MULTILAYER POLYPROYLENE FILM

Abstract

Multilayer film comprising at least a skin layer, a core layer and an inner layer, the skin layer comprising a homo polypropylene or a random propylene ethylene copolymer including up to 2.5 wt.-% units derived from ethylene, the homopolypropylene or the random propylene ethylene copolymer having a MFR2 (ISO1 133, 230° C.) of 2.0 to 20 g/10 min and a melting temperature (Tm) of above 148° C. measured by DSC according to ISO 11357-3:1999 and a scan rate of 10° C./min; the core layer comprising a mixture obtainable by melt blending 20 to 100 wt.-% of a random heterophasic copolymer and 0 to 80 wt.-% of styrene based TPE, whereby the random heterophasic copolymer has a melting temperature (Tm) of 134° C.-148° C. measured by DSC according to ISO 11357-3:1999 and a scan rate of 10° C./min and includes a propylene ethylene copolymer rubber; and whereby the styrene based TPE has a styrene content of from 5 to 20 wt.-%, and the inner layer comprising a random propylene ethylene copolymer having a melting temperature (Tm) from 132° C. to 144° C. measured by DSC according to ISO 11357-3:1999 and a scan rate of 10° C./min, wherein the multilayer film is free of phthalic acid esters as well as decomposition products thereof.

Claims

1: Multilayer film comprising: at least a skin layer, a core layer and an inner layer, the skin layer comprising a homo polypropylene or a random propylene ethylene copolymer including up to 2.5 wt. % units derived from ethylene, the homo polypropylene or the random propylene ethylene copolymer having a MFR2 (ISO1133, 230° C.) of 2.0 to 20 g/10 min and a melting temperature (Tm) of above 148° C. measured by DSC according to ISO 11357-3:1999 and a scan rate of 10° C./min; the core layer comprising a mixture obtainable by melt blending 20 to 100 wt. % of a random heterophasic copolymer and 0 to 80 wt. % of styrene based thermoplastic elastomer (TPE), whereby the random heterophasic copolymer has a melting temperature (Tm) of 134° C.-148° C. measured by DSC according to ISO 11357-3:1999 and a scan rate of 10° C./min and includes a propylene ethylene copolymer rubber; and whereby the styrene based TPE has a styrene content of from 5 to 20 wt. %, and the inner layer comprising a random propylene ethylene copolymer having a melting temperature (Tm) from 132° C. to 144° C. measured by DSC according to ISO 11357-3:1999 and a scan rate of 10° C./min, wherein the multilayer film is free of phthalic acid esters as well as decomposition products thereof.

2: Multilayer film according to claim 1, whereby xylene cold soluble fraction (XCS) of the random heterophasic copolymer contributing to the core layer has an intrinsic viscosity of 1.0 to 2.0 dl/g (DIN ISO 1628/1, 10/1999; Decalin, 135° C.).

3: Multilayer film according to claim 1, in which the random heterophasic copolymer of the core layer is a random heterophasic copolymer of propylene.

4: Multilayer film according to claim 1, which has a total thickness of 150 to 250 micrometer determined according to ISO4593.

5: Multilayer film according to claim 1, whereby the core layer has a thickness of 70 to 85% with respect to the thickness of the multilayer film.

6: Multilayer film according to claim 1, whereby the thicknesses of the skin layer is 10 to 15% with respect to the total thickness of the multilayer film, and whereby the thicknesses of the inner layer is 10 to 15% with respect to the total thickness of the multilayer film.

7: Multilayer film according to claim 1, whereby: the skin layer consists of the homo polypropylene or random propylene ethylene copolymer; and/or the core layer consists of a mixture obtainable by melt blending 20 to 100 wt. % of a random heterophasic copolymer and 0 to 80 wt. % of styrene based TPE.

