Catalyst Transfer Method

Abstract

1. A method for transitioning two different catalysts during the production of a polypropylene homopolymer or copolymer in a sequential multi-stage polymerization reaction, said method comprising: a) polymerizing propylene and optionally a comonomer in the presence of a first catalyst in a multi-stage polymerization reactor system comprising a prepolymerization reactor followed by a slurry reactor and then a gas phase reactor; b) discontinuing the supply of the first catalyst to the prepolymerization reactor; c) subsequently introducing propylene, optionally a comonomer, and a second catalyst into said prepolymerization reactor, and further introducing an aluminum alkyl into said polymerization reactor simultaneously with said introduction of said second catalyst; d) polymerizing propylene and optionally a comonomer in the presence of a second catalyst in said multi-stage polymerization reactor system. The process includes the steps of: wherein the first catalyst is a Ziegler-Natta catalyst and the second catalyst is a single-site catalyst; and wherein the amount of aluminum alkyl supplied in step c) is 0.5 to 10.0 g per ton of total propylene supplied into the prepolymerization reactor and the slurry reactor in steps c) and d). The method.

Description

[Technical Field]

[0001] The present invention relates to a method by which polymerizations conducted in a multi-reactor system can be switched from using a Ziegler-Natta catalyst to using a single-site catalyst, such as a metallocene catalyst. In particular, the present invention addresses the problem of restarting a polymerization reaction after a switchover, since catalyst poisons remaining after a Ziegler-Natta (ZN) polymerization can limit the catalytic activity of the single-site catalyst. [Background technology]

[0002] During the production of olefin polymers in commercial reactors, it is often necessary to transition from one type of catalyst system that produces polymers with specific properties and characteristics to another catalyst system capable of producing polymers with different chemical and / or physical attributes. In the past, to achieve an effective transition between incompatible catalysts, the olefin polymerization process using the first catalyst was shut down by various techniques known in the art. The reactor was then emptied, washed, and recharged, and a second catalyst was introduced into the reactor. Such catalyst conversions are time-consuming and costly due to the need to shut down the reactor for an extended period of time during the transition.

[0003] Another transition method involved halting the polymerization of a first catalyst system to terminate the polymerization and then introducing a second catalyst system into the polymerization reactor. However, stopping the first catalyst system feed into the reactor does not immediately stop the polymerization reaction occurring in the reactor. Therefore, two catalysts may simultaneously produce polymer for a period of time, potentially resulting in the formation of "off-specification" product over an extended period of time. The production of off-specification product is costly and time-consuming.

[0004] It is well known that an active Ziegler-Natta catalyst can "poison" an active metallocene catalyst, which is why transitioning from one catalyst to another is typically complicated. For example, changing from a Ziegler-Natta catalyst to a metallocene catalyst, or vice versa, usually requires a long transition period. Furthermore, during this transition period, the polyolefins produced undergo continuous changes in properties. If transitioning from one catalyst system to another requires significant changes in reactor conditions, there is a high risk of encountering production problems or producing polymers with extreme properties.

[0005] Therefore, there is a need for a new transition method that allows for the transition from a ZN catalyst to a single-site catalyst with reduced reactor downtime and without problems such as reactor fouling. Such a method should minimize the transition time, thus enabling the production of the target second polymer product as quickly as possible. Importantly, the effect of catalyst poisoning on the single-site catalyst should be minimized.

[0006] The possibility of transition between catalysts is described in the following documents: EP-A-0751965 describes a method for transitioning from a polymerization reaction catalyzed by a first catalyst to a polymerization reaction catalyzed by a second catalyst, including a metallocene catalyst, where the first and second catalysts are incompatible. The method requires that the supply of the first catalyst be stopped before an irreversible catalyst killer is used to stop catalyst activity. Examples of catalyst killers are CO and CO2.

[0007] In EP-A-1 578 808 a process is described for the transition from a first polymerization reaction carried out in the presence of a first catalyst system to a second polymerization reaction carried out in the presence of a second catalyst system. As well as carefully controlling the fluidized bed set-up, the invention uses alkoxylated amides or amines between steps.

[0008] EP-A-1620472 describes a polymerization process in which a catalyst killer is used to terminate a first polymerization reaction and allow a second catalyst system to be introduced into the polymerization reactor in the presence of the catalyst killer. Exemplary catalyst killers include one or more compounds selected from the group consisting of water, oxygen, alcohols, glycols, phenols, ethers, carbonyl compounds (e.g., ketones, aldehydes, carboxylic acids, esters, fatty acids), alkynes (e.g., acetylene), amines, nitrous acid, nitrous compounds, pyridine, pyrrole, carbonyl sulfide (COS), mercaptans, derivatives thereof, or any mixture or combination thereof.

[0009] EP-A-3237458 describes a method for transitioning from a first sequential polymerization reaction to a second polymerization reaction in which the catalysts are incompatible, and a catalyst killer is used to deactivate the first catalyst.

[0010] EP-A-3394111 claims a process for transitioning from a first continuous polymerization in a gas-phase reactor carried out in the presence of a metallocene catalyst to a second polymerization in the gas-phase reactor carried out in the presence of a Ziegler-Natta catalyst, where the process metallocene catalyst and the Ziegler-Natta catalyst are incompatible: an organometallic compound is introduced, and cyclohexylamine is used to deactivate the metallocene catalyst before reacting with cyclohexylamine.

[0011] EP-A-1182216 relates to a method for transitioning between two different catalysts in olefin polymerization, which transitions between a chromium oxide-based catalyst and a metallocene catalyst in the absence of any agents that deactivate or kill the catalyst.

[0012] WO2010086392 describes a method for transitioning between two different catalysts in the production of polypropylene homopolymers or copolymers in a continuous slurry / gas phase polymerization reaction with a prior prepolymerization reaction, comprising: (a) discontinuing the feeding of the first catalyst into the prepolymerization reactor; and then (b) introducing the second catalyst into the prepolymerization reactor; (c) adapting the reaction conditions in the prepolymerization reactor, the slurry reactor, and the subsequent gas-phase reactor; The process includes the steps of: Here, we describe the above method in which the transition is performed between a Ziegler-Natta catalyst and a self-supported, solid metallocene catalyst prepared by using emulsion / solidification techniques, or vice versa, thereby performing the transition in the absence of any additional agents that would deactivate or kill the catalyst. There is no disclosure of flushing the aluminum alkyl once the ZN catalyst feed is stopped, or of flushing the aluminum alkyl once the external donor feed is stopped. A significant problem with the transition from a ZN catalyst to a single-site catalyst is the slow initiation of single-site catalyst polymerization after the transition. The primary cause of the slow initiation is catalyst poisons present from the ZN polymerization. These poisons include the external donor used in the ZN polymerization and any antistatic agents that may be present from the ZN reaction. Other catalyst poisons include water and oxygen. Single-site catalysts are highly sensitive to catalyst poisoning due to the low amount of active metal in such catalysts and the fact that no external co-catalyst is used in single-site catalytic processes. Summary of the Invention [Problem to be solved by the invention]

[0013] The present inventors have discovered that adding an aluminum alkyl scavenger after the initial ZN polymerization significantly reduces the effects of these catalyst poisons, allowing for the rapid production of an "on specification" second polymer product. The presence of this alkyl aluminum additive overcomes the adverse effects of any catalyst poisons that may be present. [Means for solving the problem]

[0014] In one embodiment, the present invention requires the use of an aluminum alkyl flush during the polymerization process to reduce or eliminate the effects of catalyst poisons on the single-site catalyst. In a second embodiment, the present invention uses an aluminum alkyl feed immediately prior to or simultaneously with the addition of the second catalyst to significantly reduce the effects of these poisons. Optionally, both of these embodiments can be used together.

[0015] In one aspect, the present invention provides a method for transitioning between two different catalysts during the production of a polypropylene homopolymer or copolymer in a sequential multi-stage polymerization reaction, the method comprising: a) polymerizing propylene and optionally a comonomer in the presence of a first catalyst in a multi-stage polymerization reactor system comprising a prepolymerization reactor followed by a slurry reactor and then a gas phase reactor; b) discontinuing the supply of the first catalyst to the prepolymerization reactor; c) subsequently introducing propylene, optionally a comonomer, and a second catalyst into the prepolymerization reactor; and further, simultaneously with the introduction of the second catalyst, introducing an aluminum alkyl into the polymerization reactor; d) polymerizing propylene and optionally a comonomer in the presence of a second catalyst in said multi-stage polymerization reactor system. The process includes the steps of: wherein the first catalyst is a Ziegler-Natta catalyst and the second catalyst is a single-site catalyst; and wherein the amount of aluminum alkyl supplied in step c) is 0.5 to 10.0 g per ton of total propylene supplied into the prepolymerization reactor and the slurry reactor in steps c) and d), i.e., 0.5 to 10.0 g per 1,000 kg of total propylene. However, the above method is provided.

[0016] Viewed from another perspective, the present invention is a method for transitioning between two different catalysts during the production of a polypropylene homopolymer or copolymer in a sequential multi-stage polymerization reaction, the method comprising: a) polymerizing propylene and optionally a comonomer in the presence of a first catalyst in a multi-stage polymerization reactor system comprising a prepolymerization reactor followed by a slurry reactor and then a gas phase reactor; b) discontinuing the supply of the first catalyst into the prepolymerization reactor; c-1) introducing an aluminum alkyl compound into the prepolymerization reactor; c-2) subsequently introducing propylene, optionally a comonomer, and a second catalyst into the prepolymerization reactor; d) polymerizing propylene and optionally a comonomer in the presence of a second catalyst in said multi-stage polymerization reactor system; The process includes the steps of: wherein the first catalyst is a Ziegler-Natta catalyst and the second catalyst is a single-site catalyst; and Here, the amount of aluminum alkyl supplied in step c-2) is 0.5 to 10.0 g per ton of total propylene supplied into the prepolymerization reactor and the slurry reactor in steps c-2) and d), i.e., 0.5 to 10.0 g per 1,000 kg of total propylene. However, the above method is provided.

[0017] In these embodiments, the amount of aluminum alkyl fed is 0.5 to 10.0 g per ton of total propylene fed per hour into the prepolymerization reactor and the slurry reactor in steps c) and d), i.e., 0.5 to 10.0 g per 1000 kg of total propylene fed per hour.

[0018] Viewed from a second aspect, the present invention is a method for transitioning two different catalysts during the production of a polypropylene homopolymer or copolymer in a sequential multi-stage polymerization reaction, the method comprising: a) polymerizing propylene and optionally a comonomer in the presence of a first catalyst in a multi-stage polymerization reactor system comprising a prepolymerization reactor followed by a slurry reactor and then a gas phase reactor; b) discontinuing the supply of the first catalyst to the prepolymerization reactor; c) subsequently introducing propylene, optionally a comonomer, and a second catalyst into the prepolymerization reactor; d) polymerizing propylene and optionally a comonomer in the presence of a second catalyst in said multi-stage polymerization reactor system; The process includes the steps of: wherein the first catalyst is a Ziegler-Natta catalyst and the second catalyst is a single-site catalyst; wherein, between step b) and step c), propylene and an aluminum alkyl are introduced into the prepolymerization reactor, and the amount of aluminum alkyl is 100-300 g per ton of propylene introduced in this step, i.e., propylene fed into the prepolymerization reactor between steps b) and c), i.e., 100-300 g per 1000 kg of propylene. However, the above method is provided.

[0019] In this second aspect, the aluminum alkyl is introduced into the prepolymerization reactor only after step b), i.e., after the supply of the first catalyst to the prepolymerization reactor has been discontinued. In other words, the aluminum alkyl supply is initiated only after step b). Preferably, the aluminum alkyl is introduced as a flash after step b) and before step c).

[0020] The amount of alkylaluminum supplied after step b) is preferably 0.5 to 10.0 g per ton of the total propylene supplied to the prepolymerization reactor and the slurry reactor in steps c) and d), i.e., 0.5 to 10.0 g per 1,000 kg.

