Process for producing polypropylene
Propylene is polymerised in the presence of a polymerisation catalyst comprising a solid catalyst component, an organoaluminium compound and an external electron donor, the process comprising the steps of (i) contacting propylene and hydrogen with the polymerisation catalyst in polymerisation conditions in a polymerisation reactor to produce a polymer of propylene; (ii) recovering the polymer of propylene from the polymerisation reactor; wherein the polymer of propylene has MFR of from more than 100 to 10000 g/10 min. The solid catalyst component comprises titanium, magnesium, halogen and an internal electron donor, characterised in that the internal electron donor is a compound according to formula (I):
1. A process for polymerising propylene in the presence of a polymerisation catalyst comprising a solid catalyst component, an organoaluminium compound and an external electron donor, the process comprising the steps of (i) contacting propylene and hydrogen with the polymerisation catalyst in polymerisation conditions in a polymerisation reactor to produce a polymer of propylene; (ii) recovering the polymer of propylene from the polymerisation reactor; wherein the polymer of propylene has MFR 2 of from more than 100 to 10000 g/10 min; and the solid catalyst component comprises titanium, magnesium, halogen and an internal electron donor, characterised in that the internal electron donor is a compound according to formula (I):
with R 1 and R 2 being the same or different and being a linear or branched C 1 -C 12 -alkyl group, and with R being H or a linear, branched or cyclic C 1 to C 12 -alkyl; and the external electron donor is a silane compound having the formula Si(OR 11 ) n R 10 4-n , wherein n is 2 or 3, each R 11 is independently a linear or branched C 1 -C 4 alkyl; each R 10 is independently a linear or branched alkyl group having from 1 to 24 carbon atoms and optionally containing an atom of group 15 of periodic table of elements or comprises a cyclic group having from 6 to 12 carbon atoms, and the finally obtained catalyst particles have surface areas below 20 m 2 /g.
2. The process according to claim 1 wherein R 1 and R 2 are a linear or branched C 1 -C 8 -alkyl group.
3. The process according to claim 1 wherein R 1 and R 2 are the same.
4. The process according to claim 1 wherein R is a linear or branched C 1 to C 3 -alkyl.
5. The process according to claim 4 wherein R is methyl.
6. The process according to claim 1 wherein each R 10 is independently selected from the group consisting of methyl, ethyl, propyl, isopropyl, tert-butyl, cyclohexyl and phenyl.
7. The process according to claim 1 wherein each R 10 is independently selected from the group consisting of methyl, ethyl, iso-butyl or cyclohexyl.
8. The process according to claim 6 wherein n is 2.
9. The process according to claim 1 wherein the polymerisation is conducted as a slurry polymerisation in a loop reactor wherein solid polymer particles are suspended in a fluid phase in said loop reactor.
10. The process according to claim 9 wherein the ratio of hydrogen concentration to propylene concentration in the fluid phase in the loop reactor is from 3 to 40 mol/kmol and the polymer of propylene has MFR 2 of from 100 to 2000 g/10 min.
11. The process according to claim 9 comprising the additional steps of passing the polymer of propylene recovered from the polymerisation reactor into a subsequent polymerisation reactor together with additional propylene and at least one comonomer selected from the group consisting of ethylene, linear 1-alkenes having 4 to 10 carbon atoms and mixtures thereof, to produce a copolymer of propylene comprising a semicrystalline matrix and a predominantly non-crystalline copolymer of propylene with the at least one comonomer.
12. A process for polymerising propylene in the presence of a polymerisation catalyst comprising a solid catalyst component, an organoaluminium compound and an external electron donor, the process comprising the steps of (i) contacting propylene and hydrogen with the polymerisation catalyst in polymerisation conditions in a polymerisation reactor to produce a polymer of propylene; (ii) recovering the polymer of propylene from the polymerisation reactor; wherein the polymer of propylene has MFR 2 of from more than 100 to 10000 g/10 min; and the solid catalyst component comprises titanium, magnesium, halogen and an internal electron donor, characterised in that the internal electron donor is a compound according to formula (I):
with R 1 and R 2 being the same or different and being a linear or branched C1-C12-alkyl group, and with R being H or a linear, branched or cyclic C1 to C12-alkyl; and the external electron donor is a silane compound having the formula Si(OR 11 ) n R 10 4-n , wherein n is 2 or 3, each R 11 is independently a linear or branched C1-C4 alkyl; and each R 10 is independently NR 12 R 13 and R 12 and R 13 are independently selected from the group consisting of methyl, ethyl, n-propyl, n-butyl, octyl, decanyl, iso-propyl, iso-butyl, iso-pentyl, tert-butyl, tert-amyl, cyclohexyl, methylcyclopentyl and cycloheptyl, and
the finally obtained catalyst particles have surface areas below 20 m 2 /g.
13. The process according to claim 12 wherein R 12 and R 13 are ethyl.
14. The process according to claim 12 wherein n is 3.
15. The process according to claim 12 wherein R 11 is the same and is selected from the group consisting of methyl and ethyl.