8: Multilayer film according to claim 1, whereby: the inner layer consists of the random propylene ethylene copolymer, or the inner layer consists of a mixture obtainable by blending the random propylene ethylene copolymer and a propylene ethylene elastomer having an ethylene content of less than 20 wt. %; or the inner layer consists of a mixture obtainable by blending the random propylene ethylene copolymer and a styrene ethylene butylene styrene copolymer (SEBS).

9: Multilayer film according to claim 1, whereby the propylene homopolymer of the skin layer has an MFR (230° C., 2.16 kg, ISO1133) of 4.0 to 13 g/10 min, and/or a melting temperature of above 162° C. measured by DSC according to ISO 11357-3:1999 and a scan rate of 10° C./min, and/or a flexural modulus of above 1450 MPa when measured on injection molded specimens (23° C., 50% humidity, ISO 178), or the random propylene ethylene copolymer of the skin layer has, an MFR (230° C., 2.16 kg, ISO1133) of 4.0 to 13 g/10 min, an ethylene content of 0.5 to 2.2 wt. % and/or, a melting temperature of 152 to 155° C. measured by DSC according to ISO 11357-3:1999 and a scan rate of 10° C./min, and/or, a flexural modulus of above 975 MPa when measured on injection molded specimens (23° C., 50% humidity, ISO 178).

10: Multilayer film according to claim 1, whereby the random heterophasic copolymer having a melting temperature (Tm) of 134 to 148° C. measured by DSC according to ISO 11357-3:1999 and a scan rate of 10° C./min contributing to the core layer has, a MFR2 of 3.0 to 7.0 g/10 min (ISO 1133, 230° C., 2.16 kg) and/or a total ethylene content of 7.0 to 14.0 wt. % and/or an amount of the xylene cold soluble fraction (XCS) in the range of 18.0 to 25.0 wt. % and/or an intrinsic viscosity of 1.0 to 1.6 dl/g (DIN ISO 1628/1, 10/1999; Decalin, 135° C.) of the xylene cold soluble fraction (XCS).

11: Multilayer film according to claim 1, whereby the propylene ethylene copolymer of the inner layer having a melting temperature (Tm) from 132° C. to 144° C. measured by DSC according to ISO 11357-3:1999 and a scan rate of 10° C./min has an ethylene content of 3.5 to 6.0 wt.-% and/or has a melt flow rate of 6.0 to 13.0 g/10 min (230° C., 2.16 kg, ISO1133), and/or a flexural modulus of from 600 to 900 MPa when measured on injection molded specimens (23° C., 50% humidity, ISO 178).

12: Multilayer film according to claim 1, whereby the core layer comprises a mixture obtainable by melt blending 40 to 91 wt. % of a random heterophasic copolymer and 9 to 60 wt. % of styrene based TPE.

13: Multilayer film according to claim 1, whereby the core layer comprises a mixture obtainable by melt blending 45 to 65 wt. % of a random heterophasic copolymer and 35 to 55 wt. % of styrene based TPE.

14: Pouches made from the multilayer film as defined in claim 1.

15: Process for preparing a film according to claim 1, comprising: extruding on a multilayer cast film line the components forming the skin layer, the core layer and the inner layer of claim 1.

Description

EXPERIMENTAL PART

1. Measuring Methods

[0187] 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.

[0188] Phthalic acid esters and decomposition products Detection is carried out by gas chromatography coupled with one- or two dimensional mass spectrometry (GC-MS respectively GC-MS/MS) optionally preceded by enrichment on a suitable adsorption material. “Free of phthalic acid esters as well as decomposition products thereof” indicates

[0189] a maximum of 10 μg/kg, i.e. 10 ppb by weight. Typical equipment to be used is for example given in H. Fromme, T. Kiichler, T. Otto, K. Pilz, J. Müller, A. Wenzel Water Research 36 (2002) 1429-1438 which is incorporated by reference herewith. Calculation of comonomer content of the second propylene copolymer fraction (R-PP2):