[0021] Therefore, alternatively, the present invention provides a method for transitioning between two different catalysts during the production of polypropylene homopolymer or copolymer in a sequential multi-stage polymerization reaction, comprising: a) polymerizing propylene and optionally a comonomer in the presence of a first catalyst in a multi-stage polymerization reactor system comprising a prepolymerization reactor followed by a slurry reactor and then a gas phase reactor; b) discontinuing the supply of the first catalyst to the prepolymerization reactor; c-1) introducing propylene and an aluminum alkyl into the prepolymerization reactor, preferably as a flash, wherein the amount of aluminum alkyl is 100-300 g per ton of propylene introduced in this step, i.e., propylene fed into the prepolymerization reactor between step b) and step c-2), i.e., 100-300 g per 1000 kg of propylene; c-2) subsequently introducing propylene, optionally a comonomer, and a second catalyst into the prepolymerization reactor; d) polymerizing propylene and optionally a comonomer in the presence of a second catalyst in said multi-stage polymerization reactor system. The process includes the steps of: wherein the first catalyst is a Ziegler-Natta catalyst and the second catalyst is a single-site catalyst; Preferably, the amount of the aluminum alkyl supplied in step c-2) is 0.5 to 10.0 g per ton of the total propylene supplied to the prepolymerization reactor and the slurry polymerization reactor in step c-2) and step d). However, the above method is provided.

[0022] In this embodiment, propylene and an aluminum alkyl are introduced into the prepolymerization reactor, where the amount of aluminum alkyl can also be considered to be 100 to 300 g / hour based on the ton of propylene introduced per hour in this flash step c-1).

[0023] Most preferably, the present invention provides a method for transitioning two different catalysts during the production of polypropylene homopolymer or copolymer in a sequential multi-stage polymerization reaction, comprising: a) polymerizing propylene and optionally a comonomer in the presence of a first catalyst in a multi-stage polymerization reactor system comprising a prepolymerization reactor followed by a slurry reactor and then a gas phase reactor; b) discontinuing the supply of the first catalyst to the prepolymerization reactor; c-1) introducing propylene and an aluminum alkyl into the prepolymerization reactor, wherein the amount of aluminum alkyl is 100-300 g per ton of propylene introduced in this step, i.e., 100-300 g per 1000 kg of propylene; c-2) adjusting the amount of aluminum alkyl fed to the prepolymerization reactor and the slurry reactor in step c-3) and step d) so that the amount of aluminum alkyl fed is 0.5 to 10.0 g per ton of total propylene, i.e., 0.5 to 10.0 g per 1,000 kg; c-3) subsequently introducing propylene, optionally a comonomer, and a second catalyst into the prepolymerization reactor; d) polymerizing propylene and optionally a comonomer in the presence of a second catalyst in said multi-stage polymerization reactor system. The process includes the steps of: wherein the first catalyst is a Ziegler-Natta catalyst and the second catalyst is a single-site catalyst. However, the above method is provided.

[0024] definition

[0025] The term "first polymer product" is used to define the target polypropylene, eg, first propylene homopolymer, produced during ZN catalyzed polymerisation.

[0026] The term "second polymer product" is used to define the target polypropylene, e.g., second propylene homopolymer, produced during single site catalyzed polymerisation.

[0027] The method of the present invention is carried out in a multi-stage polymerization reactor system comprising a prepolymerization reactor, at least one slurry reactor, and at least one gas-phase reactor. Therefore, the ZN-catalyzed process will include a first prepolymerization reaction, a first slurry polymerization reaction, and a first gas-phase polymerization reaction, which are carried out in the multi-stage polymerization reactor system, i.e., in the prepolymerization reactor, the at least one slurry reactor, and the at least one gas-phase reactor, respectively.

[0028] The single-site catalyst catalyzed process will include a second prepolymerization reaction, a second slurry polymerization reaction, and a second gas-phase polymerization reaction, which are carried out in the same multistage polymerization reactor system, i.e., the prepolymerization reactor, the at least one slurry reactor, and the at least one gas-phase reactor, respectively.

[0029] It will be appreciated that the first and second polymerization reactions may actually take place in the same vessel.

[0030] The term "aluminum alkyl" defines a compound containing Al bonded to three alkyl groups, and no halogenated groups are present in the aluminum alkyl compound. [Brief explanation of the drawings]

[0031] [Figure 1] FIG. 1 shows a prepolymerization reactor equipped with an agitator and feed lines to the reactor. DETAILED DESCRIPTION OF THE INVENTION

[0032] The present invention relates to a process for transitioning between a ZN catalyst and a single-site catalyst in a continuous multi-stage reaction, particularly in a multi-stage polymerization process where there is a multi-stage polymerization reactor system comprising a prepolymerization reactor, a slurry reactor and a gas phase reactor.

[0033] Therefore, initially, the multi-stage polymerization reactor system is expected to carry out a propylene polymerization reaction (first polymerization) catalyzed by a ZN catalyst. After the transition, the multi-stage polymerization reactor system will carry out a propylene polymerization reaction (second polymerization) catalyzed by a single-site catalyst, particularly a metallocene catalyst. The present invention describes a method to ensure a smooth transition between the two processes.

[0034] The properties of the two catalysts will be described first, followed by details of the polymerization process before and after the transition as well as how the transition should be carried out.

[0035] catalyst

[0036] Ziegler-Natta (ZN) catalyst

[0037] The Ziegler-Natta catalyst can be any Ziegler-Natta catalyst known in the art. The Ziegler-Natta catalyst typically used in the present invention for propylene polymerization is a stereospecific, solid, high-yield Ziegler-Natta catalyst component containing compounds of Mg, Ti, and Cl and an internal donor component. In addition to the solid catalyst component, one or more cocatalysts and one or more external donors are typically used in propylene processes.

[0038] The catalyst components may be supported on a particulate support, for example on an inorganic oxide, such as silica or alumina, or magnesium halide may form the solid support. Solid catalyst components may also be prepared by emulsion-solidification methods or by precipitation methods.

[0039] The solid catalyst component for propylene polymerization usually contains an internal electron donor and an aluminum compound acting as a cocatalyst. Suitable internal electron donors are, inter alia, esters of carboxylic or dicarboxylic acids, such as phthalic acid esters, unsubstituted or substituted malonic acid esters, unsubstituted or substituted maleic acid esters, ethers and diethers, or oxygen- or nitrogen-containing silicon compounds, or combinations thereof.

[0040] The optional aluminum cocatalyst used in combination with the catalyst preparation is typically selected from aluminum alkyl, aluminum alkyl halide, aluminum alkyl alkoxide or aluminum alkyl halide alkoxide compounds, wherein the alkyl group comprises 1 to 20 C atoms, preferably 1 to 10 C atoms, in particular 1 to 6 C atoms.

[0041] The cocatalyst typically comprises an aluminum trialkyl or aluminum alkyl halide compound, where the alkyl group typically comprises 1 to 20 carbon atoms, for example, 1 to 10 carbon atoms. The aluminum alkyl compound is preferably a trialkyl aluminum, such as trimethyl aluminum, triethyl aluminum (TEAL), triisobutyl aluminum, or tri-n-octylaluminum. Aluminum alkyl halides of interest include dialkyl aluminum halides, alkyl aluminum dihalides, or alkyl aluminum sesquihalides, such as diethyl aluminum chloride, dimethyl aluminum chloride, ethyl aluminum dichloride, or ethyl aluminum sesquichloride.

[0042] For catalyst activation, a cocatalyst is used together with the ZN catalyst. The cocatalyst is preferably an aluminum alkyl compound. The use of TEAL is particularly preferred.

[0043] It is also typical to use an external donor in the ZN polymerization process. Suitable external electron donors for use in propylene polymerization are well known in the art and include ethers, ketones, amines, alcohols, phenols, phosphines, esters, and silanes. Silane-type external donors are typically organosilane compounds containing a Si-OCOR bond, a Si-OR bond, or a Si-NR2 bond, with a silicon atom as the central atom, and R having 1 to 20 C atoms and being alkyl, alkenyl, aryl, arylalkyl, or cycloalkyl, as known in the art.

[0044] Preferred external donors are silane donors and include diisopropyldiethoxysilane (DIPDES), cyclohexylmethyldiethoxysilane (CHMDES), dicyclopentyldimethoxysilane (DCPDMS), cyclohexylmethyldimethoxysilane and dicyclopentadienyldiethoxysilane (DCPDES) and diethylaminotriethoxysilane.

[0045] The amount of external donor used can range from 2 to 70 wtppm, preferably from 5 to 50 wtppm, based on the weight of the propylene feed to the first prepolymerization reactor and the first slurry reactor.

[0046] Examples of suitable catalysts and compounds therein are described, inter alia, in WO 87 / 07620, WO 92 / 21705, WO 93 / 11165, WO 93 / 11166, WO 93 / 19100, WO 97 / 36939, WO 98 / 12234, WO 99 / 33842, WO 03 / 000756, WO 04 / 000766, WO 05 / 000767, WO 06 / 000769, WO 07 / 000768, WO 08 / 000769, WO 09 / 000769, WO 10 / 000769, WO 11 / 000769, WO 12 / 000769, WO 13 / 000769, WO 14 / 000769, WO 15 / 000769, WO 16 / 000769, WO 17 / 000769, WO 18 / 000769, WO 19 ... WO03 / 000757, International Publication No. WO03 / 000754, International Publication No. WO03 / 000755, International Publication No. WO2004 / 029112, European Patent No. EP2610271, International Publication No. WO2012 / 007430, International Publication No. WO92 / 19659, International Publication No. WO92 / 19653, International Publication No. WO92 / 19658, U.S. Patent No. US4382019, U.S. Patent No. It is shown in Patent No. 4435550, U.S. Pat. No. 4465782, U.S. Pat. No. 4473660, U.S. Pat. No. 4560671, U.S. Pat. No. 5539067, U.S. Pat. No. 5618771, European Patent No. EP45975, European Patent No. EP45976, European Patent No. EP45977, International Publication No. WO95 / 32994, U.S. Pat. No. 4107414, U.S. Pat. No. 4186107, U.S. Pat. No. 4226963, U.S. Pat. No. 4347160, U.S. Pat. No. 4472524, U.S. Pat. No. 4522930, U.S. Pat. No. 4530912, U.S. Pat. No. 4532313, U.S. Pat. No. 4657882, U.S. Pat. No. 4581342, U.S. Pat. No. 4657882.

[0047] The Ziegler-Natta catalyst used is most preferably a solid Ziegler-Natta catalyst selected from MgCl-supported titanium Ziegler-Natta catalyst and self-supported solid Ziegler-Natta catalyst.

[0048] Generally, the present invention relates to a method for transitioning from a conventional ZN catalyst catalyzed process to a conventional single-site catalyst catalyzed process. The specific nature of the ZN catalyst is not critical, but it is preferred that the ZN catalyzed process includes the use of an alkyl aluminum cocatalyst compound. It is also preferred that the single-site catalyst catalyzed process uses an aluminum alkyl cocatalyst.

[0049] The inventors have found that adding an alkylaluminum scavenger after the initial ZN polymerization significantly reduces the effects of poisoning and allows for rapid production of an "on-spec" second polymer product. The presence of this alkylaluminum additive overcomes the adverse effects of any catalyst poisons that may be present. Therefore, these principles are applicable to all Ziegler-Natta catalysts, and the use of this alkylaluminum allows for successful transition to any single-site catalyst because the poisons are removed.

[0050] Single-site catalyst

[0051] The single-site catalyst is preferably a metallocene catalyst or a non-metallocene catalyst. The single-site catalyst preferably comprises a transition metal compound containing at least one cyclopentadienyl, indenyl, or fluorenyl ligand. Preferably, the single-site catalyst comprises two cyclopentadienyl, indenyl, or fluorenyl ligands, particularly two bridged cyclopentadienyl, indenyl, or fluorenyl ligands. Furthermore, the ligand may have a substituent, such as an alkyl group, an aryl group, an arylalkyl group, an alkylaryl group, a silyl group, a siloxy group, an alkoxy group, or another heteroatom group. Examples of suitable metallocene compounds are given, inter alia, in EP 629631, EP 629632, WO 00 / 26266, WO 02 / 002576, WO 02 / 002575, WO 99 / 12943, WO 98 / 40331, EP 776913, EP 1074557 and WO 99 / 42497, EP 2402353, EP 2729479 and EP 2746289.

