Pre-polymerized Ziegler-Natta catalyst

Abstract

The present disclosure relates to a process for producing a prepolymerized Ziegler-Natta catalyst. The present invention relates to a process for preparing vinyl cycloalkanes, comprising: Ai) reacting at least one acyclic alpha-olefin having from 2 to 10 carbon atoms in the presence of a Ziegler-Natta catalyst, and Aii) subsequently reacting vinyl cycloalkanes, vinyl cycloolefins, and / or vinyl aromatics in the presence of a Ziegler-Natta catalyst; or Bi) reacting vinyl cycloalkanes, vinyl cycloolefins and / or vinyl aromatics in the presence of a Ziegler-Natta catalyst, and Bii) subsequently reacting at least one acyclic alpha-olefin having 2 to 10 carbon atoms in the presence of a Ziegler-Natta catalyst, when vinyl cycloalkanes, vinyl cycloolefins and / or vinyl arenes are reacted in Bi) in the presence of a Ziegler-Natta catalyst and at least one acyclic alpha-olefin having 2 to 10 carbon atoms is subsequently reacted in Bii) in the presence of a Ziegler-Natta catalyst, the weight ratio of the at least one acyclic alpha-olefin to the Ziegler-Natta catalyst is less than 200: 1.

Description

Technical Field

[0001] This disclosure relates to a method for producing prepolymerized Ziegler-Natta catalyst compositions. This disclosure also relates to prepolymerized Ziegler-Natta catalyst compositions; catalyst systems for propylene polymerization; and methods for producing polypropylene. Background Technology

[0002] Ziegler-Natta catalysts typically comprise (a) at least one catalyst component formed from transition metal compounds of Groups 4 to 6 of the Periodic Table (IUPAC, Inorganic Chemical Nomenclature, 1989) and metal compounds of Groups 1 to 3 of the Periodic Table (IUPAC). Ziegler-Natta catalysts may also comprise compounds of Group 13 of the Periodic Table (IUPAC) and / or internal donor compounds. Ziegler-Natta catalysts can be used in conjunction with (b) other catalyst components, such as co-catalysts and / or external donors.

[0003] Several methods for preparing Ziegler-Natta catalysts are known. For example, EP 1403292 A1, EP 0949280 A1, US-A-4294948, US-A-5413979, US-A-5409875 and EP 1273595 A1 describe methods for preparing such catalysts.

[0004] Prepolymerized Ziegler-Natta catalyst compositions can be formed by polymerizing vinyl monomers in the presence of a Ziegler-Natta catalyst. The prepolymerized Ziegler-Natta catalyst compositions are then used to catalyze the polymerization of olefins. Using prepolymerized Ziegler-Natta catalyst compositions can impart improved properties to the final polymer.

[0005] WO 2018 / 011165 and EP 2960256 describe solid catalyst particles comprising a Ziegler-Natta catalyst and a polymeric nucleating agent, wherein the polymeric nucleating agent comprises a vinyl monomer unit, such as vinylcyclohexane, and can be obtained in the presence of the Ziegler-Natta catalyst. WO 2020 / 064568 describes the prepolymerization of a solid ZN catalyst component in the presence of one or more olefin monomers selected from C2, C3, or C4 olefin monomers and mixtures thereof to obtain a prepolymerized solid ZN catalyst. Summary of the Invention

[0006] According to a first aspect, this disclosure provides a method for producing a prepolymerized Ziegler-Natta catalyst composition. The method includes:

[0007] Ai) reacts at least one acyclic α-olefin having 2 to 10 carbon atoms in the presence of a Ziegler-Natta catalyst, and

[0008] Aii) Subsequently, vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics are reacted in the presence of a Ziegler-Natta catalyst; or

[0009] Bi) reacts vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics in the presence of a Ziegler-Natta catalyst, and

[0010] Bii) then reacts at least one acyclic α-olefin having 2 to 10 carbon atoms in the presence of a Ziegler-Natta catalyst.

[0011] in,

[0012] When vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics react in Bi) in the presence of a Ziegler-Natta catalyst, and when at least one acyclic α-olefin having 2-10 carbon atoms subsequently reacts in Bi) in the presence of a Ziegler-Natta catalyst, the weight ratio of at least one acyclic α-olefin to the Ziegler-Natta catalyst is less than 200:1.

[0013] According to the second aspect, this disclosure also provides prepolymerized Ziegler-Natta catalyst compositions that can be obtained by or through the methods of the first aspect herein.

[0014] According to a third aspect, this disclosure provides a catalyst system for propylene polymerization, the catalyst system comprising a prepolymerized Ziegler-Natta catalyst composition according to the second aspect herein, a cocatalyst, and an external donor.

[0015] According to a fourth aspect, this disclosure provides a method for producing polypropylene, comprising polymerizing propylene in the presence of a prepolymerized Ziegler-Natta catalyst composition according to the second aspect herein. Detailed Implementation

[0016] As described above, the first aspect of this disclosure provides a method for producing prepolymerized Ziegler-Natta catalyst compositions.

[0017] The method includes:

[0018] Ai) reacts at least one acyclic α-olefin having 2 to 10 carbon atoms in the presence of a Ziegler-Natta catalyst, and

[0019] Aii) Subsequently, vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics are reacted in the presence of a Ziegler-Natta catalyst; or

[0020] Bi) reacts vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics in the presence of a Ziegler-Natta catalyst, and

[0021] Bii) then reacts at least one acyclic α-olefin having 2 to 10 carbon atoms in the presence of a Ziegler-Natta catalyst.

[0022] in,

[0023] When vinylcycloalkanes, vinylcycloolefins and / or vinyl aromatics react in Bi) in the presence of a Ziegler-Natta catalyst and when at least one acyclic α-olefin having 2-10 carbon atoms subsequently reacts in Bi) in the presence of a Ziegler-Natta catalyst, the weight ratio of at least one acyclic α-olefin to the Ziegler-Natta catalyst is less than 200:1, preferably less than 100:1, for example 10:90 to 90:10.

[0024] This disclosure also relates to a method for producing prepolymerized Ziegler-Natta catalyst compositions. The method includes:

[0025] a) Reacting at least one acyclic α-olefin having 2 to 10 carbon atoms in the presence of a Ziegler-Natta catalyst; and

[0026] b) Polymerizing vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics in the presence of the same Ziegler-Natta catalyst.

[0027] Steps a) and b) are performed, either individually or subsequently in any order, to provide a prepolymerized Ziegler-Natta catalyst composition comprising: a Ziegler-Natta catalyst, a polymer having polymeric units derived from at least one acyclic α-olefin having 2 to 10 carbon atoms, and a polymer having polymeric units derived from vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics, provided that when step a) is performed prior to step a), the weight ratio of at least one acyclic α-olefin to the Ziegler-Natta catalyst is less than 200:1.

[0028] Prepolymerized Ziegler-Natta catalyst compositions can be used as catalysts for polymer polymerization, such as propylene polymerization.

[0029] Advantageously, the prepolymerization process results in the formation of a polymer that acts as a nucleating agent. Without wishing to be bound by any theory, the polymer comprises polymeric units derived from at least one acyclic α-olefin (e.g., 1-butene) having 2 to 10 carbon atoms, and polymeric units derived from vinylcycloalkanes or vinyl aromatics (e.g., vinylcyclohexane). When polypropylene is subsequently produced in the presence of the prepolymerized catalyst composition, these polymers influence the crystallinity of the produced polypropylene. By improving crystallinity, the produced polypropylene can possess improved mechanical, thermal, and / or optical properties.

[0030] The higher crystallinity of polypropylene can be achieved by using a higher crystallization temperature T. cTo demonstrate this, higher crystallinity can result in higher moduli in polypropylene, such as tensile modulus. In some instances, prepolymerized Ziegler-Natta catalysts can be used to produce polypropylene with improved stiffness.

[0031] Prepolymerized Ziegler-Natta catalysts can be used to produce polypropylene with improved thermal properties. Such thermal properties include, for example, improved mechanical properties upon exposure to high temperatures. For instance, prepolymerized Ziegler-Natta catalysts can be used to produce polypropylene with reduced elongation at high temperatures, or improved dimensional stability and / or reduced creep.

[0032] In some instances, prepolymerized Ziegler-Natta catalysts can be used to produce products with high enthalpy of melting (H0). m Polypropylene.

[0033] In some instances, prepolymerized Ziegler-Natta catalysts can be used to produce polypropylene with improved optical properties, such as clarity, transparency, and / or haze. In some instances, these properties can be improved, for example, when exposed to high temperatures, such as those encountered during sterilization or pasteurization.

