Process for producing high flow heterophasic propylene copolymer composition

Abstract

The present invention relates to a process for producing a heterophasic propylene copolymer composition, said process comprising the steps of: a) preparing a bimodal matrix phase (A) of a heterophasic propylene copolymer by a1) polymerizing propylene in a first reactor to obtain a first propylene polymer component, as determined according to ISO 1133 at 230 DEG C and a load of 2.16 kg, and a2) polymerizing propylene in a second reactor to obtain a second propylene polymer component, as determined according to ISO 1133 at 230 DEG C and a load of 2.16 kg; the first propylene polymer component has a melt flow rate MFR2 of from 25 g / 10 min to 85 g / 10 min, a2) transferring the first propylene polymer component to a second reactor and polymerizing propylene in the second reactor to obtain a second propylene polymer component, the first propylene polymer component and the second propylene polymer component in combination having an MFR2 of at least 2.2 times the MFR2 of the first propylene polymer component, the MFR2 determined according to ISO 1133 at 230 DEG C and a load of 2.16 kg; b) preparing a dispersed phase (B) of the heterophasic propylene copolymer by: b1) transferring the first propylene polymer component and the second propylene polymer component to a third reactor and polymerizing propylene and an alpha-olefin having 2 or 4 to 10 carbon atoms in the third reactor to obtain a third propylene polymer component; c) withdrawing a heterophasic propylene copolymer comprising the first propylene polymer component, a second propylene polymer component and a third propylene polymer component from the third reactor; and d) obtaining a heterophasic propylene copolymer composition comprising the heterophasic propylene copolymer; wherein the heterophasic propylene copolymer composition has a melt flow rate MFR2 of from 75 g / 10 min to 250 g / 10 min as determined according to ISO 1133 at 230 DEG C and a 2.16 kg load, and wherein the polymerization in steps a1), a2) and b1) is carried out in the presence of a metallocene catalyst system comprising a metallocene complex and a support wherein the support comprises silica, and wherein the polymerization in steps a1), a2) and b1) is carried out in the presence of a metallocene catalyst system comprising a metallocene complex and a support comprising silica. And wherein the metallocene complex has a structure represented by formula (I).

Description

Technical Field

[0001] The present invention relates to a process for producing a heterophasic propylene copolymer composition and to a heterophasic propylene copolymer composition obtainable by this process. Background Art

[0002] As the need to save energy, thickness reduction and lightweighting become more important, the demand for heterophasic propylene copolymers with excellent stiffness at high flow continues to increase. High-flow polypropylene is often used for molding, especially in the automotive business, where injection molding is the preferred conversion process. In addition, the addition of high-flow homopolymers with excellent impact strength and stiffness balance can increase the MFR of composites for automotive use without losing the required mechanical properties.

[0003] From a process point of view, one problem is the balancing of the production rates in the different reactors in a multistage propylene polymerization process.

[0004] In a dual reactor system or a multistage polymerization process, one of the most important parameters is the reactor balance and the reactor distribution between the reactors. This is important not only from a plant economic point of view, but also from a product performance point of view.

[0005] Typically, the production split ratio in a two-reactor system is between 40% / 60% and 60% / 40%, and if the elastomer for the heterophasic copolymer is produced in the third reactor, the reactor split ratio in the last reactor is typically 5% to 30%. In a four-reactor mode, two rubber gas phase reactors (GPR) are typically used, and the total split ratio of the heterophasic product can be 10%-40%, while the split ratio between the rubber GPRs is 50% / 50% to 90% / 10%. In the case of a trimodal process, typically the first three reactors produce homo-PP or random PP, and the split ratio can be, for example, 45% / 35% / 20%.

[0006] However, in each reactor system described above, a problem that needs to be solved is how to control the production distribution ratio according to the plant design. Otherwise, the plant may run at a low speed and low production rate, and the plant economy will deteriorate.

[0007] One of the main reasons for the above problems is that the bulk density (BD) of the polymer is poor. In addition, one reason for the poor bulk density is that the MFR2 of the polymer is too high. If the MFR2 exceeds 80g / 10min, the polymer is generally more porous and more brittle, so the bulk density is lower. When the bulk density is lower, the quality of the polymer is lower, that is, the polymer has a larger volume. In addition, a longer residence time in the polymerization reactor may lead to lower production rate and production efficiency. Summary of the invention

[0008] Therefore, it is an object of the present invention to provide a process for producing a heterophasic propylene copolymer composition, thereby overcoming the above mentioned technical problems.

[0009] It is also an object of the present invention to provide a process for producing a heterophasic propylene copolymer composition, in particular a metallocene-catalyzed heterophasic propylene copolymer composition, having an improved balance of stiffness and impact strength.

[0010] Another object of the present invention is to provide such a process which can increase production and plant speed, thereby improving reactor balance and plant economics.

[0011] It has now surprisingly been found that the above object can be achieved by a process for producing a heterophasic propylene copolymer composition comprising the following steps:

[0012] a) preparing the bimodal matrix phase (A) of the heterophasic propylene copolymer by

[0013] a1) polymerizing propylene in a first reactor to obtain a first propylene polymer component having a melt flow rate MFR2 of 25 to 85 g / 10 min, measured according to ISO 1133 at 230° C. and 2.16 kg load,

[0014] a2) transferring the first propylene polymer component to a second reactor and polymerizing propylene in the second reactor to obtain a second propylene polymer component, the combined first and second propylene polymer components having an MFR2 of at least 2.2 times the MFR2 of the first propylene polymer component, the MFR2 being determined according to ISO 1133 at 230°C and 2.16 kg load,

[0015] b) preparing the dispersed phase (B) of the heterophasic propylene copolymer by

[0016] b1) transferring the first propylene polymer component and the second propylene polymer component to a third reactor, and polymerizing propylene and an α-olefin having 2 or 4 to 12 carbon atoms in the third reactor to obtain a third propylene polymer component,

[0017] c) withdrawing a heterophasic propylene copolymer comprising the first propylene polymer fraction, the second propylene polymer fraction and the third propylene polymer fraction from the third reactor, and

[0018] d) obtaining a heterophasic propylene copolymer composition comprising said heterophasic propylene copolymer.

[0019] wherein the heterophasic propylene copolymer composition has a melt flow rate MFR2 of 70 g / 10 min to 250 g / 10 min, measured according to ISO 1133 at 230°C and 2.16 kg load, and

[0020] Wherein, the polymerization in steps a1), a2) and b1) is carried out in the presence of a metallocene catalyst system, wherein the metallocene catalyst system comprises a metallocene complex and a support, wherein the support comprises silicon dioxide, and wherein the metallocene complex has a structure represented by formula (I):

[0021]

[0022] wherein each X is independently a σ donor ligand,

[0023] L is a divalent bridge selected from -R'2C-, -R'2C-CR'2-, -R'2Si-, -R'2Si-SiR'2- and -R'2Ge-, wherein each R' is independently a hydrogen atom or a C1-C ... 20 A hydrocarbon group, or optionally two R' groups taken together can form a ring,

[0024] Each R 1 are independently the same or different and are hydrogen, linear or branched C1-C6 alkyl, C 7-20 Arylalkyl, C 7-20 -alkylaryl or C 6-20 Aryl or OY group, where Y is C 1-10 A hydrocarbon group, and optionally two adjacent R 1 The groups may be part of a ring including the phenyl carbon to which they are bonded,

[0025] Each R 2 are independently the same or different and are CH2-R 8 Group, where R 8 H or a straight or branched C 1-6 Alkyl, C 3-8 Cycloalkyl or C 6-10 Aryl,

[0026] R 3 is a straight or branched C1-C6 alkyl group, C 7-20 Arylalkyl, C 7-20 Alkyl aryl or C6-C 20 Aryl,

[0027] R 4 C(R 9 )3 groups, wherein R 9is a linear or branched C1-C6 alkyl group,

[0028] R 5 is hydrogen or an aliphatic C1-C ... 20 Hydrocarbon;

[0029] R 6 is hydrogen or an aliphatic C1-C ... 20 Hydrocarbyl; or

[0030] R 5 and R 6 can be joined together to form a 5-membered saturated carbocyclic ring, which is optionally substituted by n R 10 Group substitution, n is 0 to 4;

[0031] Each R 10 are the same or different and are selected from C1-C 20 The hydrocarbon group and optionally a C1-C ... 20 Hydrocarbon;

[0032] R 7 is H, a linear or branched C1-C6 alkyl group, or an aryl or heteroaryl group having 6 to 20 carbon atoms, which aryl or heteroaryl group is optionally substituted by 1 to 3 R 11 Group substitution,

[0033] Each R 11 are independently the same or different and are hydrogen, linear or branched C1-C6 alkyl, C 7-20 Arylalkyl, C 7-20 Alkyl aryl or C 6-20 Aryl or OY group, where Y is C 1-10 Hydrocarbon.

[0034] Therefore, the above objects are achieved by moderately broadening the molecular weight distribution (MWD) of the polypropylene homopolymer used for the matrix, i.e. bimodal production. Moderately broadening and bimodal production of the polypropylene homopolymer means that a polypropylene homopolymer of higher weight average molecular weight (Mw) (i.e. low melt flow rate (MFR)) is produced in the first reactor, and a polypropylene homopolymer of lower Mw (i.e. high melt flow rate (MFR)) is produced in the second reactor.

[0035] The present invention provides many benefits. Significantly improved fluidity can enable polypropylene homopolymers to be used in molding applications, particularly injection molding applications. Excellent fluidity is also accompanied by high stiffness. High stiffness is important for many polypropylene applications. In addition, the present invention can more easily optimize the balance between stiffness and impact strength, particularly to achieve higher propylene-ethylene rubber content.

[0036] At the same time, the method according to the invention can be advantageous in terms of plant economy and reactor balance. Fine-tuning of the desired distribution ratio between reactors can be achieved by molecular weight Mw or melt flow rate control, which in turn can be controlled by hydrogen feed. This may contribute to higher overall catalyst productivity and / or better polymer powder morphology, and / or improved bulk density (BD). In this article, "bulk density" (or "fluidized bed density" for fluidized bed polymerization reactors) refers to the mass of polymer powder divided by the reactor volume, excluding optional separation zones that may be present in the reactor.

[0037] When high Mw PP homopolymer is produced in the first reactor, a small amount of hydrogen is used to control the Mw, so the reactivity is lower. In the second polymerization reactor, the PP homopolymer produced has a lower Mw than the one produced in the first reactor, so more hydrogen is needed, which speeds up the production and helps with the distribution ratio control. This is important because the polymerization reaction will decay over time due to the limited catalyst life.

