PROCESS FOR PREPARING POLYMER COMPOSITIONS

Abstract

The present invention relates to an olefin polymerization process, wherein propylene and a C4 to C10 -olefin monomer, preferably 1-butene- and optionally ethylene are reacted in the presence of a Ziegler-Natta catalyst so as to obtain a polypropylene, wherein the polypropylene comprises C4 to C10 -olefin, preferably 1-butene-derived comonomer units in an amount of from 0,5 to 15 wt % and ethylene-derived comonomer units in an amount of 0 to 3 wt %, and wherein the Ziegler-Natta catalyst comprises i) an external donor of the formula (I): (R.sup.3).sub.z(R.sup.2O).sub.ySi(R.sup.1).sub.x, and ii) a solid catalyst component being free of external carrier material.

Claims

1. An olefin polymerization process, wherein propylene and C4 to C10 -olefin and optionally ethylene are reacted in the presence of a Ziegler-Natta catalyst so as to obtain a propylene polymer composition, wherein the polypropylene comprises C4 to C10 -olefin-derived comonomer units in an amount of from 0.5 wt % to 15 wt % and ethylene-derived comonomer units in an amount of 0 wt % to 3 wt %, and the Ziegler-Natta catalyst comprises i) an external donor of the following formula (I):
(R.sup.3).sub.z(R.sup.2O).sub.ySi(R.sup.1).sub.x(I) wherein x is 1; y is 2 or 3; and z is 0 or 1; under the provision that x+y+z=4; R.sup.1 is an organic residue of the following formula (II): ##STR00009## wherein the carbon atom bonded to the Si atom is a tertiary carbon atom and each of the residues R.sup.4, R.sup.5 and R.sup.6 bonded to the tertiary carbon atom is, independently from each other, a C.sub.1-4 alkyl, or two of R.sup.4, R.sup.5 and R.sup.6, together with the tertiary carbon atom C they are attached to can be part of a carbocycle of 4-10 carbon atoms; R.sup.2 is a linear C.sub.1-4 alkyl R.sup.3 is a C.sub.1-4 alkyl and ii) a solid Ziegler-Natta catalyst component, which is free of any external carrier material.

2. The process according to claim 1, wherein y is 2 or 3, z is 0 or 1, R.sup.2 is a linear C.sub.1-4 alkyl R.sup.3 is C.sub.1-4 alkyl, R.sup.4, R.sup.5 and R.sup.6 are independently from each other linear C.sub.1-4 alkyl.

3. The process according to claim 1, wherein the propylene polymer composition comprises 2 to 12 wt % C4 to C10 -olefin derived comonomer units and optionally 0.5 wt % to 2.5 wt % of ethylene.

4. The process according to claim 1, wherein the propylene polymer composition is a propylene-1-butene copolymer or propylene-1-butene-ethylene terpolymer composition.

5. The process according to claim 1, wherein the propylene-1-butene copolymer has an amount of xylene solubles of 3.5 wt % or less;

6. The process according to claim 1, wherein particles of the solid Ziegler-Natta catalyst component ii) have a surface area less than 20 m.sup.2/g.

7. The process according to claim 1, wherein the solid Ziegler-Natta catalyst component ii) is obtainable or obtained by the method where no external carrier material is used and comprising the steps: A) preparing a solution of Group 2 metal complex by reacting a Group 2 metal alkoxy compound and an electron donor or a precursor thereof in a reaction medium comprising C.sub.6-C.sub.10 aromatic liquid; B) reacting said Group 2 metal complex with at least one compound of a transition metal of Group 4 to 6, and C) obtaining the solid catalyst component particles.

8. The process according to claim 1, wherein the solid Ziegler-Natta catalyst component ii) is free of any phthalic compounds.