[0034] In this disclosure, at least one acyclic α-olefin having 2 to 10 carbon atoms is reacted in the presence of a Ziegler-Natta catalyst (e.g., Ai or Bi). Suitable acyclic α-olefins will be discussed in further detail below. However, the acyclic α-olefin is preferably selected from at least one of ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and 1-octene. For example, the acyclic α-olefin can be 1-butene. This reaction can produce polymers having polymeric units derived from at least one acyclic α-olefin having 2 to 10 carbon atoms (e.g., 1-butene).

[0035] The weight ratio of at least one acyclic α-olefin having 2 to 10 carbon atoms to the Ziegler-Natta catalyst can be 200:1 or lower, for example, 100:1 or lower. Wherein the method includes steps Bi) and Bii), the weight ratio of at least one acyclic α-olefin having 2 to 10 carbon atoms to the Ziegler-Natta catalyst is 200:1 or lower, for example, 100:1 or lower. When the method includes steps Ai) and Aii), the weight ratio of at least one acyclic α-olefin having 2 to 10 carbon atoms to the Ziegler-Natta catalyst can preferably be 200:1 or lower, for example, 100:1 or lower. The weight ratio of at least one acyclic α-olefin having 2 to 10 carbon atoms to the Ziegler-Natta catalyst can be from 10:90 to 90:10. For example, the weight ratio of at least one acyclic α-olefin to the Ziegler-Natta catalyst is 20:80 to 80:20, preferably 30:70 to 70:30, more preferably 40:60 to 60:40, and even more preferably 55:45 to 45:55.

[0036] Preferably, in step Ai) or step Bi) the weight ratio of at least one acyclic α-olefin having 2 to 10 carbon atoms to the Ziegler-Natta catalyst is 10:90 to 90:10. For example, in step Ai) or step Bi) the weight ratio of at least one acyclic α-olefin to the Ziegler-Natta catalyst is 20:80 to 80:20, preferably 30:70 to 70:30, more preferably 40:60 to 60:40, and even more preferably 55:45 to 45:55.

[0037] In this disclosure, vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics are reacted in the presence of a Ziegler-Natta catalyst (e.g., in step Aii or Bi). Suitable vinylcycloalkanes, vinylcycloalkanes, and vinyl aromatics are discussed below. However, vinylcycloalkanes are preferred. Vinylcycloalkanes may be selected from vinylcyclohexane, vinylcyclopentane, vinyl-2-methylcyclohexane, and vinylnorbornene. More preferably, the vinylcycloalkanes are vinylcyclohexane.

[0038] The sequential reactions in steps Ai) and Aii) or Bi) and Bi) can lead to a prepolymerized Ziegler-Natta catalyst composition comprising a polymer having polymeric units derived from at least one acyclic α-olefin having 2 to 10 carbon atoms and a polymer having polymeric units derived from vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics. The polymers in the prepolymerized Ziegler-Natta catalyst composition can act as nucleating agents, imparting improved crystallinity to the final polypropylene. The sequential nature of reactions Ai) and Aii), and Bi) and Bi) can allow for the sequential production of different polymers used as nucleating agents (e.g., (1) a polymer having polymeric units derived from at least one acyclic α-olefin having 2 to 10 carbon atoms, and (2) a polymer having polymeric units derived from vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics).

[0039] Preferably, in step Aii) or step Bi), the weight ratio of vinylcycloalkane or vinyl aromatic hydrocarbon to Ziegler-Natta catalyst can be less than 200:1, more preferably less than 100:1, for example, 10:90 to 90:10. In some examples, the weight ratio of vinylcycloalkane to Ziegler-Natta catalyst is 20:80 to 80:20, preferably 30:70 to 70:30, more preferably 40:60 to 60:40, and even more preferably 55:45 to 45:55.

[0040] Preferably, the Ziegler-Natta catalyst comprises a compound selected from transition metals of Groups 4 to 6 of the periodic table; a compound selected from Groups 1 to 3 of the periodic table; and an internal donor. More preferably, the Ziegler-Natta catalyst comprises a titanium compound, a magnesium compound, and an internal donor. As discussed in further detail below, the internal donor may be a non-phthalate ester.

[0041] In some instances, at least one of steps Ai) and Ai) or at least one of steps Bi) and Bi) is carried out in the presence of a co-catalyst and an optional external donor.

[0042] As described above, this disclosure also provides a method for producing polypropylene. The method includes polymerizing propylene in the presence of a prepolymerized Ziegler-Natta catalyst composition, which can be obtained by or through the method described herein for producing a prepolymerized Ziegler-Natta catalyst composition. The prepolymerized Ziegler-Natta catalyst composition can be used as part of a catalyst system that also includes a co-catalyst and an external donor.

[0043] Prepolymerized Ziegler-Natta catalyst

[0044] In one embodiment of this disclosure ((Ai) and Aii), at least one acyclic α-olefin is reacted in the presence of a Ziegler-Natta catalyst. Vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics are subsequently reacted in the presence of the Ziegler-Natta catalyst. Thus, in step Aii), vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics are reacted in the presence of a Ziegler-Natta catalyst present in the reaction of at least one acyclic α-olefin in step Ai). In some instances, the Ziegler-Natta catalyst remains unchanged (identical) between steps Ai) and Aii).

[0045] Because step Aii) follows step Ai), step Aii) occurs after step Ai). However, Aii) does not need to immediately follow Ai; intermediate reaction steps may occur between Ai) and Aii). However, in some embodiments, Aii) is performed immediately after Ai).

[0046] Preferably, in step Ai), at least one acyclic α-olefin can be reacted in the presence of a Ziegler-Natta catalyst to produce an intermediate or modified Ziegler-Natta catalyst composition comprising a polymer having units derived from at least one acyclic α-olefin. In step Ai), vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics are subsequently reacted in the presence of an intermediate or modified Ziegler-Natta catalyst. The resulting product mixture may comprise polymers having units derived from at least one acyclic α-olefin and polymers having units derived from vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics.

[0047] In another embodiment (Bi) and Bii), vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics are reacted in the presence of a Ziegler-Natta catalyst. At least one acyclic α-olefin group is subsequently reacted in the presence of the Ziegler-Natta catalyst. Thus, in step Bii), at least one acyclic α-olefin is reacted in the presence of a Ziegler-Natta catalyst, which is present in the reaction of the at least one acyclic α-olefin in step Bi). In some instances, the Ziegler-Natta catalyst remains unchanged (identical) in steps Bi) and Bii).

[0048] Because step Bii) follows step Bi), step Bii) occurs after step Bi). However, Bii) does not need to immediately follow Bi; intermediate reaction steps may occur between Bi) and Bii). However, in some embodiments, Bii) occurs immediately after Bi).

[0049] Preferably, in step Bi), vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics can be reacted in the presence of a Ziegler-Natta catalyst to produce an intermediate Ziegler-Natta catalyst composition comprising a polymer having units derived from vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics. In step Bii), at least one acyclic α-aromatic hydrocarbon is subsequently reacted in the presence of the intermediate Ziegler-Natta catalyst composition. The resulting product mixture may comprise a polymer having units derived from at least one acyclic α-olefin and a polymer having units derived from vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics.

[0050] Sequential reactions allow the formation of the first polymer before the formation of the second polymer.

[0051] The prepolymerization process results in the formation of a polymer that can act as a nucleating agent. These polymers may have polymeric units derived from at least one acyclic α-olefin (e.g., 1-butene) having 2 to 10 carbon atoms. The polymer may also have polymeric units derived from vinylcycloalkanes (e.g., vinylcyclohexane), vinylcycloolefins, or vinyl aromatics. In some instances, the polymer may have polymeric units derived from at least one acyclic α-olefin (e.g., 1-butene) having 2 to 10 carbon atoms, as well as polymeric units derived from vinylcycloalkanes, vinylcycloolefins, or vinyl aromatics (e.g., vinylcyclohexane).

[0052] These polymers can be incorporated into the final polypropylene. The polymers formed during the prepolymerization reaction act as nucleating agents, affecting the crystallinity and / or crystallization behavior of the produced polypropylene. For example, when propylene is subsequently formed in the presence of a prepolymerized Ziegler-Natta catalyst, the present polymerization nucleating agent affects the crystallinity and / or crystallization behavior of the produced polypropylene. However, these polymers may not be present in detectable amounts in the final polypropylene composition.