[0052] The single-site catalyst is ideally an organometallic compound (C) comprising a transition metal (M) from groups 3 to 10 of the periodic table (IUPAC 2007) or an actinide or lanthanide transition metal (M). The term "organometallic compound (C)" according to the present invention encompasses any metallocene compound of a transition metal having at least one organic (coordinating) ligand and exhibiting catalytic activity alone or together with a cocatalyst. Such transition metal compounds are well known in the art, and the present invention covers compounds of metals from groups 3 to 10 of the periodic table (IUPAC 2007), such as groups 3 to 7, or groups 3 to 6, such as groups 4 to 6, as well as lanthanides or actinides.

[0053] In one embodiment, the organometallic compound (C) has the following formula (I): (L) m Rn MX q (I) where: "M" is a transition metal (M) from groups 3 to 10 of the periodic table (IUPAC 2007); each "X" is independently a monoanionic ligand, e.g., a σ-ligand; each "L" is independently an organic ligand that coordinates to said transition metal "M"; "R" is a bridging group connecting the organic ligands (L); "m" is 1, 2 or 3, preferably 2; "n" is 0, 1 or 2, preferably 1; "q" is 1, 2 or 3, preferably 2; and m+q is equal to the valence of the transition metal (M).

[0054] "M" is preferably selected from the group consisting of zirconium (Zr), hafnium (Hf), or titanium (Ti), and more preferably selected from the group consisting of zirconium (Zr) and hafnium (Hf).

[0055] In a more preferred definition, each organic ligand (L) independently represents: (a) substituted or unsubstituted cyclopentadienyl, or bicyclic or polycyclic derivatives of cyclopentadienyl, optionally bearing further substituents and / or one or more hetero ring atoms from groups 13 to 16 of the periodic table; or (b) Acyclic η atoms composed of atoms from groups 13 to 16 of the periodic table 1 - to η 4 - or η 6 -ligand, and the open-chain ligand may be fused to one or two, preferably two, aromatic or non-aromatic rings and / or may carry further substituents; or (c) a cyclic η group consisting of an unsubstituted or substituted monodentate, bidentate or polydentate ring system selected from aromatic, non-aromatic or partially saturated ring systems; 1 - to η 4 - or η 6- monodentate, bidentate or polydentate ligands, wherein such ring systems optionally contain one or more heteroatoms selected from groups 15 and 16 of the periodic table, is.

[0056] The organometallic compound (C), preferably the organometallic compound (C) used in the present invention, has at least one organic ligand (L) belonging to the above group (a). Such organometallic compounds are called metallocenes.

[0057] More preferably, at least one organic ligand (L), preferably both organic ligands (L), are selected from the group consisting of cyclopentadienyl, indenyl, tetrahydroindenyl, fluorenyl, which can independently be substituted or unsubstituted.

[0058] Further, when the organic ligand (L) is substituted, at least one organic ligand (L), preferably both organic ligands (L), independently, are C1-C 20 It preferably contains one or more substituents selected from hydrocarbyl or silyl groups, which may optionally contain one or more heteroatoms selected from Groups 14 to 16 and / or may optionally be substituted by one or more halogen atoms.

[0059] Word “C1~C 20 Whenever used in this application, a "hydrocarbyl group" is a C1-C 20 Alkyl, C2-C 20 Alkenyl, C2-C 20 Alkynyl, C3-C 20 Cycloalkyl, C3-C 20 Cycloalkenyl, C6-C 20 Aryl, C7-C 20 Alkylaryl or C7-C 20 Arylalkyl groups, or combinations of these groups, such as cycloalkyl substituted by alkyl, are included.

[0060] Furthermore, two substituents, which may be identical or different, attached to adjacent C atoms of a ring of the ligand (L) can also together form a further monocyclic or polycyclic ring fused to said ring.

[0061] Preferred hydrocarbyl groups are independently straight or branched C1-C6 groups optionally interrupted by one or more heteroatoms of Groups 14-16, such as O, N, or S. 10 Alkyl groups and substituted or unsubstituted C6-C 20 aryl groups.

[0062] Straight or branched C1-C 10 The alkyl group may be optionally substituted with one or more heteroatoms of groups 14 to 16, and more preferably is methyl, ethyl, propyl, isopropyl, tertbutyl, isobutyl, C 5~6 Cycloalkyl, OR, SR, where R is C1-C 10 is an alkyl group.

[0063] C6~C 20 The aryl group is more preferably a phenyl group, optionally containing one or two C1-C6 alkyl groups, as defined above. 10 It may be substituted with an alkyl group.

[0064] By "σ-ligand" is meant throughout the present invention a group that is bonded to a transition metal (M) via a sigma bond.

[0065] Furthermore, the ligands "X" are independently preferably hydrogen atoms, halogen atoms, C1-C 20 Alkyl, C1-C 20 Alkoxy, C2-C 20 Alkenyl, C2-C 20 Alkynyl, C3-C 12 Cycloalkyl, C6-C 20 Aryl, C6-C 20 Aryloxy, C7-C 20 Aryl alkyl, C7-C 20arylalkenyl, -SR", -Pr", -SiR", -OSiR", and -NR", where each R is independently a hydrogen atom, C1-C6 20 Alkyl, C2-C 20 Alkenyl, C2-C 20 Alkynyl, C3-C 12 Cycloalkyl or C6-C 20 It is aryl.

[0066] More preferably, the "X" ligand is selected from a halogen atom, a C1-C6 alkyl group, a C5-C6 cycloalkyl group, a C1-C6 alkoxy group, a phenyl group, and a benzyl group.

[0067] The bridging group "R" may be a divalent bridge, preferably a divalent bridge selected from -R'2C-, -R'2C-CR'2-, -R'2Si-, -R'2Si-SiR'2-, -R'2Ge-, where each R' is independently a hydrogen atom, a C1-C 20 Alkyl, C2-C 10 Cycloalkyl, tri(C1-C 20 Alkyl)silyl, C6-C 20 Aryl, C7-C 20 Aryl alkyl and C7-C 20 It is alkylaryl.

[0068] More preferably, the bridging group "R" is a divalent bridge selected from -R'2C-, -R'2Si-, where each R' is independently a hydrogen atom, a C1-C 20 Alkyl, C2-C 10 Cycloalkyl, C6-C 20 Aryl, C7-C 20 Aryl alkyl and C7-C 20 It is alkylaryl.

[0069] Another subgroup of organometallic compounds (C) of formula (I) is known as nonmetallocenes, in which the transition metal (M), preferably a transition metal of Groups 4 to 6, suitably Ti, Zr or Hf, has coordinating ligands other than cyclopentadienyl ligands.

[0070] As used herein, the term "nonmetallocene" refers to a compound that does not have a cyclopentadienyl ligand or a fused derivative thereof, but has one or more non-cyclopentadienyl η- or σ-, monodentate, bidentate, or polydentate ligands. Such ligands can be selected, for example, from groups (b) and (c) as defined above and described, for example, in WO 01 / 70395, WO 97 / 10248, WO 99 / 41290, and WO 99 / 10353, as well as in V.C. Gibson et al., Angew. Chem. Int. Ed., engl., vol. 38, 1999, pp. 428-447, the disclosures of which are incorporated herein by reference.

[0071] However, the organometallic compound (C) of the present invention is preferably a metallocene as defined above.

[0072] Metallocenes are described in numerous patents, some of which are listed below: EP 260130, WO 97 / 28170, WO 98 / 46616, WO 98 / 49208, WO 98 / 040331, WO 99 / 12981, WO 99 / 19335, WO 98 / 56831, WO 00 / 34341, WO 00 / 148034, EP 423101, EP 143102, EP 143103, EP 143104, EP 143105, EP 143106, EP 143107, EP 143109, EP 143110, EP 143111, EP 143112, EP 143113, EP 143114, EP 143115, EP 143116, EP 143117, EP 143118, EP 143119 ... No. 537130, WO 2002 / 02576, WO 2005 / 105863, WO 2006097497, WO 2007 / 116034, WO 2007 / 107448, WO 2009 / 027075, WO 2009 / 054832, WO 2012 / 001052, and European Patent No. EP 2532687, the disclosures of which are incorporated herein by reference. Furthermore, metallocenes have been widely described in academic and scientific literature.

[0073] In a preferred embodiment, the organometallic compound (C) has the following formula (Ia): (L)2R n MX2(Ia) where: "M" is Zr or Hf; Each "X" is a σ-ligand; each "L" is an optionally substituted cyclopentadienyl, indenyl, or tetrahydroindenyl; "R" is a SiMe2 bridging group linking the organic ligands (L); "n" is 0 or 1, preferably 1.

[0074] The metallocene catalyst complexes of the present invention are preferably asymmetric, which simply means that the two ligands that form the metallocene are different, i.e., each ligand has a chemically different set of substituents.

[0075] The metallocene catalyst complexes of the present invention are typically chiral, racemic-bridged, bis-indenyl C1-symmetric metallocenes in their anti-configuration. Although such complexes are formally C1-symmetric, they ideally possess pseudo-C2-symmetry because they maintain C2-symmetry adjacent to the metal center, not around the ligands. Due to their chemical nature, both anti- and syn-enantiomeric pairs (in the case of C1-symmetric complexes) are formed during the synthesis of the complexes. For purposes of this invention, the racemic anti-form means that the two indenyl ligands are oriented in opposite directions relative to the cyclopentadienyl-metal-cyclopentadienyl plane, while the racemic syn-form means that the two indenyl ligands are oriented in the same direction relative to the cyclopentadienyl-metal-cyclopentadienyl plane, as shown in the diagram below.

[0076] [ka]

[0077] Formula (I), and any subformulas, are intended to cover both the syn and anti configurations. Preferred metallocene catalyst complexes are in the anti configuration.

[0078] The metallocene catalyst complexes of the present invention are typically used as the rac-anti isomer, and therefore, ideally, at least 95 mole (mol) % of the metallocene catalyst complex is in the rac-anti isomer form, such as at least 98 mole %, particularly at least 99 mole %.

[0079] More preferably, the single-site catalyst is of formula (II): [ka] where: Mt is Hf or Zr; each X is a sigma ligand; Each R 1 may independently be the same or different, and CH-R 7 is a group, where R 7 is H or linear or branched C 1~6 Alkyl group, C 3~8 Cycloalkyl groups, C 6~10 is an aryl group; Each R 2 are independently a -CH= group, a -CY= group, a -CH2- group, a -CHY- group, or a -CY2- group, where Y is C 1~10 is a hydrocarbyl group, and n is 2 to 6; Each R 3 and R 4 may be independently the same or different and are each a hydrogen atom, a linear or branched C1 to C6 alkyl group, an OY group, or C 7~20 Aryl alkyl, C 7~20 Alkylaryl group or C 6~20 aryl groups, where at least one R per phenyl group 3 , and at least one R 4is not a hydrogen atom, and two adjacent R 3 or R 4 The groups may be part of a ring that includes the phenyl carbon to which they are attached; R 5 is a linear or branched C1-C6 alkyl group, C 7~20 Aryl alkyl, C 7~20 Alkylaryl group or C6-C 20 is an aryl group; R 6 is C(R 8 ) groups, where R 8 is a linear or branched C1-C6 alkyl group; and Each R is independently C1 to C 20 It is a hydrocarbyl.

[0080] Preferably, Mt is Zr.

[0081] Preferably, each X is independently a hydrogen atom, a halogen atom, C 1~6 an alkoxy group or an R' group, where R' is C 1~6 Preferably, X is an alkyl group, a phenyl group, or a benzyl group. Most preferably, X is a chlorine atom, a benzyl group, or a methyl group. Preferably, both X groups are the same. Most preferably, X is two chlorine atoms, two methyl groups, or two benzyl groups, especially two chlorine atoms.

[0082] Each R is independently C1 to C 20 Hydrocarbyl, for example, C-C 20 Aryl, C7-C 20 Aryl alkyl or C7-C 20 Alkylaryl. The word "C 1~20 The "hydrocarbyl group" also includes C 1~20 Alkyl, C 2~20 Alkenyl, C 2~20 Alkynyl, C 3~20 Cycloalkyl, C 3~20 Cycloalkenyl, C 6~20 Aryl group, C 7~20 Alkylaryl group or C 7~20arylalkyl groups, or combinations of these groups, such as cycloalkyl substituted with alkyl. Unless otherwise specified, preferred C 1~20 The hydrocarbyl group is C 1~20 Alkyl, C 4~20 Cycloalkyl, C 5~20 Cycloalkylalkyl groups, C 7~20 Alkylaryl group, C 7~20 Aryl alkyl group or C 6~20 It is an aryl group.