[00001]$\begin{array}{cc}\frac{C\left(\mathrm{PP}\right)-w\left(\mathrm{PP}1\right)\times C\left(\mathrm{PP}1\right)}{w\left(\mathrm{PP}2\right)}=C\left(\mathrm{PP}2\right)& \left(I\right)\end{array}$

[0190] wherein [0191] w(PP1) is the weight fraction [in wt.-%] of the first propylene copolymer fraction (R-PP1), [0192] w(PP2) is the weight fraction [in wt.-%] of second propylene copolymer fraction (R-PP2), [0193] C(PP1) is the comonomer content [in mol-%] of the first propylene copolymer fraction (R-PP1), [0194] C(PP) is the comonomer content [in mol-%] of the random propylene copolymer (R-PP), [0195] C(PP2) is the calculated comonomer content [in mol-%] of the second propylene copolymer fraction (R-PP2).

[0196] Calculation of the xylene cold soluble (XCS) content of the second propylene copolymer fraction (R-PP2):

[00002]$\begin{array}{cc}\frac{\mathrm{XS}\left(\mathrm{PP}\right)-w\left(\mathrm{PP}1\right)\times \mathrm{XS}\left(\mathrm{PP}1\right)}{w\left(\mathrm{PP}2\right)}=\mathrm{XS}\left(\mathrm{PP}2\right)& \left(I\right)\end{array}$

[0197] wherein [0198] w(PP1) is the weight fraction [in wt.-%] of the first propylene copolymer fraction (R-PP1), [0199] w(PP2) is the weight fraction [in wt.-%] of second propylene copolymer fraction (R-PP2), [0200] XS(PP1) is the xylene cold soluble (XCS) content [in wt.-%] of the first propylene copolymer fraction (R-PP1), [0201] XS(PP) is the xylene cold soluble (XCS) content [in wt.-%] of the random propylene copolymer (R-PP), [0202] XS(PP2) is the calculated xylene cold soluble (XCS) content [in wt.-%] of the second propylene copolymer fraction (R-PP2), respectively.

[0203] Calculation of melt flow rate MFR.sub.2 (230° C./2.16 kg) of the second propylene copolymer fraction (R-PP2):

[00003]$\begin{array}{cc}\mathrm{MFR}\left(\mathrm{PP}2\right)={10}^{\left[\frac{\log \left(\mathrm{MFR}\left(\mathrm{PP}\right)\right)-w\left(\mathrm{PP}1\right)\times \log \left(\mathrm{MFR}\left(\mathrm{PP}1\right)\right)}{w\left(\mathrm{PP}2\right)}\right]}& \left(\mathrm{III}\right)\end{array}$

[0204] wherein [0205] w(PP1) is the weight fraction [in wt.-%] of the first propylene copolymer fraction (R-PP1), [0206] w(PP2) is the weight fraction [in wt.-%] of second propylene copolymer fraction (R-PP2), [0207] MFR(PP1) is the melt flow rate MFR.sub.2 (230° C./2.16 kg) [in g/10 min] of the first propylene copolymer fraction (R-PP1), [0208] MFR(PP) is the melt flow rate MFR.sub.2 (230° C./2.16 kg) [in g/10 min] of the random propylene copolymer (R-PP), [0209] MFR(PP2) is the calculated melt flow rate MFR.sub.2 (230° C./2.16 kg) [in g/10 min] of the second propylene copolymer fraction (R-PP2).