[0053] The acyclic α-olefin used to form the prepolymerized Ziegler-Natta catalyst composition can be a branched or unbranched hydrocarbon with a single carbon-carbon double bond, having the molecular formula C2. n H 2n Where n is 2 to 10. In this disclosure, the carbon-carbon double bond is present at the α-position. Preferably, n can be 2 to 9, for example 2 to 8. In some embodiments, n is 2 or 4 to 8, for example 2, 4, 5, 6, 7 or 8. In a preferred embodiment, n is 4. For example, the acyclic α-olefin used in step Ai) can be 1-butene.

[0054] Acyclic α-olefins are preferably linear.

[0055] Suitable acyclic α-olefins include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and 1-octene. Preferably, the acyclic α-olefin is ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and / or 1-octene. In some embodiments, the acyclic α-olefin is not propylene. More preferably, the acyclic α-olefin is ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and / or 1-hexene; even more preferably, the acyclic α-olefin is ethylene, 1-butene, 1-pentene, or 1-hexene. More preferably, the acyclic α-olefin is 1-butene. However, other examples of acyclic α-olefins include 3-methyl-1-butene, 3-ethyl-1-hexene, 3-methyl-1-pentene, and 4-methyl-1-pentene. Combinations of two or more acyclic α-olefins can be used. For example, 1-butene and ethylene can be used together to produce copolymers that can act as nucleating agents.

[0056] Preferably, one type of acyclic α-olefin is reacted in the presence of a Ziegler-Natta catalyst. However, in some instances, in the copolymerization reaction of step Ai) or Bi) , the Ziegler-Natta catalyst is reacted in the presence of a mixture of two or more acyclic α-olefins.

[0057] In step Bii), the weight ratio of at least one acyclic α-olefin having 2 to 10 carbon atoms to the Ziegler-Natta catalyst is less than 200:1, preferably less than 100:1. The weight ratio can be less than 50:1, preferably less than 20:1, and more preferably less than 10:1. In one embodiment, the ratio is 10:90 to 90:10, preferably 20:80 to 80:20, more preferably 30:70 to 70:30, and even more preferably 40:60 to 60:40, for example, 45:55 to 55:45.

[0058] In step Ai), the weight ratio of at least one acyclic α-olefin having 2 to 10 carbon atoms to the Ziegler-Natta catalyst is less than 200:1, preferably less than 100:1, for example, 10:90 to 90:10. The weight ratio can be less than 50:1, preferably less than 20:1, more preferably less than 10:1. In one embodiment, the ratio is 10:90 to 90:10, preferably 20:80 to 80:20, more preferably 30:70 to 70:30, and even more preferably 40:60 to 60:40, for example, 45:55 to 55:45.

[0059] As described above, when acyclic α-olefins react in the presence of a Ziegler-Natta catalyst, a polymer is produced having polymeric units derived from at least one acyclic α-olefin (e.g., 1-butene) having 2 to 10 carbon atoms. For example, the polymer can be polyethylene, polypropylene, polybutene, polypentene, polyhexene, polyhedene, or polyoctene. Preferably, the polymer is polybutene (e.g., in step Ai). The polymer is preferably a homopolymer. However, in some instances, the polymer chain can be a copolymer chain formed from two or more different acyclic α-olefins as comonomers. For example, the copolymer chain can contain units derived from 1-butene and ethylene.

[0060] In steps Aii) and Bi), vinyl cycloalkanes, vinyl cycloolefins, or vinyl aromatics are reacted in the presence of a Ziegler-Natta catalyst.

[0061] Vinylcycloalkanes, vinylcycloolefins, or vinyl aromatics can have the following formula:

[0062] CH2=CR 1 R 2

[0063] Where R 1 It is H or -CH3, preferably H; and

[0064] R 2 It is an optionally substituted cycloalkyl ring, optionally substituted cycloalkenyl ring, and / or optionally substituted aryl ring, or optionally substituted fused ring system. The ring or fused ring system may contain 4 to 20 carbon atoms. Preferably, the ring or fused ring system may contain 5 to 12 carbon atoms. The ring or fused ring system may be unsubstituted or optionally substituted with one or more C1 to C6 alkyl groups such as methyl. When R 2 When the cyclic alkenyl group is optionally substituted, the cyclic alkenyl group may have one, two, or three C=C double bonds.

[0065] In some instances, R 2 It can contain 5 to 7 carbon atoms.

[0066] Where R 2 It is an aryl group that can be optionally substituted, and it can be a benzene ring that can be optionally substituted.

[0067] Where R 2 It is an optionally substituted cycloalkenyl group, which can be an optionally substituted cyclohexenyl ring.

[0068] Preferably, R 2 It is an optionally substituted cycloalkyl ring. More preferably, R 2 It can be cyclopentyl, cyclohexyl, or norbornel ring.

[0069] Preferably, a vinylcycloalkane is used. The vinylcycloalkane may be selected from vinylcyclohexane, vinylcyclopentane, vinyl-2-methylcyclohexane, and vinylnorbornene. More preferably, the vinylcycloalkane is vinylcyclohexane.

[0070] In some instances, vinyl aromatics may be used. A suitable vinyl aromatic is styrene. In one instance, 1-methylstyrene is used.

[0071] In step Aii) or Bi), the weight ratio of vinylcycloalkane, vinylcycloolefin and / or vinyl aromatic to Ziegler-Natta catalyst may be less than 200:1, preferably less than 100:1. The weight ratio may be less than 50:1, preferably less than 20:1, and more preferably less than 10:1.

[0072] In some examples, in step Aii) or Bi), the weight ratio of vinylcycloalkane, vinylcycloolefin, and / or vinyl aromatic to Ziegler-Natta catalyst can be from 10:90 to 90:10. In some examples, the weight ratio of vinylcycloalkane, vinylcycloolefin, and / or vinyl aromatic to Ziegler-Natta catalyst is from 20:80 to 80:20, preferably from 30:70 to 70:30, more preferably from 40:60 to 60:40, and even more preferably from 45:55 to 55:45.

[0073] When vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics react in the presence of a Ziegler-Natta catalyst, a polymer is produced having polymeric units derived from vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics (e.g., vinylcyclohexane). The polymer is preferably a homopolymer. In one example, the polymer is polyvinylcyclohexane.

[0074] In some instances, the weight ratio of the acyclic α-olefin reacting in the presence of a Ziegler-Natta catalyst to the weight of the vinylcycloalkane, vinylcycloolefin, or vinyl aromatic hydrocarbon reacting in the presence of a Ziegler-Natta catalyst can be from 10:90 to 90:10, for example from 20:80 to 80:20, preferably from 30:70 to 70:30, more preferably from 40:60 to 60:40, and even more preferably from 45:55 to 55:45.

[0075] The prepolymerized Ziegler-Natta catalyst may have a degree of prepolymerization of 0.1 to 100 g polyolefin / g Ziegler-Natta catalyst, more preferably 0.2 to 80 g polyolefin / g Ziegler-Natta catalyst, even more preferably 0.3 to 50 g polyolefin / g Ziegler-Natta catalyst, more preferably 0.4 to 40 g polyolefin / g Ziegler-Natta catalyst, and even more preferably 0.5 to 30 g polyolefin / g Ziegler-Natta catalyst. The degree of prepolymerization can be determined by the mass of the reacted monomers and the mass of the Ziegler-Natta catalyst used in the reaction.

[0076] Prepolymerization can be carried out in any inert fluid that does not dissolve the polymer formed. The viscosity of the final catalyst / polymerized vinyl compound / inert liquid mixture should also be high enough to prevent catalyst particles from settling during storage and transportation. The viscosity of the mixture can be adjusted before or after the polymerization of the vinyl compound. For example, prepolymerization can be carried out in a low-viscosity oil, and the viscosity can be adjusted by adding a high-viscosity substance after the prepolymerization of the vinyl compound. This high-viscosity substance can be a "wax," such as an oil or a mixture of oil and a solid or high-viscosity substance (oil-grease). The viscosity of such a viscous substance is typically 1,000 to 15,000 centipoise at room temperature. The advantage of using waxes is improved catalyst storage and feeding into the process.

[0077] The weight ratio between oil and solid or high-viscosity polymer is preferably less than 5:1. A suitable weight ratio can be determined experimentally.

[0078] In addition to viscous substances, liquid hydrocarbons such as isobutane, propane, pentane, and hexane can also be used as media in the modification process.

[0079] Preferably, the polypropylene produced using the prepolymerization catalyst is substantially free of free (unreacted) vinyl compounds. This means that the vinyl compounds can be completely reacted during prepolymerization. For this purpose, the total weight ratio of the vinyl compounds added in stages Ai) and Ai) or Bi) and Bi) to the catalyst should be in the range of 0.2 to 10, preferably less than 3, more preferably about 0.2 to 2.0, and particularly about 0.3 to 1.5. It should be noted that excessive use of vinyl compounds yields only limited benefits.

