PROPYLENE COPOLYMER COMPOSITION WITH EXCELLENT OPTICAL AND MECHANICAL PROPERTIES

Abstract

The present invention is directed to a polypropylene composition (P) comprising a copolymer (C) of propylene and 1-hexene comprising a first random propylene copolymer (A) of propylene and a 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) as well as a plastomer (PL) being an elastomeric copolymer of ethylene and at least one C.sub.4 to C.sub.10 α-olefin. Further, the present invention is directed to an article comprising said polypropylene composition (P) and the use of said polypropylene composition (P) as a sealing layer in a multi-layer film.

Claims

1-16. (canceled)

17. A polypropylene composition (P), comprising a) 80.0 to 99.0 wt. %, based on the overall weight of the polypropylene composition (P), of a copolymer (C) of propylene and 1-hexene, comprising i) a first random propylene copolymer (A) of propylene and a 1-hexene, and ii) a second random propylene copolymer (B) of propylene and 1-hexene having a higher 1-hexene content than the 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 overall weight of the polypropylene composition (P), of a plastomer (PL) which is an elastomeric copolymer of ethylene and at least one C.sub.4 to C.sub.10 α-olefin having a density in the range of 0.860 to 0.930 g/cm.sup.3.

18. The polypropylene composition (P) according to claim 17, wherein the copolymer (C) has an amount of 2,1 erythro regio-defects of at least 0.4 mol. %.

19. The polypropylene composition (P) according to claim 17, wherein the copolymer (C) has a melt flow rate MFR.sub.2 (230° C., 2.16 kg) determined according to ISO 1133 in the range of 0.4 to 12.0 g/10 min.

20. The polypropylene composition (P) according to claim 17, wherein the weight ratio between the first random propylene copolymer (A) and the second random propylene copolymer (B) within the copolymer (C) is in the range of 30:70 to 70:30.

21. The polypropylene composition (P) according to claim 17, wherein the copolymer (C) fulfils in-equation (1)
MFR(C)/MFR(A)≤1.0  (1), wherein MFR(A) is the melt flow rate MFR.sub.2 (230° C., 2.16 kg) determined according to ISO 1133 in [g/10 min] of the first random propylene copolymer (A) and MFR(C) is the melt flow rate MFR.sub.2 (230° C., 2.16 kg) determined according to ISO 1133 in [g/10 min] of the copolymer (C).

22. The polypropylene composition (P) according to claim 17, wherein the copolymer (C) has a 1-hexene content of the xylene soluble fraction C6 (XCS) in the range of 2.0 to 8.0 wt. %.

23. The polypropylene composition (P) according to claim 17, wherein i) the first random propylene copolymer (A) has a melt flow rate MFR.sub.2 (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 MFR.sub.2 (230° C., 2.16 kg) determined according to ISO 1133 in the range of 0.1 to 14.0 g/10 min.

24. The polypropylene composition (P) according to claim 17, wherein the copolymer (C) fulfils in-equation (2) $\begin{array}{cc}4.5\le \frac{C6\left(C\right)}{C6\left(A\right)*\frac{\left[A\right]}{\left[C\right]}}\le 9.0& \left(2\right)\end{array}$ wherein C6(A) is the 1-hexene content of the first random propylene copolymer (A) based on the total weight of the first random propylene copolymer (A) [in wt. %]; C6(C) is the 1-hexene content of the copolymer (C) based on the total weight of the copolymer (C) [in wt. %]; and [A]/[C] is the weight ratio between the first random propylene copolymer (A) and the copolymer (C) [in g/g].

25. The polypropylene composition (P) according to claim 17, wherein the plastomer (PL) has a density in the range of 0.865 to 0.920 g/cm.sup.3.

26. The polypropylene composition (P) according to claim 17, wherein the plastomer (PL) is a copolymer of ethylene and 1-octene.

27. An article comprising at least 90.0 wt. % of the polypropylene composition (P) according to claim 17.

28. The article according to claim 27, wherein the article is a film.

29. The article according to claim 28, wherein the film has i) a haze before steam sterilization determined according to ASTM D 1003-00 measured on a 50 μm blown film below 10.0%, and ii) a haze after steam sterilization determined according to ASTM D 1003-00 measured on a 50 μm blown film below 12.0%.

30. A sealing layer in a multi-layer film, the sealing layer comprising a film comprising at least 90.0 wt. % of the polypropylene composition (P) according to claim 17.

