Machine direction oriented films comprising multimodal copolymer of ethylene and at least two alpha-olefin comonomers

Abstract

A machine direction oriented film comprising a multimodal copolymer of ethylene and at least two alpha-olefin-comonomers having: a) a density of from 906 to 925 kg/m.sup.3 determined according to ISO 1183, b) an MFR.sub.21 of 10-200 g/10 min determined according to ISO1133, wherein the multimodal copolymer of ethylene comprises c) a first copolymer of ethylene and a first alpha-olefin comonomer having 4 to 10 carbon atoms; and d) a second copolymer of ethylene having an alpha-olefin comonomer different from the first copolymer, said second alpha-olefin comonomer having 6 to 10 carbon atoms.

Claims

1. A machine direction oriented (MDO) monolayer film comprising a multimodal copolymer of ethylene and at least two alpha-olefin-comonomers having: a) a density of from 906 to 925 kg/m.sup.3 determined according to ISO 1183, b) an MFR.sub.21 of 10 to 200 g/10 min determined according to ISO1133, wherein the multimodal copolymer of ethylene comprises c) a first copolymer of ethylene and a first alpha-olefin comonomer having 4 to 10 carbon atoms; and d) a second copolymer of ethylene having an alpha-olefin comonomer different from that of the first copolymer, said second alpha-olefin comonomer having 6 to 10 carbon atoms; and wherein the machine directed oriented monolayer film has been stretched uniaxially in the machine direction (MD) in a draw ratio of at least 1:1.5.

2. The MDO monolayer film as claimed in claim 1 which has been stretched uniaxially in the machine direction (MD) in a draw ratio of at least 1:2.

3. The MDO monolayer film as claimed in claim 1 wherein the multimodal copolymer of ethylene comprises 50 wt % or less of the first copolymer of ethylene; 50 wt % or more of the second copolymer of ethylene.

4. The MDO monolayer film as claimed in claim 1 wherein the first copolymer of ethylene has i) a density of from 945 to 955 kg/m.sup.3; and ii) a melt flow rate MFR.sub.2 of 150 to 1500 g/10 min.

5. The MDO monolayer film as claimed in claim 1 wherein the second copolymer of ethylene has a density of ≤903 kg/m.sup.3 when calculated according to Equation 5 based on values determined according to ISO 1183:
ρ.sub.b=w.sub.1.Math.ρ.sub.1+w.sub.2.Math.ρ.sub.2  Equation 5, where ρ is density in kg/m.sup.3, w is weight fraction of component in a mixture and subscripts b, 1 and 2 refer to the mixture b, component 1 (first copolymer) and component 2 (second copolymer), respectively.

6. The MDO monolayer film as claimed in claim 1 wherein the second copolymer of ethylene has MFR.sub.21 of <20 g/10 min when calculated according to Equation 4: Hagström formula: $\begin{array}{cc}{\mathrm{MI}}_b={\left(w.Math.{\mathrm{MI}}_1^{-\frac{w^{-b}}{a}}+\left(1-w\right).Math.{\mathrm{MI}}_2^{-\frac{w^{-b}}{a}}\right)}^{-a.Math.w^b},& \mathrm{Equation}4\end{array}$ where a=10.4, b=0.5 for MFR.sub.21, w is the weight fraction of the polymer component having higher MFR, MI.sub.b is the MFR.sub.21 of the second copolymer mixture, MI.sub.1 is MFR.sub.21 of a first copolymer of ethylene, and MI.sub.2 is MFR.sub.21 of the second copolymer of ethylene.

7. The MDO monolayer film as claimed in claim 1 having a thickness of 10 to 30 microns after stretching.

8. The MDO monolayer film as claimed in claim 1 having one or more of: an Elmendorf tear resistance of at least 310 N/mm in the TD; an Elmendorf tear resistance of at least 90 N/mm in the MD; a normalised peak force of 2000 to 3500 N/mm; a normalised energy to peak force of 30 to 120 J/mm; and/or a normalised total penetration energy of 30 to 90 J/mm.

9. The MDO monolayer film as claimed in claim 1 wherein the first copolymer of ethylene has i) a density of from 945 to 955 kg/m.sup.3; and ii) a melt flow rate MFR2 of 150 to 1500 g/10 min.