[0083] Preferably, both R groups are the same. 10 Hydrocarbyl group or C6-C 10 Aryl groups, such as methyl, ethyl, propyl, isopropyl, tertbutyl, isobutyl, C 5~6 -cycloalkyl, cyclohexylmethyl, phenyl or benzyl, more preferably both R are C1-C6 alkyl, C 3~8 Cycloalkyl or C6 aryl groups, such as C1-C4 alkyl, C 5~6 It is a cycloalkyl or C aryl group, most preferably both R are methyl, or one R is methyl and the other R is cyclohexyl. Most preferably, the bridge is -Si(CH)-.

[0084] Each R 1 may independently be the same or different, and CH-R 7 is a group, where R 7 is H or a linear or branched C 1~6 Alkyl groups, such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl and tert.-butyl, or C 3~8 Cycloalkyl groups (e.g., cyclohexyl), C 6~10 an aryl group (preferably phenyl).

[0085] Preferably, both R 1 The groups are the same, CH2-R 7 is a group, where R7 is H or a linear or branched C1-C4 alkyl group, more preferably both R 1 The groups are the same, CH2-R 7 is a group, where R 7 are H or a linear or branched C1-C3 alkyl group. Most preferably, both R 1 are both methyl.

[0086] Each R 2 are independently a -CH= group, a -CY= group, a -CH2- group, a -CHY- group, or a -CY2- group, where Y is C 1~10 Hydrocarbyl groups, preferably C 1~4 a hydrocarbyl group, and n is 2 to 6, preferably 3 to 4.

[0087] Each substituent R 3 and R 4 may be independently the same or different and are a hydrogen atom, a linear or branched C1 to C6 alkyl group, an OY group, or C 7~20 Aryl alkyl, C 7~20 Alkylaryl group or C 6~20 An aryl group, preferably a hydrogen atom, a linear or branched C1 to C6 alkyl group, or a C 6~20 an aryl group, and optionally two adjacent R 3 group or R 4 The groups may be part of a ring that includes the phenyl carbon to which they are attached. More preferably, R 3 and R 4 is a hydrogen atom, a linear or branched C1-C4 alkyl group, or an OY- group, where Y is C 1~4 Even more preferably, each R 3 and R 4 are independently a hydrogen atom, methyl, ethyl, isopropyl, tert-butyl or methoxy, in particular a hydrogen atom, methyl or tert-butyl, where at least one R 3 , and at least one R 4 is not a hydrogen atom.

[0088] Thus, preferably, there are one or two R per phenyl group. 3 is not hydrogen, and more preferably, for both phenyl groups, R 3 The groups are the same, such as 3',5'-di-methyl or 4'-tert-butyl.

[0089] In the case of an indenyl moiety, preferably one or two R on the phenyl group 4 is not a hydrogen atom, and more preferably, two R 4 are not hydrogen atoms, and most preferably, these two R 4 is the same as 3',5'-dimethyl or 3',5'-di-tert-butyl.

[0090] R 5 is a linear or branched C1-C6 alkyl group, such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl and tert-butyl; 7~20 Aryl alkyl, C 7~20 Alkylaryl group or C6-C 20 is an aryl group. 5 is preferably a linear or branched C1 to C6 alkyl group or a C6 to C6 alkyl group. 20 An aryl group is more preferred, a linear C1-C4 alkyl group is even more preferred, a C1-C2 alkyl group is even more preferred, and methyl is the most preferred.

[0091] R 6 is C(R 8 ) groups, where R 8 is a linear or branched C1 to C6 alkyl group.

[0092] Each R is independently C1 to C 20 Hydrocarbyl, C6-C 20 Aryl, C7-C 20 Aryl alkyl or C7-C 20 Preferably, each R 8 may be the same or different, where R 8is a linear or branched C1-C4 alkyl group, and more preferably, 8 are the same and are C1-C2 alkyl groups. Most preferably, all R 8 The group is methyl.

[0093] In a further preferred embodiment, the organometallic compound (C) has the following formula (III): [ka] where: Mt is Zr or Hf, preferably Zr; Each R 3 and R 4 are independently the same or different and are a hydrogen atom or a linear or branched C1-C6 alkyl group, wherein at least one R 3 , and at least one R 4 is not a hydrogen atom.

[0094] Specific metallocene catalyst complexes include: rac-anti-dimethylsilanediyl[2-methyl-4,8-bis-(4'-tert-butylphenyl)-1,5,6,7-tetrahydro-s-indacen-1-yl][2-methyl-4-(3',5'-dimethyl-phenyl)-5-methoxy-6-tert-butylinden-1-yl]zirconium dichloride; rac-anti-dimethylsilanediyl[2-methyl-4,8-bis-(3',5'-dimethylphenyl)-1,5,6,7-tetrahydro-s-indacen-1-yl][2-methyl-4-(3',5'-dimethylphenyl)-5-methoxy-6-tert-butylinden-1-yl]zirconium dichloride; rac-anti-dimethylsilanediyl[2-methyl-4,8-bis-(3',5'-dimethylphenyl)-1,5,6,7-tetrahydro-s-indacen-1-yl][2-methyl-4-(3',5'-ditert-butyl-phenyl)-5-methoxy-6-tert-butylinden-1-yl]zirconium dichloride, or their corresponding zirconium dimethyl analogues Includes. [ka]

[0095] synthesis

[0096] The ligands required to form the single-site catalysts of the present invention can be synthesized by any method, and one skilled in the art will be able to devise various synthetic protocols for the preparation of the required ligand materials. For example, WO 2007 / 116034 discloses the necessary chemical reactions. Synthetic protocols can also generally be found in WO 2002 / 02576, WO 2011 / 135004, WO 2012 / 084961, WO 2012 / 001052, WO 2011 / 076780, and WO 2015 / 158790.

[0097] To form an active single-site catalyst species, it is usually necessary to use a cocatalyst, as is well known in the art. In accordance with the present invention, a cocatalyst system may be used that includes a boron-containing cocatalyst and / or an aluminoxane cocatalyst.

[0098] The aluminoxane cocatalyst can be one of the following formulas (X): [ka] Here, n is usually 6 to 20, and R has the following meaning.

[0099] Aluminoxanes are formed by partial hydrolysis of organoaluminum compounds such as those of formula AlR3, AlR2Y and Al2R3Y3, where R is, for example, C1-C 10 Alkyl, preferably C1 to C5 alkyl or C3 to 10 Cycloalkyl, C7-C 12arylalkyl or alkylaryl and / or phenyl or naphthyl, and Y is a hydrogen atom, a halogen atom, preferably a chlorine atom or a bromine atom, or a C1-C 10 It can be alkoxy, preferably methoxy or ethoxy. The resulting oxygen-containing aluminoxanes are generally not pure compounds but mixtures of oligomers of formula (X).

[0100] A preferred aluminoxane is methylaluminoxane (MAO). Such aluminoxanes used according to the present invention as cocatalysts are not pure compounds due to their preparation method, but hereinafter the molar concentrations of the aluminoxane solutions are based on their aluminum content.

[0101] In accordance with the present invention, a boron-containing cocatalyst may also be used in place of an aluminoxane cocatalyst, or an aluminoxane cocatalyst may be used in combination with a boron-containing cocatalyst.

[0102] It will be appreciated by those skilled in the art that when a boron-based cocatalyst is used, it is common to pre-alkylate the complex by reaction with an aluminum alkyl compound, such as TIBA. This procedure is well known and can be carried out with any suitable aluminum alkyl, such as Al(C 1~6 Alkyl)3, can be used. Preferred aluminum alkyl compounds are triethylaluminum, triisobutylaluminum, triisohexylaluminum, tri-n-octylaluminum and triisooctylaluminum.

[0103] Alternatively, when a borate cocatalyst is used, the metallocene catalyst complex may be an alkylated version thereof, ie, for example, a dimethyl or dibenzyl metallocene catalyst complex.

[0104] Boron-based cocatalysts of interest include those of formula (Z): BY3(Z) wherein Y are the same or different and are a hydrogen atom, an alkyl group having 1 to about 20 carbon atoms, an aryl group having 6 to about 15 carbon atoms, an alkylaryl, an arylalkyl, a haloalkyl, or a haloaryl (each having 1 to 10 carbon atoms in the alkyl radical and 6 to 20 carbon atoms in the aryl radical), or a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. Preferred examples of Y are methyl, propyl, isopropyl, isobutyl, or trifluoromethyl, unsaturated groups such as aryl or haloaryl, for example, phenyl, tolyl, benzyl, p-fluorophenyl, 3,5-difluorophenyl, pentachlorophenyl, pentafluorophenyl, 3,4,5-trifluorophenyl, and 3,5-di(trifluoromethyl)phenyl.

[0105] Preferred choices are trifluoroborane, triphenylborane, tris(4-fluorophenyl)borane, tris(3,5-difluorophenyl)borane, tris(4-fluoromethylphenyl)borane, tris(2,4,6-trifluorophenyl)borane, tris(pentafluorophenyl)borane, tris(tolyl)borane, tris(3,5-dimethyl-phenyl)borane, tris(3,5-difluorophenyl)borane and / or tris(3,4,5-trifluorophenyl)borane.

[0106] Tris(pentafluorophenyl)borane is particularly preferred.

[0107] However, it is preferred to use borates, i.e., compounds containing the borate 3+ ion. Such ionic cocatalysts preferably include non-coordinating anions, such as tetrakis(pentafluorophenyl)borate and tetraphenylborate. Suitable counterions are protonated amine or aniline derivatives, such as methylammonium, anilinium, dimethylammonium, diethylammonium, N-methylanilinium, diphenylammonium, N,N-dimethylanilinium, trimethylammonium, triethylammonium, tri-n-butylammonium, methyldiphenylammonium, pyridinium, p-bromo-N,N-dimethylanilinium, or p-nitro-N,N-dimethylanilinium.

[0108] Preferred ionic compounds that can be used according to the present invention are: triethylammonium tetra(phenyl)borate, tributylammonium tetra(phenyl)borate, trimethylammonium tetra(tolyl)borate, tributylammonium tetra(tolyl)borate, tributylammonium tetra(pentafluorophenyl)borate, tripropylammonium tetra(dimethylphenyl)borate, tributylammonium tetra(trifluoromethylphenyl)borate, tributylammonium tetra(4-fluorophenyl)borate, N,N-dimethylcyclohexylammonium tetrakis(pentafluorophenyl)borate, N,N-dimethylbenzylammonium tetrakis(pentafluorophenyl)borate, N,N-dimethylanilinium tetra(phenyl)borate, N,N-diethylanilinium tetra(phenyl)borate, N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, N,N-di(propyl)ammonium tetrakis(pentafluorophenyl)borate, di(cyclohexyl)ammonium tetrakis(pentafluorophenyl)borate, triphenylphosphonium tetrakis(phenyl)borate, triethylphosphonium tetrakis(phenyl)borate, diphenylphosphonium tetrakis(phenyl)borate, tri(methylphenyl)phosphonium tetrakis(phenyl)borate, tri(dimethylphenyl)phosphonium tetrakis(phenyl)borate, triphenylcarbenium tetrakis(pentafluorophenyl)borate, or Ferrocenium tetrakis(pentafluorophenyl)borate Includes.

[0109] triphenylcarbenium tetrakis(pentafluorophenyl)borate, N,N-dimethylcyclohexylammonium tetrakis(pentafluorophenyl)borate, or N,N-Dimethylbenzylammonium tetrakis(pentafluorophenyl)borate is preferably given.

[0110] It has surprisingly been found that certain boron cocatalysts are particularly preferred. Therefore, preferred borates for use in the present invention contain a trityl ion. Thus, the use of N,N-dimethylammonium-tetrakispentafluorophenylborate and PhCB(PhF) and their analogs is particularly preferred.

[0111] In accordance with the present invention, preferred cocatalysts are alumoxanes, more preferably methylalumoxanes, combinations of alumoxanes with Al alkyls, or boron or borate cocatalysts, and combinations of alumoxanes with boron-based cocatalysts.