[0038] In other words, the H2 / C3 ratio in the first reactor and the second reactor can be adjusted so as to produce a higher Mw polypropylene homopolymer in the first reactor and a lower Mw polypropylene homopolymer in the second reactor, the Mw of the lower Mw polypropylene homopolymer being lower than the Mw of the higher Mw polypropylene homopolymer produced in the first reactor. The combination of the higher Mw polypropylene homopolymer and the lower Mw polypropylene homopolymer forms a bimodal polypropylene homopolymer for the matrix. Thus, a broadened MWD of the polypropylene homopolymer of the heterophasic propylene copolymer matrix and a desired melt flow rate MFR can be achieved.

[0039] In addition to using hydrogen, the distribution ratio between the first reactor and the second reactor can be adjusted to control the weight average molecular weight (Mw) of the polypropylene homopolymer used in the matrix, thereby controlling the melt flow rate MFR.

[0040] In practice, typically the split ratio between the first and second reactors and the adjustment of the Mw, and thus the melt flow rate (MFR) of the polypropylene homopolymer produced in the second reactor, are used to produce the desired polypropylene homopolymer for the matrix.

[0041] The expression "homopolymer" as used herein refers to a polypropylene consisting essentially of propylene units, i.e. at least 99.5 wt.-%, more preferably at least 99.8 wt.-% of propylene units. In a preferred embodiment only propylene units in the propylene homopolymer are detectable.

[0042] The "modality" of a polymer refers to the form of its molecular weight distribution curve, i.e. the shape of the curve showing the polymer weight fraction as a function of its molecular weight. If the polymer is produced in a continuous step process, using reactors connected in series and using different conditions in each reactor, then the different components produced in the different reactors will each have their own molecular weight distribution. When the molecular weight distribution curves of these components are superimposed on the molecular weight distribution curve of the total resulting polymer product, the curve will show two or more maxima, or at least will be significantly broadened compared to the curves of the individual components. Such a polymer product produced in two or more continuous steps is called bimodal or multimodal, depending on the number of steps. In the following, all polymers produced in two or more continuous steps are referred to as "multimodal". It should be noted that the chemical composition of the different components may also be different.

[0043] As used herein, the term "unimodal matrix" means that the MFR2 (230°C, 2.16 kg) difference between the propylene polymer components contained in the matrix is ​​at most 15%, preferably at most 10%. For example, with reference to the present invention, a unimodal matrix is ​​considered to be produced if the difference between the MFR2 of the first propylene polymer component produced in the first reactor and the MFR2 of the second propylene polymer component produced in the second reactor is at most 15%, preferably at most 10%.

[0044] Heterophasic propylene copolymer

[0045] The heterophasic propylene copolymer comprises a bimodal matrix phase (A) and a dispersed phase (B) dispersed in the bimodal matrix phase (A). The isopropylene copolymer preferably consists of a bimodal matrix phase (A) and a dispersed phase (B) dispersed in the bimodal matrix phase (A).

[0046] In step a) of the process of the present invention a bimodal matrix phase (A) of the heterophasic propylene copolymer is produced and in step b) of the process of the present invention a dispersed phase (B) of the heterophasic propylene copolymer is produced.

[0047] The first propylene polymer component has a melt flow rate MFR2, measured according to ISO 1133 at 230°C and 2.16 kg load, of 25 to 85 g / 10 min, preferably 35 to 75 g / 10 min.

[0048] The calculated melt flow rate MFR2 (230°C, 2.16 kg load) of the second propylene polymer component is preferably from 150 g / 10 min to 2500 g / 10 min, preferably from 250 g / 10 min to 2200 g / 10 min, more preferably from 500 g / 10 min to 1900 g / 10 min, more preferably from 700 g / 10 min to 1600 g / 10 min.

[0049] Preferably, the first propylene polymer component and / or the second propylene polymer component is a propylene homopolymer component and / or the third propylene polymer component is an ethylene-propylene rubber component.

[0050] The matrix phase (A) produced in step a) is bimodal. Preferably, the combined first propylene polymer component and the second propylene polymer component form a bimodal propylene composition, preferably a bimodal propylene homopolymer composition.

[0051] Preferably, the combined first and second propylene polymer components have a melt flow rate MFR2 measured according to ISO 1133 at 230°C and 2.16 kg load of 120 to 500 g / 10 min, preferably 130 to 400 g / 10 min.

[0052] The MFR2 of the combined first and second propylene polymer components is at least 2.2 times, preferably at least 2.5 times, more preferably at least 2.8 times, most preferably at least 4.0 times the MFR2 of the first propylene polymer component, measured at 230°C and 2.16 kg load according to ISO 1133. Typically, the MFR2 of the combined first and second propylene polymer components is preferably at most 30.0 times, more preferably at most 25.0 times, more preferably at most 20.0 times the MFR2 of the first propylene polymer component, measured at 230°C and 2.16 kg load according to ISO 1133.

[0053] Preferably, the first propylene polymer component and the second propylene polymer component combined have a content of the component soluble in cold xylene at 25°C (XCS component) as determined according to ISO 16152, based on the total weight of the first propylene polymer component and the second propylene polymer component combined, less than 2.0 wt.-%, more preferably in the range of 0.3 to 1.8 wt.-%.

[0054] Preferably, the first propylene polymer component is produced in an amount of 35 wt.-% to 70 wt.-%, based on the total weight of the first, second and third propylene polymer components combined, and / or

[0055] Preferably, the second propylene polymer component is produced in an amount of 25 wt.-% to 55 wt.-%, based on the total weight of the first, second and third propylene polymer components combined, and / or

[0056] Preferably, the third propylene polymer component is produced in an amount of 2 to 25 wt.-% or 5 to 25 wt.-%, based on the total weight of the first, second and third propylene polymer components combined.

[0057] More preferably, the first propylene polymer component is produced in an amount of 35 wt.-% to 70 wt.-%, based on the total weight of the first, second and third propylene polymer components combined, and

[0058] the second propylene polymer component is produced in an amount of 25 wt.-% to 55 wt.-%, based on the total weight of the first, second and third propylene polymer components combined, and

[0059] The third propylene polymer component is produced in an amount of 2 to 25 wt.-% or 5 to 25 wt.-%, based on the total weight of the first, second and third propylene polymer components combined.

[0060] More preferably, the first propylene polymer component is produced in an amount of 45 wt.-% to 65 wt.-%, based on the total weight of the first, second and third propylene polymer components combined, and / or

[0061] The second propylene polymer component is produced in an amount of 30 wt.-% to 50 wt.-%, based on the total weight of the first, second and third propylene polymer components combined, and / or

[0062] The third propylene polymer component is produced in an amount of 7 wt.-% to 20 wt.-%, based on the total weight of the first, second and third propylene polymer components combined.

[0063] Most preferably, the first propylene polymer component is produced in an amount of 45 wt.-% to 65 wt.-%, based on the total weight of the first, second and third propylene polymer components combined, and

[0064] the second propylene polymer component is produced in an amount of 30 wt.-% to 50 wt.-%, based on the total weight of the first, second and third propylene polymer components combined, and

[0065] The third propylene polymer component is produced in an amount of 7 wt.-% to 20 wt.-%, based on the total weight of the first, second and third propylene polymer components combined.

[0066] Preferably, the first propylene polymer component is produced in an amount of 70 to 40 wt.-%, based on the total weight of the first and second propylene polymer components combined, and the second propylene polymer component is produced in an amount of 30 to 60 wt.-%, based on the total weight of the first and second propylene polymer components combined.

[0067] Preferably, the first reactor is a slurry reactor, preferably a loop reactor, and / or wherein the second reactor is a first gas phase reactor (GPR1) and / or wherein the third reactor is a second gas phase reactor (GPR2).

[0068] The first reactor is preferably a slurry phase reactor, such as a loop reactor. Preferably, the operating temperature in the first reactor (preferably a loop reactor) is in the range of 60°C to 90°C, more preferably in the range of 65°C to 85°C, and even more preferably in the range of 67°C to 80°C.

[0069] Typically, the pressure in the first reactor (preferably in the loop reactor) is in the range of 20 to 80°C, preferably 30 to 70°C, more preferably 48 to 58°C.

[0070] Preferably, a propylene homopolymer is produced in the first reactor, preferably a loop reactor. Thus, it is preferred that the first propylene polymer component is a propylene homopolymer component.

[0071] Preferably, hydrogen is added in the first reactor to control molecular weight, i.e. melt flow rate MFR2. Preferably, in step a1), the ratio of hydrogen feed to propylene feed is 0.10mol / kmol to less than 0.40mol / kmol, preferably 0.15mol / kmol to 0.39mol / kmol, more preferably 0.20mol / kmol to 0.38mol / kmol, more preferably 0.20mol / kmol to 0.38mol / kmol, and most preferably 0.20mol / kmol to 0.36mol / kmol. It should be noted that slight changes in the ratio of hydrogen feed to propylene feed in the first reactor may result in significant changes in the melt flow rate of the first propylene polymer component.

[0072] The average residence time in the first reactor (preferably a loop reactor) is generally 15 to 120 min, preferably 20 to 80 min. As is well known in the art, the average residence time τ can be calculated by the following equation (1):

[0073]

[0074] in

[0075] V R is the volume of the reaction space (for a loop reactor it is the volume of the reactor, for a fluidized bed reactor it is the volume of the fluidized bed)

[0076] Q o is the volume flow rate of the product stream (comprising polymer product and fluid reaction mixture).

[0077] The production rate is appropriately controlled by the catalyst feed rate and the polymerization temperature. The production rate can also be influenced by appropriate selection of the monomer concentration. The desired monomer concentration can then be achieved by appropriate adjustment of the propylene feed rate.

[0078] The second reactor is preferably a first gas phase reactor (GPR1), such as a first fluidized bed gas phase reactor. Preferably, the operating temperature in the second reactor (preferably the first gas phase reactor) is in the range of 65°C to 95°C, more preferably in the range of 70°C to 90°C.

[0079] Preferably, the pressure in the second reactor (preferably in the first gas phase reactor) is in the range of 5 to 50, preferably 20 to 30.

[0080] The average residence time in the second reactor (preferably the first gas phase reactor) is typically from 30 min to 130 min. Reference is made to equation (1) above.

[0081] Preferably, a propylene homopolymer is produced in the second reactor, preferably the first gas phase reactor. Thus, preferably, the second propylene polymer component is a propylene homopolymer component.