9. The process according to claim 1, wherein the solid Ziegler-Natta catalyst component ii) is prepared according to the procedure comprising: a) providing a solution of: a.sub.1) at least a Group 2 metal alkoxy compound (Ax), which is the reaction product of a Group 2 metal compound and an alcohol (A) comprising in addition to the hydroxyl moiety at least one ether moiety optionally in an organic liquid reaction medium; or a.sub.2) at least a Group 2 metal alkoxy compound (Ax), which is the reaction product of a Group 2 metal compound and an alcohol mixture of the alcohol (A) and a monohydric alcohol (B) of formula ROH, optionally in an organic liquid reaction medium; or a.sub.3) a mixture of the Group 2 metal alkoxy compound (Ax) and a Group 2 metal alkoxy compound (Bx), which is the reaction product of a Group 2 metal compound and the monohydric alcohol (B), optionally in an organic liquid reaction medium; or a.sub.4) Group 2 metal alkoxy compound of formula M(OR.sub.1).sub.n(OR.sub.2).sub.mX.sub.2-n-m or mixture of Group 2 alkoxides M(OR.sub.1).sub.nX.sub.2-n, and M(OR.sub.2).sub.mX.sub.2-m, where M is Group 2 metal, X is halogen, R.sub.1 and R.sub.2 are different alkyl groups of C.sub.2 to C.sub.16 carbon atoms, and 0n<2; 0m<2 and n+m2, provided that both n and m0, 0<n2 and 0<m2; and b) adding said solution from step a) to at least one compound of a transition metal of Group 4 to 6 and c) obtaining the solid catalyst component particles, and adding a non-phthalic internal electron donor at any step prior to step c).

10. The process according to claim 1, wherein the solid Ziegler-Natta catalyst component is prepared by an emulsion-solidification method.

11. The process according to claim 1, wherein the propylene polymer composition is prepared in a process comprising a liquid phase polymerization.

12. A propylene polymer composition, obtainable by the process according to claim 1.

13. A film, comprising the propylene polymer composition according to claim 12.

14. The film according to claim 13, wherein the film is a blown film, a cast film, a biaxially oriented film, or any combination thereof.

15. The film according to claim 13, wherein the film is a multi-layered biaxially oriented film comprising a sealing layer.

16-17. (canceled)

Description

EXAMPLES

Measuring Methods

[0123] If not otherwise indicated, the parameters mentioned in the present application are measured by the methods outlined below.

1. Comonomer Content by IR Spectroscopy

[0124] The content of 1-butene was measured by quantitative Fourier transform infrared spectroscopy (FTIR), as described in the following.

[0125] Before measuring, the stabilized powder was pressed in a press as follows:

[0126] Press Settings to Homogenise the Material: [0127] press temperature: 210 C. [0128] melting time: 90 sec [0129] cooling rate: 12 C./min [0130] de-moulding temperature: between 35 and 45 C.

TABLE-US-00001 step 1 2 (cooling) duration (sec.) 90 900 Temperature ( C.) 210 30 pressure (bar) 0 0

Press Settings for IR Plate:

[0131] press temperature: 210 C. [0132] melting time: 45 sec [0133] press pressure: 3 steps (10/30/90 bar) [0134] cooling rate: 12 C./min [0135] de-moulding temperature: between 35 and 45 C.

TABLE-US-00002 step 1 2 3 4 5 (cooling) duration (sec.) 45 15 15 15 900 Temperature ( C.) 210 210 210 210 30 pressure (bar) 0 10 30 90 90

[0136] The films had a thickness of between 260 and 300 m

[0137] Spectra have been recorded in transmission mode. Relevant instrument settings include a spectral window of 5000 to 400 wave-numbers (cm.sup.1), a resolution of 2.0 cm.sup.1 and 16 scans. The butene content of the propylene-butene copolymers was determined using the baseline corrected peak maxima of a quantitative band at 767 cm.sup.1, with the baseline defined from 1945 to 625 cm.sup.1. The comonomer content in mol % was determined using a film thickness method using the intensity of the quantitative band I.sub.767 (absorbance value) and the thickness (T, in cm) of the pressed film using the following relationship:

mol % C4=[(I.sub.767/T)1.8496]/1.8233(Equation 1)