[0112] In accordance with the most preferred embodiment of the present invention, the preferred cocatalyst is an alumoxane, most preferably methylalumoxane.

[0113] Suitable amounts of cocatalyst will be known to those skilled in the art. The molar ratio of boron to metal ion of the metallocene may range from 0.5:1 to 10:1 mol / mol, preferably from 1:1 to 10:1 mol / mol, in particular from 1:1 to 5:1 mol / mol.

[0114] The molar ratio of Al in the aluminoxane to the metal ion of the metallocene can range from 1:1 to 2000:1 mol / mol, preferably from 10:1 to 1000:1 mol / mol, more preferably from 50:1 to 500:1 mol / mol.

[0115] Catalyst production

[0116] The single-site (preferably metallocene) catalyst complex can be used in supported or unsupported form. The particulate support material used is preferably an organic or inorganic material, such as silica, alumina, or zirconia, or a mixed oxide, such as silica-alumina, in particular silica, alumina, or silica-alumina. The use of a silica support is preferred. Those skilled in the art are aware of the procedures required to support such catalysts.

[0117] Particularly preferably, the support is a porous material such that the complex can be loaded into the pores of the support using methods similar to those described in, for example, WO 94 / 14856, WO 95 / 12622, and WO 2006 / 097497. The particle size is not critical but is preferably in the range of 5 to 200 μm, more preferably 20 to 80 μm. The use of these supports is routine in the art.

[0118] In an alternative embodiment, no support is used at all. Such catalysts can be prepared in solution, e.g., in an aromatic solvent such as toluene, by contacting the metallocene (as a solid or in solution) with a cocatalyst, e.g., methylaluminoxane, borane, or a borate salt previously dissolved in an aromatic solvent, or by sequentially adding the dissolved catalyst components to the polymerization medium.

[0119] In one embodiment, no external carrier is used, but the catalyst is still present in solid particulate form, and therefore no external support material, such as an inert organic or inorganic carrier, such as the silica described above, is used.

[0120] To provide the catalyst of the present invention in solid form without the use of an external carrier, a liquid / liquid emulsion system is preferably used, which method comprises dispersing catalyst components (i) and (ii) in a solvent and solidifying the dispersed droplets to form solid particles.

[0121] In particular, the method includes preparing a solution of one or more catalyst components; dispersing the solution in a solvent to form an emulsion in which the one or more catalyst components are present in dispersed phase droplets; solidifying the catalyst components in the dispersed droplets in the absence of an external particulate porous support to form solid particles comprising the catalyst, and optionally recovering the particles.

[0122] This method allows for the production of active catalyst particles with improved morphology, e.g., predetermined spherical shape, surface properties, and particle size, without the use of additional external porous support materials, such as inorganic oxides, e.g., silica. The term "preparing a solution of one or more catalyst components" means that the catalyst-forming compounds may be combined in one solution, which may be dispersed in an immiscible solvent, or at least two separate catalyst solutions may be prepared, one for each portion of the catalyst-forming compounds, which may then be dispersed sequentially in the solvents. A complete disclosure of the necessary processes is described in International Publication No. WO 03 / 051934.

[0123] The single-site polymerization process must be carried out in the presence of an aluminum alkyl scavenging agent, such as a trialkylaluminum compound (TEAL, TMA and / or TIBAL).

[0124] As mentioned above, the key to the present invention is not the specific nature of the single-site catalyst used, which can therefore be widely selected. However, the second prepolymerization process is required to be capable of being carried out in the presence of an aluminum alkyl compound. The key to the present invention is how the transition method is carried out.

[0125] Polymerization Process

[0126] The process according to the present invention is a "flying" transition in which the change from one type of produced polymer (herein referred to as the first polymer product) to another type of produced polymer (the second polymer product) is carried out continuously, i.e., without shutting down the reactor. When switching from the first catalyst to the second catalyst, the supply of the first catalyst is stopped. The second catalyst is then introduced. It will be understood that to produce the second polymer product, the reactor conditions must be adapted relative to the conditions used to produce the first polymer product. The change in conditions can be before or after introducing the second catalyst. Alternatively, some conditions can be changed before introducing the second catalyst, and other conditions can be changed after introducing the second catalyst.

[0127] The transition method of the present invention occurs between two multi-stage polymerization processes, particularly in a multi-stage polymerization reactor system in which there is a prepolymerization reactor and at least two reactors connected in series. Therefore, it requires the presence of a prepolymerization reactor, at least one slurry reactor, and at least one gas-phase reactor. The slurry reactor is typically a loop reactor.

[0128] A preferred "loop gas phase" polymerization process is developed by Borealis and is known as BORSTAR 登録商標 It is known in the art and is widely described in the patent literature, for example in EP 0 887 379, in WO 92 / 12182 or in WO 2005 / 002744.

[0129] Changing from producing one grade of polymer to producing another grade of polymer typically requires a transition period to switch the polymerization reactor over to the new resin specification. Time is required to adjust the process conditions, such as reaction temperature, reactants and reactant concentration ratios, to allow for the formation of the targeted new polymer. It will be apparent that some "off-grade" polymer may be produced due to the transition process that occurs during the transition from a first multi-stage polymerization reaction intended to produce a first resin product meeting a first specification, to a second multi-stage polymerization reaction intended to produce a second target resin product meeting a second specification.

[0130] Unless the transition is performed properly, such off-grade product may become sticky under the conditions (including temperature) during the transition, resulting in clumping or sheeting (on the reactor walls or dome) and product discharge problems. The formation of sticky polymer may force the reactor to be shut down for cleaning. The process of the present invention minimizes this risk.

[0131] It will also be apparent that the longer the transition, the more "off-grade" polymer may be produced, and there is a commercial incentive to make the conversion from the first polymer product to the second polymer product as clean and fast as possible.

[0132] The specific conditions for the first and second polymerizations depend on various factors, such as catalyst activity, the type and amount of optional comonomer, the type of polymer to be produced, and the production equipment. Consequently, the specific conditions for the transition between Ziegler-Natta and single-site catalysts must be determined for each specific product in each specific plant. This is within the skill of those skilled in the art.

[0133] The transfer method of the present invention is carried out in a multistage polymerization process comprising a multistage polymerization reactor system comprising a prepolymerization reactor followed by a slurry reactor, and involves the production of a polypropylene homopolymer or polypropylene copolymer. Therefore, a suitable plant for the continuous production of a polypropylene homopolymer or copolymer comprises a feed system for feeding catalyst, monomers, comonomers, additives, etc. to the reactors, i.e., the prepolymerization reactor, the slurry phase reactor, and the gas phase reactor, e.g., a fluidized bed gas phase reactor (GPR).

[0134] In a first embodiment, the invention relies on the use of an aluminum alkyl scavenger in the second prepolymerization, which reduces the concentration of catalyst killers (poisons) in the prepolymerization reactor and subsequent reactors by scavenging the catalyst killers (poisons) with which they can react to form compounds that can be easily purged or removed from the reactor.

[0135] The aluminum alkyl of the present invention is of the formula Al(C1- 10 alkyl)3, such as Al(C 1~6 alkyl). Each alkyl may be the same or different, preferably the same. Combinations thereof may also be used.

[0136] Preferred aluminum alkyls include triethylaluminum (TEAL), trimethylaluminum (TMA), triisobutylaluminum (TIBAL) and tri-n-hexylaluminum (TNHAL).

[0137] The use of triethylaluminum (TEAL), triisobutylaluminum (TIBA) or a combination thereof is particularly preferred.

[0138] A method for transitioning from Ziegler-Natta catalyzed polymerization to metallocene catalyzed polymerization according to the present invention may comprise the following steps:

[0139] In step a) of the process of the present invention, an initial prepolymerization is carried out, preferably as a bulk slurry polymerisation, for example in a continuous stirred tank reactor (CSTR) or loop reactor, in liquid propylene (i.e. the liquid phase comprises mainly propylene with small amounts of other reactants and optionally inert components dissolved therein).

[0140] The first prepolymerization reaction is typically carried out at a temperature of 0 to 50° C., preferably 10 to 45° C., more preferably 15 to 40° C. The pressure in the first prepolymerization reactor is not critical but must be high enough to maintain the reaction mixture in the liquid phase. Thus, the pressure can be 20 to 100 bar, for example 30 to 70 bar.

[0141] Residence times will generally be in the range of 0.1 to 1 hour.

[0142] The ZN catalyst component is preferably introduced entirely in the first prepolymerization step. However, if the Ziegler-Natta catalyst, preferably a solid Ziegler-Natta catalyst, and the separate cocatalyst can be fed separately, it is possible to introduce only a portion of the cocatalyst in the first prepolymerization step and the remaining portion in the subsequent polymerization step. In such a case, it is also necessary to introduce a sufficient amount of the separate cocatalyst (if necessary) in the prepolymerization step so that a sufficient polymerization reaction can be obtained therein.

[0143] It is also possible to add other components to the first prepolymerization stage. Thus, hydrogen may be added to the first prepolymerization stage to control the molecular weight of the prepolymer, as is known in the art. Furthermore, antistatic additives may be used to prevent catalyst or polymer particles from adhering to each other or to the walls of the reactor.

[0144] The precise control of the first prepolymerization conditions and reaction parameters is within the skill of one skilled in the art.

[0145] The prepolymerized first catalyst thus obtained is then fed to a subsequent slurry reactor, such as a continuous stirred tank reactor, preferably a loop reactor, in step a) of the process of the present invention. In the case of a slurry phase reactor, the reaction temperature is generally in the range of 50 to 110°C (e.g., 60 to 100°C or 70 to 110°C), and the reactor pressure is generally in the range of 20 to 80 bar (e.g., 30 to 70 bar).

[0146] The residence time in the slurry reactor is generally in the range of 0.2 to 5 hours (e.g., 0.3 to 2 hours). Preferably, the residence time is in the range of 0.2 to 1 hour, more preferably in the range of 0.3 to 0.6 hours. As is well known in the art, the average residence time τ can be calculated from Equation 1 below:

number

[0147] The diluents used are generally aliphatic hydrocarbons having a boiling point in the range of −70 to +100° C. In such reactors, polymerization can be carried out under supercritical conditions, if necessary.

[0148] The polymer produced in the slurry-phase reactor is then fed into a gas-phase reactor in step a) of the process of the present invention. The slurry may be withdrawn from the reactor either continuously or intermittently. A preferred method of intermittent withdrawal is the use of settling legs to thicken the slurry and then withdraw batches of concentrated slurry from the reactor.

[0149] In the case of a gas phase reactor, the reaction temperature used is generally in the range of 50 to 130°C (e.g., 60 to 115°C, or 60 to 100°C), the reactor pressure is generally in the range of 5 to 60 bar, preferably 10 to 40 bar, and the residence time is generally 1 to 8 hours. The gas used is generally a non-reactive gas, such as nitrogen, together with the monomer.

[0150] As is well known and routine in the art, hydrogen can be introduced into any reactor to control the molecular weight of the polymer. In one embodiment, the molar ratio of hydrogen to total olefin monomers in the cycle gas stream ranges from 0.001, 0.002, or 0.003 to 0.014, 0.016, 0.018, or 0.024, where desirable ranges can include any combination of any upper molar ratio limit and any lower molar ratio limit described herein. Expressed another way, the amount of hydrogen in the reactor at any time can range from 1,000 ppm to 20,000 ppm in one embodiment, from 2,000 to 10,000 ppm in another embodiment, from 3,000 to 8,000 ppm in yet another embodiment, and from 4,000 to 7,000 ppm in yet another embodiment, where desirable ranges can include any combination of any upper hydrogen limit and any lower hydrogen limit described herein.

[0151] In the process of the present invention, the Ziegler-Natta catalyzed polymerization is preferably initiated as known in the art by introducing the above-described Ziegler-Natta catalyst into a prepolymerization reactor via a catalyst feed tank, preferably via an oil catalyst feed system or via a wax catalyst feed system, and then adding propylene and hydrogen, and optionally, a cocatalyst and an external donor (in whole or in part), to the prepolymerization reactor.