[0082] Preferably, hydrogen is added in the second reactor to control molecular weight, i.e. melt flow rate MFR2. Preferably, in step a2), the ratio of hydrogen feed to propylene feed (H2 / C3 ratio) in the second reactor (preferably the first gas phase reactor) is greater than 4.65mol / kmol to 10.0mol / kmol, more preferably 4.90mol / kmol to 8.00mol / kmol, more preferably 5.10mol / kmol to 6.00mol / kmol, more preferably 5.20mol / kmol to 5.80mol / kmol, and most preferably 5.30mol / kmol to 5.70mol / kmol. It is worth noting that a slight change in the ratio of hydrogen feed to propylene feed in the second reactor may result in a significant change in the melt flow rate of the second propylene polymer component.

[0083] The third reactor is located downstream of the second reactor, and the third reactor is preferably a gas phase reactor. In the case where both the second reactor and the third reactor are gas phase reactors, for simplicity, the second reactor is referred to as the first gas phase reactor herein, and the third reactor is referred to as the second gas phase reactor (GPR2). Preferably, the third reactor is a fluidized bed gas phase reactor. Preferably, the operating temperature in the third reactor is in the range of 60°C to 90°C, more preferably in the range of 65°C to 85°C. If the third reactor is a gas phase reactor, these temperatures are also applicable. Typically, the operating temperature in the third reactor is lower than the operating temperature in the second reactor. Typically, the pressure in the third reactor is in the range of 5 to 50, preferably 20 to 30. If the third reactor is a gas phase reactor, these pressures are also applicable.

[0084] The average residence time in the third reactor is typically 30 min to 130 min. Reference is made to equation (1) above. These times also apply if the third reactor is a gas phase reactor.

[0085] In the third reactor, the dispersed phase (B) of the heterophasic propylene copolymer is produced, i.e. a copolymer of propylene and an alpha-olefin selected from 2 or 4 to 12 carbon atoms as a comonomer is produced, as a comonomer, preferably an alpha-olefin with 2 or 4 to 10 carbon atoms, more preferably ethylene, 1-butene and / or 1-hexene, even more preferably ethylene and / or 1-butene and most preferably ethylene. Preferably, in the third reactor, a propylene ethylene copolymer is produced. Therefore, the third propylene polymer component is preferably a propylene ethylene copolymer component.

[0086] The ethylene to propylene feed ratio (C2 / C3 ratio) in the third reactor is preferably in the range of 700 mol / kmol to 1000 mol / kmol, more preferably 800 mol / kmol to 950 mol / kmol. If the third reactor is a gas phase reactor, these C2 / C3 ratios are also applicable.

[0087] Preferably, the hydrogen to ethylene feed ratio (H2 / C2 ratio) in the third reactor is in the range of 0.5 mol / kmol to 3.5 mol / kmol, more preferably 1.0 mol / kmol to 2.5 mol / kmol. If the third reactor is a gas phase reactor, these H2 / C3 ratios are also applicable.

[0088] The first propylene polymer component, the second propylene polymer component and the third propylene polymer component of the combination form a heterophasic propylene copolymer. In other words, the heterophasic propylene copolymer of the present invention comprises the first propylene polymer component, the second propylene polymer component and the third propylene polymer component of the combination. Preferably, the heterophasic propylene copolymer of the present invention consists of the first propylene polymer component, the second propylene polymer component and the third propylene polymer component of the combination.

[0089] Multistage reactor designs comprising a series of different types of reactors and operating in a slurry-gas phase process are known, one example of which includes the one developed by Borealis and known as The method of the present invention preferably uses the method described in detail in EP 0 887 379 A1 and EP 0 517 868 A1. The multi-stage reactor design of the technology operates different reactors simultaneously according to the parameters listed above (temperature, pressure, residence time, feed ratio, etc.).

[0090] The preparation of the first, second and third propylene polymer components may comprise, in addition to the (main) polymerization stage in at least three reactors, also a prepolymerization preceding them in a prepolymerization reactor upstream of the first reactor.

[0091] In the prepolymerization reactor, polypropylene is produced. The prepolymerization is carried out in the presence of a metallocene catalyst system. However, this does not exclude the option of adding other cocatalysts in subsequent stages (e.g. in the first reactor), for example during the polymerization process. In one embodiment, if a prepolymerization is carried out, all components of the metallocene catalyst system are only added to the prepolymerization reactor.

[0092] The prepolymerization reaction is generally carried out at a temperature of 15°C to 40°C, preferably 17°C to 35°C. The pressure in the prepolymerization reactor is not critical, but must be high enough to maintain the reaction mixture in liquid phase. Thus, the pressure may be from 20 to 100 bar, preferably from 45 to 55 bar. The average residence time in the prepolymerization reactor is generally from 0.2h to 1.0h, preferably from 0.25h to 0.75h, and most preferably from 0.28h to 0.6h. Reference is made to equation (1) above.

[0093] In a preferred embodiment, the prepolymerization is carried out as a bulk slurry polymerization in liquid propylene, wherein the liquid phase comprises propylene with optional inert components dissolved therein.

[0094] Other components may also be added to the prepolymerization stage. Thus, hydrogen may be added to the prepolymerization stage to control the molecular weight of the polypropylene during the prepolymerization. Precise control of prepolymerization conditions and reaction parameters is within the conventional art of the art.

[0095] Due to the above-defined process conditions in the prepolymerization, a mixture of the metallocene catalyst system and the polypropylene produced in the prepolymerization reactor is preferably obtained. Preferably, the metallocene catalyst system is (finely) dispersed in the polypropylene. In other words, the metallocene catalyst particles introduced into the prepolymerization reactor are divided into smaller fragments, which are evenly distributed in the growing polypropylene. The size of the introduced metallocene catalyst particles and the obtained fragments has no essential relevance for the present invention and is known to the person skilled in the art.

[0096] As mentioned above, if prepolymerization is used, then after the prepolymerization, the mixture of the metallocene catalyst system and the polypropylene produced in the prepolymerization reactor is transferred to the first reactor. Typically, the total amount of polypropylene produced in the prepolymerization reactor is quite low in the first propylene polymer component, the second propylene polymer component and the third propylene polymer component, typically not more than 5.0 wt.-%, more preferably not more than 4.0 wt.-%, still more preferably in the range of 0.1 wt.-% to 4.0 wt.-%, such as in the range of 0.5 wt.-% to 3.0 wt.-%.

[0097] Without using prepolymerization, propylene and other ingredients (eg, metallocene catalyst system) are introduced directly into the first reactor.

[0098] Preferably, the method further comprises the following steps:

[0099] b2) transferring the first propylene polymer component, the second polymer component and the third propylene copolymer component to a fourth reactor, preferably a gas phase reactor (referred to herein as the third gas phase reactor-GPR3), and polymerizing propylene with an α-olefin having 2 or 4 to 12 carbon atoms in the fourth reactor to obtain a fourth propylene polymer component, preferably an ethylene-propylene rubber component.

[0100] Therein, step b2) is carried out after step b1) and before step c).

[0101] All operating conditions and parameters as described above for the second gas phase reactor (GPR2), such as temperature, pressure, residence time, hydrogen feed, comonomer, may also be used in the third gas phase reactor (GPR3).

[0102] In step c), a heterophasic propylene copolymer comprising the first propylene polymer component, the second propylene polymer component and the third propylene polymer component is extracted. Preferably, a heterophasic propylene copolymer comprising the first propylene polymer component, the second propylene polymer component, the third propylene polymer component and the fourth propylene polymer component is extracted. More preferably, a heterophasic propylene copolymer consisting of the first propylene polymer component, the second propylene polymer component and the third propylene polymer component is extracted in step c), and most preferably, a heterophasic propylene copolymer consisting of the first propylene polymer component, the second propylene polymer component, the third propylene polymer component and the fourth propylene polymer component is extracted.

[0103] Preferably, the heterophasic propylene copolymer comprises a content of a fraction soluble in cold xylene at 25 °C (XCS fraction) determined according to ISO 16152 in the range of 6 to 22 wt.-%, more preferably 7 to 20 wt.-%, more preferably 8 to 18 wt.-%, based on the total weight of the heterophasic propylene copolymer.

[0104] Preferably, based on the total weight of the XCS component, 13The ethylene content of the fraction soluble in cold xylene at 25°C (XCS fraction) of the heterophasic propylene copolymer (C2(XCS)) is from 15 to 30 wt.-%, preferably from 18 to 28 wt.-%, more preferably from 20 to 26 wt.-%, determined by Fourier transform infrared spectroscopy (FTIR) calibrated with C-NMR spectroscopy.

[0105] Preferably, the fraction of the heterophasic propylene copolymer soluble in cold xylene at 25 °C (XCS fraction) has an intrinsic viscosity (IV(XCS)) of 1.8 to 3.2 dl / g, preferably of 2.0 to 3.0 dl / g and most preferably of 2.2 to 2.8 dl / g, as determined in decalin according to ISO 1628-3.

[0106] Preferably, based on the total weight of the heterophasic propylene copolymer, 13 The total ethylene content (total C2) of the heterophasic propylene copolymer, determined by Fourier transform infrared spectroscopy (FTIR) calibrated with C-NMR spectroscopy, is in the range of 1.8 to 6.5 wt.-%, more preferably in the range of 1.9 to 6.0 wt.-%, most preferably in the range of 2.0 to 5.5 wt.-%.

[0107] Preferably, the heterophasic propylene copolymer has a 3 Bulk density, for example greater than 300 kg / m 3 Up to 600kg / m 3 The bulk density is preferably 350 kg / m 3 Up to 500kg / m 3 The bulk density.

[0108] Preferably the heterophasic propylene copolymer has an IV(XCS) / XCS ratio of 180 to 350 ml / g, more preferably of 250 to 350 ml / g and most preferably of 270 to 350 ml / g.

[0109] Preferably, the heterophasic propylene copolymer has an MFR2, measured according to ISO 1133 at 230 °C and 2.16 kg load, of 70 to 250 g / 10 min, preferably 70 to 200 g / 10 min, more preferably 75 to 150 g / 10 min, most preferably 80 to 120 g / 10 min, measured according to ISO 1133 at 230 °C and 2.16 kg load.

[0110] Heterophasic propylene copolymer composition

[0111] In step d) a heterophasic propylene copolymer composition comprising said heterophasic propylene copolymer is obtained. Preferably in step d) a heterophasic propylene copolymer composition consisting of said heterophasic propylene copolymer is obtained.

[0112] Preferably, the heterophasic propylene copolymer composition has an MFR2, measured according to ISO 1133 at 230 °C and 2.16 kg load, of 70 to 250 g / 10 min, preferably of 70 to 200 g / 10 min, more preferably of 75 to 150 g / 10 min, most preferably of 80 to 120 g / 10 min, measured according to ISO 1133 at 230 °C and 2.16 kg load.