[0080] Furthermore, the prepolymerization reaction time should be sufficient to allow the vinyl monomers to react completely, i.e., the polymerization reaction continues until the amount of unreacted vinyl compounds in the reaction mixture (including the polymerization medium and reactants) is less than 0.5 wt%, particularly less than 2000 ppm by weight (as shown by analysis). In some embodiments, the first monomer (i.e., step Ai) or Bi) reacts completely in the presence of the catalyst before the addition of the second monomer (i.e., step Aii) or Bi). Therefore, when the prepolymerization catalyst contains at most about 0.1 wt% of vinyl compounds, the final vinyl compound content in the polypropylene may be lower than the limit (less than 0.01 ppm (by weight)) determined by GC-MS. Typically, when operating on an industrial scale, a polymerization time of at least 30 minutes is required, preferably at least 1 hour, particularly at least 5 hours. Polymerization times in the range of 6 to 50 hours can even be used. Prepolymerization of the Ziegler-Natta catalyst can be carried out at temperatures of 10-90°C, preferably 20-65°C. The reaction temperature can vary depending on the nature of the monomers reacting in the presence of the Ziegler-Natta catalyst. For example, the reaction temperature for polymerization of at least one acyclic α-olefin can be lower than the reaction temperature for polymerization of vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics. Therefore, stage Ai) is preferably carried out at a lower temperature than stage Ai).

[0081] Prepolymerization can be carried out in the presence of a co-catalyst and an optional external donor.

[0082] General conditions for catalyst prepolymerization are also disclosed in WO 00 / 6831, which is incorporated herein by reference.

[0083] In this disclosure, prepolymerization can advantageously be carried out in successive stages. Preferably, stages Ai) and Ai) or Bi) and Bi) are carried out sequentially in the same reactor or reaction medium.

[0084] In one example of this disclosure, the Ziegler-Natta catalyst can be dispersed in a solvent to form a slurry. In step Ai), at least one acyclic α-olefin (e.g., 1-butene) can be added to the slurry. The reaction temperature can be maintained between 10 and 90 °C. In some examples, the temperature of this stage Ai) can be between 15 and 40 °C, for example, 20 to 30 °C, particularly when the acyclic α-olefin is 1-butene. Before adding at least one acyclic α-olefin (e.g., 1-butene), a co-catalyst and an external donor can be added to the slurry. The co-catalyst and the external donor can activate the catalyst.

[0085] At least one acyclic α-olefin (e.g., 1-butene) and a Ziegler-Natta catalyst can react for a sufficient time to polymerize at least one acyclic α-olefin. In some instances, the reaction is carried out such that most of the added acyclic α-olefin (e.g., 1-butene) is consumed. During the reaction, the slurry can be stirred or otherwise agitated.

[0086] Prior to the second stage (stage Aii) of this method, an intermediate containing the Ziegler-Natta catalyst and the polymerized acyclic α-olefin (e.g., 1-butene) can be separated. However, the second stage of the prepolymerization reaction, stage Aii), is preferably carried out in the same reactor or reaction medium. For example, vinylcycloalkanes (e.g., vinylcyclohexane), vinylcycloolefins, or vinyl aromatics can be introduced into the same reaction medium. The reaction temperature can be varied accordingly. For example, in one embodiment, the reaction temperature can be increased to 40 to 90°C, preferably 50 to 70°C, more preferably 55 to 65°C. The reaction can proceed for a sufficiently long time to polymerize the vinylcycloalkanes (e.g., vinylcyclohexane), vinylcycloolefins, or vinyl aromatics and produce a prepolymerized Ziegler-Natta catalyst composition.

[0087] In an alternative embodiment, the Ziegler-Natta catalyst can be dispersed in a solvent to form a slurry. In step Bi), a vinylcycloalkane (e.g., vinylcyclohexane), vinylcycloolefin, or vinyl aromatic hydrocarbon can be added to the slurry. A co-catalyst and an external donor can be added to the slurry prior to the addition of the monomer. The co-catalyst and external donor can activate the catalyst.

[0088] Vinylcycloalkanes (e.g., vinylcyclohexane), vinylcycloolefins, or vinyl aromatics, along with a Ziegler-Natta catalyst, can react for a sufficient time to polymerize the monomers. In some instances, the reaction is carried out such that most of the added monomers are consumed. During the reaction, the slurry can be stirred or otherwise agitated.

[0089] Prior to the second stage (stage Bii) of this method, intermediates containing the Ziegler-Natta catalyst and polymerized vinylcycloalkanes (e.g., vinylcyclohexane), vinylcycloolefins, or vinyl aromatics can be separated. However, the second stage (stage Bii) of the prepolymerization reaction is preferably carried out in the same reactor or reaction medium. For example, at least one acyclic α-olefin can be introduced into the same reaction medium. The reaction temperature can be varied accordingly. The reaction can proceed for a sufficient time to polymerize at least one acyclic α-olefin and produce a prepolymerized Ziegler-Natta catalyst composition.

[0090] The prepolymerized catalyst can be recycled and used in the propylene polymerization process.

[0091] Ziegler-Natta catalyst

[0092] Ziegler-Natta catalysts are solid components comprising: compounds of transition metals selected from Groups 4 to 6 of the Periodic Table (IUPAC); compounds of metals from Groups 1 to 3 of the Periodic Table (IUPAC); and internal donors.

[0093] Preferably, the transition metal compound selected from Groups 4 to 6 of the periodic table (IUPAC) is a titanium compound. More preferably, the titanium compound is titanium halide, most preferably TiCl4. The transition metal compound (e.g., the titanium compound) may be present in an amount of about 1 to about 6% by weight.

[0094] Preferably, the metal compounds in Groups 1 to 3 of the periodic table (IUPAC) are magnesium compounds. The metal compound (e.g., a magnesium compound) may be present in an amount of about 10 to about 20% by weight.

[0095] In some instances, the internal donor is a non-phthalic acid compound. Preferably, the internal donor is a non-phthalic acid ester, more preferably a diester of a non-phthalic acid carboxylic acid. The internal donor can be a non-phthalic acid ester selected from: optionally substituted malonates, maleates, succinates, glutarates, citrates and their derivatives and / or mixtures. Even more preferably, the internal donor is selected from substituted maleates and citrates, with citrate being the most preferred internal donor. The internal donor (e.g., a non-phthalic acid compound such as citrate) may be present in an amount of about 5 to about 10% by weight.

[0096] Ideally, the catalyst is substantially or completely free of unwanted phthalic acid compounds. For example, if present, the amount of phthalic acid compounds is less than 1% by weight of the catalyst, preferably less than 0.5% by weight, and even more preferably less than 0.2% by weight. In a preferred embodiment, the catalyst is completely free of phthalic acid compounds. Furthermore, the solid catalyst does not contain any external support material, such as silica, but is self-supporting. Surprisingly, in the case of a catalyst substantially or completely free of phthalic acid compounds, effective nucleation can occur during prepolymerization with "bulky" monomers vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics, because such internal donors are considered preferred for the efficient formation of prepolymers. However, it has been surprisingly found that desirable prepolymers can be produced in the absence of such phthalic acid compounds. Prepolymerization is so remarkably effective that when polypropylene is subsequently produced in the presence of such prepolymerized catalyst compositions, these polymers affect the crystallinity of the produced polypropylene. By improving crystallinity, the produced polypropylene can have improved mechanical, thermal, and / or optical properties.

[0097] In a preferred embodiment, the Ziegler-Natta catalyst comprises a titanium compound, a magnesium compound and an internal donor, preferably wherein the titanium compound is present in an amount of about 1 to about 6% by weight, the magnesium compound is present in an amount of about 10% to 20% by weight, and the internal donor is present in an amount of about 5% to 10% by weight.

[0098] A detailed description of the preparation of the Ziegler-Natta catalyst is disclosed in WO2012 / 007430, EP2415790, EP2610270, EP2610271, EP2610272, WO / 2020064568 and EP2960256, which are incorporated herein by reference.

