Process for the preparation of copolymers of propylene

Abstract

A process for the preparation of a copolymer of propylene and ethylene comprising polymerizing propylene and ethylene in the gas phase in the presence of a solid particulate catalyst free from an external carrier comprising: (i) a symmetrical complex of formula (I), wherein M is zirconium or hafnium; each X is a sigma ligand; L is a divalent bridge selected from R.sub.2C, R.sub.2CCR.sub.2, R.sub.2Si, R.sub.2SiSiR.sub.2, R.sub.2Ge, wherein each R is independently a hydrogen atom, C.sub.1-C.sub.20-alkyl, tri(C.sub.1-C.sub.20-alkyl)silyl, C.sub.6-C.sub.20-aryl, C.sub.7-C.sub.20-arylalkyl or C.sub.7-C.sub.20-alkylaryl; R.sup.2 is a C.sub.1-C.sub.20 hydrocarbyl radical; m is 2 to 5; R.sup.9 is a H or C.sub.1-C.sub.20 hydrocarbyl radical; R.sup.7 is a hydrogen atom or a C.sub.1-10 hydrocarbyl radical; n is 0 to 3; R.sup.1 is a C.sub.1-C.sub.20 hydrocarbyl radical and optionally two adjacent R.sup.1 groups taken together can form a further mono or multicyclic ring condensed to Ph ring optionally substituted by one or two groups R.sup.4; and R.sup.4 is a C.sub.1-C.sub.10 alkyl radical; and (ii) a cocatalyst, preferably comprising an organometallic compound of a Group 13 metal; wherein the xylene soluble fraction of the propylene ethylene copolymer has an ethylene content of at least 10 wt % and an intrinsic viscosity of at least 1.2 dl/g. ##STR00001##

Claims

1. A process for the preparation of a copolymer of propylene and ethylene comprising polymerising propylene and ethylene in the gas phase in the presence of a solid particulate catalyst free from an external carrier comprising: (i) a symmetrical complex of formula (I): ##STR00011## wherein M is zirconium or hafnium; each X is a sigma ligand; L is a divalent bridge selected from R.sub.2C, R.sub.2CCR.sub.2, R.sub.2Si, R.sub.2SiSiR.sub.2, R.sub.2Ge, wherein each R is independently a hydrogen atom, C1-C20-alkyl, tri(C1-C20-alkyl)silyl, C6-C20-aryl, C7-C20-arylalkyl or C7-C20-alkylaryl; R.sup.2 is a C1-C20 hydrocarbyl radical; m is 2 to 5; R.sup.9 is a H or C1-C20 hydrocarbyl radical; R.sup.7 is a hydrogen atom or a C.sub.1-10-hydrocarbyl radical; n is 0 to 3; R.sup.1 is a C1-C20 hydrocarbyl radical and optionally two adjacent R.sup.1 groups taken together can form a further mono or multicyclic ring condensed to Ph ring optionally substituted by one or two groups R.sup.4; and R.sup.4 is a C1-C10 alkyl radical; and (ii) a cocatalyst; wherein the xylene soluble fraction of the propylene ethylene copolymer has an ethylene content of at least 10 wt % and an intrinsic viscosity of at least 1.2 dl/g, and wherein the xylene soluble fraction of the copolymer of propylene and ethylene has an ethylene content of at least 20 wt %.

2. A process as claimed in claim 1 wherein the catalyst used is in solid particulate form free from an external carrier.

3. A process as claimed claim 1 wherein the catalyst is obtainable by a process in which (a) a liquid/liquid emulsion system is formed, said liquid/liquid emulsion system comprising a solution of the catalyst components (i) and (ii) dispersed in a solvent so as to form dispersed droplets; and (b) solid particles are formed by solidifying said dispersed droplets.

4. A process as claimed in claim 1 wherein the catalyst is prepared by obtaining a complex of formula (I) and a cocatalyst; forming a liquid/liquid emulsion system, which comprises a solution of catalyst components (i) and (ii) dispersed in a solvent, and solidifying said dispersed droplets to form solid particles.

5. A process as claimed in claim 1 wherein the copolymer of propylene and ethylene is a random propylene copolymer or heterophasic propylene copolymer.

6. A process as claimed in claim 1 wherein the gas phase polymerisation process takes place at a temperature of at least 60 C.

7. A process for the preparation of a copolymer of propylene and ethylene comprising: (A) polymerising propylene and optionally ethylene in bulk to form a propylene homopolymer component or propylene-ethylene random copolymer component in the presence of a solid particulate catalyst free from an external carrier comprising: (i) a symmetrical complex of formula (I): ##STR00012## wherein M is zirconium or hafnium; each X is a sigma ligand; L is a divalent bridge selected from R.sub.2C, R.sub.2CCR.sub.2, R.sub.2Si, R.sub.2SiSiR.sub.2, R.sub.2Ge, wherein each R is independently a hydrogen atom, C1-C20-alkyl, tri(C1-C20-alkyl)silyl, C6-C20-aryl, C7-C20-arylalkyl or C7-C20-alkylaryl; R.sup.2 is a C1-C20 hydrocarbyl radical; m is 2 to 5; each R.sup.9 is a H or C1-C20 hydrocarbyl radical; R.sup.7 is a hydrogen atom or a C.sub.1-10-hydrocarbyl radical; n is 0 to 3; R.sup.1 is a C1-C20 hydrocarbyl radical and optionally two adjacent R.sup.1 groups taken together can form a further mono or multicyclic ring condensed to Ph ring optionally substituted by one or two groups R.sup.4; and R.sup.4 is a C1-C10 alkyl radical; and (ii) a cocatalyst; (B) polymerising propylene and ethylene in the gas phase in the presence of the polymer prepared in step (A) and in the presence of the catalyst from step (A) so as to form a propylene ethylene copolymer component; wherein the xylene soluble fraction of the copolymer of propylene and ethylene has an ethylene content of at least 10 wt % and a intrinsic viscosity of at least 1.2 dl/g.