[0210] Calculation of comonomer content of the elastomeric propylene copolymer (E), respectively:

[00004]$\begin{array}{cc}\frac{C\left(\mathrm{RAHECO}\right)-w\left(\mathrm{PP}\right)\times C\left(\mathrm{PP}\right)}{w\left(E\right)}=C\left(E\right)& \left(\mathrm{IV}\right)\end{array}$

[0211] wherein [0212] w(PP) is the weight fraction [in wt.-%] of the random propylene copolymer (R-PP), i.e. polymer produced in the first and second reactor (R1+R2), [0213] w(E) is the weight fraction [in wt.-%] of the elastomeric propylene copolymer (E), i.e. polymer produced in the third reactor (R3) [0214] C(PP) is the comonomer content [in mol-%] of the random propylene copolymer (R-PP), i.e. comonomer content [in mol-%] of the polymer produced in the first and second reactor (R1+R2), [0215] C(RAHECO) is the comonomer content [in mol-%] of the propylene copolymer, i.e. is the comonomer content [in mol-%] of the polymer obtained after polymerization in the third reactor (R3), [0216] C(E) is the calculated comonomer content [in mol-%] of elastomeric propylene copolymer (E), i.e. of the polymer produced in the third reactor (R3).

[0217] MFR.sub.2 (230° C./2.16 kg) is measured according to ISO 1133 at 230° C. and 2.16 kg load.

[0218] Quantification of Microstructure by NMR Spectroscopy

[0219] Quantitative nuclear-magnetic resonance (NMR) spectroscopy was used to quantify the comonomer content and comonomer sequence distribution of the polymers. Quantitative .sup.13C{.sup.1H} NMR spectra were recorded in the solution-state using a Bruker Advance III 400 NMR spectrometer operating at 400.15 and 100.62 MHz for .sup.1H and .sup.13C respectively. All spectra were recorded using a .sup.13C optimised 10 mm extended temperature probehead at 125° C. using nitrogen gas for all pneumatics. Approximately 200 mg of material was dissolved in 3 ml of 1,2-tetrachloroethane-d.sub.2 (TCE-d.sub.2) along with chromium-(III)-acetylacetonate (Cr(acac).sub.3) resulting in a 65 mM solution of relaxation agent in solvent (Singh, G., Kothari, A., Gupta, V., Polymer Testing 285 (2009), 475). To ensure a homogenous solution, after initial sample preparation in a heat block, the NMR tube was further heated in a rotatory oven for at least 1 hour. Upon insertion into the magnet the tube was spun at 10 Hz. This setup was chosen primarily for the high resolution and quantitatively needed for accurate ethylene content quantification. Standard single-pulse excitation was employed without NOE, using an optimised tip angle, 1 s recycle delay and a bi-level WALTZ16 decoupling scheme (Zhou, Z., Kuemmerle, R., Qiu, X., Redwine, D., Cong, R., Taha, A., Baugh, D. Winniford, B., J. Mag. Reson. 187 (2007) 225; Busico, V., Carbonniere, P., Cipullo, R., Pellecchia, R., Severn, J., Talarico, G., Macromol. Rapid Commun. 2007, 28, 1128). A total of 6144 (6k) transients were acquired per spectra.

[0220] Quantitative .sup.13C{.sup.1H} NMR spectra were processed, integrated and relevant quantitative properties determined from the integrals using proprietary computer programs. All chemical shifts were indirectly referenced to the central methylene group of the ethylene block (EEE) at 30.00 ppm using the chemical shift of the solvent. This approach allowed comparable referencing even when this structural unit was not present. Characteristic signals corresponding to the incorporation of ethylene were observed Cheng, H. N., Macromolecules 17 (1984), 1950).

[0221] With characteristic signals corresponding to 2,1 erythro regio defects observed (as described in L. Resconi, L. Cavallo, A. Fait, F. Piemontesi, Chem. Rev. 2000, 100 (4), 1253, in Cheng, H. N., Macromolecules 1984, 17, 1950, and in W-J. Wang and S. Zhu, Macromolecules 2000, 331157) the correction for the influence of the regio defects on determined properties was required. Characteristic signals corresponding to other types of regio defects were not observed.

[0222] The comonomer fraction was quantified using the method of Wang et. al. (Wang, W-J., Zhu, S., Macromolecules 33 (2000), 1157) through integration of multiple signals across the whole spectral region in the .sup.13C{.sup.1H} spectra. This method was chosen for its robust nature and ability to account for the presence of regio-defects when needed. Integral regions were slightly adjusted to increase applicability across the whole range of encountered comonomer contents.