31. A process for the preparation of the polypropylene composition (P) according to claim 17, wherein the process is a sequential polymerization process comprising at least two reactors connected in series, wherein said process comprises: (A) polymerizing in a first reactor (R-1) being a slurry reactor (SR), propylene and 1-hexene, obtaining a first random propylene copolymer (A), (B) transferring said first random propylene copolymer (A) and unreacted comonomers of the first reactor (R-1) in a second reactor (R-2) which is a gas phase reactor (GPR-1), (C) feeding to said second reactor (R-2) propylene and 1-hexene, (D) polymerizing in said second reactor (R-2) and in the presence of said first random propylene copolymer (A) propylene and 1-hexene obtaining a second random propylene copolymer (B), said first random propylene copolymer (A) and said second random propylene copolymer (B) form the copolymer (C), and (E) blending the copolymer (C) with the plastomer (PL) and obtaining the polypropylene composition (P), wherein further in the first reactor (R-1) and second reactor (R-2), the polymerization takes place in the presence of a solid catalyst system (SCS), said solid catalyst system (SCS) comprising a transition metal compound of formula (I)
R.sub.n(Cp).sub.2MX.sub.2  (I) wherein: each Cp independently is an unsubstituted or substituted and/or fused cyclopentadienyl ligand, substituted or unsubstituted indenyl or substituted or unsubstituted fluorenyl ligand, wherein the optional one or more substituent(s) is/are independently selected from the group consisting of halogen, C.sub.1-C.sub.20-alkyl, C.sub.2-C.sub.20-alkenyl, C.sub.2-C.sub.20-alkynyl, C.sub.3-C.sub.12-cycloalkyl, C.sub.6-C.sub.20-aryl, C.sub.7-C.sub.20-arylalkyl, C.sub.3-C.sub.12-cycloalkyl which contains 1, 2, 3 or 4 heteroatom(s) in the ring moiety, C.sub.6-C.sub.20-heteroaryl, C.sub.1-C.sub.20-haloalkyl, —SiR″.sub.3, —OSiR″.sub.3, —SR″, —PR″.sub.2, —OR″, and —NR″.sub.2, wherein each R″ is independently a hydrogen or a hydrocarbyl selected from the group consisting of C.sub.1-C.sub.20-alkyl, C.sub.2-C.sub.20-alkenyl, C.sub.2-C.sub.20-alkynyl, C.sub.3-C.sub.12-cycloalkyl, and C.sub.6-C.sub.20-aryl or in case of —NR″.sub.2, the two substituents R″ optionally form a five- 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 heteroatom(s) can be Si, Ge and/or O atom(s), wherein each of the bridge atoms optionally bears independently substituents selected from the group consisting of C.sub.1-C.sub.20-alkyl, tri(C.sub.1-C.sub.20-alkyl)silyl, tri(C.sub.1-C.sub.20-alkyl)siloxy, and C.sub.6-C.sub.20-aryl substituents, or R is a bridge of one or two heteroatoms selected from the group consisting of silicon, germanium, oxygen atom(s), and any combination thereof, M is Zr or Hf, each X is independently a sigma-ligand selected from the group consisting of H, halogen, C.sub.1-C.sub.20-alkyl, C.sub.1-C.sub.20-alkoxy, C.sub.2-C.sub.20-alkenyl, C.sub.2-C.sub.20-alkynyl, C.sub.3-C.sub.12-cycloalkyl, C.sub.6-C.sub.20-aryl, C.sub.6-C.sub.20-aryloxy, C.sub.7-C.sub.20-arylalkyl, C.sub.7-C.sub.20-arylalkenyl, —SR″, —PR″.sub.3, —SiR″.sub.3, —OSiR″.sub.3, —NR″.sub.2, and —CH.sub.2—Y, wherein Y is C.sub.6-C.sub.20-aryl, C.sub.6-C.sub.20-heteroaryl, C.sub.1-C.sub.20-alkoxy, C.sub.6-C.sub.20-aryloxy, NR″.sub.2, —SR″, —PR″.sub.3, —SiR″.sub.3, or —OSiR″.sub.3; each of the above mentioned ring moieties alone or as a part of another moiety as the substituent for Cp, X, R″ or R optionally is further substituted with C.sub.1-C.sub.20-alkyl which may contain Si and/or O atoms; and n is 1 or 2.