8. A process for the preparation of a copolymer of propylene and ethylene comprising: (A) polymerising propylene and optionally ethylene in bulk to form a propylene homopolymer component or a propylene ethylene random copolymer component in the presence of a solid particulate catalyst free from an external carrier comprising: (i) a symmetrical complex of formula (I): ##STR00013## wherein M is zirconium or hafnium; each X is a sigma ligand; L is a divalent bridge selected from R.sub.2C, R.sub.2CCR.sub.2, R.sub.2Si, R.sub.2SiSiR.sub.2, R.sub.2Ge, wherein each R is independently a hydrogen atom, C1-C20-alkyl, tri(C1-C20-alkyl)silyl, C6-C20-aryl, C7-C20-arylalkyl or C7-C20-alkylaryl; R.sup.2 is a C1-C20 hydrocarbyl radical; m is 2 to 5; each R.sup.9 is a H or C1-C20 hydrocarbyl radical; R.sup.7 is a hydrogen atom or a C.sub.1-10-hydrocarbyl radical; n is 0 to 3; R.sup.1 is a C1-C20 hydrocarbyl radical and optionally two adjacent R.sup.1 groups taken together can form a further mono or multicyclic ring condensed to Ph ring optionally substituted by one or two groups R.sup.4; and R.sup.4 is a C1-C10 alkyl radical; and (ii) a cocatalyst; (B) polymerising propylene and optionally ethylene in the gas phase in the presence of the polymer prepared in step (A) and in the presence of the catalyst from step (A) so as to form a propylene homopolymer or propylene ethylene copolymer component; (C) polymerising propylene and ethylene in the gas phase in the presence of the polymer prepared in step (B) and in the presence of the catalyst from step (B) so as to form a propylene ethylene copolymer component; wherein the xylene soluble fraction of the copolymer of propylene and ethylene has an ethylene content of at least 10 wt % and a intrinsic viscosity of at least 1.2 dl/g.

9. A process as claimed in claim 1 wherein the xylene soluble fraction of the copolymer of propylene and ethylene has an intrinsic viscosity of at least 1.7 dl/g.

10. A process as claimed in claim 1 wherein the xylene soluble fraction of the copolymer of propylene and ethylene has an MFR.sub.2 of 0.1 to 100 g/10 min.

11. A process as claimed in claim 1 wherein the xylene soluble fraction of the copolymer of propylene and ethylene has an IV(XS)>-0.032x(C2(XS))+2.82.

12. A process as claimed in claim 1 wherein the xylene soluble fraction of the copolymer of propylene and ethylene has a Charpy Impact strength at 23 C. of at least 10 kJ/m2.

13. A process as claimed in claim 1 wherein the xylene soluble fraction forms 10 to 60 wt % of the polymer.

14. A process as claimed in claim 1 wherein said complex is of formula (II) ##STR00014## wherein M is Zr or Hf; each X is a hydrogen atom, benzyl, OR, a halogen atom, or an R group; R is C.sub.1-10 alkyl or C.sub.6-10 aryl; L is methylene, ethylene or SiR.sup.8.sub.2; R.sup.8 is C1-10 alkyl, C.sub.6-10-aryl, C.sub.7-12-alkylaryl, or C.sub.7-12-arylalkyl; R.sup.2 is Me, CH.sub.2-Ph, CH.sub.2C(R.sup.3).sub.3-q(H).sub.q wherein R.sup.3 is a C.sub.1-6-alkyl group or together two R.sup.3 groups form a C.sub.3-7-cycloalkyl ring wherein said ring is optionally substituted by a C.sub.1-6 alkyl group and q can be 1 or 0; R.sup.7 is H or C.sub.1-3-alkyl; n is 0 to 2; preferably 1; each R.sup.1 is C.sub.1-10-alkyl; each R.sup.9 is H or C.sub.1-10-alkyl; m is 2 to 4; and wherein the two ligands forming the complex are identical.

15. A process as claimed in claim 1 wherein said complex is of formula (III) ##STR00015## in which: M is Zr; or Hf each R.sup.2 is Me, CH.sub.2-Ph, CH.sub.2C(R.sup.3).sub.3-q(H).sub.q wherein R.sup.3 is a C.sub.1-6-alkyl group or together two R.sup.3 groups form a C.sub.3-7-cycloalkyl ring wherein said ring is optionally substituted by a C.sub.1-6 alkyl group and q can be 1 or 0; L is SiR.sup.8.sub.2; R.sup.8 is C.sub.1-8 alkyl; each X is a halogen atom, methoxy, benzyl or methyl; n is 0 or 1; R.sup.1 is C.sub.1-6 alkyl; m is 3 or 4; and wherein the two ligands forming the complex are identical.