[0138] In the case of C3C4C2 terpolymers, the comonomer content was determined using the baseline corrected peak maxima of the quantitative bands at 767 cm.sup.1 for butene and at 732 cm.sup.1 for ethylene with the baseline defined from 1945 to 625 cm.sup.1. The comonomer content in mol % was determined using a film thickness method using the intensity of the quantitative bands (I.sub.767 and I.sub.732 absorbance values) and the thickness (T, in cm) of the pressed film using the following relationships:

mol % C4=[(I.sub.767/T)3.1484]/1,5555(Equation 2)

mol % C2=[(I.sub.732/T)0,6649]/1,2511(Equation 3)

2. Amount of Xylene Solubles (XS, wt %)

[0139] The amount of xylene solubles was determined based on the principles of ISO 16152; first edition; 2005-Jul. 2001. at 25 C., but using the following conditions: A weighed amount of a sample was dissolved under reflux conditions for 1 h. The solution was first cooled for 60 min at room temperature and then maintained at 25 C. for 200 min to achieve the complete crystallization of the insoluble fraction. After filtration and solvent evaporation the amount of xylene soluble fraction was gravimetrically determined.

3. MFR.SUB.2

[0140] Melt flow rate MFR.sub.2 was measured according to ISO 1133 (230 C., 2.16 kg load).

4. Melting Temperature

[0141] The melting points (Tm) were determined according to ISO standards 11357 on a DSC Q2000 T A Instrument, by placing a 5-7 mg polymer sample, into a closed DSC aluminum pan, heating the sample from 10 C. to 225 C. at 10 C./min, holding for 10 min at 225 C., cooling from 225 C. to 10 C., holding for 5 min at 10 C., heating from 10 C. to 225 C. at 10 C./min. The reported values are those of the peak of the endothermic heat flow determined from the second heating scan.

5. ICP Analysis

[0142] The elemental analysis of a catalyst was performed by taking a solid sample of mass, M, cooling over dry ice. Samples were diluted up to a known volume, V, by dissolving in nitric acid (HNO.sub.3, 65%, 5% of V) and freshly deionised (DI) water (5% of V). The solution was further diluted with DI water up to the final volume, V, and left to stabilize for two hours.

[0143] The analysis was run at room temperature using a Thermo Elemental iCAP 6300 Inductively Coupled Plasma-Optical Emmision Spectrometer (ICP-OES) which was calibrated using a blank (a solution of 5% HNO.sub.3), and standards of 0.5 ppm, 1 ppm, 10 ppm, 50 ppm, 100 ppm and 300 ppm of Al, Mg and Ti in solutions of 5% HNO.sub.3.

[0144] Immediately before analysis the calibration is resloped using the blank and 100 ppm standard, a quality control sample (20 ppm Al, Mg and Ti in a solution of 5% HNO.sub.3 in DI water) is run to confirm the reslope. The QC sample is also run after every 5.sup.th sample and at the end of a scheduled analysis set.

[0145] The content of Mg was monitored using the 285.213 nm line and the content for Ti using 336.121 nm line. The content of aluminium was monitored via the 167.079 nm line, when Al concentration in ICP sample was between 0-10 ppm (calibrated only to 100 ppm) and via the 396.152 nm line for Al concentrations above 10 ppm. The reported values are an average of three successive aliquots taken from the same sample and are related back to the original catalyst by inputting the original mass of sample and the dilution volume into the software.

6. Surface area: BET with N2 gas ASTM D 3663, apparatus Micromeritics Tristar 3000: sample preparation at a temperature of 50 C., 6 hours in vacuum.
7. Pore volume was measured according to ASTM 4641.
8. Mean particle size is given in m and measured with Coulter Counter LS200 at room temperature with n-heptane as medium. The given mean particle size is arithmetic mean size and is based on volumetric amount.

Polymerisation Experiments

[0146] The external donors as disclosed in Table 1 were used in the examples. In Inventive examples external donors ID0, ID1 and ID3 were used, and in comparative examples external donors D, C and CD4 were used.

