each R 1 are independently C1-C20 hydrocarbon groups.

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