32. The process according to claim 31, wherein the transition metal compound of formula (I) is an organo-zirconium compound of formula (II) or (II′): ##STR00003## wherein: M is Zr; each X is independently a hydrogen atom, a halogen atom, a C.sub.1-C.sub.6 alkoxy group, C.sub.1-C.sub.6 alkyl, a phenyl group, or a benzyl group; L is a divalent bridge selected from the group consisting of —R′.sub.2C—, —R′.sub.2C—CR′.sub.2, —R′.sub.2Si—, —R′.sub.2Si—SiR′.sub.2—, and —R′.sub.2Ge—, wherein each R′ is independently a hydrogen atom, C.sub.1-C.sub.20 alkyl, C.sub.3-C.sub.10 cycloalkyl, tri(C.sub.1-C.sub.20-alkyl)silyl, C.sub.6-C.sub.20-aryl or C.sub.7-C.sub.20 arylalkyl; each R.sup.2 or R.sup.2′ is a C.sub.1-C.sub.10 alkyl group; R.sup.5′ is a C.sub.1-C.sub.10 alkyl group or a Z′R.sup.3′ group; R.sup.6 is hydrogen or a C.sub.1-C.sub.10 alkyl group; R.sup.6′ is a C.sub.1-C.sub.10 alkyl group or a C.sub.6-C.sub.10 aryl group; R.sup.7 is hydrogen, a C.sub.1-C.sub.6 alkyl group or a ZR.sup.3 group; R.sup.7′ is hydrogen or a C.sub.1-C.sub.10 alkyl group; Z and Z′ are independently O or S; R.sup.3′ is a C.sub.1-C.sub.10 alkyl group, or a C.sub.6-C.sub.10 aryl group optionally substituted by one or more halogen groups; R.sup.3 is a C.sub.1-C.sub.10 alkyl group; each n is independently 0 to 4; and each R.sup.1 is independently a C.sub.1-C.sub.20 hydrocarbyl group.

Description

EXAMPLES

[0219] A. Measuring methods

[0220] The following definitions of terms and determination methods apply for the above general description of the invention as well as to the below examples unless otherwise defined.

Comonomer Content of 1-Hexene for a Propylene 1-Hexene Copolymer

[0221] Quantitative .sup.13C{.sup.1H} NMR spectra recorded in the molten-state using a Bruker Avance III 500 NMR spectrometer operating at 500.13 and 125.76 MHz for .sup.1H and .sup.13C respectively. All spectra were recorded using a .sup.13C optimised 7 mm magic-angle spinning (MAS) probehead at 180° C. using nitrogen gas for all pneumatics. Approximately 200 mg of material was packed into a 7 mm outer diameter zirconia MAS rotor and spun at 4 kHz. This setup was chosen primarily for the high sensitivity needed 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). Standard single-pulse excitation was employed utilising the NOE at short recycle delays of 3s (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 45, S1, 5198). A total of 16384 (16 k) transients were acquired per spectra.

[0222] Quantitative .sup.13C{.sup.1H} NMR spectra were processed, integrated and relevant quantitative properties determined from the integrals. All chemical shifts are internally referenced to the methyl isotactic pentad (mmmm) at 21.85 ppm.

[0223] Characteristic signals corresponding to the incorporation of 1-hexene were observed and the comonomer content quantified in the following way.

[0224] The amount of 1-hexene incorporated in PHP isolated sequences was quantified using the integral of the αB4 sites at 44.2 ppm accounting for the number of reporting sites per comonomer:

H=IαB4/2

The amount of 1-hexene incorporated in PHHP double consecutive sequences was quantified using the integral of the ααB4 site at 41.7 ppm accounting for the number of reporting sites per comonomer:

HH=2*IααB4

[0225] When double consecutive incorporation was observed the amount of 1-hexene incorporated in PHP isolated sequences needed to be compensated due to the overlap of the signals αB4 and αB4B4 at 44.4 ppm:

H=(IαB4−2*IααB4)/2

The total 1-hexene content was calculated based on the sum of isolated and consecutively incorporated 1-hexene:

Htotal=H+HH

[0226] When no sites indicative of consecutive incorporation observed the total 1-hexeen comonomer content was calculated solely on this quantity:

Htotal=H

[0227] Characteristic signals indicative of regio 2,1-erythro defects were observed (Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem. Rev. 2000, 100, 1253).