TABLE-US-00003 TABLE 1 Acro- nym structure name CAS# D [00003] Dicyclopentyl dimethoxy silane 126990-35-0 C [00004] Cyclo- hexyl(methyl) dimethoxy silane 17865-32-6 CD4 [00005] di-tert-butyl- dimethoxy silane 79866-98-1 ID0 [00006] tert-butyl trimethoxy silane 18395-29-4 ID1 [00007] trimethoxy(1,1,2- trimethylpropyl) silane or thexyl trimethoxy silane 142877-45-0 ID3 [00008] tert-butyl di- methoxy(methyl) silane 18293-81-7

[0147] The following solid Ziegler-Natta catalyst components were used in the Examples:

Catalyst 1

[0148] The solid catalyst component was prepared by emulsion-solidification method according to Example 8 of WO 2004/029112, except that diethylaluminum chloride was used as an aluminium compound instead of triethylaluminum. Ti content was 2.9 wt-%. Surface area is <5 m.sup.2/g (below the detection limit).

Catalyst 2

[0149] The solid catalyst component was prepared by emulsion-solidification method as follows:

[0150] 3.4 litre of 2-ethylhexanol and 810 ml of propylene glycol butyl monoether (in a molar ratio 4/1) were added to a 20 l reactor. Then 7.8 litre of a 20% solution in toluene of BEM (butyl ethyl magnesium) provided by Crompton GmbH, were slowly added to the well stirred alcohol mixture. During the addition the temperature was kept at 10 C. After addition the temperature of the reaction mixture was raised to 60 C. and mixing was continued at this temperature for 30 minutes. Finally after cooling to room temperature the obtained Mg-alkoxide was transferred to a storage vessel. [0151] 21.2 g of Mg alkoxide prepared above was mixed with 4.0 ml bis(2-ethylhexyl) citraconate for 5 min. After mixing the obtained Mg complex was used immediately in the preparation of the catalyst component. [0152] 19.5 ml of titanium tetrachloride was placed in a 300 ml reactor equipped with a mechanical stirrer at 25 C. Mixing speed was adjusted to 170 rpm. 26.0 g of Mg-complex prepared above was added within 30 minutes keeping the temperature at 25 C. 3.0 ml of Viscoplex 1-254 and 1.0 ml of a toluene solution with 2 mg Necadd 447 was added. Then 24.0 ml of heptane was added to form an emulsion. Mixing was continued for 30 minutes at 25 C., after which the reactor temperature was raised to 90 C. within 30 minutes. The reaction mixture was stirred for a further 30 minutes at 90 C. Afterwards stirring was stopped and the reaction mixture was allowed to settle for 15 minutes at 90 C. The solid material was washed 5 times: Washings were made at 80 C. under stirring for 30 min with 170 rpm. After stirring was stopped the reaction mixture was allowed to settle for 20-30 minutes and followed by siphoning.
Wash 1: Washing was made with a mixture of 100 ml of toluene and 1 ml donor
Wash 2: Washing was made with a mixture of 30 ml of TiCl4 and 1 ml of donor.
Wash 3: Washing was made with 100 ml of toluene.
Wash 4: Washing was made with 60 ml of heptane.
Wash 5: Washing was made with 60 ml of heptane under 10 minutes stirring.

[0153] Afterwards stirring was stopped and the reaction mixture was allowed to settle for 10 minutes while decreasing the temperature to 70 C. with subsequent siphoning, followed by N2 sparging for 20 minutes to yield an air sensitive powder. Ti content was 3.76 wt-%. The catalyst was prepared without any phthalic compounds. Surface area is <5 m.sup.2/g (below the detection limit).