[0152] Next, prepolymerized catalyst, additional propylene, hydrogen, optional additional cocatalyst, and external donors are introduced into the slurry-phase reactor, after which a polymerization product is recovered from the slurry-phase reactor and conducted to a gas-phase reactor fluidized bed, additional propylene and optional comonomer are optionally fed to the gas-phase reactor, additional hydrogen is optionally fed to the gas-phase reactor, the hydrogen to propylene ratio is controlled to provide the desired molecular weight of the polymerization product, and the polymerization product is recovered from the gas-phase reactor.

[0153] The reaction conditions in the slurry and gas phase reactors (e.g., temperature, pressure, amount of propylene and optional comonomer, amount of hydrogen) are selected according to the desired product parameters of the first product. Generally, such processes are conventional.

[0154] Transition

[0155] During the Ziegler-Natta catalyzed polymerization in step a) of the process of the present invention, a single-site catalyst, such as the single-site catalysts described above, can be introduced into a catalyst feed tank connected to the prepolymerization reactor. Typically, the catalyst is prepared about 130 to 400 minutes before its desired introduction into the prepolymerization reactor.

[0156] Prior to introducing the single-site catalyst into the prepolymerization reactor, the reaction conditions in the prepolymerization reactor and the slurry reactor can be adapted to reflect the conditions required to produce the second polymer product. If a prepolymerization reactor is used, then it is considered part of the first reactor (and thus the prepolymerization reactor and the slurry reactor are the first reactor in this respect).

[0157] Therefore, the hydrogen concentration in the prepolymerization reactor and the slurry reactor may be adjusted. The temperature in the prepolymerization reactor and the slurry reactor may also be adjusted. Such adjustments in the prepolymerization reactor and the slurry reactor may be made about 15 to 100 minutes before the single-site catalyst is introduced into the slurry reactor. The hydrogen supply to the prepolymerization reactor and the slurry reactor is preferably adjusted to reflect the hydrogen supply required to produce the second polymer product before the single-site catalyst is introduced.

[0158] Adjustments of other polymerization conditions (e.g., monomer content, temperature) required to target a second polymer product are preferably made after introduction of the single-site catalyst into the prepolymerization reactor in step c).

[0159] When adjustments in conditions are required in both the prepolymerization reactor and the slurry reactor, the order of adjustments does not matter: the prepolymerization conditions may be adjusted first, or the slurry reactor conditions may be adjusted first, or these adjustments may be made simultaneously.

[0160] Preferably, an antistatic agent is introduced into the prepolymerization reactor before the second catalyst is introduced, which can be done 30 to 120 minutes before the single-site catalyst is introduced.

[0161] The external electron donor feed in the ZN-catalyzed process is preferably discontinued shortly before the single-site catalyst is to be introduced into the prepolymerization reactor. Ideally, this occurs 5 to 30 minutes before the single-site catalyst is introduced. It is also necessary for the ZN catalyst feed itself to be discontinued around this time, for example 5 to 30 minutes before the introduction of the single-site catalyst (step b).

[0162] Advantageously, the supply of ZN catalyst is stopped at the same time that the supply of external electron donor is stopped.

[0163] The ZN catalyst includes a cocatalyst. The cocatalyst may be an aluminum alkyl cocatalyst. Alternatively, a different cocatalyst may be used in the ZN polymerization. When an aluminum alkyl cocatalyst is not used and a different cocatalyst is used, the feed of the different cocatalyst is preferably stopped at the same time as the ZN catalyst feed is stopped, for example, 5 to 30 minutes before the single-site catalyst is introduced.

[0164] If the cocatalyst used with the ZN catalyst was an alkylaluminum, this feed can be adjusted as explained below rather than being turned off completely.

[0165] It is preferred that the ZN catalyst contain an alkylaluminum cocatalyst, and therefore, the amount of alkylaluminum needs to be adjusted, typically reduced, to meet the requirements of the present invention. It is believed that the alkylaluminum cocatalyst feed to ZN-catalyzed polymerizations occurs at much higher concentrations than desired during single-site catalyst polymerization steps, and therefore, it is believed that the alkylaluminum concentration needs to be reduced when used as a cocatalyst in ZN polymerization processes.

[0166] It is preferred that the total amount of aluminum alkyl fed to the prepolymerization reactor and the slurry reactor in step a) is at least 20 g of aluminum alkyl (e.g., TEAL) per tonne of total propylene added to the prepolymerization reactor and the slurry reactor in step a), i.e., at least 20 g per 1000 kg, preferably 150 to 200 g of aluminum alkyl per tonne of total propylene, i.e., 150 to 200 g per 1000 kg.

[0167] The goal is to adjust or start the aluminum alkyl feed so that the amount of aluminum alkyl fed to the prepolymerization reactor is 0.5 to 10.0 g per ton of total propylene fed to the prepolymerization reactor and the slurry reactor during the second polymerization, i.e., 0.5 to 10.0 g per 1000 kg. Note that when a mixture of aluminum alkyl compounds is used, this number refers to the combined content of all aluminum alkyls used.

[0168] This level of aluminum alkyl is typically initiated 5 to 30 minutes before the single-site catalyst is introduced into the prepolymerization reactor; i.e., the target aluminum alkyl concentration is preferably established before the single-site catalyst is introduced. However, a reduced aluminum alkyl concentration can be initiated simultaneously with the introduction of the single-site catalyst. If the aluminum alkyl feed is established before the single-site catalyst is introduced, the aluminum alkyl feed should still be maintained when the single-site catalyst is introduced.

[0169] Preferably, the amount of aluminum alkyl fed is 0.5 to 5.0 g per ton of total propylene fed to the prepolymerization reactor and the slurry reactor in step c) and step d), i.e., 0.5 to 5.0 g per 1000 kg, for example, 1.0 to 3.0 g per ton of total propylene, i.e., 1.0 to 3.0 g per 1000 kg.

[0170] Alternatively, the alkylaluminum is fed in an amount of 0.5 to 5.0 g / hour, for example 1.0 to 3.0 g / hour, per ton, i.e., 1000 kg, of total propylene fed per hour to the prepolymerization reactor and the slurry reactor in step c) and step d).

[0171] Therefore, if the prepolymerization reactor and the slurry reactor are combined and fed 4000 kg of C3 per hour during the transition and second polymerization, the amount of alkylaluminum fed into the prepolymerization reactor will be in the range of 2 g to 40 g per hour.

[0172] The adjustment of the aluminum alkyl feed is preferably performed after step b), i.e., after the first catalyst feed is discontinued, and may be adjusted just prior to the simultaneous addition of the single-site catalyst and the aluminum alkyl.

[0173] It is also preferred that the adjustment of the aluminum alkyl feed be made after the external donor feed has been stopped.

[0174] The aluminum alkyl is preferably introduced into the prepolymerization reactor through the catalyst feed line. Therefore, once catalyst feed is started, the catalyst and the aluminum alkyl are fed together. The aluminum alkyl can be added through the top or bottom of the catalyst feed line.

[0175] It will be understood that all catalyst and aluminum alkyl are fed through the prepolymerization reactor, in contrast to which propylene may be fed to the prepolymerization reactor and directly to the slurry reactor and one or more of the gas phase reactors.

[0176] The single-site catalyst is then fed into the prepolymerization reactor. After the single-site catalyst is introduced into the prepolymerization reactor, the reaction conditions in the prepolymerization reactor and the slurry reactor are preferably adapted to reflect the conditions required to produce the second polymer product. Accordingly, the temperature, pressure, comonomer feed, and hydrogen in the prepolymerization reactor and the slurry reactor can be adjusted. Such adjustments in the prepolymerization reactor and the slurry reactor can be made about 0 to about 40 minutes after the single-site catalyst is introduced into the prepolymerization reactor.

[0177] When adjustments are required in both the prepolymerization reactor and the slurry reactor, the order of adjustments does not matter. The prepolymerization conditions may be adjusted first, or the slurry reactor conditions may be adjusted first, or the adjustments may be made simultaneously. Preferably, however, the prepolymerization conditions are adjusted before the conditions in the slurry reactor are adjusted to reflect the conditions necessary to produce the second polymer product.

[0178] The conditions for the second prepolymerization are similar to those described above for the first prepolymerization, and preferably it is carried out as a bulk slurry polymerization, for example in a continuous stirred tank reactor (CSTR) or in a loop reactor, in liquid propylene (i.e., the liquid phase comprises primarily propylene with small amounts of other reactants and optionally inert components dissolved therein).

[0179] The second prepolymerization reaction is typically carried out at a temperature of 0 to 50°C, preferably 10 to 45°C, more preferably 15 to 40°C. The pressure in the prepolymerization reactor is not critical but must be high enough to maintain the reaction mixture in the liquid phase. Thus, the pressure can be 20 to 100 bar, for example 30 to 70 bar.

[0180] Residence times will generally be in the range of 0.1 to 1 hour.

[0181] The prepolymerized first catalyst thus obtained is then fed to the slurry reactor, preferably a loop reactor. In the case of a slurry reactor, the reaction temperature is generally in the range of 50 to 110°C (e.g., 60 to 100°C or 70 to 110°C). The reactor pressure is generally in the range of 20 to 80 bar (e.g., 30 to 70 bar).

[0182] The residence time in the slurry reactor is generally in the range of 0.2 to 5 hours (e.g., 0.3 to 2 hours), preferably in the range of 0.2 to 1 hour, more preferably in the range of 0.3 to 0.6 hours.

[0183] The diluents used are generally aliphatic hydrocarbons having a boiling point in the range of −70 to +100° C. In such reactors, polymerization can be carried out under supercritical conditions, if necessary.

[0184] About 20 to about 120 minutes after introducing the single-site catalyst into the prepolymerization reactor, gas phase reactor conditions are adjusted to reflect desired second product parameters, preferably after conditions in the slurry reactor have been adjusted.

[0185] The polymer produced in the slurry-phase reactor is then fed into the gas-phase reactor. In the case of a gas-phase reactor, the reaction temperature used is generally in the range of 50 to 130°C (e.g., 60 to 115°C, or 60 to 100°C), the reactor pressure is generally in the range of 5 to 60 bar, preferably 10 to 40 bar, and the residence time is generally in the range of 1 to 8 hours. The residence time is in the range of 1 to 8 hours.

[0186] The gas used is generally a gas that is non-reactive with the monomer, such as nitrogen.

[0187] As is well known and routine in the art, hydrogen can be introduced into any reactor to control the molecular weight of the polymer. In one embodiment, the molar ratio of hydrogen to total olefin monomers in the cycle gas stream ranges from 0.001, 0.002, or 0.003 to 0.014, 0.016, 0.018, or 0.024, where desirable ranges can include any combination of any upper molar ratio limit and any lower molar ratio limit described herein. Expressed another way, the amount of hydrogen in the reactor at any time can range from 1,000 ppm to 20,000 ppm in one embodiment, from 2,000 to 10,000 ppm in another embodiment, from 3,000 to 8,000 ppm in yet another embodiment, and from 4,000 to 7,000 ppm in yet another embodiment, where desirable ranges can include any combination of any upper hydrogen limit and any lower hydrogen limit described herein.

[0188] The monomer propylene and any comonomers can be introduced into either the prepolymerization, slurry polymerization, or gas phase polymerization. If a comonomer is present, it is preferably added only to the gas phase reactor.

[0189] The amount of propylene fed to the prepolymerization reactor and the slurry reactor is calculated from the point at which the single-site catalyst is introduced into the prepolymerization reactor.

[0190] The amount of propylene fed to the prepolymerization reactor and the slurry reactor is preferably calculated based on the amount required to prepare the second polymer product, i.e., based on the amount required after any transition adjustments have occurred. Therefore, for the purpose of determining the ratio of aluminum alkyl to propylene, the amount of C3 fed to the prepolymerization reactor and the slurry reactor is calculated from the time when the single-site catalyst is fed, and the amount of C3 fed from the time when the single-site catalyst is fed can be assumed to be the target amount required to prepare the second polymer product. Any transition adjustments can be ignored.

[0191] However, it is preferred that the propylene levels in the prepolymerization reactor and the slurry reactor not change during polymerization in the presence of the single-site catalyst, it being further noted that the propylene feed to the polymerization is coordinated with the aluminum alkyl feed to ensure that any fluctuations can be accounted for.