[0223] For systems where only isolated ethylene in PPEPP sequences was observed the method of Wang et. al. was modified to reduce the influence of non-zero integrals of sites that are known to not be present. This approach reduced the overestimation of ethylene content for such systems and was achieved by reduction of the number of sites used to determine the absolute ethylene content to:

E=0.5(Sββ+Sβγ+Sβδ+0.5(Sαβ+Sαγ))

Through the use of this set of sites the corresponding integral equation becomes:

E=0.5(I.sub.H+I.sub.G+0.5(I.sub.C+I.sub.D))

[0224] using the same notation used in the article of Wang et. al. (Wang, W-J., Zhu, S., Macromolecules 33 (2000), 1157). Equations used for absolute propylene content were not modified.

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

E [mol %]=100*fE

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

E [wt %]=100*(fE*28.06)/((fE*28.06)+((1−fE)*42.08))

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

[0226] The relative content of isolated to block ethylene incorporation was calculated from the triad sequence distribution using the following relationship (equation (I)):

[00005]$\begin{array}{cc}I\left(E\right)=\frac{\mathrm{fPEP}}{\left(\mathrm{fEEE}+\mathrm{fPEE}+\mathrm{fPEP}\right)}\times 100& \left(I\right)\end{array}$

[0227] wherein

[0228] I(E) is the relative content of isolated to block ethylene sequences [in %]; fPEP is the mol fraction of propylene/ethylene/propylene sequences (PEP) in the sample;

[0229] fPEE is the mol fraction of propylene/ethylene/ethylene sequences (PEE) and of ethylene/ethylene/propylene sequences (EEP) in the sample;

[0230] fEEE is the mol fraction of ethylene/ethylene/ethylene sequences (EEE) in the sample.

[0231] Film Thickness

[0232] Film thickness was determined according to ISO4593.

[0233] The layer thickness distribution in the multilayer films can be detected by any known method, the most preferred ones are microscopes methods, e.g. atomic force microscope (AFM) on the cross section of the multilayer films. Reference is made to A. BIRONEAU et al., Journal of Microscopy, Vol. 264, Issue 12016, pp. 48-58.

[0234] Intrinsic viscosity is measured according to DIN ISO 1628/1, October 1999 (in Decalin at 135° C.).

[0235] The xylene cold solubles (XCS, wt.-%): Content of xylene cold solubles (XCS) is determined at 25° C. according ISO 16152; first edition; 2005 Jul. 1. The part which remains insoluble is the xylene cold insoluble (XCI) fraction.

[0236] The hexane extractable fraction (C6 soluble) is determined according to the European Pharmacopeia 6.0 EP613. Test bar specimens of 80×10×4 mm.sup.3 injection molded at 23° C. in line with EN ISO 1873-2 were used in an amount of 10 g, and the extraction was performed in 100 ml n-hexane by boiling under reflux for 4 h, followed by cooling in ice water for 45 min. The resulting solution is filtered under vacuum in less than 5 min, followed by evaporation under nitrogen stream. After drying the evaporation residue it is weighed and the hexane extractable fraction calculated.

[0237] Melting temperature (T.sub.m) crystallization temperature (T.sub.c) and heat of crystallization (H.sub.c): measured with Mettler TA820 differential scanning calorimetry (DSC) on 5 to 10 mg samples. DSC is run according to ISO 11357-3:1999 in a heat/cool/heat cycle with a scan rate of 10° C./min in the temperature range of +23 to +210° C. The crystallization temperature is determined from the cooling step, while the melting temperature is determined from the second heating step.

[0238] Transparency, haze and clarity were determined according to ASTM D1003-00 on a 200 μm cast film as described herein.