Catalyst 3 (Comparative)

[0154] MgCl.sub.2 supported catalyst-comparative catalyst

[0155] First, 0.1 mol of MgCl.sub.23 EtOH was suspended under inert conditions in 250 ml of decane in a reactor at atmospheric pressure. The solution was cooled to the temperature of 15 C. and 300 ml of cold TiCl.sub.4 was added while maintaining the temperature at said level. Then, the temperature of the slurry was increased slowly to 20 C. At this temperature, 0.02 mol of dioctylphthalate (DOP) was added to the slurry. After the addition of the phthalate, the temperature was raised to 135 C. during 90 minutes and the slurry was allowed to stand for 60 minutes. Then, another 300 ml of TiCl.sub.4 was added and the temperature was kept at 135 C. for 120 minutes. After this, the catalyst was filtered from the liquid and washed six times with 300 ml heptane at 80 C. Then, the catalyst was filtered and dried. Catalyst and its preparation concept is described in general e.g. in patent publications EP491566, EP591224 and EP586390. Ti content in the catalyst component was 1.9 wt-%.

Description of Catalyst Pre-Activation

[0156] In the glove-box, a defined amount of catalyst previously slurried in white oil, was well homogenized at least for 20 min by shaking. Then the chosen amount of the catalyst-oil slurry sample was drawn with a syringe and transferred into a 20 ml stainless steel vial with 10 ml heptane. 80% of the total TEA (triethylaluminium) solution (0,62 molar solution in heptane provided by Chemtura) and the whole donor amount (0.3 molar solution in heptane) were mixed for 5 minutes in an appropriate syringe and injected into the catalyst vial which was then mounted on the autoclave.

Polymerisation Procedures

[0157] In all Examples, triethylaluminium (TEA) was used as the organometallic cocatalyst.

Propylene-1-Butene Copolymerisation

[0158] A stirred autoclave reactor equipped with a ribbon stirrer, with a volume of 21,2-L containing 0.2 bar-g propylene pressure was filled with 3.45 kg propylene and the desired amount of 1-butene. After adding 20% of the total TEA solution by flushing it into the reactor with 250 g propylene, the chosen amount of H2 was added via mass flow controller (MFC). The solution was stirred at 20 C. and 250 rpm. After a total contact time of 5 min between the oil catalyst slurry in heptane and the TEA/Donor solution, the catalyst slurry was injected by means of 250 g propylene. Pre-polymerisation was run for 10 min. The polymerisation temperature was then increased to 75 C. and kept constant throughout the polymerisation experiment. The reactor pressure was also kept constant by feeding propylene throughout the polymerisation experiment at 75 C. The polymerisation time was measured starting when the temperature reached 73. After 1 hour the reaction was stopped by adding 5 ml methanol, cooling the reactor and flashing the volatile components.

[0159] After purging the reactor twice with N2 and one vacuum/N2 cycle, the product was taken out and dried overnight in a fume hood. 100 g of the polymer was additivated with 0.2 wt % Ionol and 0.1 wt % PEPQ (dissolved in acetone) and then dried overnight in a hood plus 2 hours in a vacuum drying oven at 60 C.

Propylene-1-Butene-Ethylene Terpolymerisation

[0160] A stirred autoclave reactor equipped with a ribbon stirrer, with a volume of 21,2-L containing 0.2 bar-g propylene pressure was filled with 3.45 kg propylene and the chosen amount of 1-butene (see tables). Afterwards 20% of the total amount of TEA was injected in a stainless-steel vial having a total volume of about 2 ml. This vial was mounted on the reactor and the solution was injected into the reactor by flushing with 250 g propene. After a contact time of about 20 min between TEA and the monomers (at 20 C., 250 rpm), the catalyst vial (catalyst feeder) was mounted on the reactor. Then the chosen amount of H2 was added via mass flow controller (MFC) in the reactor. The solution was stirred at 250 rpm and 20 C. After a total contact time of 5 min between the catalyst oil slurry and the TEA/Donor solution in the catalyst feeder, the suspension was injected by flushing with 250 g propylene. Stirring speed was kept at 250 rpm and pre-polymerisation was run for 10 minutes at 20 C. The polymerisation temperature was then increased to 70 C. and kept constant throughout the polymerisation. During the reactor heating-up phase, a defined amount of ethylene was added (see Tables). The polymerisation time was measured starting when the reactor temperature reached 68 C. Ethylene was dosed continuously via MFC at a fixed rate and the reactor pressure was kept constant by feeding propylene throughout the polymerisation experiment at 70 C.