[0228] The presence of 2,1-erythro regio defects was indicated by the presence of the Pa (21e8) and Pay (21e6) methyl sites at 17.7 and 17.2 ppm and confirmed by other characteristic signals.

[0229] The total amount of secondary (2,1-erythro) inserted propene was quantified based on the αα21e9 methylene site at 42.4 ppm:

P21=Iαα21e9

The total amount of primary (1,2) inserted propene was quantified based on the main Sαα methylene sites at 46.7 ppm and compensating for the relative amount of 2,1-erythro, αB4 and ααB4B4 methylene unit of propene not accounted for (note H and HH count number of hexene monomers per sequence not the number of sequences):

P12=I.sub.sαα+2*P21+H+HH/2

[0230] The total amount of propene was quantified as the sum of primary (1,2) and secondary (2,1-erythro) inserted propene:

Ptotal=P12+P21=I.sub.sαα+3*Iαα21e9+(IαB4−2*IααB4)/2+IααB4

[0231] This simplifies to:

Ptotal=I.sub.sαα+3*Iαα21e9+0.5*IαB4

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

fH=Htotal/(Htotal+Ptotal)

[0232] The full integral equation for the mole fraction of 1-hexene in the polymer was:

fH=(((IαB4−2*IααB4)/2)+(2*IααB4))/((I.sub.sαα+3*Iαα21e9+0.5*IαB4)+((IαB4−2*IααB4)/2)+(2*Iαα1B4))

[0233] This simplifies to:

fH=(IαB4/2+IααB4)/(I.sub.sαα+3*Iαα21e9+IαB4+IααB4)

[0234] The total comonomer incorporation of 1-hexene in mole percent was calculated from the mole fraction in the usual manner:

H[mol %]=100*fH

The total comonomer incorporation of 1-hexene in weight percent was calculated from the mole fraction in the standard manner:

H[wt %]=100*(fH*84.16)/((fH*84.16)+((1−fH)*42.08))

[0235] Calculation of comonomer content of the second random propylene copolymer (B):

[00002]$\frac{C\left(CPP\right)-w\left(A\right)xC\left(A\right)}{w\left(B\right)}=C\left(B\right)$

[0236] wherein

[0237] w(A) is the weight fraction of the first random propylene copolymer (A),

[0238] w(B) is the weight fraction of the second random propylene copolymer (B), [0239] C(A) is the comonomer content [in wt.-%] measured by .sup.13C NMR spectroscopy of the first random propylene copolymer (A), i.e. of the product of the first reactor (R1), [0240] C(CPP) is the comonomer content [in wt.-%] measured by .sup.13C NMR spectroscopy of the product obtained in the second reactor (R2), i.e. the mixture of the first random propylene copolymer (A) and the second random propylene copolymer (B) [of the propylene copolymer (C-PP)], [0241] C(B) is the calculated comonomer content [in wt.-%] of the second random propylene copolymer (B).

Comonomer Content of 1-Octene of a Linear Low Density Polyethylene Plastomer (PL)

[0242] Quantitative nuclear-magnetic resonance (NMR) spectroscopy was used to quantify the comonomer content of the polymers.

[0243] Quantitative .sup.13C{.sup.1H} NMR spectra recorded in the molten-state using a Bruker Avance III 500 NMR spectrometer operating at 500.13 and 125.76 MHz for .sup.1H and .sup.13C respectively. All spectra were recorded using a .sup.13C optimised 7 mm magic-angle spinning (MAS) probehead at 150° C. using nitrogen gas for all pneumatics. Approximately 200 mg of material was packed into a 7 mm outer diameter zirconia MAS rotor and spun at 4 kHz. This setup was chosen primarily for the high sensitivity needed 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; NMR Spectroscopy of Polymers: Innovative Strategies for Complex Macromolecules, Chapter 24, 401 (2011)). Standard single-pulse excitation was employed utilising the transient NOE at short recycle delays of 3s (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. 2007 45, S1, S198). A total of 1024 (1 k) transients were acquired per spectrum. This setup was chosen due its high sensitivity towards low comonomer contents.

[0244] Quantitative .sup.13C{.sup.1H} NMR spectra were processed, integrated and quantitative properties determined using custom spectral analysis automation programs. All chemical shifts are internally referenced to the bulk methylene signal (δ+) at 30.00 ppm (J. Randall, Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201.).

[0245] Characteristic signals corresponding to the incorporation of 1-octene were 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 calculated with respect to all other monomers present in the polymer.