[0239] Flexural Modulus: The flexural modulus was determined in 3-point-bending according to ISO 178 on 80×10×4 mm.sup.3 test bars injection molded at 23° C. in line with EN ISO 1873-2.

[0240] Charpy notched impact strength is determined according to ISO 179 1 eA at 23 and at −20° C. by using an 80×10×4 mm.sup.3 test bars injection molded in line with EN ISO 1873-2.

[0241] Tensile modulus in machine and transverse direction was determined according to ISO 527-3 at 23° C. on 200 μm cast films produced as described herein. Testing was performed at a cross head speed of 1 mm/min.

[0242] 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.

2. Examples

[0243] Preparation of the Phthalate Free Catalyst

[0244] The phthalate free catalyst used in the polymerization processes for the inventive resins (IE) was prepared as follows:

[0245] Used Chemicals:

[0246] 20% solution in toluene of butyl ethyl magnesium (Mg(Bu)(Et), BEM), provided by Chemtura

[0247] 2-ethylhexanol, provided by Amphochem

[0248] 3-Butoxy-2-propanol—(DOWANOL™ PnB), provided by Dow

[0249] bis(2-ethylhexyl)citraconate, provided by SynphaBase

[0250] TiCl.sub.4, provided by Millenium Chemicals

[0251] Toluene, provided by Aspokem

[0252] Viscoplex® 1-254, provided by Evonik

[0253] Heptane, provided by Chevron

[0254] Preparation of a Mg Alkoxy Compound

[0255] Mg alkoxide solution was prepared by adding, with stirring (70 rpm), into 11 kg of a 20 wt-% solution in toluene of butyl ethyl magnesium (Mg(Bu)(Et)), a mixture of 4.7 kg of 2-ethylhexanol and 1.2 kg of butoxypropanol in a 201 stainless steel reactor. During the addition the reactor contents were maintained below 45° C. After addition was completed, mixing (70 rpm) of the reaction mixture was continued at 60° C. for 30 minutes. After cooling to room temperature 2.3 kg g of the donor bis(2-ethylhexyl)citraconate was added to the Mg-alkoxide solution keeping temperature below 25° C. Mixing was continued for 15 minutes under stirring (70 rpm).

[0256] Preparation of Solid Catalyst Component

[0257] 20.3 kg of TiCl.sub.4 and 1.1 kg of toluene were added into a 201 stainless steel reactor. Under 350 rpm mixing and keeping the temperature at 0° C., 14.5 kg of the Mg alkoxy compound prepared in example 1 was added during 1.5 hours. 1.71 of Viscoplex® 1-254 and 7.5 kg of heptane were added and after 1 hour mixing at 0° C. the temperature of the formed emulsion was raised to 90° C. within 1 hour. After 30 minutes mixing was stopped catalyst droplets were solidified and the formed catalyst particles were allowed to settle. After settling (1 hour), the supernatant liquid was siphoned away. Then the catalyst particles were washed with 45 kg of toluene at 90° C. for 20 minutes followed by two heptane washes (30 kg, 15 min). During the first heptane wash the temperature was decreased to 50° C. and during the second wash to room temperature.

[0258] The thus obtained catalyst was used along with triethyl-aluminium (TEAL) as co-catalyst and dicyclopentyl dimethoxy silane (D-Donor) as donor.

[0259] The aluminium to donor ratio, the aluminium to titanium ratio and the polymerization conditions are indicated in the respective tables

[0260] Preparation of the Skin Layer Material

[0261] The polypropylene used for the skin layer material was prepared in a loop reactor using the catalyst as described above.