[0192] For example, if the amount of C3 feed required to a slurry reactor to produce a second polymer product is 1000 kg / hr, this amount of C3 can be considered to be fed to the slurry reactor from the time the single-site catalyst is introduced into the prepolymerization reactor.

[0193] The amount of alkyl aluminum fed to the prepolymerization reactor can be counted from the moment the second catalyst is introduced. Although a small amount of aluminum alkyl and propylene may be introduced into the prepolymerization reactor before the second catalyst is added, these amounts are small and can be ignored.

[0194] Preferably, the majority of the second polymer product is derived from a slurry phase stage, which may be divided, for example, between 50 and 80% by weight of slurry phase and 50 to 20% by weight of gas phase. Any contribution from a prepolymerization step is considered part of the slurry phase stage.

[0195] Advantages

[0196] By adjusting the alkylaluminum feed to the prepolymerization reactor to 0.5 to 10.0 g per ton of propylene co-fed to the second prepolymerization and second slurry stage polymerization, several advantages were obtained: the overall productivity of the second polymer product was improved compared to a process in which an aluminum alkyl was not used; reactor balance was improved, and therefore reactor splitting could be better controlled; and the amorphous fraction (xylene-soluble fraction) in the second polymer product was reduced compared to a process in which an alkylaluminum was not used.

[0197] The mean particle size (PSD) of the final polymer powder was narrower, i.e., more monodisperse, compared to the process in which no alkylaluminum was used. In general, there were fewer large polymer particles.

[0198] The bulk density of the second polymer product was increased, the time to normal production was accelerated, and the polymer product also had excellent thermal properties.

[0199] The transition occurs smoothly without causing process disturbances such as clogging or fouling.

[0200] Without wishing to be limited by theory, it is postulated that when the aluminum alkyl is provided at the concentrations defined herein, poisons from the first stage polymerization, such as external donors and antistatic agents, water and oxygen, react with the aluminum alkyl and are unable to poison the novel single-site catalyst, which is notoriously sensitive to poisons.

[0201] Once the second polymerization process is established, i.e., when the second polymerization process produces a second polymer product that is within the target range, the transition method is complete and the aluminum alkyl feed can be discontinued if desired, although there is also the option of continuing the aluminum alkyl feed at a low concentration to act as a scavenger of any residual catalyst poisons.

[0202] Any off-spec polymer generated during the transition can be discarded.

[0203] Aluminum Alkyl Flash

[0204] In an alternative embodiment, propylene and aluminum alkyl are introduced as a flash into the prepolymerization reactor between the time the ZN catalyst feed is stopped and the time the exothermic single-site catalyst feed is started.

[0205] Therefore, in this embodiment, the ZN catalyst supply is stopped. Thereafter (for example, 5 to 30 minutes later), aluminum alkyl and propylene are introduced into the prepolymerization reactor as a flash. The amount of aluminum alkyl introduced during the flash, i.e., between steps b) and c), in the propylene supplied to the prepolymerization reactor is 100 to 300 g per ton of propylene, i.e., 100 to 300 g per 1,000 kg, for example, 150 to 200 g per ton of propylene, i.e., 150 to 200 g per 1,000 kg.

[0206] The flash lasts for 30 minutes to 10 hours, for example, 0.5 to 4 hours, for example, 1 to 3 hours.

[0207] It is preferred that the propylene / aluminum alkyl flush be introduced into the prepolymerization reactor at the bottom of the catalyst feed line. The location of the aluminum alkyl in the catalyst feed line is not critical, but it is useful to minimize the time the aluminum alkyl is in contact with the catalyst in the feed line; therefore, the preferred feed location is at the end of the catalyst feed line.

[0208] Ideally, the flash consists of propylene and an aluminum alkyl component, and no other feeds to the prepolymerization reactor occur during the flash.

[0209] The single-site catalyst can then be introduced according to the protocol described above. Therefore, specifically, once the flash is complete, the amount of aluminum alkyl feed can be adjusted to 0.5 to 10.0 g of aluminum alkyl per ton, i.e., 1000 kg, of propylene co-fed to the second prepolymerization and second slurry stage polymerization. This target range can be established before, e.g., 5 to 30 minutes before, the single-site catalyst is introduced, or the single-site catalyst can be introduced simultaneously with the aluminum alkyl adjustment.

[0210] The second polymerization continues according to the protocol described above.

[0211] Advantages of Flash

[0212] The advantages associated with this flash process are similar to those described above. The overall productivity of the second polymer product is increased compared to a process in which flash and an aluminum alkyl are not used, and compared to the process of the first embodiment. The amorphous fraction (xylene soluble fraction) in the second polymer product is reduced compared to a process in which flash and an aluminum alkyl are not used.

[0213] The mean particle size (PSD) of the final polymer powder was narrower, ie, more monodisperse, compared to a process in which no flash and aluminum alkyl were used, or compared to the process of the embodiment.

[0214] The transition occurs smoothly without causing process disturbances such as clogging or fouling.

[0215] Without wishing to be limited by theory, it is postulated that when the aluminum alkyl is provided at the concentrations defined herein, poisons from the first stage polymerization, such as external donors and antistatic agents, water and oxygen, react with the aluminum alkyl and are unable to poison the novel single-site catalyst, which is notoriously sensitive to poisons.

[0216] Once the second polymerization process is established, i.e., when the second polymerization process produces a second polymer product that is within the target range, the transition method is complete and the aluminum alkyl feed can be discontinued if desired, although there is also the option of continuing the aluminum alkyl feed at a low concentration to act as a scavenger of any residual catalyst poisons.

[0217] Advantageously, the single-site catalysts used in accordance with the present invention are not sensitive to poisoning.

[0218] In a preferred embodiment, no catalyst killer, such as carbon monoxide, is required, and therefore it is particularly preferred that the process of the present invention does not involve adding a catalyst killer to kill the activity of the ZN catalyst.

[0219] The polypropylene produced before and after the transition may be a homopolymer or a copolymer. The polypropylene produced before the transition may be a homopolymer or a copolymer. Suitable comonomers are ethylene and C4-C 10 The comonomer is preferably an alkylene. When a comonomer is present, ethylene is preferably used. Furthermore, the polypropylene produced may be unimodal or bimodal in terms of molecular weight distribution. It is preferred that the first polymer product is a homopolymer.

[0220] The second polymer product may be a copolymer or a homopolymer. Suitable comonomers are ethylene and C4-C10 The comonomer is preferably an alkylene. When a comonomer is present, ethylene is preferably used. Preferably, the single-site catalyzed polypropylene is a polypropylene homopolymer, suitable for example for the production of biaxially oriented films.

[0221] It is generally observed that the MFR2 of the polypropylene formed (which can range from 0.5 to 50 g / 10 min) is higher when the method of the present invention is performed than when it is not performed. Therefore, it may be necessary to adjust the hydrogen concentration to account for this change in molecular weight.

[0222] Poisons

[0223] The main poisons for the second catalyst are the external donors used during the ZN-catalyzed process and any antistatic agents used in the polymerization process to prevent particle agglomeration. Typical antistatic agents include glycerol monostearate (GMS), ethoxylated fatty acid amines, sorbitan monooleate, and diethanolamide. Other poisons include HO and O. Since single-site catalysts are generally known to be highly sensitive to catalyst poisons (mainly due to the low amount of active metal in the catalyst and the absence of an external cocatalyst in the process), the present invention solves the problems caused by these poisons through the use of alkylaluminums to scavenge these poisons.

[0224] The invention will now be further described with reference to the following non-limiting examples and figures.

[0225] Figure 1 shows a prepolymerization reactor equipped with an agitator and feed lines to the reactor. The feed lines allow the introduction of catalyst, flash or aluminum alkyl into the prepolymerization reactor. The aluminum alkyl can be introduced into the lower or upper part of the catalyst feed line.

[0226] The alkylaluminum and propylene flash can also be introduced into the prepolymerization reactor through the catalyst feed line.

[0227] Analytical Testing

[0228] The following definitions of terms and methods of determination apply to the above general description of the invention as well as the following examples, unless otherwise defined.

[0229] MFR2 (230°C) is measured according to ISO 1133 (230°C, 2.16 kg load).

[0230] Bulk Density: The bulk density of the polymer powder was determined according to ASTM D1895-96, Method A.

[0231] Particle size (PS) and average particle size (APS) were measured using image analysis methods with a Camsizer P4 analyzer according to ISO 13322-2.

[0232] Xylene solubles

[0233] The xylene soluble fraction (XS), as defined and described in this invention, was determined as follows: 2.0 g of polymer was dissolved in 250 mm of p-xylene at 135°C under stirring. After 30 minutes, the solution was cooled to ambient temperature for 15 minutes and then allowed to settle at 25±0.5°C for 30 minutes. The solution was filtered through filter paper and placed into two 100 mm flasks. The solution from the first 100 mm vessel was evaporated in a nitrogen stream, and the residue was dried under vacuum at 90°C until a constant weight was reached. The xylene soluble fraction (percent) can then be determined by the following formula:

number

[0234] DSC analysis

[0235] The melting temperature Tm and crystallization temperature Tcr are -1 The measurements were performed on approximately 5 mg samples using a Mettler-Toledo 822e differential scanning calorimeter (DSC) in accordance with ISO 11357-3 in the temperature range +23 to +225 °C, at a scan rate of 10 °C / min, in a hot / cold / hot cycle. The melting temperatures were taken as the endothermic peaks in the second heating step, respectively. The instrument was calibrated with H2O, lead, tin, and indium according to ISO 11357-1.

[0236] Example

[0237] Example 1 Example 1 provides a small amount of TEAL as a scavenger and demonstrates the transformation from a ZN catalyst to a single-site catalyst. CE01 Reference Example, TEAL not added in second catalyst feed IE01 TEAL is fed into the bottom of the catalyst supply line · IE02: TEAL is fed into the top of the catalyst feed line.

[0238] The following catalysts are used in the present invention:

[0239] Single-site catalyst For all experiments, the single-site catalyst used in the polymerization process was anti-dimethylsilanediyl[2-methyl-4,8-di(3,5-dimethylphenyl)-1,5,6,7-tetrahydro-s-indacen-1-yl][2-methyl-4-(3,5-dimethylphenyl)-5-methoxy-6-tert-butylinden-1-yl]zirconium dichloride, disclosed as MC-2 in International Publication No. WO 2019 / 179959 A1.

[0240] The supported metallocene catalyst was prepared similarly to IE2 in WO2019 / 179959A1.

[0241] Ziegler-Natta catalyst The Ziegler-Natta catalysts used in the examples were prepared as follows: raw materials TiCl4 (CAS 7550-45-90) was supplied by a commercial source. 20% solution of butylethylmagnesium (Mg(Bu)(Et)) in toluene, provided by Crompton 2-Ethylhexanol, provided by Merck Chemicals 3-Butoxy-2-propanol, provided by Sigma-Aldrich Bis(2-ethylhexyl) citraconate (internal donor), provided by Contract Chemicals Dicyclopentyldimethoxysilane (DCPDMS) - external donor Viscoplex 登録商標 1-254, provided by Evonik Heptane, provided by Chevron.

[0242] Preparation of Mg complexes 3.4 liters of 2-ethylhexanol and 810 ml of propylene glycol butyl monoether (molar ratio 4 / 1) were added to a 20-liter reactor. Next, 7.8 liters of a 20% solution of BEM (butylethylmagnesium) in toluene, provided by Crompton GmbH, was slowly added to the well-stirred alcohol mixture. During the addition, the temperature was maintained at 10°C. After the addition, the temperature of the reaction mixture was raised to 60°C, and stirring was continued at this temperature for 30 minutes. Finally, after cooling to room temperature, the resulting Mg-alkoxide was transferred to a storage container.

[0243] 21.2 g of the Mg alkoxide prepared above was mixed with 4.0 ml of bis(2-ethylhexyl)citraconate for 5 minutes, and the resulting Mg complex was immediately used in the preparation of the catalyst component.