[0246] Characteristic signals resulting from isolated 1-octene incorporation i.e. EEOEE comonomer sequences, were observed. Isolated 1-octene incorporation was quantified using the integral of the signal at 38.37 ppm. This integral is assigned to the unresolved signals corresponding to both .sub.*B6 and .sub.*βB6B6 sites of isolated (EEOEE) and isolated double non-consecutive (EEOEOEE) 1-octene sequences respectively. To compensate for the influence of the two .sub.*βB6B6 sites the integral of the ββB6B6 site at 24.7 ppm is used:

O=I.sub.*B6+*βB6B6−2*I.sub.ββB6B6

[0247] Characteristic signals resulting from consecutive 1-octene incorporation, i.e. EEOOEE comonomer sequences, were also observed. Such consecutive 1-octene incorporation was quantified using the integral of the signal at 40.57 ppm assigned to the ααB6B6 sites accounting for the number of reporting sites per comonomer:

OO=2*I.sub.ααB6B6

[0248] Characteristic signals resulting from isolated non-consecutive 1-octene incorporation, i.e. EEOEOEE comonomer sequences, were also observed. Such isolated non-consecutive 1-octene incorporation was quantified using the integral of the signal at 24.7 ppm assigned to the ββB6B6 sites accounting for the number of reporting sites per comonomer:

OEO=2*I.sub.ββB6B6

[0249] Characteristic signals resulting from isolated triple-consecutive 1-octene incorporation, i.e. EEOOOEE comonomer sequences, were also observed. Such isolated triple-consecutive 1-octene incorporation was quantified using the integral of the signal at 41.2 ppm assigned to the ααγB6B6B6 sites accounting for the number of reporting sites per comonomer:

OOO=3/2*I.sub.ααγB6B6B6

[0250] With no other signals indicative of other comonomer sequences observed the total 1-octene comonomer content was calculated based solely on the amount of isolated (EEOEE), isolated double-consecutive (EEOOEE), isolated non-consecutive (EEOEOEE) and isolated triple-consecutive (EEOOOEE) 1-octene comonomer sequences:

O.sub.total=O+OO+OEO+OOO

[0251] Characteristic signals resulting from saturated end-groups were observed. Such saturated end-groups were quantified using the average integral of the two resolved signals at 22.84 and 32.23 ppm. The 22.84 ppm integral is assigned to the unresolved signals corresponding to both 2B6 and 2S sites of 1-octene and the saturated chain end respectively. The 32.23 ppm integral is assigned to the unresolved signals corresponding to both 3B6 and 3S sites of 1-octene and the saturated chain end respectively. To compensate for the influence of the 2B6 and 3B6 1-octene sites the total 1-octene content is used:

S=(½)*(I.sub.2S+2B6+I.sub.3S+3B6−2*O.sub.total)

[0252] The ethylene comonomer content was quantified using the integral of the bulk methylene (bulk) signals at 30.00 ppm. This integral included the γ and 4B6 sites from 1-octene as well as the δ.sup.+ sites. The total ethylene comonomer content was calculated based on the bulk integral and compensating for the observed 1-octene sequences and end-groups:

E.sub.total=(½)*[I.sub.bulk+2*O+1*OO+3*OEO+0*OOO+3*S]

[0253] It should be noted that compensation of the bulk integral for the presence of isolated triple-incorporation (EEOOOEE) 1-octene sequences is not required as the number of under and over accounted ethylene units is equal.

[0254] The total mole fraction of 1-octene in the polymer was then calculated as:

fO=(O.sub.total/(E.sub.total+O.sub.total)

[0255] The total comonomer incorporation of 1-octene in mol percent was calculated from the mole fraction in the standard manner:

O[mol %]=100*fO

[0256] The mole percent ethylene incorporation was calculated from the formula:

E[mol %]=100−O[mol %].

Melt Flow Rate (MFR)

[0257] The melt flow rates MFR.sub.2 are measured with a load of 2.16 kg at 230° C. for propylene copolymers and with a load of 2.16 kg at 190° C. for ethylene copolymers. The melt flow rate is that quantity of polymer in grams which the test apparatus standardised to ISO 1133 extrudes within 10 minutes at a temperature of 230° C., respectively 190° C. under a load of 2.16 kg.