[0113] Preferably, the heterophasic propylene copolymer composition has a melting temperature Tm determined according to ISO 11357 by differential scanning calorimetry (DSC) in the range of 145 to 160 °C, preferably in the range of 148 to 158 °C.

[0114] Preferably, the heterophasic propylene copolymer composition has a crystallization temperature Tc, determined according to ISO 11357 by differential scanning calorimetry (DSC), in the range of 110 to 120 °C.

[0115] In addition to the heterophasic propylene copolymer, the heterophasic propylene copolymer composition may comprise one or more further components. Preferably, the heterophasic propylene copolymer composition further comprises an additive. The additive may be present in an amount of 0.1 wt.-% to 5.0 wt.-%, based on the total weight of the heterophasic propylene copolymer composition.

[0116] The additive may be a compound or a mixture of two or more compounds. Preferably, the additive comprises one or more antioxidants, UV stabilizers, antistatic agents, acid scavengers, nucleating agents, carbon black or a mixture thereof, more preferably, the additive consists of one or more antioxidants, UV stabilizers, antistatic agents, acid scavengers, nucleating agents, carbon black or a mixture thereof. At least one additive may be added to the composition in the form of a masterbatch. Preferably, the carbon black is in the form of a carbon black masterbatch.

[0117] These additives are commercially available and are described, for example, in "Plastic Additives Handbook", 6th edition 2009 of Hans Zweifel (pages 1141 to 1190).

[0118] Metallocene catalyst system

[0119] The heterophasic propylene copolymer composition is produced in the presence of a metallocene catalyst system, preferably in the presence of at least one metallocene catalyst system.

[0120] The metallocene catalyst system may be any supported metallocene catalyst system suitable for the production of heterophasic propylene copolymers.

[0121] Preferably, the metallocene catalyst system comprises (i) a metallocene complex, (ii) a cocatalyst system comprising a boron-containing cocatalyst and / or an aluminoxane cocatalyst, and (iii) a support, preferably a support comprising silica, more preferably a support consisting of silica.

[0122] The term "σ donor ligand" is well known to those skilled in the art, i.e., a group that binds to the metal via a σ bond. Thus, the anionic ligand "X" can independently be a halogen, or selected from R', OR', SiR'3, OSiR'3, OSO2CF3, OCOR', SR', NR'2 or PR'2 groups, wherein R' is independently hydrogen, a linear or branched, cyclic or non-cyclic C1 to C 20 Alkyl, C2 to C 20 Alkenyl, C2 to C 20 Alkynyl, C3 to C 12 Cycloalkyl, C6 to C 20 Aryl, C7 to C 20 Arylalkyl, C7 to C 20 Alkyl aryl, C8 to C 20 Arylalkenyl, wherein the R' group may optionally contain one or more heteroatoms belonging to Groups 14 to 16. In a preferred embodiment, the anionic ligands "X" are the same and are either halogen (such as Cl), or methyl or benzyl. A preferred monovalent anionic ligand is halogen, especially chlorine (Cl).

[0123] More information, in particular regarding the preparation of such catalysts, can be found, for example, in WO 2013 / 007650 A1.

[0124] Preferred metallocene complexes (i) of the metallocene catalyst include:

[0125] rac-dimethylsilanediylbis[2-methyl-4-(3',5'-dimethylphenyl)-5-methoxy-6-tert-butylinden-1-yl]zirconium dichloride,

[0126] rac-anti-dimethylsilanediyl[2-methyl-4-(4′-tert-butylphenyl)-inden-1-yl][2-methyl-4-(4′-tert-butylphenyl)-5-methoxy-6-tert-butylinden-1-yl]zirconium dichloride,

[0127] rac-anti-dimethylsilanediyl[2-methyl-4-(4′-tert-butylphenyl)-inden-1-yl][2-methyl-4-phenyl-5-methoxy-6-tert-butylinden-1-yl]zirconium dichloride,

[0128] rac-anti-dimethylsilanediyl[2-methyl-4-(3′,5′-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,

[0129] 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,

[0130] 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,

[0131] 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'-5-ditert-butyl-phenyl)-5-methoxy-6-tert-butylinden-1-yl]zirconium dichloride,

[0132] or their corresponding dimethyl zirconium analogs.

[0133] Particularly preferred is rac-trans-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.

[0134] It is also particularly preferred that the metallocene catalyst system comprises a metallocene complex (i) of the formula (II):

[0135]

[0136] Among them, each R 1 are independently the same or different and are hydrogen or a linear or branched C1-C6 alkyl group, wherein R on each phenyl group 1 At least one of them is not hydrogen,

[0137] R′ is C1-C 10 The hydrocarbon group is preferably a C1-C4 hydrocarbon group, and more preferably a methyl group, and X is independently a hydrogen atom, a halogen atom, a C1-C6 alkoxy group, a C1-C6 alkyl group, a phenyl group or a benzyl group.

[0138] Most preferably, X is chlorine, benzyl or methyl. Preferably, the two X groups are the same. The most preferred options are two chlorines, two methyls or two benzyls, especially two chlorines.

[0139] Particularly preferred is rac-trans-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 according to formula (III):

[0140]

[0141] The ligands required to form the complex and the catalyst of the present invention can be synthesized by any method, and a skilled organic chemist will be able to design various synthesis schemes for making the necessary ligand materials. For example, WO 2007 / 116034 discloses the necessary chemical components. Synthesis schemes can also be generally found in WO 2002 / 02576, WO 2011 / 135004, WO2012 / 084961, WO 2012 / 001052, WO 2011 / 076780, WO 2015 / 158790 and WO 2018 / 122134. In particular, reference is made to WO 2019 / 179959, which describes the most preferred catalysts of the present invention.

[0142] Co-catalyst system

[0143] Preferably, the metallocene catalyst system further comprises (ii) a cocatalyst system comprising a boron-containing cocatalyst and / or an aluminoxane cocatalyst.

[0144] The aluminoxane cocatalyst may be one of formula (IV):

[0145]

[0146] wherein n is usually 6 to 20, and R has the following meanings.

[0147] Aluminoxanes are formed upon partial hydrolysis of organoaluminum compounds, such as those of the formula AlR3, AlR2Y, and Al2R3Y3, wherein R can be, for example, C1-C 10 Alkyl (preferably C1-C5 alkyl), or C3-C 10 Cycloalkyl, C7-C 12 wherein Y is hydrogen, halogen (preferably chlorine or bromine) or C1-C 10 Alkoxy (preferably methoxy or ethoxy). The oxygen-containing aluminoxane obtained is generally not a pure compound but a mixture of oligomers of formula (IV).

[0148] The preferred aluminoxane is methylaluminoxane (MAO).Since the aluminoxanes used as cocatalysts according to the invention are not pure compounds due to the way they are prepared, the molar concentrations of the aluminoxane solutions hereinafter are based on their aluminum content.

[0149] Furthermore, a boron-containing cocatalyst may be used instead of the aluminoxane cocatalyst, or the aluminoxane cocatalyst may be used in combination with the boron-containing cocatalyst.

[0150] It will be appreciated by those skilled in the art that where a boron-based cocatalyst is employed, the complex is typically pre-alkylated by reaction with an alkylaluminum compound such as TIBA. This process is well known and any suitable alkylaluminum may be used, such as Al(C1-C6 alkyl)3. Preferred alkylaluminum compounds are triethylaluminum, triisobutylaluminum, triisohexylaluminum, tri-n-octylaluminum and triisooctylaluminum.

[0151] Alternatively, when a borate cocatalyst is used, the metallocene complex is in its alkylated form, ie, for example, a dimethyl metallocene complex or a benzhydryl metallocene complex may be used.

[0152] Valuable boron-based co-catalysts include those of formula (V)

[0153] BY3(V)

[0154] wherein Y is the same or different and is a hydrogen atom, an alkyl group of 1 to about carbon atoms, an aryl group of 6 to about 15 carbon atoms, an alkylaryl group, an arylalkyl group, a haloalkyl group or a haloaryl group (each of which has 1 to 10 carbon atoms in the alkyl group and 6-20 carbon atoms in the aryl group), or fluorine, chlorine, bromine or iodine. Preferred examples of Y are methyl, propyl, isopropyl, isobutyl or trifluoromethyl, unsaturated groups such as aryl or haloaryl groups, for example phenyl, tolyl, benzyl, p-fluorophenyl, 3,5-difluorophenyl, pentachlorophenyl, pentafluorophenyl, 3,4,5-trifluorophenyl and 3,5-bis(trifluoromethyl)phenyl. Preferred options are trifluoroborane, triphenylborane, tri(4-fluorophenyl)borane, tri(3,5-difluorophenyl)borane, tri(4-fluoromethylphenyl)borane, tri(2,4,6-trifluorophenyl)borane, tri(pentafluorophenyl)borane, tri(tolyl)borane, tri(3,5-dimethylphenyl)borane, tri(3,5-difluorophenyl)borane and / or tri(3,4,5-trifluorophenyl)borane.

[0155] Tris(pentafluorophenyl)borane is particularly preferred.

[0156] However, preference is given to using borates, ie compounds containing borate 3+ ions.

[0157] Such ionic cocatalysts preferably contain non-coordinating anions, such as tetrakis(pentafluorophenyl)borate and tetraphenylborate. Suitable counterions are protonated amines or aniline derivatives, such as methylammonium, aniline, dimethylammonium, diethylammonium, N-methylaniline, diphenylammonium, N,N-dimethylaniline, trimethylammonium, triethylammonium, tri-n-butylammonium, methyldiphenylammonium, pyridinium, p-bromo-N,N-dimethylaniline or p-nitro-N,N-dimethylaniline.

[0158] Preferred ionic compounds that can be used according to the present invention include:

[0159] triethylammoniumtetra(phenyl)borate,

[0160] Tributylammoniumtetra(phenyl)borate,

[0161] trimethylammoniumtetra(tolyl)borate,

[0162] Tributylammoniumtetra(tolyl)borate,

[0163] Tributylammoniumtetra(pentafluorophenyl)borate,

[0164] tripropylammoniumtetra(dimethylphenyl)borate, tributylammoniumtetra(trifluoromethylphenyl)borate,

[0165] Tributylammoniumtetra(4-fluorophenyl)borate,

[0166] N,N-dimethylcyclohexylammoniumtetrakis(pentafluorophenyl)borate,

[0167] N,N-dimethylbenzylammoniumtetrakis(pentafluorophenyl)borate,

[0168] N,N-dimethylaniliniumtetra(phenyl)borate,

[0169] N,N-diethylaniliniumtetra(phenyl)borate,

[0170] N,N-dimethylaniliniumtetrakis(pentafluorophenyl)borate,

[0171] N,N-di(propyl)ammoniumtetrakis(pentafluorophenyl)borate,

[0172] di(cyclohexyl)ammoniumtetrakist(pentafluorophenyl)borate,

[0173] triphenylphosphoniumtetrakis(phenyl)borate,

[0174] triethylphosphoniumtetrakis(phenyl)borate,

[0175] diphenylphosphoniumtetrakis(phenyl)borate,

[0176] tri(methylphenyl)phosphoniumtetrakis(phenyl)borate,

[0177] tri(dimethylphenyl)phosphoniumtetrakis(phenyl)borate,

[0178] triphenylcarbeniumtetrakis(pentafluorophenyl)borate,

[0179] Or ferroceniumtetrakis(pentafluorophenyl)borate.