10. A machine direction oriented (MDO) film comprising a multimodal copolymer of ethylene and at least two alpha-olefin-comonomers having: a) a density of from 906 to 925 kg/m.sup.3 determined according to ISO 1183, b) an MFR.sub.21 of 10 to 200 g/10 min determined according to ISO1133, wherein the multimodal copolymer of ethylene comprises c) 35 to 50 wt % of a first copolymer of ethylene comprising at least a first and a second fraction; said first fraction comprising ethylene and a first alpha-olefin comonomer having 4 to 10 carbon atoms and said second fraction comprising ethylene and the first alpha-olefin comonomer having 4 to 10 carbon atoms said first and second fraction are present in a weight ratio of 2:1 up to 1:2; and d) 50 to 65 wt % of a second copolymer of ethylene having an alpha-olefin comonomer different from the first copolymer, said second alpha-olefin comonomer having 6 to 10 carbon atoms; and wherein the machine directed oriented film has been stretched uniaxially in the machine direction (MD) in a draw ratio of at least 1:1.5.

11. A machine direction oriented (MDO) film according to claim 10, wherein component (d) comprises a second copolymer of ethylene having an alpha-olefin comonomer different from the first copolymer having a density of below 900 kg/m.sup.3 when calculated according to Equation 5, based on values determined according to ISO 1183:
ρ.sub.b=w.sub.1.Math.ρ.sub.1+w.sub.2.Math.ρ.sub.2  Equation 5, where ρ is density in kg/m.sup.3, w is weight fraction of component in a mixture and subscripts b, 1 and 2 refer to the mixture b, component 1 (first copolymer) and component 2 (second copolymer), respectively.

12. The MDO film as claimed in claim 10 wherein the first and the second fraction of the first copolymer of ethylene are produced in two consecutive steps.

13. The MDO film as claimed in claim 10 which has been stretched uniaxially in the machine direction (MD) in a draw ratio of at least 1:2.

14. The MDO film as claimed in claim 10 wherein the second copolymer of ethylene has a density of from ≤903 kg/m.sup.3 when calculated according to Equation 3 based on values determined according to ISO 1183: $\begin{array}{cc}\tau =\frac{\mathrm{Vr}}{\mathrm{Qo}},& \mathrm{Equation}5\end{array}$ where τ is residence time Vr is volume of the reaction space and Qo is volumetric flow rate of a product stream.

15. The MDO film as claimed in claim 10 wherein the second copolymer of ethylene has MFR.sub.21 of <20 g/10 min when calculated according to Equation 4: $\begin{array}{cc}{\mathrm{MI}}_b={\left(w.Math.{\mathrm{MI}}_1^{-\frac{w^{-b}}{a}}+\left(1-w\right).Math.{\mathrm{MI}}_2^{-\frac{w^{-b}}{a}}\right)}^{-a.Math.w^b},,& \mathrm{Equation}4\end{array}$ where a=10.4, b=0.5 for MFR.sub.21, w is the weight fraction of a polymer component having higher MFR, MI.sub.b is the MFR.sub.21 of the second copolymer mixture, MI.sub.1 is MFR.sub.21 of the first copolymer of ethylene, and MI.sub.2 is MFR.sub.21 of the second copolymer of ethylene.

16. The MDO film as claimed in claim 10 having one or more of: an Elmendorf tear resistance of at least 375 N/mm in the TD; an Elmendorf tear resistance of at least 100 N/mm in the MD; a normalised peak force of 2250 to 2750 N/mm; a normalised energy to peak force of 50 to 120 J/mm and/or a normalised total penetration energy of 35 to 80 J/mm.