TABLE-US-00001 TABLE 1 Polymerization conditions used for preparation of the material for the skin layer. dicyclopentyl Donor dimethoxy silane Teal/donor 12.5/1 (wt./wt.) Teal/C3 0.15 kg/ton loop temperature 75° C. loop pressure 35Bar Raw polymer 99.8700 wt.-% stabilization package 0.1300 wt.-% Irganox 1010FF/ Irgafos 168/synthetic hydrotalcite in weight ratio of 25.6/51.3/23.1

[0262] The polypropylenes powders were compounded with the desired amount of additives, as indicated in Table 1, in a ZSK 57 twin screw extruder with melt temperature of 200° C. The properties of the materials are shown in Table 2.

TABLE-US-00002 TABLE 2 Properties skin layer material MFR (2.16 kg, 8.0 g/10 min 230° C., ISO 1133) Tm (ISO 11357-3) 163° C. Tcr (ISO 11357-3) 122 Flexural modulus 1350 MPa (+23° C., ISO 178)

TABLE-US-00003 TABLE 3 Preparation of the random heterophasic copolymer (RAHECO) for the core layer RAHECO for core layer Catalyst inventive Donor as described above dicyclopentyl dimethoxy silane TEAL/Ti [mol/mol] 220 TEAL/donor [mol/mol] 6.1 Temperature [° C.] 31 Loop Temperature [° C.] 70 Split [%] 33 H2/C3 ratio [mol/kmol] 0.5 C2/C3 ratio [mol/kmol] 5.7 MFR.sub.2 [g/10 min] 4 XCS [wt.-%] 9.8 C2 content [mol-%] 4.4 GPR 1 Temperature [° C.] 80 Pressure [kPa] 2500 Split [%] 54 H2/C3 ratio [mol/kmol] 7.8 C2/C3 ratio [mol/kmol] 26.3 MFR.sub.2 [g/10 min] 6.3 XCS [wt.-%] 8.1 C2 content [mol-%] 6 GPR 2 Temperature [° C.] 75 Split [%] 13 C2/C3 ratio [mol/kmol] 555 H2/C2 ratio [mol/kmol] 502 MFR.sub.2 [g/10 min] 4.9 XCS [wt.-%] 20.5 C2 content [mol-%] 13.2 IV (XCS) dl/g 1.3 Tm ° C. 141

[0263] The polypropylenes powders were compounded with the desired amount of additives (333 ppm of Irganox 1010 (FF); 667 ppm of Irgafos 168, 150 ppm of Magnesium oxide) in a ZSK 57 twin screw extruder with melt temperature of 200° C.

[0264] Preparation of Core Layer Material:

[0265] The core layer material was made by compounding the RAHECO as obtained above with 10.0, 25.0 or 50.0 wt.-% of Kraton G1645MO based on the total amount of the core-layer material in a ZSK 57 twin screw extruder with melt temperature of 200° C.

[0266] Kraton G1645MO is a linear triblock copolymer based on styrene and ethylene/butylene (SEBS) having a melt flow rate (230° C., 2.16 kg) of about 3 g/10 min, a polystyrene content (KM 03 test method) of 11.5 to 13.5 wt. % measured on the polymer.

TABLE-US-00004 TABLE 4 Preparation of the random polypropylene copolymer for inner layer material PP-random for inner Catalyst layer inventive Donor as described above dicyclopentyl dimethoxy silane TEAL/Ti [mol/mol] 220 TEAL/donor [mol/mol] 6.1 Temperature [° C.] 31 Loop Temperature [° C.] 70 Split [%] 41 H2/C3 ratio [mol/kmol] 0.6 C2/C3 ratio [mol/kmol] 7.5 MFR.sub.2 [g/10 min] 1.8 XCS [wt.-%] 10 C2 content [mol-%] 4.6 GPR 1 Temperature [° C.] 80 Pressure [kPa] 2119 Split [%] 59 H2/C3 ratio [mol/kmol] 5.8 C2/C3 ratio [mol/kmol] 27 MFR.sub.2 [g/10 min] 1.8 XCS [wt.-%] 8.5 C2 content [mol-%] 6.2

[0267] The polypropylene random copolymer of the inner layer was further mixed with Trigonox 101, the amount adjusted by man skilled in the art to reach the final MFR of 8 g/10 min.