[0099] The Ziegler-Natta catalyst can be further defined by the way it is obtained. Thus, the Ziegler-Natta catalyst is preferably obtainable by a process comprising:

[0100] a1) providing a solution of at least one Group 2 metal alkoxide (Ax), said Group 2 metal alkoxide being the reaction product of a Group 2 metal compound (MC) and a monohydric alcohol (A) which further comprises at least one ether moiety in addition to the hydroxyl moiety, optionally in an organic liquid reaction medium; or

[0101] a2) a solution of at least one Group 2 metal alkoxide (Ax'), said Group 2 metal alkoxide being the reaction product of a Group 2 metal compound (MC) with a monohydric alcohol (A) and an alcohol mixture of a monohydric alcohol (B) of the formula ROH, optionally in an organic liquid reaction medium; or

[0102] a3) providing a solution of a mixture of a Group 2 alkoxide (Ax) and a Group 2 metal alkoxide (Bx), said Group 2 metal alkoxide (Bx) being the reaction product of a Group 2 metal compound (MC) and a monohydric alcohol (B), optionally in an organic liquid reaction medium; or

[0103] a4) providing a solution of a Group 2 alkoxide of the formula M(OR i ) n (OR2) m X 2-n-m or a mixture of a Group 2 alkoxide M(OR i ) n’ X 2-n and M(OR2) m' X 2-m where M is a Group 2 metal, X is a halogen, R1 and R2 are different alkyl groups of C2 to C 16 carbon atoms, 0 ≤ n < 2, 0 ≤ m < 2 and n + m + (2 - n - m) = 2, provided that m ≠ 0, 0 < n' ≤ 2 and 0 < m' ≤ 2; and

[0104] b) Contact the solution from step a) with at least one compound (TC) of a group 4 to 6 transition metal, and

[0105] c) Obtain solid catalyst component particles, and

[0106] Optionally, an internal electron donor (ID) is added in any step prior to step c), preferably a non-phthalic acid internal donor (ID).

[0107] Preferably, the internal donor (ID) or its precursor is added to the solution of step a) or the transition metal compound before contact with the solution of step a).

[0108] According to the above procedure, the Ziegler-Natta catalyst can be obtained by precipitation or emulsion solidification, depending on the physical conditions, especially the temperatures used in steps b) and c). In this application, the emulsion is also referred to as a liquid / liquid two-phase system. The chemical properties of the catalyst are the same in both methods (precipitation or emulsion solidification).

[0109] In the precipitation method, the solution from step a) is combined with at least one transition metal compound (TC) in step b). The entire reaction mixture is maintained at a temperature of at least 50°C, more preferably in the temperature range of 55 to 110°C, and even more preferably in the temperature range of 70 to 100°C, to ensure complete precipitation of the catalyst component in the form of solid particles (step c). In the emulsion curing method, the solution from step a) is typically added to at least one transition metal compound (TC) from step b) at a lower temperature, for example -10 to below 50°C, preferably -5 to 30°C. During the stirring of the emulsion, the temperature is typically maintained at -10 to below 40°C, preferably -5 to 30°C. Droplets of the dispersed phase of the emulsion form an active catalyst composition. Curing of the droplets (step c) is suitably carried out by heating the emulsion to a temperature of 70 to 150°C, preferably 80 to 110°C.

[0110] In a preferred embodiment, in step a), a solution of a2) or a3) is used, i.e., a solution of (Ax') or a mixture of (Ax) and (Bx), especially a solution of a2). Preferably, the Group 2 metal (MC) is magnesium.

[0111] Magnesium alkoxy compounds as defined above can be prepared in situ in the first step (step a) of the catalyst preparation method by reacting a magnesium compound with one or more alcohols as described above, or the magnesium alkoxy compounds can be prepared separately, or they can even be commercially available as ready-made magnesium alkoxy compounds and used as is in the catalyst preparation method of the present invention.

[0112] An illustrative example of alcohol (A) is ethylene glycol monoether. Preferred alcohol (A) is a C2 to C4 glycol monoether, wherein the ether moiety comprises 2 to 18 carbon atoms, preferably 4 to 12 carbon atoms. Preferred examples are 2-(2-ethylhexyloxy)ethanol, 2-butoxyethanol, 2-hexyloxyethanol, and 1,3-propanediol monobutyl ether, 3-butoxy-2-propanol, wherein 2-(2-ethylhexyloxy)ethanol, 1,3-propanediol monobutyl ether, and 3-butoxy-2-propanol are particularly preferred.

[0113] The illustrative monohydric alcohol (B) has the formula ROH, where R is a straight-chain or branched C2-C group. 16 Alkyl groups, preferably C4-C 10 More preferably, C6-C8 alkyl. The most preferred monohydric alcohol is 2-ethyl-1-hexanol or octanol. It is preferred to use a mixture of Mg alkoxy compounds (Ax) and (Bx) or a mixture of alcohols (A) and (B) respectively, and to use a molar ratio of Bx:Ax or B:A of 10:1 to 1:10, more preferably 6:1 to 1:6, and most preferably 4:1 to 1:4.

[0114] The alkoxymagnesium compound can be the reaction product of one or more alcohols as defined above and a magnesium compound selected from dialkylmagnesium, alkylmagnesium alkoxides, dialkoxymagnesium, alkoxymagnesium halides, and alkylmagnesium halides. Alternatively, dialkoxymagnesium, diaryloxymagnesium, aryloxymagnesium halides, aryloxymagnesium, and alkylaryloxymagnesium can be used. The alkyl group can be similar or different C1-C. 20 Alkyl groups, preferably C2-C 10 Alkyl groups. Typical alkyl-alkoxy magnesium compounds used are ethylbutoxide magnesium, butylpentoxide magnesium, octylbutoxide magnesium, and octyloctanol magnesium. Dialkyl magnesium is preferred. The most preferred dialkyl magnesium is butyloctyl magnesium or butylethyl magnesium.

[0115] Magnesium compounds can also react with formula R"(OH) m The magnesium alkoxide compound is obtained by reacting a polyol (C) with a carbonyl group. If used, the preferred polyol is one in which R″ is a straight-chain, cyclic, or branched C2 to C3 group. 10 Hydrocarbon residues, where m is an integer from 2 to 6 for alcohols.

[0116] Therefore, the alkoxymagnesium compound in step a) is selected from the group consisting of: dialkoxymagnesium, diaryloxymagnesium, alkoxymagnesium halide, aryloxymagnesium halide, alkyl magnesium alkoxide, aryl magnesium alkoxide, and alkylaryl magnesium alkoxide. Alternatively, a mixture of dihalides and dialkoxymagnesium can be used.

[0117] The solvent used to prepare the catalyst of the present invention can be selected from aromatic and aliphatic straight-chain, branched, and cyclic hydrocarbons, or mixtures thereof, having 5 to 20 carbon atoms, more preferably 5 to 12 carbon atoms. Suitable solvents include benzene, toluene, cumene, xylene, pentane, hexane, heptane, octane, and nonane. Hexane and pentane are particularly preferred. The reaction for preparing the magnesium alkoxy compound can be carried out at a temperature of 40 to 70°C. The most suitable temperature is selected according to the magnesium compound and alcohol used.

[0118] Transition metal compounds from groups 4 to 6 are preferably titanium compounds, with titanium halides, such as TiCl4, being the most preferred.

[0119] The internal donor (ID) used to prepare the catalyst used in this invention is preferably selected from diesters of non-phthalic (di)carboxylic acids, 1,3-diethers, derivatives, and mixtures thereof. Particularly preferred donors are diesters of monounsaturated dicarboxylic acids, particularly esters belonging to the group comprising malonic acid esters, maleic acid esters, succinic acid esters, citrate esters, glutaric acid esters, cyclohexene-1,2-dicarboxylic acid esters, and benzoic acid esters, and any derivatives and / or mixtures thereof. Preferred examples are, for example, substituted maleic acid esters and citrate esters, with citrate esters being most preferred.

[0120] In emulsion processes, a two-phase liquid-liquid system can be formed by simple stirring and optional addition of (other) solvents and additives, such as turbulence minimizing agents (TMAs) and / or emulsifiers and / or emulsion stabilizers, such as surfactants, which are used in a manner known in the art to promote emulsion formation and / or stabilize the emulsion. Preferably, the surfactant is an acrylic or methacrylic acid polymer. Particularly preferred are unbranched C... 12 To C 20 (Meth)acrylates, such as poly(hexadecyl)-methacrylate and poly(octadecyl)-methacrylate and mixtures thereof. If used, the turbulence minimizing agent (TMA) is preferably selected from α-olefin polymers of α-olefin monomers having 6 to 20 carbon atoms, such as polyoctene, polynonene, polydecene, polyundecene, or polydodecene or mixtures thereof. Polydecene is most preferred.