17. A process for the preparation of the machine direction oriented film as claimed in claim 10 comprising: in a first reactor polymerising ethylene and a first alpha-olefin comonomer having 4 to 10 carbon atoms to produce a first polyethylene fraction; in a second reactor and in the presence of the first polyethylene fraction, polymerising ethylene and said first alpha-olefin comonomer having 4 to 10 carbon atoms to produce a second polyethylene fraction, said first and second polyethylene fractions forming a first copolymer of ethylene; in a third reactor and in the presence of the first copolymer of ethylene, polymerising ethylene and a second alpha-olefin comonomer different from the first alpha-olefin comonomer, said second alpha-olefin comonomer having 6 to 10 carbon atoms to produce a second copolymer of ethylene; said first and second copolymers of ethylene forming a multimodal copolymer of ethylene and at least two alpha-olefin-comonomers having: a) a density of from 906 to 925 kg/m.sup.3 determined according to ISO 1183, b) an MFR.sub.21 of 10-200 g/10 min determined according to ISO1133, blowing said multimodal copolymer of ethylene to form a first film; stretching said first film in a machine direction in a draw ratio of at least 1:1.5.

18. The process as claimed in claim 17 wherein the second copolmer of ethylene does not contain a residue of an alpha olefin with fewer than 6 carbons atoms or wherein there is at least one alpha olefin present in the second copolmer of ethylene which is different from any alpha olefin present in said first copolymer of ethylene.

Description

(1) The invention will now be described with reference to the following non-limiting examples and figures.

(2) FIG. 1 shows penetration energy values before stretching for the polymers of the invention vs the prior art comparative examples and then looks at values after stretching 1:2 and 1:3 times in the machine direction.

(3) FIG. 2 shows Elmendorf tear values before stretching for the polymers of the invention vs the prior art comparative examples and then looks at values after stretching 1:2 and 1:3 times in the machine direction. Results are for MD tear.

(4) FIG. 3 shows Elmendorf tear values before stretching for the polymers of the invention vs the prior art comparative examples and then looks at values after stretching 1:2 and 1:3 times in the machine direction. Results are for TD tear.

DETERMINATION METHODS

(5) Melt flow rate (MFR) was determined according to ISO 1133 at 190° C. The load under which the measurement is conducted is given as a subscript. Thus, the MFR under the load of 2.16 kg is denoted as MFR2. The melt flow rate MFR21 is correspondingly determined at 190° C. under a load of 21.6 kg and MFR5 under a load of 5 kg.

(6) The melt index MFR is herein assumed to follow the mixing rule given in Equation 4 (Hagström formula):

(7) ${\mathrm{MI}}_b={\left(w.Math.{\mathrm{MI}}_1^{-\frac{w^{-b}}{a}}+\left(1-w\right).Math.{\mathrm{MI}}_2^{-\frac{w^{-b}}{a}}\right)}^{-a.Math.w^b}$

(8) As proposed by Hagström, a=10.4 and b=0.5 for MFR21. Further, unless other experimental information is available, MFR21/MFR2 for one polymer component (i.e. first copolymer or second copolymer) can be taken as 30. Furthermore, w is the weight fraction of the polymer component having higher MFR. The first copolymer can thus be taken as the component 1 and the second copolymer as the component 2. The MFR21 of the second copolymer (MI2) can then be solved from equation 1 when the MFR21 of the first copolymer mixture (MI1) and the second copolymer mixture (MIb) are known.

(9) It is herewith stated, that the following expressions are to be understood as defined: “MFR2 loop1” is understood as the MFR of the polymer available after the first loop, comprising the “first fraction of the first copolymer” and optionally any polymer fraction produced in the prepolymerization-step (if any).

(10) “Density Loop1” is understood as the density of the polymer available after the first loop, comprising the first fraction of the first copolymer and optionally any polymer fraction produced in the prepolymerization-step (if any).

(11) “MFR2 loop2” or “MFR2 after loop2” is understood as the MFR of the polymer available after the second loop, i.e. comprising the first fraction of the first copolymer and the second fraction of the first copolymer and optionally polymer produced in any prepolymerization-step (if any).

(12) The MFR2 of the polymer fraction produced in the second loop (i.e. the second fraction of the first copolymer) is to be calculated according to Equation 4: Hagström formula and denominates as “MFR2 of the second loop”, i.e. the MFR2 of second fraction of the first copolymer.
Log MFR2(loop)=n*log MFI(split1)+(1−n)*log MFR(split2)  Equation 6: MFR mixing rule
“Loop density after Loop2” (or “Density Loop2) is understood as the density of the polymer available after the second loop, i.e. comprising the first fraction of the first copolymer and the second fraction of the first copolymer and optionally polymer produced in any prepolymerization—step (if any).