16. A process as claimed in claim 1 wherein said complex is of formula (IV) ##STR00016## wherein L is SiR.sup.8.sub.2; q is 1 or 2; R.sup.1 is C.sub.1-6 alkyl; R.sup.8 is C.sub.1-8 alkyl; R.sup.2 is Me, CH.sub.2-Ph, CH.sub.2C(R.sup.3).sub.3-q(H).sub.q wherein R.sup.3 is a C.sub.1-6-alkyl group or together two R.sup.3 groups form a C.sub.3-7-cycloalkyl ring wherein said ring is optionally substituted by a C.sub.1-6 alkyl group and q can be 1 or 0; each X is a halogen atom, methoxy, benzyl or methyl; M is Zr; or Hf; and wherein the two ligands forming the complex are identical.

17. A process as claimed in claim 1 wherein said complex is of formula (V) ##STR00017## wherein L is SiR.sup.8.sub.2; R.sup.8 is C.sub.1-8 alkyl; R.sup.1 is C.sub.1-6 alkyl ideally at the 4-position; R.sup.2 is C.sub.1-6 alkyl; each X is a halogen atom, methoxy, benzyl or methyl; and M is Zr or Hf.

18. A process as claimed in claim 1 wherein said cocatalyst comprises an organometallic compound of a Group 13 metal.

Description

(1) The invention will now be illustrated by reference to the following non-limiting Examples and figures.

(2) FIG. 1 compares the Intrinsic viscosity of the xylene soluble fraction as a function of catalyst, GP2 pressure and temperature, and copolymer composition. Except were indicated, GP2 conditions are 20 barg and 70 C. Inventive area lies above the dotted line.

(3) FIG. 2 shows catalyst activity (per gram of metallocene per hour) as a function of copolymer composition in terms of C2 XS content.

(4) In FIG. 3, the improvements of mechanical properties of the heterophasic polymers compositions produced with the process of the invention using specific catalysts are shown.

(5) FIG. 3a (Inventive example PI-1-1 and comparative example PC-2-4) and 3b (Inventive example PI-1-2 and comparative example PC-2-2) show impact strength as a function of increasing temperature. It is clear that the invention examples have improved impact in a wide temperature range, especially at low temperature.

(6) FIG. 4 shows that the BDTT of polymers of inventive examples with reference to C2(XS) wt %. It is clear that the BDTT is lower than of the polymers of the comparative examples at the same C2 content.

(7) FIG. 5 plots tensile modulus vs charpy impact strength. This shows improved impact/stiffness balance, which is highly desired. I.e. high impact is desired at lower temperature, but still the stiffness has to be as high as possible.

(8) FIG. 6 compares the effects of nucleation on tensile modulus as a function of impact strength.

MEASUREMENT METHODS

(9) ICP Analysis

(10) 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 (HNO3, 65%, 5% of V) and freshly deionised (DI) water (5% of V). The solution was then added to hydrofluoric acid (HF, 40%, 3% of V), diluted with DI water up to the final volume, V, and left to stabilise for two hours. The analysis was run at room temperature using a Thermo Elemental iCAP 6300 Inductively Coupled PlasmaOptical Emission Spectrometer (ICP-OES) which was calibrated using a blank (a solution of 5% HNO3, 3% HF in DI water), and 6 standards of 0.5 ppm, 1 ppm, 10 ppm, 50 ppm, 100 ppm and 300 ppm of Al, with 0.5 ppm, 1 ppm, 5 ppm, 20 ppm, 50 ppm and 100 ppm of Hf and Zr in solutions of 5% HNO3, 3% HF in DI water.

(11) Immediately before analysis the calibration is resloped using the blank and 100 ppm Al, 50 ppm Hf, Zr standard, a quality control sample (20 ppm Al, 5 ppm Hf, Zr in a solution of 5% HNO3, 3% HF in DI water) is run to confirm the reslope. The QC sample is also run after every 5th sample and at the end of a scheduled analysis set.

(12) The content of hafnium was monitored using the 282.022 nm and 339.980 nm lines and the content for zirconium using 339.198 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.

(13) The values reported in Table 4 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.

(14) Melt Flow Rate

(15) The melt flow rate (MFR) is determined according to ISO 1133 and is indicated in g/10 min. The MFR is an indication of the flowability, and hence the processability, of the polymer. The higher the melt flow rate, the lower the viscosity of the polymer. The MFR is determined at 230 C. and may be determined at different loadings such as 2.16 kg (MFR.sub.2) or 21.6 kg (MFR.sub.21).

(16) GPC: Molecular weight averages, molecular weight distribution, and polydispersity index (Mn, Mw, MWD)

(17) Molecular weight averages (Mw, Mn), Molecular weight distribution (MWD) and its broadness, described by polydispersity index, PDI=Mw/Mn (wherein Mn is the number average molecular weight and Mw is the weight average molecular weight) were determined by Gel Permeation Chromatography (GPC) according to ISO 16014-4:2003 and ASTM D 6474-99. A Waters GPCV2000 instrument, equipped with differential refractive index detector and online viscosimeter was used with 2GMHXL-HT and 1G7000HXL-HT TSK-gel columns from Tosoh Bioscience 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. 209.5 L of sample solution were injected per analysis. The column set was calibrated using universal calibration (according to ISO 16014-2:2003) with at least 15 narrow MWD polystyrene (PS) standards in the range of 1 kg/mol to 12 000 kg/mol. Mark Houwink constants for PS, PE and PP used are as per ASTM D 6474-99. All samples were prepared by dissolving 0.5-4.0 mg of polymer in 4 mL (at 140 C.) of stabilized TCB (same as mobile phase) and keeping for max. 3 hours at max. 160 C. with continuous gentle shaking prior sampling into the GPC instrument.