[0180] Preferred are triphenylcarbonium tetrakis(pentafluorophenyl)borate, N,N-dimethylcyclohexylammonium tetrakis(pentafluorophenyl)borate or N,N-dimethylbenzylammonium tetrakis(pentafluorophenyl)borate.

[0181] Surprisingly, it has been found that certain boron promoters are particularly preferred.

[0182] Preferred borates for use in the present invention therefore contain trityl ions. Thus, the use of N,N-dimethylammonium tetrakis(pentafluorophenyl)borate and Ph3CB(PhF5)4 and the like is therefore particularly preferred.

[0183] According to the present invention, preferred cocatalysts are aluminoxanes, more preferably methylaluminoxane, combinations of aluminoxanes with aluminum alkyls, boron or borate cocatalysts, and combinations of aluminoxanes with boron-based cocatalysts.

[0184] Suitable amounts of promoters are well known to those skilled in the art.

[0185] The molar ratio of boron to the metal ion of the metallocene may be in the range of 0.5:1 mol / mol to 35 10:1 mol / mol, preferably 1:1 mol / mol to 10:1 mol / mol, in particular 1:1 mol / mol to 5:1 mol / mol.

[0186] The molar ratio of Al to the metal ion of the metallocene in the aluminoxane may range from 1:1 mol / mol to 2000:1 mol / mol, preferably from 10:1 mol / mol to 1000:1 mol / mol, and more preferably from 50:1 mol / mol to 500:1 mol / mol.

[0187] The metallocene catalyst system used in the polymerization method of the present invention is used in a supported form. The support (iii) used comprises silicon dioxide, and more preferably the support (iii) used consists of silicon dioxide. In other words, the support is preferably a silicon dioxide support. Those skilled in the art are aware of the steps required for supporting the metallocene catalyst.

[0188] Particularly preferably, the support is a porous material so that the metallocene complex can be loaded into the pores of the support, for example using methods similar to those described in WO 94 / 14856 (Mobil), WO 95 / 12622 (Borealis) and WO 2006 / 097497.

[0189] The average particle size of the carrier may generally be from 10 μm to 100 μm. However, it has proven to be particularly advantageous if the carrier has an average particle size of from 15 μm to 80 μm, preferably from 18 μm to 50 μm.

[0190] The particle size distribution of the carrier is described below. The silica carrier has a D50 of 10 to 80 μm, more preferably a D50 of 18 to 50 μm. In addition, the silica carrier preferably has a D10 of 5 to 30 μm and a D90 of 30 to 90 μm.

[0191] The average particle size of the metallocene catalyst system is preferably from 20 μm to 50 μm, more preferably from 25 μm to 45 μm, and most preferably from 30 μm to 40 μm.

[0192] The particle size distribution of the metallocene catalyst system is described below. The D50 of the metallocene catalyst system is preferably 30 μm to 80 μm, preferably 32 μm to 50 μm, and most preferably 34 μm to 40 μm. In addition, the D10 of the metallocene catalyst system is preferably at most 29 μm, more preferably 15 μm to 29 μm, preferably 20 μm to 28 μm, and most preferably 25 μm to 27 μm. The D90 of the metallocene catalyst system is preferably at least 45 μm, more preferably 45 μm to 70 μm and most preferably 40 μm to 60 μm.

[0193] Preferably, the process for producing a heterophasic propylene copolymer composition comprises the following steps

[0194] a) preparing the bimodal matrix phase (A) of the heterophasic propylene copolymer by

[0195] a1) polymerizing propylene in a first reactor to obtain a first propylene polymer component having a melt flow rate MFR2 (measured according to ISO 1133 at 230°C and 2.16 kg load) of 25 to 85 g / 10 min, wherein the ratio of hydrogen feed to propylene feed is from 0.10 to less than 0.40 mol / kmol, preferably from 0.15 to 0.39 mol / kmol, more preferably from 0.20 to 0.38 mol / kmol, more preferably from 0.20 to 0.38 mol / kmol, and most preferably from 0.20 to 0.36 mol / kmol,

[0196] a2) transferring the first propylene polymer component to a second reactor and polymerizing propylene in the second reactor to obtain a second propylene polymer component, the combined first and second propylene polymer components having an MFR2 (measured according to ISO 1133 at 230°C and 2.16 kg load) of at least 2.2 times the MFR2 of the first propylene polymer component,

[0197] b) preparing the dispersed phase (B) of the heterophasic propylene copolymer by

[0198] b1) transferring the first propylene polymer component and the second propylene polymer component to a third reactor, and polymerizing propylene and an α-olefin having 2 or 4 to 12 carbon atoms in the third reactor to obtain a third propylene polymer component,

[0199] c) withdrawing a heterophasic propylene copolymer comprising said first propylene polymer component, a second propylene polymer component and a third propylene polymer component, and

[0200] d) obtaining a heterophasic propylene copolymer composition comprising said heterophasic propylene copolymer.

[0201] wherein the heterophasic propylene copolymer composition has a melt flow rate MFR2 of 70 g / 10 min to 250 g / 10 min, measured at 230° C. and 2.16 kg load according to ISO 1133, and

[0202] Wherein, the polymerization in steps a1), a2) and b1) is carried out in the presence of a metallocene catalyst system, wherein the metallocene catalyst system comprises a metallocene complex and a support, wherein the support comprises silicon dioxide, and wherein the metallocene complex has a structure represented by formula (I):

[0203]

[0204] wherein each X is independently a σ donor ligand,

[0205] L is a divalent bridge selected from -R'2C-, -R'2C-CR'2-, -R'2Si-, -R'2Si-SiR'2- and -R'2Ge-, wherein each R' is independently a hydrogen atom or a C1-C ... 20 A hydrocarbon group, or optionally two R' groups can be combined together to form a ring,

[0206] Each R 1 are independently the same or different and are hydrogen, linear or branched C1-C6 alkyl, C 7-20 Arylalkyl, C7-20 Alkyl aryl or C 6-20 Aryl or OY group, wherein Y is C 1-10 A hydrocarbon group, and optionally two adjacent R 1 The groups may be part of a ring including the phenyl carbon to which they are bonded,

[0207] Each R 2 are independently the same or different and are CH2-R 8 Group, where R 8 is H or a linear or branched C1-C6 alkyl group, C 3-8 Cycloalkyl or C 6-10 Aryl,

[0208] R 3 is a straight or branched C1-C6 alkyl group, C 7-20 Arylalkyl, C 7-20 Alkyl aryl or C6-C 20 Aryl,

[0209] R 4 C(R 9 )3 groups, wherein R 9 is a linear or branched C1-C6 alkyl group,

[0210] R 5 is hydrogen or an aliphatic C1-C ... 20 Hydrocarbon;

[0211] R 6 is hydrogen or an aliphatic C1-C ... 20 Hydrocarbyl; or

[0212] R 5 and R 6 can be combined to form optionally n groups R 10 a substituted 5-membered saturated carbocyclic ring, wherein n is 0 to 4;

[0213] Each R 10 The same or different and selected from C1-C 20 The hydrocarbon group and optionally a C1-C ... 20 Hydrocarbon;

[0214] R 7 is H or a linear or branched C1-C6 alkyl group, or an aryl or heteroaryl group having 6 to 20 carbon atoms, the aryl or heteroaryl group being optionally substituted by 1 to 3 groups R 11 replace,

[0215] Each R 11 are independently the same or different and are hydrogen, linear or branched C1-C6 alkyl, C 7-20 Arylalkyl, C 7-20 Alkyl aryl or C 6-20 Aryl or OY group, where Y is C 1-10 Hydrocarbon.

[0216] Preferably, the process for producing a heterophasic propylene copolymer composition comprises the following steps

[0217] a) preparing the bimodal matrix phase (A) of the heterophasic propylene copolymer by

[0218] a1) polymerizing propylene in a first reactor to obtain a first propylene polymer component having a melt flow rate MFR2 (measured according to ISO 1133 at 230° C. and 2.16 kg load) of 25 to 85 g / 10 min,

[0219] a2) transferring the first propylene polymer component to a second reactor and polymerizing propylene in the second reactor to obtain a second propylene polymer component, the combined first and second propylene polymer components having an MFR2 (measured according to ISO 1133 at 230°C and 2.16 kg load) of at least 2.2 times the MFR2 of the first propylene polymer component, wherein the feed ratio of hydrogen to propylene is in the range of above 4.65 mol / kmol to 10.0 mol / kmol, more preferably from 4.90 mol / kmol to 8.00 mol / kmol, more preferably from 5.10 mol / kmol to 6.00 mol / kmol, more preferably from 5.20 mol / kmol to 5.80 mol / kmol and most preferably from 5.30 mol / kmol to 5.70 mol / kmol,

[0220] b) preparing the dispersed phase (B) of the heterophasic propylene copolymer by

[0221] b1) transferring the first propylene polymer component and the second propylene polymer component to a third reactor, and polymerizing propylene and an α-olefin having 2 or 4 to 12 carbon atoms in the third reactor to obtain a third propylene polymer component,

[0222] c) withdrawing a heterophasic propylene copolymer comprising said first propylene polymer component, a second propylene polymer component and a third propylene polymer component, and

[0223] d) obtaining a heterophasic propylene copolymer composition comprising said heterophasic propylene copolymer.