(13) The density of the polymer fraction produced in the second loop (i.e. the density of the second fraction of the first copolymer) is to be calculated according to Equation 5: Density mixing rule
ρ.sub.b=w.sub.1.Math.ρ.sub.1+w.sub.2.Math.ρ.sub.2

(14) “Final MFR21” is understood as the MFR of the polymer available after the gas phase reactor (GPR), i.e. comprising all the polymer fractions produced in any preceding polymerization step, i.e. comprising the first fraction and the second fraction of the first copolymer, the high molecular-weight fraction produced in the GPR and optionally polymer produced in any prepolymerization-step (if any). “GPR MFR2” denominates the MFR of the polymer fraction produced in the GPR and is to be calculated according to Equation 4.

(15) Density

(16) Density of the polymer was measured according to ISO 1183-1:2004 Method A on compression moulded specimen prepared according to EN ISO 1872-2 (February 2007) and is given in kg/m3. The density is herein assumed to follow the mixing rule as given in Equation 5: Density mixing rule
ρ.sub.b=w.sub.1.Math.ρ.sub.1+w.sub.2.Math.ρ.sub.2
Herein ρ is the density in kg/m3, w is the weight fraction of the component in the mixture and subscripts b, 1 and 2 refer to the overall mixture b, component 1 and component 2, respectively. “Density of GPR (calc)” has been calculated according to Equation 5 accordingly.
Molecular Weights, Molecular Weight Distribution, Mn, Mw, MWD

(17) The weight average molecular weight Mw and the molecular weight distribution (MWD=Mw/Mn wherein Mn is the number average molecular weight and Mw is the weight average molecular weight) is measured by a method based on ISO 16014-4:2003. A Waters 150CV plus instrument, equipped with refractive index detector and online viscosimeter was used with 3×HT6E styragel columns from Waters (styrene-divinylbenzene) and 1,2,4-trichlorobenzene (TCB, stabilized with 250 mg/L 2,6-Di tert butyl-4-methyl-phenol) as solvent at 140° C. and at a constant flow rate of 1 mL/min. 500 μL of sample solution were injected per analysis. The column set was calibrated using universal calibration (according to ISO 16014-2:2003) with 10 narrow MWD polystyrene (PS) standards in the range of 1.05 kg/mol to 11 600 kg/mol. Mark Houwink constants were used for polystyrene and polyethylene (K: 19×10.sup.−3 dL/g and a: 0.655 for PS, and K: 39×10.sup.−3 dL/g and a: 0.725 for PE). All samples were prepared by dissolving 0.5-3.5 mg of polymer in 4 mL (at 140° C.) of stabilized TCB (same as mobile phase) and keeping for 2 hours at 140° C. and for another 2 hours at 160° C. with occasional shaking prior sampling in into the GPC instrument.

(18) Comonomer Determination (NMR Spectroscopy)

(19) Quantitative nuclear-magnetic resonance (NMR) spectroscopy was used to quantify the comonomer content of the polymer Quantitative 13C{1H} NMR spectra recorded in the molten-state using a Bruker Advance III 500 NMR spectrometer operating at 500.13 and 125.76 MHz for 1H and 13C respectively. All spectra were recorded using a 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. {[1], [2], [6]} Standard single-pulse excitation was employed utilising the transient NOE at short recycle delays of 3 s {[1], [3]} and the RS-HEPT decoupling scheme {[4], [5]}. A total of 1024 (1 k) transients were acquired per spectrum. This setup was chosen due its high sensitivity towards low comonomer contents. Quantitative 13C{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 (S+) at 30.00 ppm {[9]}. Characteristic signals corresponding to the incorporation of 1-hexene were observed {[9]} and all contents calculated with respect to all other monomers present in the polymer.
H=I*B4

(20) With no other signals indicative of other comonomer sequences, i.e. consecutive comonomer incorporation, observed the total 1-hexene comonomer content was calculated based solely on the amount of isolated 1-hexene sequences:
Htotal=H