[0121] The Ziegler-Natta catalyst can be a particulate product, which can be washed at least once, preferably at least twice, and most preferably at least three times, with aromatics and / or aliphatic hydrocarbons, preferably with toluene, heptane, or pentane and / or TiCl4. The washing solution may also contain donors and / or Group 13 compounds, such as trialkylaluminum, alkylaluminum halides, or aluminum alkoxy compounds. Aluminum compounds may also be added during catalyst synthesis. The catalyst can be further dried, such as by evaporation or rinsing with nitrogen, or it can be slurried into an oily liquid without any drying step.

[0122] The final Ziegler-Natta catalyst is ideally in particulate form, typically with an average particle size ranging from 5 to 200 μm, preferably from 10 to 100 μm.

[0123] The particles are dense, with low porosity and a surface area of ​​less than 20 g / m². 2 More preferably, below 10 g / m 2 Typically, the amount of Ti is 1 to 6 wt% of the catalyst composition, Mg is 10 to 20 wt% of the catalyst composition, and the donor is 10 to 40 wt% of the catalyst composition. Detailed descriptions of catalyst preparation are disclosed in WO 2012 / 007430, EP2610271, EP 2610270 and EP2610272, which are incorporated herein by reference.

[0124] Co-catalysts and external Give body

[0125] Ziegler-Natta catalysts can be used in combination with alkylaluminum co-catalysts and external donors.

[0126] The cocatalyst is preferably a compound belonging to Group 13 of the periodic table (lUPAC), such as an organoaluminum compound, like an aluminum compound, such as an alkylaluminum, aluminum halide, or an alkylaluminum halide. Therefore, in one specific embodiment, the cocatalyst (Co) is a trialkylaluminum, such as triethylaluminum (TEAL), dialkylaluminum chloride, or alkylaluminum dichloride, or a mixture thereof. In one specific embodiment, the cocatalyst (Co) is triethylaluminum (TEAL).

[0127] Advantageously, triethylaluminum (TEAL) has a hydride content of less than 1.0% by weight relative to triethylaluminum (TEAL), denoted as AIH3. More preferably, the hydride content is less than 0.5% by weight, and most preferably, the hydride content is less than 0.1% by weight.

[0128] Suitable external donors (EDs) include certain silanes, ethers, esters, amines, ketones, heterocyclic compounds, and mixtures thereof. Silanes are particularly preferred. Silanes with the following general formulas are most preferred:

[0129] R a p R b q Si(OR c ) (4-p-q) ,

[0130] Where R a R b and R c Represents a hydrocarbon group, particularly an alkyl or cycloalkyl group, where p and q are numbers in the range of 0 to 3, and their sum p+q is equal to or less than 3. R a R band R c They can be chosen independently of each other, and can be the same or different. Specific examples of such silanes are (tert-butyl)2Si(OCH3)2, (cyclohexyl)(methyl)Si(OCH3)2, (phenyl)2Si(OCH3)2, and (cyclopentyl)2Si(OCH3)2, or those with the general formula […].

[0131] Si(OCH2CH3)3(NR 3 R 4 )

[0132] Where R 3 and R 4 They can be the same or different, representing hydrocarbon groups with 1 to 12 carbon atoms.

[0133] R 3 and R 4 Independently selected from the group consisting of: straight-chain aliphatic hydrocarbon groups having 1 to 12 carbon atoms, branched aliphatic hydrocarbon groups having 1 to 12 carbon atoms, and cyclic aliphatic hydrocarbon groups having 1 to 12 carbon atoms. Particularly preferred is R. 3 and R 4 The following are selected independently: methyl, ethyl, n-propyl, n-butyl, octyl, decyl, isopropyl, isobutyl, isopentyl, tert-butyl, tert-pentyl, neopentyl, cyclopentyl, cyclohexyl, methylcyclopentyl, and cycloheptyl.

[0134] The particularly preferred external donors (EDs) are pentyl dimethoxysilane donors (D-donors) or cyclohexylmethyl dimethoxysilane donors (C-donors).

[0135] Preferably, the ratio between the cocatalyst (Co) and the external donor (ED) [Co / ED] and / or the ratio between the cocatalyst (Co) and the transition metal (TM) [Co / TM] should be carefully selected.

[0136] Therefore, the molar ratio of the cocatalyst (Co) to the external donor (ED) [Co / ED] must be in the range of 5 to 45, preferably in the range of 5 to 35, more preferably in the range of 5 to 25; and optionally, the molar ratio of the cocatalyst (Co) to the titanium compound (TC) [Co / TC] must be in the range of 80 to 500 or more, preferably in the range of 100 to 350, more preferably in the range of 120 to 300.

[0137] propylene polymerization

[0138] As described above, this disclosure also relates to a method for producing a propylene polymer. The method includes the step of polymerizing propylene in the presence of the prepolymerized Ziegler-Natta catalyst described herein.

[0139] Propylene polymerization can be carried out in a separate reactor and / or reaction medium using prepolymerized Ziegler-Natta catalysts. For example, after the formation of a prepolymerized Ziegler-Natta catalyst, at least a portion of the catalyst slurry can be recovered, optionally stored, and used to catalyze propylene polymerization in a separate reactor or reaction medium.

[0140] Propylene polymerization can be carried out in the presence of a co-catalyst and / or an external donor. The co-catalyst and / or external donor used may be the same as or different from any co-catalyst and / or external donor used in the production of the prepolymerized Ziegler-Natta catalyst. In some instances, for example, when the prepolymerized Ziegler-Natta catalyst is recovered and introduced into a separate reactor or reaction medium, additional co-catalyst and additional external donors are used with the prepolymerized Ziegler-Natta catalyst. These additional co-catalysts and external donors may be the same as or different from those used in the production of the prepolymerized Ziegler-Natta catalyst.

[0141] Propylene can be polymerized in any suitable manner in the presence of a prepolymerized Ziegler-Natta catalyst. In some instances, propylene is used as the sole monomer. In other instances, propylene is polymerized with one or more comonomers (e.g., C2 or C4 to C5). 10 (olefin) copolymerization.

[0142] Equipment for propylene polymerization can include any polymerization reactor suitable for producing propylene homopolymers or copolymers. Therefore, polymerization is carried out in one or more polymerization reactors. Preferably, the polymerization reactor system can include one or more conventional stirred tank slurry reactors, or one or more gas-phase reactors, or combinations thereof.

[0143] For the purposes of this invention, "slurry reactor" refers to any reactor, such as a continuous or simple batch stirred tank reactor or loop reactor, that operates in bulk or slurry form, wherein the polymer is formed in particulate form. "Bulk" refers to polymerization in a reaction medium containing at least 60% by weight of monomer. According to a preferred embodiment, the slurry reactor includes a loop reactor. "Gas-phase reactor" refers to any mechanically mixed or fluidized bed reactor. Preferably, the gas-phase reactor includes a mechanically stirred fluidized bed reactor with a gas velocity of at least 0.2 m / s. In one embodiment, polymerization may be carried out in at least one gas-phase reactor.

[0144] The gas-phase reactor can be a conventional fluidized bed reactor, although other types of gas-phase reactors can also be used. In a fluidized bed reactor, the bed consists of formed and grown polymer particles and a still-active catalyst introduced along with the polymer fraction. The bed is kept fluidized by introducing a gaseous component (e.g., monomer) at this flow rate, which allows the particles to act as a fluid. The fluidizing gas may also contain an inert carrier gas, such as nitrogen, and hydrogen as a polymer molecular weight control agent. The fluidized gas-phase reactor can be equipped with a mechanical mixer. The gas-phase reactor used can operate in a temperature range of 50-100°C, preferably 65-90°C, at a reaction pressure of 10-40 bar, and a monomer partial pressure of 15-30 bar. The polymerization temperature in a loop reactor is typically 50 to 110°C, preferably 60 to 100°C, particularly 65 to 95°C. The pressure is 1 to 150 bar, preferably 10 to 100 bar.

[0145] In another embodiment, polymerization is carried out in at least two polymerization reactors selected from slurry loop reactors and gas-phase reactors, and combinations thereof. This embodiment is particularly suitable for the production of multi-(bi)modal polypropylene. Multiple reactors of each type can be used, for example, one loop reactor and two or three gas-phase reactors in series. A preferred embodiment of the invention includes polymerization in a method comprising cascaded loop reactors and gas-phase reactors, wherein the loop reactor operates in liquid propylene.

[0146] In addition to the actual polymerization reactor used to produce propylene homopolymers or copolymers, a polymerization reaction system may also include many additional reactors, such as pre-reactors and / or post-reactors.