[0244] Preparation of catalyst components 19.5 ml of titanium tetrachloride was placed in a 300 ml reactor equipped with a mechanical stirrer at 25°C. The stirring speed was adjusted to 170 rpm. 26.0 ml of the Mg complex prepared above was added within 30 minutes while maintaining the temperature at 25°C. 3.0 ml of Viscoplex 1-254 and 24.0 ml of heptane were added to form an emulsion. Mixing was continued at 25°C for 30 minutes. The reactor temperature was then increased to 90°C within 30 minutes. The reaction mixture was further stirred at 90°C for 30 minutes. The stirring was then stopped, and the reaction mixture was allowed to settle at 90°C for 15 minutes.

[0245] The solid was washed with 100 ml of toluene, 30 ml of TiCl4, 100 ml of toluene, and two 60 ml portions of heptane. 1 ml of donor (i.e., bis(2-ethylhexyl)citraconate) was added to the first two washes. The washes were carried out at 80°C with stirring at 170 rpm for 30 minutes. After stirring was stopped, the reaction mixture was allowed to settle for 20-30 minutes and then siphoned.

[0246] Afterwards, stirring was stopped and the reaction mixture was allowed to settle for 10 minutes, cooled to 70°C, and subsequently siphoned, followed by N2 sparging for 20 minutes to obtain an air-sensitive powder.

[0247] The catalyst had a surface area of ​​5 m2 measured by the BET method. 2 / g, i.e., below the detection limit.

[0248] Polymerization Example The example experiments were carried out on a pilot scale.

[0249] The first polymerization was run conventionally for 24 hours in the presence of the ZNPP catalyst described above, using 30-50 g of external donor (dicyclopentyldimethoxysilane (DCPDMS)) per ton of propylene fed to the process.

[0250] The ZN catalyst contained TEAL as an aluminum alkyl cocatalyst. It was fed at 170 g per ton of propylene co-fed to the prepolymerization reactor and the first slurry reactor. The transition procedure was operated as follows. During the transition period, both single-site and Ziegler-Natta polymers were produced.

[0251] General Transition Timing Protocol for Single-Site Catalyst Addition at Time Zero -5.0 hours Single-site catalyst was prepared in the catalyst feed tank. -1.0 hour: Antistatic feed into the prepolymerization reactor (SPAN 80) was started. ·−0.5 h The hydrogen supply to the second polymerization was adjusted to reflect the amount of hydrogen supply required for the target second polymer product; -0.1 hours: The external donor (dicyclopentyldimethoxysilane (DCPDMS)) supply was stopped. -0.1 h: the ZN catalyst feed was stopped; -0.1 hours. Based on the C3 feed rate fed together to the prepolymerization reactor and the slurry reactor, the TEAL feed was changed from 170 g / ton of C3 to 2.5 g / ton of C3. 0 hours Single-site catalyst supply started +0.1 hours. The second prepolymerization conditions were adjusted to reflect the conditions required for the second polymer product. +0.2 hours Second slurry phase conditions were adjusted to reflect the conditions required for the second polymer product +0.3 hours The second gas phase conditions were adjusted to reflect the conditions required for the second polymer product. +0.5~2 hours: GPR operation starts when loop production exceeds 25 from maximum production.

[0252] The conditions in the polymerization reactor are detailed below in Table 1. Polymer properties are measured at the end of the process described above, ie, after GPR operation is established.

[0253] [Table 1] JPEG2026501237000009.jpg251170

[0254] By using 2.5 wt-ppm TEAL as a scavenger, the following improvements were observed: Better overall productivity Better reactor balance, i.e. better production division between reactors · Less amorphous fraction, less XS Good average particle size and good PSD of the final PP powder Better bulk density of the final PP powder Faster time to reach normal production

[0255] Example 2 In Example 2, a TEAL flush was used between the stopping of the ZN catalyst feed and the starting of the single-site catalyst feed. The same catalyst as in Example 1 was used. CE02: No TEAL flash IE03: Heavy TEA flush for 2 hours, then TEAL supply per instance

[0256] The first polymerization was run for 24 hours in a conventional manner in the presence of the ZNPP catalyst described above, using 30-50 g of external donor (dicyclopentyldimethoxysilane (DCPDMS)) per ton of propylene fed to the process.

[0257] The ZN catalyst contained TEAL as an aluminum alkyl cocatalyst, which was fed at 170 g per ton of propylene co-fed to the prepolymerization reactor and the first slurry reactor. The transfer procedure was operated as follows:

[0258] General transition timing protocol for flushing at time zero -5.0 hours Single-site catalyst was prepared in the catalyst feed tank. -1.0 hour: Antistatic feed into the prepolymerization reactor (SPAN 80) was started. -0.5 hours The hydrogen supply to the second polymerization was adjusted to reflect the amount of hydrogen supply required for the target second polymer product; -0.1 hours The external donor (dicyclopentyldimethoxysilane (DCPDMS)) supply was stopped. -0.1 hours the ZN catalyst feed was stopped; 0 hours: TEAL flush 170g / ton C3 was fed into the bottom of the catalyst feed line and flushed into the prepolymerization reactor, followed by the loop reactor and gas phase reactor; +2.0 hours The TEAL feed was changed to 2.5 g / ton of C3 based on the C3 feed rate co-fed to the prepolymerization reactor and the slurry reactor. +2.1 hours Single-site catalyst supply started +2.2 hours Second prepolymerization conditions were adjusted to reflect the conditions required for the second polymer product. +2.3 hours Second slurry phase conditions were adjusted to reflect the conditions required for the second polymer product +2.4 hours Second gas phase conditions were adjusted to reflect the conditions required for the second polymer product +2.6~4.1 hours GPR operation starts when loop production exceeds 25 from maximum production.

[0259] The conditions in the polymerization reactor are detailed below in Table 2. Polymer properties are measured at the end of the process described above, ie, after GPR operation is established.

[0260] [Table 2] JPEG2026501237000011.jpg255161

[0261] Between the use of ZN catalyst and single-site catalyst, the following improvements were observed using TEAL flash at 170 g / t propylene / hr for 2 hours: Better overall productivity Better reactor balance, i.e. better production division between reactors · Less amorphous fraction, less XS Good average particle size and good PSD of the final PP powder Better bulk density of the final PP powder Faster time to reach normal production No significant change in thermal properties.

Claims

1. 1. A method for transitioning between two different catalysts during the production of a polypropylene homopolymer or copolymer in a sequential multi-stage polymerization reaction, said method comprising: a) polymerizing propylene and optionally a comonomer in the presence of a first catalyst in a multi-stage polymerization reactor system comprising a prepolymerization reactor followed by a slurry reactor and then a gas phase reactor; b) discontinuing the supply of the first catalyst to the prepolymerization reactor; c) subsequently introducing propylene, optionally a comonomer, and a second catalyst into said prepolymerization reactor, and further introducing an aluminum alkyl into said polymerization reactor simultaneously with said introduction of said second catalyst; d) polymerizing propylene and optionally a comonomer in the presence of a second catalyst in said multi-stage polymerization reactor system. The process includes the steps of: wherein the first catalyst is a Ziegler-Natta catalyst and the second catalyst is a single-site catalyst; and wherein the amount of aluminum alkyl fed in step c) is 0.5 to 10.0 g per ton of total propylene fed into the prepolymerization reactor and the slurry reactor in steps c) and d). The method.

2. 1. A method for transitioning between two different catalysts during the production of a polypropylene homopolymer or copolymer in a sequential multi-stage polymerization reaction, said method comprising: a) polymerizing propylene and optionally a comonomer in the presence of a first catalyst in a multi-stage polymerization reactor system comprising a prepolymerization reactor followed by a slurry reactor and then a gas phase reactor; b) discontinuing the supply of the first catalyst to the prepolymerization reactor; c) subsequently introducing propylene, optionally a comonomer, and a second catalyst into said prepolymerization reactor; d) polymerizing propylene and optionally a comonomer in the presence of a second catalyst in said multi-stage polymerization reactor system. The process includes the steps of: wherein the first catalyst is a Ziegler-Natta catalyst and the second catalyst is a single-site catalyst; wherein between step b) and step c), propylene and an aluminum alkyl are introduced into the prepolymerization reactor, wherein the amount of aluminum alkyl is 100 to 300 g per ton of propylene introduced during this step; and preferably wherein the amount of the aluminum alkyl fed in step c) is 0.5 to 10.0 g per ton of total propylene fed into the prepolymerization reactor and the slurry polymerization reactor in steps c) and d). The method.

3. 2. The process of claim 1, wherein the amount of aluminum alkyl fed in step c) is from 0.5 to 5.0 g per ton of total propylene fed into the prepolymerization reactor and the slurry polymerization reactor from the point at which the second catalyst is introduced into the prepolymerization reactor, for example, from 1.0 to 3.0 g per ton.

4. 3. The process of claim 2, wherein the amount of aluminum alkyl fed between steps b) and c) is 150 to 200 g of aluminum alkyl per ton of propylene fed between steps b) and c).

5. 5. The process according to claim 2 or 4, wherein the step between step b) and step c) of introducing propylene and aluminum alkyl as a flash into the prepolymerization reactor lasts for 0.5 to 4 hours, for example 1 to 3 hours.

6. 6. The method of any one of claims 1 to 5, wherein the aluminum alkyl is triethylaluminum (TEAL), triisobutylaluminum (TIBA), or a combination thereof.

7. 7. The method of any one of claims 1 to 6, wherein the transition from the first catalyst to the second catalyst is carried out in the absence of any additional agent that deactivates or kills the Ziegler-Natta catalyst, such as carbon monoxide.

8. The Ziegler-Natta catalyst used is MgCl 2 8. The method of claim 1, wherein the catalyst is a solid Ziegler-Natta catalyst selected from titanium Ziegler-Natta catalysts supported on a support material and self-supported solid Ziegler-Natta catalysts.

9. 9. The method according to claim 1, wherein an external donor to the first catalyst is used in step a), such as an external donor selected from the group consisting of diisopropyldiethoxysilane (DIPDES), cyclohexylmethyldiethoxysilane (CHMDES), dicyclopentyldimethoxysilane, cyclohexylmethyldimethoxysilane and dicyclopentadienyldiethoxysilane (DCPDES) and diethylaminotriethoxysilane.

10. 10. The process according to any one of claims 1 to 9, wherein the first catalyst of step a) is used together with a co-catalyst which is triethylaluminum (TEAL), in particular wherein the amount of TEAL used in the prepolymerization reactor of step a) is at least 20 g of TEAL per tonne of total propylene added to the prepolymerization reactor and the slurry reactor of step a).

11. The process of any one of claims 1 to 10, wherein the single-site catalyst is a metallocene catalyst.

12. 12. The method of claim 11, wherein the metallocene catalyst comprises, as catalytic components, an organometallic compound of a transition metal of formula (I) and a cocatalyst: (L) m R n MX q (I) where: "M" is a transition metal (M) from Groups 3 to 10 of the Periodic Table (IUPAC 2007); Each "X" is independently a monoanionic ligand, e.g., a σ-ligand; each "L" is independently an organic ligand that coordinates to said transition metal "M"; "R" is a bridging group connecting the organic ligands (L); "m" is 1, 2 or 3, preferably 2; "n" is 0, 1 or 2, preferably 1; "q" is 1, 2 or 3, preferably 2; and m+q is equal to the valence of the transition metal (M).

13. 10. The process of claim 9, wherein the external donor feed to the first prepolymerization reactor in step a) is discontinued before or simultaneously with the discontinuation of the feed of the first catalyst.

14. The process of any one of claims 1 to 13, wherein the second catalyst is fed to the prepolymerization reactor together with the aluminum alkyl via a catalyst feed line.

15. 10. The process of claim 1, wherein the amount of aluminum alkyl introduced into the prepolymerization reactor is reduced from 150 to 200 g per ton of propylene (based on the amount of propylene fed into the prepolymerization reactor and the slurry polymerization reactor in step a) to 0.5 to 10 g per ton of propylene (based on the amount of propylene fed into the prepolymerization reactor and the slurry polymerization reactor in steps c) and d) before the second catalyst is introduced, preferably after step b).

16. The method of any one of claims 1 to 15, wherein the polypropylene is a propylene homopolymer.

17. 17. The process of any one of claims 1 to 16, wherein after the feeding of the first catalyst is discontinued, the polymerization conditions in the prepolymerization reactor and the slurry reactor of step a) are adjusted to reflect the conditions required in the prepolymerization reactor and the slurry reactor of step d).

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