[0258] Calculation of melt flow rate MFR.sub.2 (230° C., 2.16 kg) of the second random propylene copolymer (B):

[00003]$\mathrm{MFR}\left(B\right)={10}^{\left[\frac{\log \left(\mathrm{MFR}\left(C\right)\right)-w\left(A\right)x\log \left(\mathrm{MFR}\left(A\right)\right)}{w\left(B\right)}\right]}$

[0259] wherein [0260] w(A) is the weight fraction of the first random propylene copolymer (A), [0261] w(B) is the weight fraction of the second random propylene copolymer (B), [0262] MFR(A) is the melt flow rate MFR.sub.2 (230° C., 2.16 kg) [in g/10 min] measured according ISO 1133 of the first random propylene copolymer (A), [0263] MFR(C) is the melt flow rate MFR.sub.2 (230° C., 2.16 kg) [in g/10 min] measured according ISO 1133 of the Polypropylene composition (P), [0264] MFR(B) is the calculated melt flow rate MFR.sub.2 (230° C., 2.16 kg) [in g/10 min] of the second random propylene copolymer (B).

[0265] The xylene cold solubles (XCS, wt.-%): Content of xylene cold solubles (XCS) is determined at 25° C. according ISO 16152; first edition; 2005-07-01.

Hexane Solubles (Wt.-%)

[0266] FDA section 177.1520

[0267] 1 g of a polymer film of 100 μm thickness is added to 400 ml hexane at 50° C. for 2 hours while stirring with a reflux cooler.

[0268] After 2 hours the mixture is immediately filtered on a filter paper No 41.

[0269] The precipitate is collected in an aluminium recipient and the residual hexane is evaporated on a steam bath under N.sub.2 flow.

[0270] The amount of hexane solubles is determined by the formula

((wt. sample+wt. crucible)−(wt crucible))/(wt. sample).Math.100.

[0271] Melting temperature T.sub.m, crystallization temperature T.sub.c, is measured with Mettler TA820 differential scanning calorimetry (DSC) on 5-10 mg samples. Both 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 taken as the peaks of endotherms and exotherms.

[0272] Haze was determined according to ASTM D1003-00 on blown films of 50 μm thickness.

[0273] Steam sterilization was performed in a Systec D series machine (Systec Inc., USA). The samples were heated up at a heating rate of 5° C./min starting from 23° C. After having been kept for 30 min at 121° C., they were removed immediately from the steam sterilizer and stored at room temperature till processed further.

Sealing Initiation Temperature (SIT); Sealing End Temperature (SET), Sealing Range:

[0274] The 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, in which the films can be sealed according to conditions given below. The lower limit (heat sealing initiation temperature (SIT)) is the sealing temperature at which a sealing strength of >3 N is achieved. The upper limit (sealing end temperature (SET)) is reached, when the films stick to the sealing device.

[0275] The sealing range is determined on a J&B Universal Sealing Machine Type 3000 with a film of 50 μm thickness with the following further parameters:

[0276] Specimen width: 25.4 mm

[0277] Seal Pressure: 0.1 N/mm.sup.2

[0278] Seal Time: 0.1 sec

[0279] Cool time: 99 sec

[0280] Peel Speed: 10 mm/sec

[0281] Start temperature: 80° C.

[0282] End temperature: 150° C.

[0283] Increments: 10° C.

[0284] specimen is sealed A to A at each sealbar temperature and seal strength (force) is determined at each step.

[0285] The temperature is determined at which the seal strength reaches 3 N.

[0286] Hot Tack Force:

[0287] The hot tack force is determined on a J&B Hot Tack Tester with a film of 50 μm thickness with the following further parameters:

[0288] Specimen width: 25.4 mm

[0289] Seal Pressure: 0.3 N/mm.sup.2

[0290] Seal Time: 0.5 sec

[0291] Cool time: 99 see

[0292] Peel Speed: 200 mm/sec

[0293] Start temperature: 90° C.

[0294] End temperature: 140° C.

[0295] Increments: 10° C.

[0296] The maximum hot tack force, i.e the maximum of a force/temperature diagram is determined and reported.

[0297] Tensile modulus in machine and transverse direction were determined according to ISO 527-3 on 50 μm blown films at a cross head speed of 1 mm/min.

[0298] Dart-drop strength (DDI) is measured using ASTM D1709, method A (Alternative Testing Technique) from the film samples. A dart with a 38 mm diameter hemispherical head is dropped from a height of 0.66 m onto a film clamped over a hole. Successive sets of twenty specimens are tested. One weight is used for each set and the weight is increased (or decreased) from set to set by uniform increments. The weight resulting in failure of 50% of the specimens is calculated and reported.