[0161] After 1 hour, the reaction was stopped by adding 5 ml methanol, cooling the reactor and flashing the volatile components. After purging the reactor twice with N2 and one vacuum/N2 cycle, the product was taken out and dried overnight in a fume hood. 100 g of the polymer was additivated with 0.2 wt % Ionol and 0.1 wt % PEPQ (dissolved in acetone) and then dried overnight in a hood plus 2 hours in a vacuum drying oven at 60 C.

[0162] The polymerization conditions and polymer properties of the propylene-1-butene copolymers are shown in Tables 2 and 3.

[0163] The polymerization conditions and polymer properties of the propylene-1-butene-ethylene terpolymers are shown in Tables 4 (4a and 4b) and 5.

Calculations:

[0164] The calculations for the C4 concentrations in the liquid phase were done by using the Aspen General VLE 8.2 model RRT.

[0165] The C4 concentration values used to estimate the reactivity ratio R was calculated according to the following equation:

Ratio C4/C3 w/w in liquid phase=(ratio C4/C3 w/w at start+ratio C4/C3 w/w at end of experiment)/2

[0166] The reactivity ratio R was calculated according to the following Equation:

Reactivity Ratio R=(ratio C4/C3w/w in polymer)/(ratio C4/C3w/w in liquid phase)

TABLE-US-00004 TABLE 2 Polymerization conditions in propylene-1-butene polymerization Av. calculated C4/C3 wt- ratio in Catalyst External Al/Ti Donor/Ti liquid phase Example component donor mol/mol mol/mol wt/wt InvEx1 1 ID0 250 25 0.25 InvEx2 1 ID3 250 25 0.26 InvEx3 2 ID0 100 20 0.25 InvEx4 2 ID3 100 20 0.26 CompEx1 1 D 250 25 0.25 CompEx2 1 CD4 250 25 0.26 CompEx3 2 D 100 20 0.25 CompEx4 2 CD4 100 20 0.25 CompEx5 3 D 250 25 0.26 CompEx6 3 ID0 250 25 0.26 CompEx7 3 ID3 250 25 0.26 CompEx8 3 CD4 250 25 0.26

TABLE-US-00005 TABLE 3 Polymer properties of propylene-1-butene copolymers and 1-butene reactivity ratio R C4 MFR.sub.2 total Catalyst External g/10 (IR) XS T.sub.m Example component Donor min wt % wt % C. R InvEx1 1 ID0 6.8 6.5 2.6 144.9 0.27 InvEx2 1 ID3 9.0 6.8 3.4 145.1 0.28 InvEx3 2 ID0 7.0 6.8 1.9 145.4 0.29 InvEx4 2 ID3 7.5 7.5 2.0 143.5 0.32 CompEx1 1 D 4.9 5.6 2.5 148.2 0.23 CompEx2 1 CD4 6.3 7.0 5.8 144.6 0.29 CompEx3 2 D 5.6 5.5 2.0 149.4 0.23 CompEx4 2 CD4 4.4 7.3 3.9 144.3 0.31 CompEx5 3 D 2.0 4.9 1.6 152.0 0.20 CompEx6 3 ID0 4.4 5.5 2.1 150.3 0.23 CompEx7 3 ID3 5.6 6.2 2.2 149.2 0.25 CompEx8 3 CD4 2 6.0 3.4 149.4 0.25

TABLE-US-00006 TABLE 4a Polymerization conditions (catalyst) in propylene-1-butene-ethylene terpolymerisation: TEA solution Total TEA TEA in precontact solution solution in Catalyst (0.62 molar (0.62 molar Donor amount purification Example External amount in C7) in C7) (0.3 molar) step Al/Ti Donor/Ti # Catalyst Donor mg ml ml ml mmol mol/mol mol/mol CompEx9 2 D 58.1 7.98 9.97 2.06 1.237 200 20 InvEx5 2 ID3 64.9 8.92 11.15 2.30 1.383 200 20 InvEx6 2 ID3 58.1 7.98 9.97 2.06 1.237 200 20 InvEx7 2 ID1 57.0 7.83 9.79 2.02 1.214 200 20