(21) Characteristic signals resulting from saturated end-groups were observed. The content of such saturated end-groups was quantified using the average of the integral of the signals at 22.84 and 32.23 ppm assigned to the 2 s and 2 s sites respectively:
S=(½)*(I2S+I3S)

(22) The relative content of ethylene was quantified using the integral of the bulk methylene (δ+) signals at 30.00 ppm:
E=(½)*Iδ+

(23) The total ethylene comonomer content was calculated based the bulk methylene signals and accounting for ethylene units present in other observed comonomer sequences or end-groups:
Etotal=+(5/2)*B+(3/2)*S

(24) The total mole fraction of 1-hexene in the polymer was then calculated as:
fH=(Htotal/(Etotal+Htotal)

(25) The total comonomer incorporation of 1-hexene in mole percent was calculated from the mole fraction in the usual manner:
H[mol %]=100*fH

(26) 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)*28.05)) [1] Klimke, K., Parkinson, M, Piel, C., Kaminsky, W., Spiess, Wilhelm, M., Macromol. Chem. Phys. 2006; 207:382. [2] Parkinson, M., Klimke, K., Spiess, H. W., Wilhelm, M., Macromol. Chem. Phys. 2007; 208:2128. [3] Pollard, M., Klimke, K., Graf, R., Spiess, H. W., Wilhelm, M., Sperber, O., Piel, C., Kaminsky, W., Macromolecules 2004; 37:813. [4] Filip, X., Tripon, C., Filip, C., J. Mag. Resn. 2005, 176, 239 [5] Griffin, J. M., Tripon, C., Samoson, A., Filip, C., and Brown, S. P., Mag. Res. in Chem. 2007 45, Si, S198 [6] Castignolles, P., Graf, R., Parkinson, M., Wilhelm, M., Gaborieau, M., Polymer 50 (2009) 2373 [7] Zhou, Z., Kuemmerle, R., Qiu, X., Redwine, D., Cong, R., Taha, A., Baugh, D. Winniford, B., J. Mag. Reson. 187 (2007) 225 [8] Busico, V., Carbonniere, P., Cipullo, R., Pellecchia, R., Severn, J., Talarico, G., Macromol. Rapid Commun. 2007, 28, 1128 [9] J. Randall, Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201.
Draw Down Ratio (DDR):

(27) Speed of the haul off/Speed of the extruder (represents MD orientation)

(28) It indicates the final thickness reduction in the melt after blowing. It is the ratio between the speed of the haul off over the speed of the extruder and often estimated by using the following equation:
DDR=Width of the die gap/(Film thickness×BUR)

(29) A drawdown ratio greater than 1 indicates that the melt has been pulled away from the die faster than it issued from the die. The film has been thinned and possesses an orientation in the machine direction (MD).

(30) Blow Up Ratio (BUR):

(31) Diameter of the bubble/Diameter of the die (represents TD orientation)

(32) BUR indicates the increase in the bubble diameter over the die diameter. A blow-up ratio greater than 1 indicates the bubble has been blown to a diameter greater than that of the die orifice. The film has been thinned and possesses an orientation in the transverse direction (TD).

(33) Peak Force Penetration Energy

(34) Determination of Instrumented Puncture Impact of the Films According to ISO 7765-2:

(35) The method used to assess the behavior of plastic films in impact stress perpendicular to the film plane and allowed by electronic acquisition of measured values, the energy absorption capacity, the puncture force and the compare deformability of the films.

(36) In order to assess the puncture impact properties of the plastic film, the film specimen is punctured at its centre using a non-lubricated striker, perpendicularly to the test-specimen surface, at a nominally uniform velocity of 4.4 m/s and 23° C. The test specimen is clamped in position during the test (support ring diameter of 40 mm). The force-deflection or force-time diagram is recorded electronically by the instrumented striker with a diameter of 20 mm. From these force-deflections several features and parameters of the material behaviour can be inferred, such as

(37) Peak Force is the maximum force occurring during the test in Newtons (N)

(38) Deformation at peak force: is the deformation that occurs at the peak force in millimetres (mm)

(39) Energy to peak force is the area under the force-deflection curve up to the deflection at peak force in Joules (J)

(40) Total Penetration Energy: The total energy expended in penetrating the test specimen in Joules (J)

(41) For normalized values, the respective parameter is divided by the film thickness in millimetres.