(18) Xylene Solubles (XS)

(19) 2.0 g of polymer is dissolved in 250 ml p-xylene at 135 C. under agitation. After 30 minutes the solution is allowed to cool for 15 minutes at ambient temperature and then allowed to settle for 30 minutes at 25 C. The solution is filtered with filter paper into two 100 ml flasks. The solution from the first 100 ml vessel is evaporated in nitrogen flow and the residue is dried under vacuum at 90 C. until constant weight is reached.

(20) XS %=(100.Math.m.Math.Vo)/(mo.Math.v); mo=initial polymer amount (g); m=weight of residue (g); Vo=initial volume (ml); v=volume of analysed sample (ml).

(21) Catalyst Activity

(22) The catalyst activity was calculated on the basis of following formula:

(23) $\mathrm{Catalyst}\mathrm{Activity}\left(\mathrm{kg}/g^{*}h\right)=\frac{\mathrm{amount}\mathrm{of}\mathrm{polymer}\mathrm{produced}\left(\mathrm{kg}\right)}{\mathrm{catalyst}\mathrm{loading}\left(g\right)\mathrm{polymerisation}\mathrm{time}\left(h\right)}$
ETHYLENE Content (FTIR C.sub.2)

(24) Ethylene content was measured with Fourier transform infrared spectroscopy (FTIR) calibrated to results obtained by .sup.13C NMR spectroscopy using a method which accounts for regio-irregular propylene insertion. When measuring the ethylene content in polypropylene, a thin film of the sample (thickness about 0.220 to 0.250 mm) was prepared by hot pressing at 230 C. (preheat 5 min., press 1 min., cooling (cold water) 5 min.) using a Graseby Specac press. The FTIR spectra of the sample was recorded immediately with Nicolet Protg 460 spectrometer from 4000 to 400 cm.sup.1, resolution 4 cm.sup.1, scans 64. The area of absorption peak at 733 cm.sup.1 (baseline from 700 cm.sup.1 to 760 cm.sup.1) and height of reference peak at 809 cm.sup.1 (baseline from 780 cm.sup.1 to 880 cm.sup.1) were evaluated. The result was calculated using the following formula
E.sub.tot=aA/R+b where A=area of absorption peak at 733 cm.sup.1 R=height of reference peak at 809 cm.sup.1 E.sub.tot=C2 content (wt.-%) a, b are calibration constants determined by correlation of multiple calibration standards of know ethylene content as determined by .sup.13C NMR spectroscopy to A/R.

(25) The result was reported as an average of two measurements.

(26) Intrinsic Viscosity

(27) Measured according to DIN ISO 1628/1, October 1999 (in Decalin at 135 C.).

(28) Melting temperature T.sub.m, crystallization temperature T.sub.c, is measured with Mettler TA820 differential scanning calorimetry (DSC) on 5-10 mg samples according to ISO 11357-3. Both crystallization and melting curves were obtained during 10 C./min cooling and heating scans between 30 C. and 200 C. Melting and crystallization temperatures were taken as the peaks of endotherms and exotherms.

(29) Glass Transition TemperaturesDMTA

(30) The dynamic-mechanical analysis (DMTA) data are obtained according to ISO 6721-1 (General principles) & 6721-7 (Torsional vibrationNon-resonance method).

(31) Brittle-to-ductile Transition Temperature

(32) The determination of the brittle-to-ductile transition temperature (BDTT) is based on the a(cN) values as determined from Charpy instrumented impact strength according to ISO 179-2:2000 on V-notched specimen with a geometry of 80104 mm3 as required in ISO 179-1eA.

(33) The a(cN) values are determined in intervals of 3 C. from 40 C. to +41 C. with an impact velocity of 1.5 m/s and plotted over temperature, calculating the BDTT as the average value of the step increase. For a detailed description of the determination of the BDTT reference is made to Grein, C. et al, Impact Modified Isotactic Polypropylene with Controlled Rubber Intrinsic Viscosities: Some New Aspects About Morphology and Fracture, J Appl Polymer Sci, 87 (2003), 1702-1712.

(34) Tensile Modulus

(35) Tensile properties were determined according to ISO 527-2 (cross head speed=50 mm/min; 23 C.) using injection moulded specimens as described in EN ISO 1873-2 (ISO multibar, dog bone shape, 4 mm thickness).

(36) Charpy Notched Impact Strength

(37) Charpy impact strength was determined according to ISO 179-1eA:2000 on V-notched samples of 80104 mm.sup.3 at 23 C. (Charpy impact strength (23 C.)) and 19 C. (Charpy impact strength (19 C.)). A standard impact velocity of 1.5 m/s was used.

(38) The test specimens having a dimension of 80104 mm.sup.3 were cut from the central part of ISO multibar specimens prepared by injection moulding in line with ISO 1873-2.

EXAMPLES

Metallocene Example 1 (MC-1)

(39) (rac--{bis-[.sup.5-2-methyl-4-(4-tert-butylphenyl)-1,5,6,7-tetrahydro-s-indacen-1-yl]dimethylsilanediyl}dichlorozirconium,) was prepared as described in WO2006/097497A1. The .sup.1H NMR spectrum of it corresponds to that reported in the mentioned patent application.