[0147] It should be understood that the term "propylene polymer" includes propylene homopolymers (H-PP) and / or propylene copolymers (C-PP). Furthermore, the term "propylene copolymer" includes propylene random copolymers, multiphase polymers, and mixtures thereof. In a preferred embodiment, a prepolymerized solid Ziegler-Natta catalyst is used to produce propylene homopolymers or propylene random copolymers. In another embodiment, a prepolymerized solid Ziegler-Natta catalyst is used to produce propylene homopolymers. Throughout the invention, the term propylene homopolymer (H-PP) refers to a propylene polymer consisting substantially of, i.e., more than 99.5% by weight, more preferably at least 99.7% by weight, for example at least 99.8% by weight, propylene units. In a preferred embodiment, only propylene units are detectable in the propylene homopolymer (H-PP).

[0148] Alternatively or alternatively, the propylene polymer is a propylene copolymer (C-PP). In one embodiment, the propylene homopolymer may be further polymerized in the presence of ethylene and optionally C4 to C8 α-olefins to obtain an elastic propylene copolymer (E), thereby obtaining a multiphase propylene copolymer.

[0149] In some instances, the advantage of using a prepolymerized solid Ziegler-Natta catalyst in a process for producing propylene polymers is that the resulting propylene polymer has an improved powder morphology (compared to propylene polymers prepared by prepolymerization using the same solid Ziegler-Natta catalyst but instead of a batch mode).

[0150] Polypropylene properties

[0151] The prepolymerized Ziegler-Natta catalysts described herein can be used to produce polypropylene compositions with improved properties.

[0152] For example, propylene polymers can have melt flow rates (MFR2) ranging from 0.15 to 1000 g / 10 min (230 °C, 2.16 kg) as measured according to ISO 1133, depending on the desired properties of the end application.

[0153] The propylene polymer may have a crystallization temperature of at least 115°C, preferably 115 to 145°C, more preferably 120 to 140°C, and even more preferably 122 to 137°C, for example 126 to 135°C.

[0154] The propylene polymer may have a melting enthalpy of at least 90 J / g, preferably 95 to 160 J / g, more preferably 103 to 150 J / g, for example 115 to 130 J / g.

[0155] The propylene polymer may have a tensile modulus according to ISO 527-2 of at least 1800 MPa, preferably 1900 to 3000 MPa, and more preferably 2190 to 2400 MPa.

[0156] The propylene polymer obtained by the method of producing propylene polymer can be granulated and compounded using any of the various compounding and blending methods known and commonly used in the field of resin compounding.

[0157] The invention is further illustrated below by way of examples.

[0158] Example

[0159] Test methods

[0160] Unless otherwise defined, the following terms and measurement methods apply to the above general description of the invention and the following embodiments.

[0161] MFR2 (230 ℃ / 2.16 kg) was measured at 230 ℃ and 2.16 kg load according to ISO 1133.

[0162] The melting temperature (T0) of 5 to 7 mg samples was measured using a TA Instruments Q200 differential scanning calorimeter (DSC).m The melting temperature (Tm) and enthalpy of fusion (Hm) were measured. The DSC was run in a hot / cold / hot cycle according to ISO 11357 / Part 3 / Method C2 at a scan rate of 10 °C / min, with a temperature range of -30 to +225 °C. The crystallization temperature (Tc) was determined by the cooling step, while the melting temperature (Tm) and enthalpy of fusion (Hm) were determined by the second heating step.

[0163] Tensile properties (tensile modulus, tensile strength, tensile strain at break, tensile stress at break, tensile strain at break) were determined on a 1A dog bone specimen according to ISO 527-2. The tensile modulus was tested at a speed of 1 mm / min, and all other properties were tested at a speed of 50 mm / min, according to the standard. The test temperature was 23 ± 2 °C. Injection molding was performed according to ISO 19069-2.

[0164] Example 1

[0165] a. Preparation of prepolymerized Ziegler-Natta catalyst (catalyst 1)

[0166] A commercially available Ziegler-Natta catalyst was dispersed in oil to form a slurry. First, the catalyst slurry (13 kg, 3 kg dry catalyst, Ti content 1.79 wt%) was fed into a reactor equipped with a stirrer and a heating / cooling jacket. The reactor temperature was set to 25°C, and the stirrer speed was set to 140 rpm. Then, more oil (23 kg) was added to dilute the slurry to approximately 7 wt%. After the oil addition, triethylaluminum or TEAL (100%, 452 g) was added to activate the catalyst (Al / Ti ratio 3.5 mol / mol). After stirring for 10 minutes, the internal donor Do (258 g) (Al / Do ratio 3.5 mol / mol) was added.

[0167] Add 1-butene using a feed tube, keeping the temperature below 25°C. Add a total of 3.3 kg of 1-butene over 2.5 hours, ensuring the reactor pressure and temperature remain at the desired levels. Before the next addition, check butene consumption by allowing the pressure in the reactor to stabilize. After addition, allow the 1-butene to react for 2 hours, maintaining the temperature at 25°C. Stir the reaction mixture at 140 RPM.

[0168] Two hours later, the reactor pressure was reduced to 1 bar (g), and vinylcyclohexane (VCH, CAS No. 695-12-5) (3 kg) was added to the reactor at a rate of 60 g / min, while the reactor temperature was raised to 60 °C. After the introduction of VCH, the VCH was allowed to react at 60 °C for 16 hours. After 16 hours, samples were taken and the content of unreacted VCH was analyzed by gas chromatography-mass spectrometry (GC). With results below 1000 ppm (24 ppm), a batch of prepolymerized Ziegler-Natta catalyst (catalyst 1) was recovered from the reactor for use in the following propylene polymerization. The final calculated content of Ziegler-Natta catalyst in the slurry was 7.6 wt%.

[0169] b. Propylene polymerization using catalyst 1

[0170] Propylene polymerization was carried out in a 5-liter jacketed stainless steel reactor. 139.3 mg of triethylaluminum (TEAL) (from Chemitura, used as is) as a cocatalyst, 27.6 mg of dicyclopentyldimethoxysilane (DCDS) (from Wacker, dried with molecular sieves) as an external donor, and 15 ml of n-pentane were mixed and allowed to react for 5 minutes. This mixture was then added to the polymerization reactor at 20°C. Next, 200 mmol of hydrogen and 1360 g of propylene were added to the reactor.

[0171] Polymerization was initiated by introducing a catalyst / oil mixture (172.0 mg of oil / catalyst mixture recovered in Example 1a above, mixed with 6 ml of additional oil) into a reactor with propylene (35 g) flushing (total propylene 1395 g). The amount of dried catalyst was 13.1 mg. The Al / Ti ratio was 250 mol / mol, and the Al / DCDS ratio was 10 mol / mol.

[0172] After prepolymerization at 20°C for 15 minutes, the reactor temperature was raised to the polymerization temperature (80°C) over approximately 15 minutes. The polymerization time after reaching the polymerization temperature was 60 minutes. Unreacted propylene was then flash-evaporated by opening the exhaust valve, and the reactor was cooled to room temperature. After rinsing the reactor several times with nitrogen, the polymer was collected, dried overnight, and then weighed, and the polymer yield (322 g) was recorded.

[0173] Comparative Example 1

[0174] a. Preparation of prepolymerized Ziegler-Natta catalyst (catalyst C1)

[0175] Catalyst C1 was prepared in a similar manner to Catalyst 1 in Example 1, but the Al / Ti and Al / Do ratios were slightly adjusted (1 mol / mol and 0.75 mol / mol, respectively). Furthermore, vinylcyclohexane (VCH) was not added to the catalyst formulation, but the catalyst formulation was considered ready after reacting with 1-butene for 2 hours. A batch of prepolymerized Ziegler-Natta catalyst (catalyst C1) was removed from the reactor for the propylene polymerization described below.

[0176] b. Propylene polymerization using catalyst C1

[0177] Propylene polymerization was carried out in a 5-liter jacketed stainless steel reactor. 143.4 mg of triethylaluminum (TEAL) (from Chemitura, used as is) was mixed as a cocatalyst, 28.6 mg of dicyclopentyldimethoxysilane (DCDS) (from Wacker, dried with molecular sieves) as an external donor, and 15 ml of n-pentane and allowed to react for 5 minutes. This mixture was then added to the polymerization reactor at 20°C. Next, 200 mmol of hydrogen and 1360 g of propylene were added to the reactor. Polymerization was initiated by introducing a catalyst / oil mixture (174.7 mg of oil / catalyst mixture containing the recovered catalyst C1 from Comparative Example 1a above mixed with 6 ml of additional oil) into the reactor with a propylene (35 g) flush (total propylene 1395 g). The amount of dried catalyst was 13.5 mg. The Al / Ti ratio was 250 mol / mol, and the Al / DCDS ratio was 10 mol / mol. After prepolymerization at 20°C for 15 minutes, the reactor temperature was raised to the polymerization temperature (80°C) over approximately 15 minutes. The polymerization time after reaching the polymerization temperature was 60 minutes. Unreacted propylene was then flash-evaporated by opening the exhaust valve, and the reactor was cooled to room temperature. After rinsing the reactor several times with nitrogen, the polymer was collected, dried overnight, and then weighed, and the polymer yield (279 g) was recorded.