(42) Tear resistance (determined as Elmendorf tear (N): Applies for the measurement both in machine direction and in transverse direction. The tear strength is measured using the ISO 6383/2 method. The force required to propagate tearing across a film sample is measured using a pendulum device. The pendulum swings under gravity through an arc, tearing the specimen from pre-cut slit. The specimen is fixed on one side by the pendulum and on the other side by a stationary clamp. The tear resistance is the force required to tear the specimen. The relative tear resistance (N/mm) is then calculated by dividing the tear resistance by the thickness of the film.

(43) Catalyst Preparation

(44) Complex Preparation:

(45) 87 kg of toluene was added into the reactor. Then 45.5 kg Bomag A (Butyoctyl magnesium) in heptane was also added in the reactor. 161 kg 99.8% 2-ethyl-1-hexanol was then introduced into the reactor at a flow rate of 24-40 kg/h. The molar ratio between BOMAG-A and 2-ethyl-1-hexanol was 1:1.83.

(46) Solid Catalyst Component Preparation:

(47) 275 kg silica (ES747JR of Crossfield, having average particle size of 20 □m) activated at 600° C. in nitrogen was charged into a catalyst preparation reactor. Then, 411 kg 20% EADC (2.0 mmol/g silica) diluted in 555 litres pentane was added into the reactor at ambient temperature during one hour. The temperature was then increased to 35° C. while stirring the treated silica for one hour. The silica was dried at 50° C. for 8.5 hours. Then 655 kg of the complex prepared as described above (2 mmol Mg/g silica) was added at 23° C. during ten minutes. 86 kg pentane was added into the reactor at 22° C. during ten minutes. The slurry was stirred for 8 hours at 50° C. Finally, 52 kg TiCl4 was added during 0.5 hours at 45° C. The slurry was stirred at 40° C. for five hours. The catalyst was then dried by purging with nitrogen.

(48) Polymerization:

Inventive Examples IE1-IE2

(49) A loop reactor having a volume of 50 d.sup.3 was operated at a temperature of 70° C. and a pressure of 63 bar. Into the reactor were ethylene, 1-butene, propane diluent and hydrogen so that the feed rate of ethylene was 2.0 kg/h, hydrogen was 5.0 g/h, 1-butene was 80 g/h and propane was 50 kg/h. Also 11 g/h of a solid polymerization catalyst component produced as described above was introduced into the reactor together with triethylaluminium cocatalyst so that the molar ratio of Al/Ti was about 15. The production rate was 1.9 kg/h. A stream of slurry was continuously withdrawn and directed to a loop reactor having a volume of 150 dm.sup.3 and which was operated at a temperature of 85° C. and a pressure of 61 bar. Into the reactor were further fed additional ethylene, propane diluent, 1-butene comonomer and hydrogen so that the ethylene concentration in the fluid mixture was 2.9-5.1% by mole, the hydrogen to ethylene ratio was 250-1000 mol/kmol, the 1-butene to ethylene ratio was 300-3300 mol/kmol and the fresh propane feed was 41 kg/h. The production rate was 7-21 kg/h.

(50) A stream of slurry from the reactor was withdrawn intermittently and directed into a loop reactor having a volume of 350 dm3 and which was operated at 85° C. temperature and 54 bar pressure. Into the reactor was further added fresh propane feed of 69 kg/h and ethylene, 1-butene and hydrogen so that the ethylene content in the reaction mixture was 19-4.7 mol %, the molar ratio of 1-butene to ethylene was 520-1260 mol/kmol and the molar ratio of hydrogen to ethylene was 230-500 mol/kmol. The production rate was 13-26 kg/h. The slurry was withdrawn from the loop reactor intermittently by using settling legs and directed to a flash vessel operated at a temperature of 50° C. and a pressure of 3 bar. From there the polymer was directed to a fluidized bed gas phase reactor operated at a pressure of bar and a temperature of 80° C. Additional ethylene, 1-hexene comonomer, nitrogen as inert gas and hydrogen were added so that the ethylene content in the reaction mixture was 13-25 mol-%, the ratio of hydrogen to ethylene was 4-33 mol/kmol and the molar ratio of 1-hexene to ethylene was 7-370 mol/kmol. The polymer production rate in the gas phase reactor was 43-68 kg/h and thus the total polymer withdrawal rate from the gas phase reactor was about 115 kg/h. The polymer powder was mixed under nitrogen atmosphere with 500 ppm of Ca-stearate and 1200 ppm of Irganox B225. Then it was compounded and extruded under nitrogen atmosphere to pellets by using a CIMP90 extruder so that the SEI was 230 kWh/ton and the melt temperature 260° C.