2. Examples

[0299] Preparation of the Catalyst

[0300] The catalyst used in the inventive examples is prepared as described in detail in WO 2015/011135 A1 (metallocene complex MC1 with methylaluminoxane (MAO) and borate resulting in Catalyst 3 described in WO 2015/011135 A1) with the proviso that the surfactant is 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) is prepared as described in WO 2013/007650 A1 (metallocene E2 in WO 2013/007650 A1).

Preparation of the Copolymer (C)

[0301] The copolymers (C) were prepared in a sequential process comprising a loop reactor and a gas phase reactor. The reaction conditions are summarized in Table 1.

TABLE-US-00001 TABLE 1 Preparation of the Polypropylene composition (P) C1 C2 Prepolymerization Temperature [° C.] 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 Residence time [h] 0.2 0.2 Loop (R1) Temperature [° C.] 70 70 Pressure [kPa] 5297 5292 H2/C3 ratio [mol/krnol] 0.08 0.08 C6/C3 ratio [mol/kmol] 15.5 14.1 MFR2 [g/10 min] 1.9 1.8 XCS [wt. -%] 1.9 1.9 C6 [wt. -%] 1.7 1.7 Residence time [h] 0.5 0.5 Split [wt. -%] 42.5 42.0 GPR (R2) Temperature [° C.] 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) [wt. -%] 6.9 8.2 MFR.sub.2 (GPR) [g/10 min] 1.1 1.2 Residence time [h] 2.6 2.6 Split [wt. -%] 57.5 58.0 C6 [wt. -%] 5.0 5.5 XCS [wt. -%] 13.8 25.0 C6 (XCS) [wt. -%] 6.0 7.2 1,2e [mol-%] 0.46 0.47 MFR.sub.2 (copolymer) [g/10 min] 1.4 1.4 MFR(C)/MFR(A) [-] 0.74 0.74

Preparation of the Polypropylene Composition (P)

[0302] The polypropylene composition (P) was obtained by melt blending the copolymer (C) with the plastomer (PL) in amounts as indicated in Table 2 in a co-rotating twin-screw extruder. The properties of the polypropylene composition (P) and 50 μm blown films made therefrom are summarized in Table 2. [0303] PL1 is the commercial copolymer of ethylene and 1-octene Queo 8230 of Borealis having 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., a density of 0.882 g/cm.sup.3 and an ethylene content of 76.2 wt.-%. [0304] PL2 is the commercial copolymer of ethylene and 1-octene Queo 8201 of Borealis having 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., a density of 0.882 g/cm.sup.3 and an ethylene content of 75.5 wt.-% [0305] PL3 is the commercial copolymer of ethylene and 1-octene Engage 8100 by Dow having 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., a density of 0.870 g/cm.sup.3 and an ethylene content of 74.0 wt.-%. [0306] C3 is the commercial nucleated C2/C3 copolymer RB709CF of 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.-%. [0307] 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 identical with comparative example CE1 of EP 17186987.

[0308] All film properties were determined on monolayer blown films of 50 μm thickness produced on a Collin blown film line. This line has a screw diameter of 30 millimeters (mm), 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 190° C. with an average thickness of 50 μm, with a 2.5 blow-up-ratio and an output rate of about 8 kilograms per hour (kg/h).

[0309] As can be gathered from Table 2, the inventive compositions comprising a copolymer of propylene and 1-hexene in accordance with the present invention show excellent haze values before and after sterilization while the tensile modulus remains on a high level.

TABLE-US-00002 TABLE 2 Composition and properties of the inventive and comparative examples CE1 CE2 IE1 IE2 IE3 IE4 C1 [wt. -%] 90 95 C2 [wt. -%] 90 90 C3 [wt. -%] 100 C4 [wt. -%] 90 PL1 [wt. -%] 10 10 5 PL2 [wt. -%] 10 PL3 [wt. -%] 10 Tm [° C.] 141 135 139 139 135 135 MFR.sub.2 [g/10 min] 1.5 2.8 2.7 2.0 1.6 1.5 50 μm blown film SIT [° C.] 114 105 102 105 107 102 Tm - SIT [° C.] 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 Haze b.s. [%] 12.0 8.5 6.0 4.3 3.8 1.9 Haze a.s. [%] 14.0 9.0 5.6 4.1 2.6 2.6