[0224] wherein the heterophasic propylene copolymer composition has a melt flow rate MFR2 of 70 g / 10 min to 250 g / 10 min, measured according to ISO 1133 at 230 °C and 2.16 kg load, and

[0225] Wherein, the polymerization in steps a1), a2) and b1) is carried out in the presence of a metallocene catalyst system, wherein the metallocene catalyst system comprises a metallocene complex and a support, wherein the support comprises silicon dioxide, and wherein the metallocene complex has a structure represented by formula (I):

[0226]

[0227] wherein each X is independently a σ donor ligand,

[0228] L is a divalent bridge selected from -R'2C-, -R'2C-CR'2-, -R'2Si-, -R'2Si-SiR'2- and -R'2Ge-, wherein each R' is independently a hydrogen atom or a C1-C ... 20 A hydrocarbon group, or optionally two R' groups can be combined together to form a ring,

[0229] Each R 1 are independently the same or different and are hydrogen, linear or branched C1-C6 alkyl, C 7-20 Arylalkyl, C 7-20 Alkyl aryl or C 6-20 Aryl or OY group, where Y is C 1-10 A hydrocarbon group, and optionally two adjacent R 1 The groups may be part of a ring including the phenyl carbon to which they are bonded,

[0230] Each R 2 are independently the same or different and are CH2-R 8 Group, where R 8 is H or a linear or branched C1-C6 alkyl group, C 3-8 Cycloalkyl or C 6-10 Aryl,

[0231] R 3 is a straight or branched C1-C6 alkyl group, C 7-20 Arylalkyl, C 7-20 Alkyl aryl or C6-C 20 Aryl,

[0232] R 4 C(R 9 )3 groups, wherein R 9is a linear or branched C1-C6 alkyl group,

[0233] R 5 is hydrogen or an aliphatic C1-C ... 20 Hydrocarbon;

[0234] R 6 is hydrogen or an aliphatic C1-C ... 20 Hydrocarbyl; or

[0235] R 5 and R 6 can be combined to form optionally n groups R 10 a substituted 5-membered saturated carbocyclic ring, wherein n is 0 to 4;

[0236] Each R 10 The same or different and selected from C1-C 20 The hydrocarbon group and optionally a C1-C ... 20 Hydrocarbon;

[0237] R 7 is H or a linear or branched C1-C6 alkyl group, or an aryl or heteroaryl group having 6 to 20 carbon atoms, the aryl or heteroaryl group being optionally substituted by 1 to 3 groups R 11 replace,

[0238] Each R 11 are independently the same or different and are hydrogen, linear or branched C1-C6 alkyl, C 7-20 Arylalkyl, C 7-20 Alkyl aryl or C 6-20 Aryl or OY group, where Y is C 1-10 Hydrocarbon.

[0239] Preferably, the process for producing a heterophasic propylene copolymer composition comprises the following steps

[0240] a) preparing the bimodal matrix phase (A) of the heterophasic propylene copolymer by

[0241] a1) polymerizing propylene in a first reactor to obtain a first propylene polymer component having a melt flow rate MFR2 (measured according to ISO 1133 at 230°C and 2.16 kg load) of 25 to 85 g / 10 min, wherein the ratio of hydrogen feed to propylene feed is from 0.10 to less than 0.40 mol / kmol, preferably from 0.15 to 0.39 mol / kmol, more preferably from 0.20 to 0.38 mol / kmol, more preferably from 0.20 to 0.38 mol / kmol, and most preferably from 0.20 to 0.36 mol / kmol,

[0242] a2) transferring the first propylene polymer component to a second reactor and polymerizing propylene in the second reactor to obtain a second propylene polymer component, the combined first and second propylene polymer components having an MFR2 (measured according to ISO 1133 at 230°C and 2.16 kg load) of at least 2.2 times the MFR2 of the first propylene polymer component, wherein the feed ratio of hydrogen to propylene is in the range of greater than 4.65 mol / kmol to 10.0 mol / kmol, more preferably from 4.90 mol / kmol to 8.00 mol / kmol, more preferably from 5.10 mol / kmol to 6.00 mol / kmol, more preferably from 5.20 mol / kmol to 5.80 mol / kmol, and most preferably from 5.30 mol / kmol to 5.70 mol / kmol,

[0243] b) preparing the dispersed phase (B) of the heterophasic propylene copolymer by

[0244] b1) transferring the first propylene polymer component and the second propylene polymer component to a third reactor, and polymerizing propylene and an α-olefin having 2 or 4 to 12 carbon atoms in the third reactor to obtain a third propylene polymer component,

[0245] c) withdrawing a heterophasic propylene copolymer comprising said first propylene polymer component, a second propylene polymer component and a third propylene polymer component, and

[0246] d) obtaining a heterophasic propylene copolymer composition comprising said heterophasic propylene copolymer.

[0247] wherein the heterophasic propylene copolymer composition has a melt flow rate MFR2 of 70 g / 10 min to 250 g / 10 min, measured according to ISO 1133 at 230 °C and 2.16 kg load, and

[0248] Wherein, the polymerization in steps a1), a2) and b1) is carried out in the presence of a metallocene catalyst system, wherein the metallocene catalyst system comprises a metallocene complex and a support, wherein the support comprises silicon dioxide, and wherein the metallocene complex has a structure represented by formula (I):

[0249]

[0250] wherein each X is independently a σ donor ligand,

[0251] L is a divalent bridge selected from -R'2C-, -R'2C-CR'2-, -R'2Si-, -R'2Si-SiR'2- and -R'2Ge-, wherein each R' is independently a hydrogen atom or a C1-C ... 20 A hydrocarbon group, or optionally two R' groups taken together to form a ring,

[0252] Each R 1 are independently the same or different and are hydrogen, linear or branched C1-C6 alkyl, C 7-20 Arylalkyl, C 7-20 Alkyl aryl or C 6-20 Aryl or OY group, where Y is C 1-10 A hydrocarbon group, and optionally two adjacent R 1 The groups may be part of a ring including the phenyl carbon to which they are bonded,

[0253] Each R 2 are independently the same or different and are CH2-R 8 Group, where R 8 is H or a linear or branched C1-C6 alkyl group, C 3-8 Cycloalkyl or C 6-10 Aryl,

[0254] R 3 is a straight or branched C1-C6 alkyl group, C 7-20 Arylalkyl, C 7-20 Alkyl aryl or C6-C 20 Aryl,

[0255] R 4 C(R 9 )3 groups, wherein R 9 is a linear or branched C1-C6 alkyl group,

[0256] R 5 is hydrogen or an aliphatic C1-C ... 20 Hydrocarbon;

[0257] R 6 is hydrogen or an aliphatic C1-C ... 20 Hydrocarbyl; or

[0258] R 5 and R 6 can be combined to form optionally n groups R 10 a substituted 5-membered saturated carbocyclic ring, wherein n is 0 to 4;

[0259] Each R 10 are the same or different and are selected from C1-C 20 The hydrocarbon group and optionally a C1-C ... 20 Hydrocarbon;

[0260] R 7 is H or a linear or branched C1-C6 alkyl group, or an aryl or heteroaryl group having 6 to 20 carbon atoms, the aryl or heteroaryl group being optionally substituted by 1 to 3 groups R 11 replace,

[0261] Each R 11 are independently the same or different and are hydrogen, linear or branched C1-C6 alkyl, C 7-20 Arylalkyl, C 7-20 Alkyl aryl or C 6-20 Aryl or OY group, where Y is C 1-10 Hydrocarbon.

[0262] The present invention also provides a heterophasic propylene copolymer composition obtainable by the process according to the present invention.

[0263] All preferred embodiments of the process according to the present invention for producing a heterophasic propylene copolymer composition are, if applicable, also preferred embodiments of the heterophasic propylene copolymer composition obtainable by the process according to the present invention. DETAILED DESCRIPTION

[0264] The invention will now be further described by way of non-limiting examples.

[0265] Experimental Section

[0266] 1. Determination method

[0267] Unless defined otherwise, the following definitions of terms and assay methods apply to the above general description of the invention as well as to the following examples.

[0268] a) Melt flow rate (MFR)

[0269] Melt flow rate (MFR) is determined according to ISO 1133 and is expressed in g / 10 min. The higher the melt flow rate, the lower the viscosity of the polymer. The MFR2 of polypropylene is determined at 230°C and 2.16 kg load, and the MFR2 of polyethylene is determined at 190°C and 2.16 kg load.

[0270] The MFR2 of component (B) produced in the presence of component (A) is calculated using the measured MFR2 of component (A) and the measured MFR2 of the resulting mixture after production of component (B) ("final"):

[0271] Log(MFR 最终 )=Weight Fraction(A)*Log(MFR A )+weight fraction(B)*Log(MFR B )

[0272] b) CRYSTEX: determination of crystalline and soluble fractions and their respective properties (IV and ethylene content)

[0273] The crystalline fraction (CF) and soluble fraction (SF) of the polypropylene composition as well as the comonomer content and intrinsic viscosity of each component were analyzed by using a CRYSTEX instrument Polymer Char (Valencia, Spain). The details of the technology and method can be found in the literature (Ljiljana Jeremic, Andreas Albrecht, Martina Sandholzer & Markus Gahleitner (2020) Rapid characterization of high-impact ethylene-propylene copolymer composition by crystallization extraction separation: comparability to standard separation methods, International Journal of Polymer Analysis and Characterization, 25: 8, 581-596).

[0274] The crystalline and amorphous components were separated by a temperature cycle of dissolution at 160° C., crystallization at 40° C. and redissolution in 1,2,4-trichlorobenzene at 160° C. Quantification of SF and CF and determination of the ethylene content (C2) were achieved by an integrated infrared detector (IR4), and for determination of the intrinsic viscosity (iV) an online 2-capillary viscometer was used.

[0275] The IR4 detector is a multi-wavelength detector that detects CH3 stretching vibrations at two different wavelengths (at about 2960 cm -1 centered) and CH stretching vibration (2700cm -1 -3000cm -1 )) measure IR absorbance, these two different bands are used to determine the concentration and ethylene content in ethylene-propylene copolymers. A series of known ethylene contents (given by 13 C-NMR measurement) and calibrated the IR4 detector in a concentration range of 2 mg / ml to 13 mg / ml for each. In order to simultaneously meet the two characteristics (concentration and ethylene content) of various polymer concentrations expected during Crystex analysis, the following calibration equation was applied:

[0276] Conc=a+b*Abs(CH)+c*(Abs(CH)) 2 +d*Abs(CH3)+e*(Abs(CH3) 2 +f*Abs(CH)*Abs(CH3) (Equation 1)

[0277] CH3 / 1000C=a+b*Abs(CH)+c*Abs(CH3)+d*(Abs(CH3) / Abs(CH))+e*(Abs(CH3) / Abs(CH)) 2 (Equation 2)

[0278] Constants a to e in Equation 1 and constants a to f in Equation 2 are determined by using least squares regression analysis.