(51) The polymers in table 2 were converted into 25 μm films on a Collin monolayer film extruder applying a draw down ratio (DDR) of 30.

(52) Machine-settings: L/D ratio: 30; die gap: 1.5 mm, die diameter: 60, blow up ratio (BUR) 2.5; frost line height: 120 mm.

(53) Temperature Profile:

(54) MFR5>1.2-2.0: 80 160 180 180 180 180 180 180 180° C.

(55) MFR5>2.0-5.0: 80 150 160 160 160 160 160 160 160° C.

(56) The 25 micron films are then stretched in the machine direction at a roller temperature of 22° C. Stretching was carried out using a monodirectional stretching machine manufactured by Hosokawa Alpine AG in Augsburg/Germany. The film obtained from blown film extrusion was pulled into the orientation machine then stretched between two sets of nip rollers where the second pair runs at higher speed than the first pair resulting in the desired draw ratio. Stretching is carried out with the draw ratios presented in Table 3. After exiting the stretching machine the film is fed into a conventional film winder where the film is slit to its desired width and wound to form reels.

(57) TABLE-US-00002 TABLE 1 characteristics of materials used for the study LLDPE Density, MFR5, MF material Modality Comonomer kg/m.sup.3 g/10 min g/10 min. IE1 Bimodal C4-loops/ 920 1.9 C6-GPR IE2 Bimodal C4-loops/ 917 2.3 C6-GPR Dowlex C8 920 1.0 2045S FK1820A-02 Bimodal 918 1.5

(58) TABLE-US-00003 TABLE 2 physical parameters reflecting the polymer structure of LLDPE Parameters Unit IE1 IE2 Loop 1 density kg/m.sup.3 951.8 951.9 Loop 1 MFR.sub.2 g/10 min 189 206 Loop 2 density kg/m.sup.3 952.1 953 Loop 2 MFR.sub.2 g/10 min 240 348 GPR split % 58.1 58.1 GPR density kg/m.sup.3 896.9 891.4 Pellet density kg/m.sup.3 920 917 Pellet MFR.sub.5 g/10 min 1.9 2.3

(59) TABLE-US-00004 TABLE 3 IE1 IE2 Dowlex 2045S FK1820A-02 MFR2 1.0 1.5 MFR5 1.9 2.3 Density 920 917.2 920 918 Before MDO Stretching BUR — 1:2.5 1:2.5 1:2.5 1:2.5 Blown film thickness μm 25 μm 25 μm 25 μm 25 μm melt T ° C. ° C. 223 222 228 230 melt pressure before bar 155 141 169 144 screw speed rpm 70 75 66 78 Take-off speed m/min 25.9 26.0 26.3 25.6 FLH, mm mm 700 600 700 700 Puncture, ISO 7765-2 Peak Force N 37.6 38.7 30.4 39.0 Deformation @ Peak Force mm 32.2 44 26.7 61.1 Total Penetration Energy J 0.9 1.3 0.6 2.2 Film thickness mm 0.025 0.023 0.023 0.023 Normalised Peak Force N/mm 1505.7 1680.8 1322.7 1696.4 Normalized Energy to Peak Force J/mm 32 51 23.5 76 Normalized Total Penetration Energy J/mm 37.7 57 24.5 96.4 Tear Elmendorf, ISO6383-2 MD Relative Tear Resistance N/mm 37.97 40.87 111.55 136.2 Tear Elmendorf, ISO6383-2 TD Relative Tear Resistance N/mm 315.75 321.17 239.63 160.45