TABLE-US-00005 TABLE 5 Properties inner layer material MFR (2.16 kg, 8 g/10 min 230° C., ISO 1133) C2 4.5 wt.-% XS 8.5 wt.-% Tm (ISO11357-3) 141° C.

[0268] The pelletization was done in a conventional way as well known in the art.

[0269] Preparation of the Film

[0270] The films according to the present invention have been produced on a multi layer cast film line equipped with 3 extruders. All three extruders were equipped with a notched feeding zone and a 3 zone screw with mixing and shear parts. The diameter of the cylinder of extruder A is 40 mm and the screw length 25D. Extruder B has a cylinder diameter of 60 mm and a screw length of SOD and extruder C a cylinder diameter of 45 mm and a screw length of 25D. Each extruder is fed by a gravimetric dosing system. A feed block with lamellas and following distribution was used as co-extrusion adapter: Extruder A 10% (skin layer), extruder C 80% (core layer) and extruder B 10% (inner layer). A coat hanger die with automatic die gap regulation was used, die width 800 mm and die gap 0.5 mm. The chill roll unit has a diameter of 450 mm and the 2nd cooling roll 250 mm. The detailed processing parameters are shown in tables 6 below.

TABLE-US-00006 TABLE 6 processing conditions for three layer cast film Extruder A Extruder C Extruder B Layer thickness micron 20 160 20 Layer function Skin layer Core layer Inner layer and functionality Outer protection mainly sealing vs. sterilization Melttemperature ° C. 250 260 250 Melt pressure Bar 45 45 45 Screw speed U/min 8 45 6 output Kg/h 6 48 6 Coex adapter 260 temperature Die temperature 250 Chill roll ° C. 12 temperature 2.sup.nd cooling roll ° C. 21 temperature Take off speed m/min 7.4 winder

[0271] The core layer material was varied, i.e. the amounts of Raheco and SEBS were varied from 60 to 100 wt.-% Raheco and 40 to 0 wt.-% SEBS (Kraton G1645MO).

TABLE-US-00007 TABLE 7 3 layer cast film composition (inventive/comparative) IE1 IE2 IE3 IE4 CE1 CE2 Inventive material for wt % 100 100 100 100 skin layer comparative material wt % 100 100 for skin layer inventive RAHECO wt % 100 90 75 60 for core layer comparative wt % 60 75 RAHECO for core layer Kraton G1645MO wt % 10 25 40 40 25 inventive PP random wt % 100 100 100 100 for inner layer comparative PP wt % 100 100 random for inner layer

[0272] The comparative examples were made with ZN catalysts not having a phthalate internal donor. All other properties were kept the same and optimized as far as possible. The comparative examples insofar did not meet the criteria free of phthalic acid esters as well as decomposition products.

TABLE-US-00008 TABLE 8 Film properties determined on 200 μm films . . . IE1 IE2 IE3 IE4 CE1 CE2 Tensile Modulus/MD MPa 334 244 146 112 111 161 Tensile Modulus/TD MPa 362 268 170 120 123 168 Haze/b.s. % 5.0 4.5 4.4 3.2 7.7 6.5 Haze/a.s. % 14.7 13.9 12.9 12.7 18.1 17.1 free of phthalic acid yes yes yes yes no no esters/decomposition products b.s = before sterilization; a.s. = after sterilization

[0273] All inventive examples show excellent haze before and after sterilization. Moreover, it can be seen the incorporation of the styrene based TPE (here KRATON G1645MO) further improves the balance of properties, particularly improves softness and also haze.

[0274] It is further a surprising finding of the present invention that the addition of TPE to the specific raheco (for the core layer) decreases haze and simultaneously lowers tensile. For the comparative films originating from traditional ZN catalysts, a reduction in tensile can be observed with increasing TPE amount. However, at the same time haze is deteriorated.