(40) ##STR00008##
Catalyst Preparation

Catalyst Example 1 (E1)

(41) The catalyst E1 was prepared according to the procedure described in the Example 5 of WO 2003/051934 with hexadecafluoro-1,3-dimethylcyclohexane as the continuous phase, a mixture of perfluoroalkylethyl acrylate esters having different perfluoroalkyl chain lengths as the surfactant precursor and (rac--{bis-[.sup.5-2-methyl 4-(4-tert-butylphenyl)-1,5,6,7-tetrahydro-s-indacen-1-yl]dimethylsilanediyl}dichlorozirconium as the metallocene.

(42) The detailed catalyst preparation was performed as follows.

(43) Inside a glovebox, 80 L of commercial mixture of dry and degassed perfluoroalkylethyl acrylate esters were mixed with 2 mL of MAO in a septum bottle and left to react overnight (surfactant solution). The following day, 61.40 mg of the metallocene (MC-1) was dissolved in 4 mL of the MAO solution in another septum bottle and left to stir inside the glovebox (catalyst solution).

(44) After 60 minutes, the 4 mL of the catalyst solution and 1 mL of the surfactant solution were successively added into a 50 mL emulsification glass reactor containing 40 mL of hexadecafluoro-1,3-dimethylcyclohexane at 10 C. and equipped with an overhead stirrer (stirring speed=600 rpm). A red-orange emulsion formed immediately and was stirred during 15 minutes at 0 C./600 rpm. The emulsion was then transferred via a 2/4 Teflon tube to 100 mL of hot hexadecafluoro-1,3-dimethylcyclohexane at 90 C., and stirred at 600 rpm until the transfer was completed. The stirring speed was reduced to 300 rpm and the oil bath was removed. Stirring was continued at room temperature for 15 more minutes. When the stirrer was switched off, the catalyst was left to settle up on top of the continuous phase which was siphoned off after 45 minutes. The remaining red solid catalyst was dried during 2 hours at 50 C. over an argon flow. 0.23 g of a red free flowing powder was obtained.

Metallocene Example 2 (MC-2)

rac-1,1-dimethylsilylene-bis[2-isobutyl-4-(4-tert-butylphenyl)-5,6,7-trihydro-s-indacen-1-yl] zirconium dichloride

(45) ##STR00009##
The synthesis of this compound is described in EP-A-2402353, example 1
Catalyst Preparation

Catalyst Example 2 (E2)

(46) The catalyst (E2) was prepared according to the procedure described in the Example 5 of WO 2003/051934 with hexadecafluoro-1,3-dimethylcyclohexane as the immiscible solvent, a mixture of perfluoroalkylethyl acrylate esters having different perfluoroalkyl chain lengths as the surfactant precursor and rac-1,1-dimethylsilylene-bis[2-isobutyl-4-(4-tert-butylphenyl)-5,6,7-trihydro-s-indacen-1-yl] zirconium dichloride as the metallocene (MC-2).

(47) The detailed catalyst preparation was performed as follows:

(48) Inside a glovebox, 80 L of a commercial mixture of dry and degassed perfluoroalkylethyl acrylate esters were mixed with 2 mL of MAO in a septum bottle and left to react overnight (surfactant solution). The following day, 68.80 mg of the metallocene MC-2 were dissolved in 4 mL of the MAO solution in another septum bottle and left to stir inside the glovebox (catalyst solution).

(49) After 60 minutes, the 4 mL of the catalyst solution and 1 mL of the surfactant solution were successively added into a 50 mL emulsification glass reactor containing 40 mL of hexadecafluoro-1,3-dimethylcyclohexane at 10 C. and equipped with an overhead stirrer (stirring speed=600 rpm). A red-orange emulsion formed immediately and was stirred during 15 minutes at 0 C./600 rpm. The emulsion was then transferred via a 2/4 Teflon tube to 100 mL of hot hexadecafluoro-1,3-dimethylcyclohexane at 90 C., and stirred at 600 rpm until the transfer was completed. The stirring speed was reduced to 300 rpm and the oil bath was removed. Stirring was continued at room temperature for 15 more minutes. When the stirrer was switched off, the catalyst was left to settle up on top of the continuous phase which was siphoned off after 45 minutes. The remaining red solid catalyst was dried during 2 hours at 50 C. over an argon flow.

Comparative Metallocene 3 (MC-C3) and Comparative Catalyst Example 3 (C3)

Anti-dimethylsilylene(2-methyl-4-phenyl-5-methoxy-6-tert-butyl-indenyl)(2-methyl-4-phenyl-6-tert-butyl-indenyl)zirconium dichloride (metallocene MC-C3)

(50) ##STR00010##
This metallocene was prepared and formed into a catalyst as described in WO2013/007650, catalyst E1. Three slightly different alternative versions were prepared as shown in table 1 (C3a, C3b and C3c). The compositions of the catalysts used are described in Table 1 below. Catalyst off-line prepolymerisations were done in the same manner as described in off-line prepolymerisation example in WO2013/007650

(51) TABLE-US-00001 TABLE 1 Catalyst composition MC amount Al/Zr molar MC in ratio amount in prepolymerised DP* catalyst** catalyst** catalyst*** catalyst wt/wt mol/mol wt % wt % C3a 2.7 253 4.99 1.35 C3b 3.2 242 5.21 1.24 C3c 3.5 250 5.05 1.12 E1 2.9 588 2.35 0.60 E2 3.9 308 4.82 0.98 *Prepolymerisation degree **in non-prepolymerised catalyst ***in prepolymerised catalyst

Comparative Metallocene 4 (MC-C4) and Comparative Catalyst Example 4 (C4)

Rac-cyclohexyl(methyl)silanediylbis(2-methyl-4-(4-tertbutylphenyl)indenyl) zirconium dichloride (MC-C4)

(52) This catalyst was prepared as described in example 10 of WO2010/052263 and off-line prepolymerized as described above, until a prepolymerisation degree of 3.1 had been reached.