TABLE-US-00007 TABLE 4b Polymerization conditions in propylene-1-butene-ethylene terpolymerisation: average average calculated calculated C4/C3 C4/(C3 + C4) C3 dosed to C3 total C2 feed wt-ratio wt-ratio Catalyst keep pressure C3 total from scale and C4 total const flow C2 feed C2 feed in liquid in liquid activity Example H2 constant from scale flowcontrol from scale transition batch total phase phase yield kgPP/ # NL g g g g g g g g/g wt % g gcat/h CompEx9 15 1291 3965 5256 927 8 15 23 0.27 21.26 2323 40.0 InvEx5 13 1331 3965 5296 927 8 15 23 0.27 21.26 2490 38.3 InvEx6 13 1080 3965 5045 927 8 15 23 0.27 20.95 2070 35.6 InvEx7 13 1157 3965 5122 927 8 15 23 0.27 21.32 2444 42.9

TABLE-US-00008 TABLE 5 Polymer properties of propylene-1-butene-ethylene terpolymerisations and 1-butene reactivity ratio R Bulk C4 C2 External MFR2 density XS (IR) (IR) R T.sub.m T.sub.c M.sub.w Example Donor g/10 min g/ml wt % wt % wt % (C4/C3) C. C. g/mol M.sub.w/M.sub.n CompEx9 D 7.5 0.45 3.9 6.2 0.8 0.24 142.1 101.3 254500 7.1 InvEx5 ID3 10 0.46 3.4 7.7 0.8 0.31 136.2 97.9 231000 5.7 InvEx6 ID3 8.5 0.46 3.4 7.8 0.9 0.32 136.6 96.2 243000 5.7 InvEx7 ID1 7.9 0.45 2.9 8.2 0.7 0.33 136.5 96.1 280800 6.6

[0167] When evaluating a catalyst for its copolymerization performance, the most useful parameter to determine is the relative comonomer reactivity ratio R, which is defined as indicated above.

[0168] R is specific for a given catalyst and monomer pair and typically applies to the whole composition range. Since the concentration of 1-butene increases over the polymerization time while that of propylene decreases, there is a significant difference in liquid phase composition between start and end of the polymerisation experiment. For this reason, as liquid phase composition values, the average of the initial and final calculated values was used.

[0169] The values of R determined for propylene-1-butene polymerisations with the Ziegler-Natta catalyst comprising as the external donor donor D, R is 0,23 with the same catalyst components 1 and 2 as used in the inventive examples, and only 0,2 with supported catalyst component 3. The Ziegler-Natta catalyst comprising as the external donor donor ID0 or ID3 R is 0,27 to 0,32 with the catalyst components 1 and 2, and only 0,23 and 0,25 for supported catalyst component 3. These results show that the external donor of the present invention increases the 1-butene reactivity of the Ziegler-Natta catalyst and still the XS value is low. In those comparative examples where R is on the same level as in inventive examples (external donor is CD4), XS values are, however, clearly higher than in inventive examples. In all other comparative examples R is clearly lower than in inventive examples.

[0170] In terpolymer examples R is clearly lower in the comparative example (catalyst 2 and external donor D) than in the inventive examples (catalyst 2, external donors ID1 and ID3). XS is also higher in the comparative example.

[0171] As demonstrated above, the Ziegler-Natta catalyst comprising the external donor as defined in the present invention and a solid catalyst component being free of any external carrier material has a very high reactivity for 1-butene, thereby requiring less 1-butene in the monomer feed. This means that less unreacted 1-butene has to be removed from the final polymer, with the operability advantage of reducing the degassing time, and resulting in a higher throughput.