(60) TABLE-US-00005 TABLE 4 Film testing after MDO Stretching 1:2 IE1 IE2 Dowlex 2045S FK1820A-02 MDO Stretch 1:2 Initial thickness μm 25 25 25 25 Final thickness μm 18 20 17 20 Stretch Ratio 1:2 1:2 1:2 1:2 Initial Width mm 600 600 600 600 Final Width mm 350 350 350 350 T ° C. Stretching Roll ° C. 22 22 22 22 Puncture, ISO7765-2 Peak Force N 39.1 39.2 23.9 26.1 Deformation @ Peak Force mm 46.5 54.7 19.8 21.6 Total Penetration Energy J 1.3 1.4 0.4 0.4 Film thickness μm 15 15 16 16 Normalised Peak Force N/mm 2610 2615.9 1491.9 1633.5 Normalized Energy to Peak Force J/mm 82.6 93.8 18.8 22.1 Normalized Total Penetration Energy J/mm 84.6 94.7 25.5 26 Tear Elmendorf, ISO6383-2 MD Relative Tear Resistance N/mm 129 104.39 108.94 53.17 Tear Elmendorf, ISO6383-2 TD Relative Tear Resistance N/mm 478.76 411.02 417.44 362.9

(61) TABLE-US-00006 TABLE 5 Film testing after MDO Stretching 1:3 IE1 IE2 Dowlex 2045S FK1820A-02 MDO Stretch 1:3 Initial thickness μm 25 25 25 25 4.4 m/s, 23° C. Final thickness μm ~12.5 ~12.5 ~12.5 ~12.5 Stretch Ratio 1:3 1:3 1:3 1:3 Initial Width mm 600 600 600 600 Final Width mm 350 350 350 350 T ° C. Stretching Roll ° C. 22 22 22 22 Puncture, ISO7765-2 Peak Force N 36.1 35.3 22.1 26.1 Peak Force SD 1.1 2.7 1.8 3.1 Deformation @ Peak Force mm 22.3 33.1 20 17.8 Total Penetration Energy J 0.6 0.8 0.3 0.3 Film thickness μm 12 12 2 12 Normalised Peak Force N/mm 3007.4 2942.6 1842.7 2175 Normalized Energy to Peak Force J/mm 32.3 59.8 22 21 Normalized Total Penetration Energy J/mm 52.2 67.9 24.7 27 Tear Elmendorf, ISO6383-2 MD Relative Tear Resistance N/mm 194.91 198.45 108.57 99.05 Tear Elmendorf, ISO6383-2 TD Relative Tear Resistance N/mm 411.7 419.41 371.63 321.64

(62) TABLE-US-00007 TABLE 6 Summary IE1 IE2 Dowlex 2045S FK1820A-02 Before stretching Normalised Peak Force N/mm 1505.7 1680.8 1322.7 1696.4 Normalized Energy to Peak Force J/mm 32 51 23.5 76 Normalized Total Penetration Energy J/mm 37.7 57 24.5 96.4 1:2 stretch Normalised Peak Force N/mm 2610 2615.9 1491.9 1633.5 Normalized Energy to Peak Force J/mm 82.6 93.8 18.8 22.1 Normalized Total Penetration Energy J/mm 84.6 94.7 25.5 26 1:3 stretch Normalised Peak Force N/mm 3007.4 2942.6 1842.7 2175 Normalized Energy to Peak Force J/mm 32.3 59.8 22 21 Normalized Total Penetration Energy J/mm 52.2 67.9 24.7 27 Materials show major increases in peak force, and penetration energy.

(63) TABLE-US-00008 TABLE 7 Data in full GPR GPR split Loop1 Loop1 split Loop2 Loop2 GPR Powder Powder GPR Pellet Pellet Pellet FRR Final GPR Lot 1-2 Density MFR2 2-2 Density MFR2 Split Density MFR5 MFR21 Density MFR5 MFR21 21/5 MFR2 Density IE1 16.9 951.8 189 22.8 952.1 240 58.1 916.5 1.73 43 920 1.9 45.8 24.11 0.49415 896.9 IE2 16.7 951.9 206 23 953 348 58.1 916.4 0.61 21 917.2 2.3 57.2 24.87 0.59818 891.4