Comparative Catalyst Example 5

(53) Catalyst was prepared using as metallocene MC-1, which was supported on a silica support (XPO-2485) following the procedure of WO2006/097497A1. Catalyst yield was 13 g.

Polymerization Examples

(54) Polymerisations of inventive polymerisation examples (series PI-1 and PI-2) and comparative polymerisation examples (series PC-1 and PC-2) were carried according to the following procedure. More details are disclosed in Table 2.

(55) Step 1: Bulk Propylene Homopolymerization

(56) A stirred autoclave (double helix stirrer) with a volume of 21.2 dm.sup.3 containing 0.2 barg of polymerisation grade propylene was filled with additional 3.97 kg propylene plus the chosen amount of H2. After adding 0.73 mmol triethylaluminium (Aldrich, 1 molar solution in n-hexane) using a stream of 250 g propylene, the solution was stirred at 20 C. and 250 rpm for 20 min. Then the catalyst was injected as described in the following. The solid, off-line pre-polymerized catalyst (type, amount and degree of pre-polymerisation as listed in the tables) was loaded into a 5-mL stainless steel vial inside the glovebox, the vial was attached to the autoclave, then a second 5-mL vial containing 4 ml n-hexane and pressurized with 10 bars of N2 was added on top, the valve between the two vials was opened and the solid catalyst was contacted with hexane under N2 pressure for 2 s, then flushed into the reactor with 250 g propylene. Stirring speed was increased to 250 rpm and pre-polymerisation was run for 10 min at 20 C. At the end of the prepolymerization step, the stirring speed was increased to 350 rpm and the polymerisation temperature increased to 80 C. When the internal reactor temperature reached 71 C., the chosen H2 amount was added with a defined flow via thermal mass flow controller (MFC). The reactor temperature was held constant throughout the polymerization. The polymerization time was measured starting when the temperature was 2 C. below the set polymerization temperature.

(57) Step 2: 1.sup.st Gas Phase (GPI), Propylene Homopolymerization.

(58) After the bulk step was finished, the stirrer speed was adjusted to 50 rpm and the reactor pressure was reduced to 0.5 bar below the set pressure by venting.

(59) Afterwards the stirrer speed was set to 180 rpm, the reactor temperature to 80 C. and the desired amount of H2 was dosed via MFC. Then the reactor P and T were held constant by feeding propylene via MFC to target pressure of 25 barg and by thermostatting at 80 C. for the time necessary to reach the target split.

(60) Step 3: 2.sup.nd Gas Phase (GP2), Ethylene/Propylene Copolymerization

(61) When the previous step was finished, the stirrer speed was reduced to 50 rpm, the reactor pressure lowered to 0.3 bar by venting, and the temperature and control device was set to 70 C. Then the reactor was filled with 200 g propylene, with flow of 70 g/min, then the pressure was lowered again to 0.3 barg by venting in order to remove all H2.

(62) Afterwards the stirrer speed was adjusted to 180 rpm and the HB-Therm to 70 C. Then the reactor was pressurized by feeding propylene and ethylene with a defined C3/C2 ratio via flow controller (transition feed). The chosen C3/C2 ratio in the transition depends on the relative reactivity ratio value R of the two comonomers for the given catalyst system, as defined by:

(63) $R=\frac{{\left(\frac{C_2}{C_3}\right)}_{\mathrm{polymer}}}{{\left(\frac{C_2}{C_3}\right)}_{\mathrm{gas}\mathrm{phase}}}$
The speed of the reactor filling during the transition was limited by the max. flow of the gas flow controllers. When the reactor temperature was 1 C. below the target temperature of 70 C. and the reactor pressure reached the set value, the composition of the dosed C3/C2 mixture was changed to match the desired copolymer composition value and the temperature and pressure were held constant as long as the amount of C3/C2 gas needed to reach the target split of rubber to matrix was consumed.

(64) The reaction was stopped by setting the stirrer speed to 20 rpm, cooling the reactor to 30 C. and flashing the volatile components.

(65) After flushing 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) (Hostanox P-EPQ) and then dried overnight in a fumehood followed by 2 hours in a vacuum drying oven at 60 C.

(66) The nucleated materials have been prepared as described below. The heterophasic copolymer powders have been pre-mixed with clarifier (1700 ppm of Millad 3988) and antioxidant (2000 ppm of Irganox B225 and 500 ppm of Ca Stearate) and then compounded and pelletized on TSE-16 twin screw extruder. The temperature profile used was 170-190-210-220-200 C., from hopper to die, the screw speed was 180 rpm and the throughput 1.8 kg/h.