[0178] Comparative Example 2

[0179] a. Preparation of prepolymerized Ziegler-Natta catalyst (catalyst C2)

[0180] The same commercially available Ziegler-Natta catalyst used in Example 1 and Comparative Example 2 was dispersed in oil to form a slurry. The catalyst slurry (21.5 kg, 5 kg dry catalyst) was fed into a reactor equipped with a stirrer and a heating / cooling jacket. The reactor temperature was set to 15°C, and the slurry was stirred at 140 rpm. More oil (13.9 kg) was added to dilute the slurry to ~12% by weight. After the oil addition, TEAL (100%, 750 g) was added to activate the catalyst (Al / Ti ratio 3.5 mol / mol). After stirring for 10 minutes, D donor (430 g) (Al / Do ratio 3.5 mol / mol) was added. VCH feed (5 kg) was added at approximately 60 g / min while the reactor temperature was raised to 60°C. After VCH feed, the VCH was allowed to react at 60°C for another 10 hours. After 10 hours, samples were taken and the content of unreacted VCH was analyzed by gas chromatography (GC). Since the result was below 1000 ppm (110 ppm), a batch was recovered for propylene polymerization, which will be discussed below.

[0181] Propylene polymerization using catalyst C2

[0182] Propylene polymerization was carried out in a 5-liter jacketed stainless steel reactor. 159.3 mg of triethylaluminum (TEAL) (from Chemitura, used as is) was mixed as a cocatalyst, 31.5 mg of dicyclopentyldimethoxysilane (DCDS) (from Wacker, dried with molecular sieves) as an external donor, and 15 ml of n-pentane and allowed to react for 5 minutes. This mixture was then added to the polymerization reactor at 20°C. Next, 200 mmol of hydrogen and 1360 g of propylene were added to the reactor. Polymerization was initiated by introducing a catalyst / oil mixture (123.8 mg of oil / catalyst mixture recovered in Comparative Example 2a above, mixed with 10 ml of additional oil) into the reactor with a propylene (35 g) flush (total propylene 1395 g). The amount of dried catalyst was 14.9 mg. The Al / Ti ratio was 250 mol / mol, and the Al / DCDS ratio was 10 mol / mol. After prepolymerization at 20°C for 15 minutes, the reactor temperature was raised to the polymerization temperature (80°C) over approximately 15 minutes. The polymerization time after reaching the polymerization temperature was 60 minutes. Unreacted propylene was then flash-evaporated by opening the vent valve, and the reactor was cooled to room temperature. After rinsing the reactor several times with nitrogen, the polymer was collected, dried overnight, and then weighed, with the polymer yield recorded (501 g).

[0183] Table 1 summarizes the properties of the polypropylene produced in Example 1b, Comparative Example 1b, and Comparative Example 2b. The polypropylene samples from Example 1b, Comparative Example 1b, and Comparative Example 2b are named IE1, CE1, and CE2, respectively.

[0184] Crystallization temperature (Tc) is a good indicator of polypropylene nucleation efficiency. A higher Tc indicates more efficient nucleation. As shown in Table 1, the prepolymerized Ziegler-Natta catalyst of IE1 has the highest Tc and the highest Hm. Its tensile modulus is also higher than that of the comparative example.

[0185] IE1 CE1 CE2 catalyst 1 C1 C2 prepolymer PB-PVCH PB PVCH Tensile modulus / MPa 2255 1879 2185 <![CDATA[MFR2(g / 10 min)]]> 13 13 11 Tc (°C) 129 117 126 Tm (°C) 166 164 170 Hm(J / g) 117 110 102

[0186] PB: Polybutene

[0187] PVCH: Polyethylene cyclohexane

Claims

1. A method for producing a prepolymerized Ziegler-Natta catalyst composition, the method comprising: Ai) reacts at least one acyclic α-olefin having 2 to 10 carbon atoms in the presence of a Ziegler-Natta catalyst, and Aii) Subsequently, vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics are reacted in the presence of a Ziegler-Natta catalyst; or Bi) reacts vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics in the presence of a Ziegler-Natta catalyst, and Bii) then reacts at least one acyclic α-olefin having 2 to 10 carbon atoms in the presence of a Ziegler-Natta catalyst. in, When vinyl cycloalkanes, vinyl cycloolefins and / or vinyl aromatics react in Bi) in the presence of a Ziegler-Natta catalyst and when at least one acyclic α-olefin having 2 to 10 carbon atoms subsequently reacts in Bi) in the presence of a Ziegler-Natta catalyst, the weight ratio of said at least one acyclic α-olefin to the Ziegler-Natta catalyst is less than 200:

1.

2. The method according to claim 1, comprising: In the presence of a Ziegler-Natta catalyst, at least one acyclic α-olefin having 2 to 8 carbon atoms, preferably 2 to 6 carbon atoms, is reacted, and Aii) Subsequently, vinyl cycloalkanes, vinyl cycloolefins and / or vinyl aromatics are reacted in the presence of a Ziegler-Natta catalyst.

3. The method according to claim 1, wherein the acyclic α-olefin is selected from ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene and any combination thereof, preferably, the acyclic α-olefin is selected from ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene and 1-octene, more preferably, the acyclic α-olefin is 1-butene.

4. The method according to any one of the preceding claims, wherein in step Aii), vinylcycloalkane, preferably vinylcyclohexane, is reacted in the presence of a Ziegler-Natta catalyst, or in step Bi), vinylcycloalkane, preferably vinylcyclohexane, is reacted in the presence of a Ziegler-Natta catalyst.

5. The method according to any one of the preceding claims, wherein, In step Ai), the weight ratio of the at least one acyclic α-olefin to the Ziegler-Natta catalyst is less than 200:

1.

6. The method according to claim 5, wherein in step Ai) or step Bi) the weight ratio of the at least one acyclic α-olefin to the Ziegler-Natta catalyst is less than 100:1, preferably 10:90 to 90:10, more preferably 20:80 to 80:20, even more preferably 30:70 to 70:30, even more preferably 40:60 to 60:40, and still more preferably 45:55 to 55:

45.

7. The method according to any one of the preceding claims, wherein in step Aii) or step Bi), the weight ratio of the vinylcycloalkane, vinylcycloolefin and / or vinyl aromatic to the Ziegler-Natta catalyst is less than 200:1, preferably less than 100:1, more preferably 10:90 to 90:10, even more preferably 20:80 to 80:20, even more preferably 30:70 to 70:30, even more preferably 40:60 to 60:40, even more preferably 45:55 to 55:

45.

8. The method according to any one of the preceding claims, wherein the Ziegler-Natta catalyst comprises: a compound selected from transition metals of Groups 4 to 6 of the periodic table; a compound of metals of Groups 1 to 3; and an internal donor.

9. The method of claim 8, wherein the Ziegler-Natta catalyst comprises a titanium compound, a magnesium compound, and an internal donor.

10. The method according to any one of the preceding claims, wherein at least one of steps Ai) and Ai) or at least one of steps Bi) and Bi) is carried out in the presence of a co-catalyst and in the presence of an external donor.

11. The method according to any one of claims 1 to 10, wherein the prepolymerized Ziegler-Natta catalyst composition comprises a Ziegler-Natta catalyst, a polymer having polymeric units derived from at least one acyclic α-olefin having 2 to 10 carbon atoms, and a polymer having polymeric units derived from vinylcycloalkanes, vinylcycloolefins, and / or vinyl aromatics.

12. A prepolymerized solid Ziegler-Natta catalyst composition, which can be obtained by the method of any one of claims 1 to 11.

13. A catalyst system for propylene polymerization, said catalyst system comprising the prepolymerized Ziegler-Natta catalyst composition according to claim 12, a cocatalyst, and an external donor.

14. A method for producing polypropylene, the method comprising polymerizing propylene in the presence of the prepolymerized Ziegler-Natta catalyst composition of claim 12.

15. The method of claim 14, wherein the prepolymerized Ziegler-Natta catalyst composition forms part of the catalyst system of claim 13.