	US 12,344,683 B2
	Process for producing a prepolymerized solid Ziegler-Natta catalyst
Torvald Vestberg, Porvoo (FI); Markku Vahteri, Porvoo (FI); Anna Fait, Linz (AT); Pauli Leskinen, Porvoo (FI); and Jingbo Wang, Linz (AT)
Assigned to BOREALIS AG, Vienna (AT)
Appl. No. 17/273,260
Filed by BOREALIS AG, Vienna (AT)
PCT Filed Sep. 20, 2019, PCT No. PCT/EP2019/075393 § 371(c)(1), (2) Date Mar. 3, 2021, PCT Pub. No. WO2020/064568, PCT Pub. Date Apr. 2, 2020.
Claims priority of application No. 18197546 (EP), filed on Sep. 28, 2018.
Prior Publication US 2021/0317242 A1, Oct. 14, 2021
Int. Cl. C08F 110/06 (2006.01); C08L 23/12 (2006.01)

CPC C08F 110/06 (2013.01) [C08L 23/12 (2013.01); C08F 2410/06 (2021.01); C08F 2500/18 (2013.01); C08L 2205/025 (2013.01)]

9 Claims

1. A process for producing a propylene polymer, the process comprising the steps of:

I) producing in batch mode a prepolymerized Ziegler-Natta catalyst by

a) providing a solid Ziegler-Natta catalyst component being free of phthalic compounds, wherein the solid Ziegler-Natta catalyst component comprises:

(a1) a compound of a transition metal (TM), which transition metal is selected from one of the groups 4 to 6 of the periodic table (IUPAC),

(a2) a compound of a metal (M) which metal is selected from one of the groups 1 to 3 of the periodic table (IUPAC), and

(a3) an internal donor (ID) being a non-phthalic compound, wherein the internal donor (ID) is selected from optionally substituted malonates, maleates, succinates, glutarates, citraconates and derivatives and/or mixtures thereof; and

b) subjecting the solid Ziegler-Natta catalyst component of step a) into a catalyst prepolymerization step, wherein the solid Ziegler-Natta catalyst component is prepolymerized in the presence of linear C4 olefin monomers to a polymerization degree from 0.2 to 50 gPO/g cat to obtain the prepolymerized solid Ziegler-Natta catalyst, and

II) producing a propylene polymer by

c) subjecting the prepolymerized Ziegler-Natta catalyst of step b) into a polymerization reactor, wherein propylene and optionally at least one other α-olefin selected from C2 and/or C4 to C8-α-olefin is/are polymerized in the presence of the prepolymerized solid Ziegler-Natta catalyst, wherein step c) comprises a process prepolymerization step and is carried out in a prepolymerization reactor and one or more polymerization reactor(s), and

d) obtaining the propylene polymer from step c) being free of phthalic compounds originating from the catalyst, wherein the propylene polymer is a propylene homopolymer or a propylene random copolymer having an amount of xylene cold soluble fraction, determined according to ISO 16152 (25° C.), of below 5.5 wt. %.