[0279] The CH3 / 1000C is converted to ethylene content (wt.-%) using the following relationship:

[0280] wt.-% (ethylene in EP copolymer) = 100 - CH3 / 1000TC*0.3 (Equation 3)

[0281] The contents of the soluble fraction (SF) and the crystalline fraction (CF) are related by means of the XS calibration to the amount of "cold xylene solubles" (XCS) and the cold xylene insolubles (XCI) fraction, which are determined gravimetrically according to ISO 16152. The XS calibration was achieved by testing various EP copolymers with an XS content in the range of 2-31 wt.-%. The determined XS calibration is linear:

[0282] wt.-%XS=1,01*wt.-%SF (Equation 4)

[0283] The intrinsic viscosity (iV) of the parent EP copolymer and its soluble and crystalline components was determined using an online 2-capillary viscometer and correlated to the corresponding iV determined by the standard method in decalin according to ISO 1628-3. The calibration was performed using various EP PP copolymers with IV = 2-4 dL / g. The calibration curve determined was linear:

[0284] iV(dL / g)=a*Vsp / c (Equation 5)

[0285] The samples to be analyzed were weighed at a concentration of 10 to 20 mg / ml. To avoid injection of possible gels and / or polymers (such as PET and PA) not soluble in TCB at 160°C, the weighed samples were loaded into a stainless steel mesh (MW 0,077 / D 0,05 mm).

[0286] After the vial was automatically filled with 1,2,4-TCB containing 250 mg / l 2,6-tert-butyl-4-methylphenol (BHT) as an antioxidant, the sample was dissolved at 160°C until complete dissolution was achieved, usually for 60 min, with continuous stirring at 400 rpm. In order to avoid sample degradation, the polymer solution was protected under N2 atmosphere during the dissolution process.

[0287] A certain volume of sample solution is injected into a column filled with an inert carrier, where crystallization of the sample and separation of the soluble and crystalline components are carried out. This process is repeated twice. In the first injection, the entire sample is measured at high temperature and the iV [dl / g] and C2 [wt.-%] of the PP composition are determined. In the second injection, the soluble components (at low temperature) and the crystalline components (at high temperature) in the crystallization cycle are measured (wt.-% SF, wt.-% CF, wt.-% C2, iV).

[0288] c) Xylene cold solubles (XCS)

[0289] Xylene cold solubles (XCS, wt.-%) were determined according to ISO 16152 1st edition (2005-07-01) at 25°C.

[0290] d) Intrinsic viscosity

[0291] The intrinsic viscosity was measured according to DIN ISO 1628 / 1, October 1999 edition (in decalin at 135° C.).

[0292] e) Quantification of microstructure by NMR spectroscopy—ethylene content in HECO

[0293] Quantitative nuclear magnetic resonance (NMR) spectroscopy was used to quantify the comonomer content of the polymers. 1 H and 13 C, respectively, at 400.15 MHz and 100.62 MHz, and quantitative 13 C{ 1 H} NMR spectroscopy. Nitrogen was used for all pneumatics and the temperature was 125 °C. 13 All spectra were recorded with a C optimized 10 mm extended temperature probe. Approximately 200 mg of material was dissolved in 3 ml of 1,2-tetrachloroethane-d2 (TCE-d2) and chromium-(III)-acetylacetone (Cr(acac)3) to obtain a 65 mM solution of the relaxation agent in the solvent (Singh, G., Kothari, A., Gupta, V., Polymer Testing 28 5 (2009), 475). To ensure a homogeneous solution, the NMR tube was further heated in a rotating oven for at least 1 hour after the initial sample was prepared in a heat block. After insertion of the magnet, the tube was rotated at 10 Hz. This setup was chosen primarily for the high resolution and quantification required for accurate quantification of ethylene content. Standard single pulse excitation, no NOE, optimized tip angle, 1s cycle delay and double-layer WALTZ16 decoupling scheme (Zhou, Z., Kuemmerle, R., Qiu, X., Redwine, D., Cong, R., Taha, A., Baugh, D. Winniford, B., J. Mag. Reson. 187 (2007) 225; Busico, V., Carbonniere, P., Cipullo, R., Pellecchia, R., Severn, J., Talarico, G., Macromol. Rapid Commun. 2007, 28, 1128) were used. A total of 6144 (6k) transients were obtained for each spectrum. The quantitative 13 C{ 1 H} NMR spectra are processed, integrated, and the relevant quantitative properties are determined from the integrals using a proprietary computer program. All chemical shifts are indirectly referenced to the central methylene group in the ethylene region (EEE) at 30.00 ppm using the chemical shift of the solvent. This method allows for comparative reference even if this structural unit is not present. Characteristic signals corresponding to ethylene incorporation are observed (Cheng, HN, Macromolecules 17 (1984), 1950).

[0294] The observation of characteristic signals corresponding to 2,1-erythro-type regional defects (as described in L. Resconi, L. Cavallo, A. Fait, F. Piemontesi, Chem. Rev. 2000, 100 (4), 1253, in Cheng, HN, Macromolecules 1984, 17, 1950 and in WJ. Wang and S. Zhu, Macromolecules 2000, 33 1157) requires correction for the effect of regional defects on the measured properties. No characteristic signals corresponding to other types of regional defects were observed.

[0295] The method of Wang et al. (Wang, WJ., Zhu, S., Macromolecules 33 (2000), 1157) was used to 13 C{ 1 The comonomer composition is quantified by integrating multiple signals across the spectral region of the H} spectrum. This approach was chosen for its robust nature and ability to account for the presence of regio defects when required. The integration region was slightly adjusted to improve applicability over the entire range of comonomer contents encountered.

[0296] For systems where only isolated ethylene is observed in the PPEPP sequence, the method of Wang et al. was modified to reduce the effect of non-zero integrals at sites known to be absent. This approach reduces the overestimation of ethylene content for such systems and does so by reducing the number of sites used to determine absolute ethylene content:

[0297] E=0.5(Sββ+Sβγ+Sβδ+0.5(Sαβ+Sαγ))

[0298] By using this set of points, the corresponding integral equation becomes:

[0299] E=0.5(I H +I G +0.5(I C +I D ))

[0300] The same symbols are used as in the article by Wang et al. (Wang, WJ., Zhu, S., Macromolecules 33 (2000), 1157). The equation for the absolute propylene content is not modified.

[0301] Calculate the mole percent of comonomer incorporation using the mole fraction:

[0302] E[mol%]=100*fE

[0303] Calculate the weight percent of comonomer incorporation using mole fraction:

[0304] E[wt.-%]=100*(fE*28.06) / ((fE*28.06)+((1-fE)*42.08))

[0305] The comonomer sequence distribution at the triplet level was determined using the analytical method of Kakugo et al. (Kakugo, M., Naito, Y., Mizunuma, K., Miyatake, T. Macromolecules 15 (1982) 1150). This method was chosen because of its robust nature and slight adjustments to the integration region to improve applicability over a wider range of comonomer contents.

[0306] f) Flexural modulus (FM)

[0307] The flexural modulus (FM) was determined by the three-point bending method according to ISO 178 on injection-molded test specimens with the dimensions 80 x 10 x 4 mm as described in EN ISO 1873-2. 3 When measuring the flexural modulus, the crosshead speed was 2 mm / min.

[0308] g) Charpy notched impact strength (Charpy NIS)

[0309] Charpy notched impact strength was determined according to ISO 179-1eA at +23°C or -20°C on injection-molded test specimens with the dimensions 80 x 10 x 4 mm as described in EN ISO 1873-2 3 .

[0310] h) Median particle size D50 (sedimentation)

[0311] The median particle size D50 (sedimentation) is calculated from the particle size distribution [mass percent] determined by gravimetric liquid sedimentation according to ISO 13317-3 (sedimentation curve).

[0312] i) Average particle size and particle size distribution

[0313] Laser diffraction measurements using Coulter LS200 are used to determine the average particle size and particle size distribution. The average particle size and particle size distribution are a measure of the size of the particles. The D values ​​(D10 (or d10), D50 (or d50) and D90 (or d90)) represent the intercepts of 10%, 50% and 90% of the cumulative mass of the sample. When the particles are arranged in ascending order of mass, the D value can be considered as the diameter of a sphere into which the mass of the sample is divided into a specific percentage. For example, D10 is the diameter at which 10% of the sample mass consists of particles with a diameter less than this value. D50 is the diameter of the particles, where 50% of the sample mass is less than this value and 50% of the sample mass is greater than this value. D90 is the diameter at which 90% of the sample mass consists of particles with a diameter less than this value. The D50 value is also called the median particle size. According to the laser diffraction measurement of ISO 13320, the volume D value is obtained based on the volume distribution.

[0314] j) Differential Scanning Calorimetry (DSC)

[0315] The melting temperature (T) of 5 mg to 7 mg samples was measured using a TA Instrument Q200 differential scanning calorimeter (DSC). m ) and melt enthalpy (H m ), crystallization temperature (T c ) and heat of crystallization (H c , H cr DSC was run according to ISO 11357 / Part 3 / Method C2 in a heating / cooling / heating cycle with a scan rate of 10°C / min in the temperature range of -30°C to +225°C.

[0316] Crystallization temperature (T c ) and heat of crystallization (H c ) is determined by the cooling step, while the melting temperature (T m ) and melting enthalpy (H m ) is determined by the second heating step.

[0317] Throughout this specification, the term T c or (T cr ) is understood to be the peak temperature of the crystallization determined by DSC at a cooling rate of 10 K / min (ie 0.16 K / sec).

[0318] k) Volatile organic compounds (VOC) and semi-volatile organic condensables (FOG)

[0319] For the thermal desorption analysis according to VDA 278 (October 2011), the samples were stored uncovered at room temperature (max. 23° C.) for 7 days directly before the start of the analysis.

[0320] Determination of the VOC value from pellets according to VDA 278 October 2011. VDA 278 October 2011, Thermal desorption analysis of organic emissions for the characterization of non-metallic materials in automobiles, VDA (Verband der automobile industrie, German Association of the Automotive Industry). According to VDA 278 October 2011, the VOC value is defined as "the sum of highly volatile to moderately volatile substances". It is calculated in toluene equivalent. The method described in this recommendation allows the determination and analysis of substances in the boiling / elution range up to n-pentacosane (C25). "

[0321] The FOG value is also determined from the pellets according to VDA 278 of October 2011. According to VDA 278 of October 2011, the FOG value is defined as "the sum of low-volatility substances eluting at the retention time of n-tetradecane (inclusive)". It is calculated as hexadecane equivalent. The substances in the boiling point range of n-alkanes "C14" to "C32" are determined and analyzed.

[0322] 1) Bulk density

[0323] According to ISO 60:1977 at 23°C using 100cm 3 Cylinders are used to determine the bulk density of polymer powders.