(67) The polymerization conditions are summarized in Table 2. The results of polymer analysis are listed in Table 3. Physic-mechanical characterization results are shown in table 4.

(68) TABLE-US-00002 TABLE 2 BULK STEP, 80 C. CATALYST Activity in GP1, T = 80 C. catalyst* Productivity bulk productivity Activity in amount total H2 time in bulk kgPP/g P H2 in GP1 time in GP1 GP1 Pol example catalyst mg ln min kgPP/gcat* cat/h* barg NL min kgPP/g cat* kgPP/g cat/h* PC-1-1 C4 61.0 2.0 30 11 21 30 0.315 67 7.4 6.6 PC-1-2 C4 75.8 1.8 30 10 19 30 0.315 55 7.1 7.8 PC-2-1 C3b 41.7 4.5 20 14 43 30 1.911 40.2 11.2 16.7 PC-2-2 C3b 40.7 4.5 20 16 47 30 1.480 41.2 12.2 17.8 PC-2-3 C3c 42.9 3.5 20 15 44 25 1.100 46.5 8.6 11.1 PC-2-4 C3c 42.0 3.5 20 14 41 25 1.100 47.8 9.9 12.4 PI-1-1 E1 30.8 1.5 20 18 53 25 0.750 59 17.9 18.2 PI-1-2 E1 31.3 1.5 20 15 46 25 0.750 67 14.4 12.9 PI-1-3 E1 30.8 1.5 20 16 48 25 0.750 71 15.6 13.2 PI-1-4 E1 31.3 1.5 30 24 49 25 0.750 63 15.0 14.3 PI-2-1 E2 24.1 1.5 27 24 53 25 0.350 67 22.8 20.5 PI-2-2 E2 24.1 1.5 30 26 52 25 0.350 77 23.7 18.4 PI-2-3 E2 24.9 1.5 30 24 49 25 0.350 76 24.1 19.0 PI-2-4 E2 24.3 1.5 30 25 50 25 0.350 75 23.3 18.6 PI-2-5 E2 24.9 1.5 30 27 53 25 0.350 71 22.9 19.3 PI-1-5 E1 31.8 1.5 20 10 31 25 0.750 61 10.7 10.5 PC-5 C5** 140.0 1.5 20 5.0 15 25 0.750 67 3.2 2.9 GP2, T = 70 C. feed C2/C3 wt feed C2/C3 Productivity Activity in P in GP2 time GP2 during wt in GP2 GP2 Pol example barg min transition during run kg/gcat* kg/gcat/h* PC-1-1 20 129 0.87 0.42 7.0 3.3 PC-1-2 25 62 0.86 0.43 9.2 8.9 PC-2-1 20 219 1.38 0.42 6.7 4.6 PC-2-2 20 183 1.38 0.43 17.2 5.6 PC-2-3 20 105 3.23 1.00 10.0 5.7 PC-2-4 20 171 0.82 0.25 9.6 3.4 PI-1-1 20 73 0.62 0.25 15.3 12.6 PI-1-2 20 73 1.68 0.67 13.3 11.0 PI-1-3 20 91 3.75 1.50 12.6 8.3 PI-1-4 20 105 0.44 0.18 17.7 10.1 PI-2-1 20 52 0.65 0.25 18.7 21.6 PI-2-2 20 58 0.42 0.18 19.7 20.6 PI-2-3 20 70 1.67 0.67 20.6 17.7 PI-2-4 20 100 3.73 1.49 21.0 12.6 PI-2-5 20 55 0.38 0.15 19.8 21.6 PI-1-5 20 87 1.67 0.65 27.1 18.7 PC-5 20 87 1.67 0.66 10.1 7.0 *based on non-prepolymerised catalyst; **silica supported catalyst, no prepolymerisation;

(69) TABLE-US-00003 TABLE 3 ANALYSIS TOTAL ANALYSIS XS Split Split Split IV MFR2 bulk GP1 GP2 XS Tc Tm (XS) C2 R GPC XS Pol example Catatyst g/10 min % % % w % C. C. dL/g (XS) (C2/C3) Mn Mw PC-1-1 C4 40 43 30 28 29.9 0.6 25.4 0.40 27000 55000 PC-1-2 C4 54 37 28 36 36.7 109.2 148.9 0.7 28.8 0.47 30000 61000 PC-2-1 C3b 31 34 27 40 40.2 1.8 30 0.31 68000 164000 PC-2-2 C3b 18.4 35 27 38 43.4 112.9 148.2 1.7 29.2 0.30 70000 165000 PC-2-3 C3c 15.2 44 26 30 30.7 110.9 148.1 1.9 53.7 0.36 78000 178000 PC-2-4 C3c 19.6 41 30 29 27.7 113.3 147.9 1.8 21.6 0.34 82000 191000 PI-1-1 E1 10.1 35 35 30 32.7 114.9 154.7 2.3 22.3 0.47 84000 234000 PI-1-2 E1 14.3 35 34 31 33.6 114.8 154.3 2.0 37.5 0.36 66000 189000 PI-1-3 E1 11.5 36 35 29 30.6 113.2 154.3 2.1 56.9 0.35 68000 216000 PI-1-4 E1 8 43 26 31 26.8 113.1 154.1 2.7 17.5 0.48 102000 302000 PI-2-1 E2 12.7 36 35 29 33.2 113 155.6 2.3 20 0.39 PI-2-2 E2 10.6 38 34 28 30.3 112.7 155.7 2.4 17 0.49 PI-2-3 E2 15.5 35 35 30 32.3 114.5 156.0 1.8 37.8 0.36 PI-2-4 E2 14.3 36 34 30 32.3 114.2 155.5 2.0 56.3 0.35 PI-2-5 E2 8.7 38 33 29 28.6 109.8 155.0 2.5 14.8 0.46 PI-1-5 E1 17.4 38 39 22 22.5 110.8 154.1 2.3 44.4 0.48 72000 219000 PC-5 C5 4.6 48 30 22 20.3 111.0 154.0 2.9 42.2 0.44 118000 310000