[0324] 2. Example

[0325] a) Polymerization of the heterophasic propylene copolymer composition

[0326] Catalyst A is a metallocene complex used as described in WO2019 / 179959A1:

[0327]

[0328] Racemic-trans-dimethylsilanediyl[2-methyl-4,8-bis(3',5'-dimethylphenyl)-1,5,6,7-tetrahydro-s-indacen-1-yl][2-

[0329] Methyl-4-(3',5'-dimethylphenyl)-5-methoxy-6-tert-butylinden-1-yl]zirconium dichloride

[0330] A supported metallocene catalyst similar to IE2 in WO 2019 / 179959 A1 was prepared.

[0331] Catalyst B is a Ziegler-Natta catalyst commercially available from Lyondell Basell under the trade name "AvantZN180M".

[0332] exist Comparative heterophasic propylene copolymer CE01 and inventive heterophasic propylene polymers IE01 and IE02 were prepared in a PP pilot plant using a sequential process comprising a prepolymerization reactor, a loop reactor and two gas phase reactors. The polymerization and reactor conditions are given in Table 1a below.

[0333] Table 1a: Preparation of heterophasic propylene copolymers using metallocene catalyst A

[0334]

[0335]

[0336] *MFR2(circulation+GPR1) / MFR2(circulation)

[0337] Comparative heterophasic propylene copolymer CE02 was prepared using a catalyst in combination with triethylaluminium (TEAL) as cocatalyst, biscyclopentadienyldimethoxysilane (donor D) as external donor in a sequential process comprising a prepolymerisation reactor, a loop reactor and two gas phase reactors. The polymerisation and reactor conditions are given in Table 1b below.

[0338] Table 1b: Preparation of heterophasic propylene copolymer compositions using Ziegler-Natta catalyst B

[0339]

[0340]

[0341] *MFR2(circulation+GPR1) / MFR2(circulation)

[0342] The properties of the obtained heterophasic propylene copolymers CE01, IE01 and IE02 are shown in Table 2a below.

[0343] Table 2a: Properties of heterophasic propylene copolymers

[0344] Example CE01 IE01 IE02 <![CDATA[MFR2(g / 10min)]]> 100.0 110.0 99.4 XCS (wt.-%) 10.5 8.8 11.9 IV(XCS) / XCS(ml / g) 248 320 300

[0345] The heterophasic propylene copolymers IE01, IE02, CE01 and CE02 were compounded at 220 °C using a co-rotating twin-screw extruder Coperion ZSK 47 with the addition of 0.15 wt.-% of an antioxidant (Irganox B215FF from BASF, Germany; a 1:2 mixture of pentaerythritol tetrakis(3-(3',5'-di-tert-butyl-4-hydroxyphenyl)propionate, CAS No. 6683-19-8, and tris(2,4-di-tert-butylphenyl)phosphite, CAS No. 31570-04-4) and 0.05 wt.-% of calcium stearate (CAS No. 1592-23-0, commercially available from Faci, Italy) as acid scavenger.

[0346] The properties of the obtained heterophasic propylene copolymer composition are given in Table 2b below.

[0347] Table 2b: Properties of heterophasic propylene copolymer compositions

[0348]

[0349] As can be seen from Table 2b above, the stiffness and impact strength of the inventive examples IE01 and IE02 are comparable to those of the comparative examples. However, VOC is significantly improved at the same time. In addition, the bulk density is also improved.

Claims

1. A process for producing a heterophasic propylene copolymer composition, said process comprising the following steps a) preparing the bimodal matrix phase (A) of the heterophasic propylene copolymer by a1) polymerizing propylene in a first reactor to obtain a first propylene polymer component having a melt flow rate MFR2 of 25 to 85 g / 10 min, measured at 230° C. and 2.16 kg load according to ISO 1133, a2) transferring the first propylene polymer component to a second reactor and polymerizing propylene in the second reactor to obtain a second propylene polymer component, the combined first and second propylene polymer components having an MFR2 of at least 2.2 times the MFR2 of the first propylene polymer component, the MFR2 being determined according to ISO 1133 at 230°C and 2.16 kg load, b) preparing the dispersed phase (B) of the heterophasic propylene copolymer by b1) transferring the first propylene polymer component and the second propylene polymer component to a third reactor, and polymerizing propylene and an α-olefin having 2 or 4 to 12 carbon atoms in the third reactor to obtain a third propylene polymer component, c) withdrawing a heterophasic propylene copolymer comprising the first propylene polymer fraction, the second propylene polymer fraction and the third propylene polymer fraction from the third reactor, and d) obtaining a heterophasic propylene copolymer composition comprising said heterophasic propylene copolymer, in, The heterophasic propylene copolymer composition has a melt flow rate MFR2, measured according to ISO 1133 at 230°C and 2.16 kg load, of 70 g / 10 min to 250 g / 10 min, and Wherein, the polymerization in steps a1), a2) and b1) is carried out in the presence of a metallocene catalyst system, wherein the metallocene catalyst system comprises a metallocene complex and a support, wherein the support comprises silicon dioxide, and wherein the metallocene complex has a structure represented by formula (I): wherein each X is independently a σ donor ligand, L is a divalent bridge selected from -R'2C-, -R'2C-CR'2-, -R'2Si-, -R'2Si-SiR'2- and -R'2Ge-, wherein each R' is independently a hydrogen atom or a C1-C ... 20 A hydrocarbon group, or optionally two R' groups taken together to form a ring, Each R 1 are independently the same or different and are hydrogen, linear or branched C1-C6 alkyl, C 7-20 Arylalkyl, C 7-20 -alkylaryl or C 6-20 Aryl or OY group, where Y is C 1-10 A hydrocarbon group, and optionally two adjacent R 1 The groups may be part of a ring including the phenyl carbon to which they are bonded, Each R 2 are independently the same or different and are CH2-R 8 Group, where R 8 H or a straight or branched C 1-6 Alkyl, C 3-8 Cycloalkyl or C 6-10 Aryl, R 3 is a straight or branched C1-C6 alkyl group, C 7-20 Arylalkyl, C 7-20 Alkyl aryl or C6-C 20 Aryl, R 4 C(R 9 )3 groups, wherein R 9 is a linear or branched C1-C6 alkyl group, R 5 is hydrogen or an aliphatic C1-C ... 20 Hydrocarbon; R 6 is hydrogen or an aliphatic C1-C ... 20 Hydrocarbyl; or R 5 and R 6 can be combined to form a 5-membered saturated carbocyclic ring, which is optionally substituted by n R 10 Group substitution, n is 0 to 4; Each R 10 are the same or different and are selected from C1-C 20 The hydrocarbon group and optionally a C1-C ... 20 Hydrocarbon; R 7 is H, a linear or branched C1-C6 alkyl group, or an aryl or heteroaryl group having 6 to 20 carbon atoms, which aryl or heteroaryl group is optionally substituted by 1 to 3 R 11 Group substitution, Each R 11 are independently the same or different and are hydrogen, linear or branched C1-C6 alkyl, C 7-20 Arylalkyl, C 7-20 Alkyl aryl or C 6-20 Aryl or OY group, where Y is C 1-10 Hydrocarbon.

2. The process according to any one of the preceding claims, wherein the metallocene catalyst system further comprises (ii) a cocatalyst system comprising a boron-containing cocatalyst and / or an aluminoxane cocatalyst.

3. The process according to any one of the preceding claims, wherein the first propylene polymer component and / or the second propylene polymer component is a propylene homopolymer component and / or the third propylene polymer component is an ethylene-propylene rubber component.

4. The process according to any of the preceding claims, wherein the combined first and second propylene polymer components form a bimodal propylene composition, preferably a bimodal propylene homopolymer composition.

5. The process according to any one of the preceding claims, wherein the first and second propylene polymer components combined have a melt flow rate MFR2, measured according to ISO 1133 at 230°C and 2.16 kg load, of 120 to 500 g / 10 min.

6. A method according to any one of the preceding claims, wherein: The combined first and second propylene polymer components have a content of cold xylene soluble fraction at 25°C (XCS fraction) determined according to ISO 16152 of less than 2.0 wt.-%, based on the total weight of the combined first and second propylene polymer components.

7. The process according to any one of the preceding claims, wherein the first propylene polymer component is produced in an amount of 35 wt.-% to 70 wt.-%, based on the total weight of the first, second and third propylene polymer components combined, and / or wherein the second propylene polymer component is produced in an amount of 25 wt.-% to 55 wt.-%, based on the total weight of the first, second and third propylene polymer components combined, and / or wherein the third propylene polymer component is produced in an amount of 5 wt.-% to 25 wt.-%, based on the total weight of the first, second and third propylene polymer components combined.

8. The process according to any one of the preceding claims, wherein the first reactor is a slurry reactor, and / or wherein the second reactor is a first gas phase reactor (GPR1) and / or wherein the third reactor is a second gas phase reactor (GPR2).

9. The method according to any one of the preceding claims, wherein the method further comprises the following steps b2) transferring the first propylene polymer component, the second polymer component and the third propylene copolymer component to a fourth reactor, preferably a third gas phase reactor (GPR3), and polymerizing propylene with an α-olefin having 2 or 4 to 12 carbon atoms in the fourth reactor to obtain a fourth propylene polymer component, preferably an ethylene-propylene rubber component, Therein, step b2) is carried out after step b1) and before step c).

10. A method according to any one of the preceding claims, wherein: The heterophasic propylene copolymer comprises a content of a fraction soluble in cold xylene at 25 °C (XCS fraction) determined according to ISO 16152 in the range of 6 to 22 wt.-%, based on the total weight of the heterophasic propylene copolymer.

11. The method according to claim 10, wherein: Based on the total weight of the components soluble in cold xylene, 13 The fraction of the heterophasic propylene copolymer soluble in cold xylene at 25°C (XCS fraction) has an ethylene content (C2(XCS)) of 15 to 30 wt.-%, determined by Fourier transform infrared spectroscopy (FTIR) calibrated with C-NMR spectroscopy.

12. The process according to any one of the preceding claims, wherein the propylene copolymer is prepared by using 13 The heterophasic propylene copolymer has a total ethylene content (total C2) in the range of 1.8 wt.-% to 6.5 wt.-%, determined by Fourier transform infrared spectroscopy (FTIR) calibrated with C-NMR spectroscopy.

13. Process according to any of the preceding claims, wherein the heterophasic propylene copolymer composition has a melting temperature Tm, determined by Differential Scanning Calorimetry (DSC) according to ISO 11357, in the range of 145 to 160 °C.

14. Process according to any of the preceding claims, wherein the heterophasic propylene copolymer composition has a crystallization temperature Tc, determined by differential scanning calorimetry (DSC) according to ISO 11357, in the range of 110 to 120 °C.

15. Heterophasic propylene copolymer composition obtainable by the process according to any of the preceding claims.

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