(70) TABLE-US-00004 TABLE 4 Charpy a.sub.cN/ Tensile test DMTA BDT kJ/m.sup.2@1.5 m/s Tensile Elongation T.sub. T.sub. G@ T.sub.flex 19 C. 23 C. Modulus @ break (EPR) (PP) 23 C. Pol Example Catalyst C. kJ/m.sup.2 kJ/m.sup.2 Mpa % C. C. Mpa PC-1-1 C4 29 3.4 16.4 660 448 45.1 1.0 396 PC-1-2 C4 PC-2-1 C3b 2 9.5 32.4 817 243 46.6 1.2 357 PC-2-24 C3b 7 10.5 46.0 946 83 46.6 1.4 373 PC-2-3 C3c 26 7.8 16.6 1101 304 56.0 2.1 444 PC-2-4 C3c 1 5.3 44.6 946 412 41.4 0.7 451 PI-1-1 E1 22 45.0 56.0 812 351 36.0 0.0 361 PI-1-2 E1 25 44.5 56.0 1017 383 52.1 2.0 417 PI-1-3 E1 17 9.4 53.7 1141 351 52.1 1.9 395
Discussion

(71) At the same ethylene content, the inventive examples have higher impact strength both at low and high temperature. This is without any reduction in tensile modulus.

(72) The polymers of the inventive examples also have high melting points.

(73) The comparison examples series 1 catalyst C4 (metallocene MC-C4) show that a metallocene without substituents on positions 5 and 6 of the indenyl rings, produces a copolymer with very low molecular weight. Comparison examples series 2 with catalyst C3 (metallocene MC-C3) show that a metallocene in which only one indenyl ligand bears substituents on positions 5 and 6, while the second one does not, still produces a copolymer with lower molecular weight.

(74) It can also be seen from polymerisation examples PI-1-5 (inventive) and PC-5 (comparative) that Comparative catalyst C5, (silica supported catalyst) has much lower activity in gas phase polymerisations under the same conditions than Inventive solid catalyst E1 (same metallocene complex (MC-1), but prepared without any external carrier). Further, it was seen that the elastomeric material (rubber) produced in the copolymerisation in gas phase grew outside the pores of the supported catalyst leading to loss of flowability at C2 40 wt %, whereas the morphology of the corresponding polymer produced using inventive catalyst E1 gives a much better morphology (free flowing powder).

(75) Brief Description of the Figures

(76) The results are also plotted graphically in the attached figures. FIG. 1 shows the intrinsic viscosity of the xylene soluble fraction of examples and comparative examples of the invention. The preferred inventive area lies above the dotted line. With the present invention IV values of the XS fraction are higher with the polymers produced according to the invention than with polymers of the comparative examples.

(77) FIG. 2 shows the high catalyst activities achievable in gas phase reactor in the current invention

(78) In FIGS. 3 to 5 the improvements of mechanical properties of the heterophasic polymers compositions produced with the process of the invention using specific catalysts are shown. Results can be seen in the tables 4 and 5 as well.

(79) FIG. 3a (Inventive example PI-1-1 and comparative example PC-2-4) and 3b (Inventive example PI-1-2 and comparative example PC-2-2) show impact strength as a function of increasing temperature. It is clear that the invention example have improved impact in a wide temperature range, especially at low temperature impact is clearly higher than comparative polymers.

(80) FIG. 4 shows that the BDTT of polymers of inventive examples is lower than of the polymers of the comparative examples at the same C2 content.

(81) FIG. 5 plots tensile modulus vs charpy impact strength. This shows improved impact/stiffness balance, which is highly desired. I.e. high impact is desired at lower temperature, but still the stiffness has to be as high as possible.

(82) FIG. 6 compares the effects of nucleation on tensile modulus.

(83) The subscript N represents a nucleated polymer. Table 5 shows a comparison of a nucleated and non nucleated polymer.

(84) TABLE-US-00005 TABLE 5 a.sub.cN/ BDT kJ/m.sup.2@1.5 m/s Tensile Elongation T.sub. T.sub. G MC-1 T.sub.flex 19 C. 23 C. Modulus @ break EPR (PP) @23 C. Example C. kJ/m.sup.2 kJ/m.sup.2 Mpa % C. C. Mpa PI-2-5 10 4.8 58.8 727 347 30.0 0.0 330 PI 2-5N 16 8.3 58.9 817 357 30.1 1.9 371

(85) It is further preferred therefore if the polymers of the invention are nucleated with a nucleating agent.

(86) Overall, the polymers of the invention, in particular those from MC-1, show lower BDTT and higher absolute values of impact strength in a wide temperature range, and an improved impact/stiffness balance.

(87) In addition, nucleation improves both BDTT and stiffness.