BR112020008768B1 - PROCESS FOR PREPARING A POLYPROPYLENE COMPOSITION - Google Patents

Abstract

The invention relates to a process for producing a polypropylene composition that has an improved balanced combination of high fluidity, high stiffness and impact, and a high level of optical properties. Furthermore, the invention relates to the polypropylene composition having the properties mentioned above, as well as to an article comprising the polypropylene composition.

Description

[001] The present invention relates to a process for producing a polypropylene composition. More specifically, the invention relates to a process for producing a polypropylene composition comprising propylene and one or more comonomers selected from ethylene and C4-C10 alpha-olefins and to the polypropylene composition obtained by said process. The invention further relates to an article comprising polypropylene composition.

[002] Propylene homopolymers and copolymers are suitable for many applications, such as packaging, textile, automotive and piping. An important area of application for propylene homopolymers and copolymers is the packaging industry, particularly in film and molding applications.

[003] In the field of packaging, it is of great importance to have a good flow of polypropylene composition with good mechanical properties, that is, a high tensile modulus and good impact resistance. Good fluidity is necessary to achieve good processability in various article manufacturing processes, for example in injection molding processes, thus allowing a high production speed, which is generally required in the mass production market. Mechanical properties are also important in these types of applications, particularly in the field of containers, where it is necessary to retain the contents, such as food or fluids, contained therein. Furthermore, it is necessary to have sufficient rigidity for the container to be stacked.

[004] Furthermore, the polypropylene composition must also withstand mechanical compression damage, which is often caused by, for example, falling articles.

[005] Furthermore, fog must also be acceptable. In particular, a good balance between stiffness and haze is needed.

[006] However, at least some of these properties can only be achieved at the expense of other of these properties. For example, with increasing melt flow rate, stiffness can be improved while impact properties decrease significantly. Thus, the impact resistance and melt flow rate of the polypropylene composition behave in a conflicting manner.

[007] Furthermore, a high degree of crystallinity of the polypropylene composition makes it quite rigid, but also increases its haze. Therefore, the balance of stiffness and haze in the polypropylene composition is of great importance.

[008] Therefore there is a general need for a process for manufacturing a polypropylene composition that is characterized by a balanced combination of high fluidity, high rigidity and impact and a high level of optical properties (low haze value).

[009] Document EP2539398 discloses a process for preparing a random copolymer of propylene in a sequential polymerization process, wherein said process comprises the steps of a) polymerizing propylene and at least one ethylene and/or one C4 to C20 α-olefin in a first reactor (R1) obtaining a polypropylene (PP1) being a random copolymer of propylene (R-PP1), said polypropylene (PP 1) having a melt flow rate MFR10 (230 C ) measured according to ISO 1133 of not more than 1.5 g/10min, b) transfer the first polypropylene (PP1) into a second reactor (R2) c) polymerize, in the second reactor (R2) and in the presence of said first polypropylene (PP1), propylene and, optionally, at least one ethylene and/or a C4 to C20 α-olefin, thus obtaining a second polypropylene (PP2), said first polypropylene (PP1) and said second polypropylene (PP2) form an (intimate) mixture and said second polypropylene (PP2) is a first propylene homopolymer (H-PP1) or a second random propylene copolymer (R-PP2), d) transferring the mixture from the first polypropylene (PP1) and the second polypropylene (PP2) in a third reactor (R3), and e) polymerize, in the third reactor (R3) and in the presence of a mixture of the first polypropylene (PP1) and the second polypropylene (PP2), propylene and , optionally, at least one ethylene and/or a C4 to C20 α-olefin, thus obtaining a third polypropylene (PP3), said third polypropylene (PP3) being a second propylene homopolymer (H-PP2 ) or a third random copolymer of propylene (R-PP3) and the first polypropylene (PP1), the second polypropylene (PP2) and the third polypropylene (PP3) form an (intimate) mixture.

[0010] However, the invention in document EP2539398 is directed to pipes, thus the MFR2 of the resulting propylene random copolymer is between 0.5 and 10.0 g/10 min and may comprise, in particular, beta nucleating agents . Furthermore, EP2539398 is silent about the mist penetration properties of the resulting propylene random copolymer.

[0011] Document EP2338657 refers to a heterophasic polypropylene composition with a very high melt flow rate, high rigidity, acceptable impact properties and an advantageous balance between rigidity and transparency. The disclosed composition comprises 30 to 60% by weight of a propylene homopolymer fraction (A), 10 to 50% by weight of a propylene random copolymer fraction (B), 1 to 20% by weight of a first fraction of ethylene propylene elastomeric copolymer (C), 1 to 20% by weight of a second ethylene propylene elastomeric copolymer fraction (D) and 5 to 25% by weight of an ethylene homo- or copolymer fraction (E). The document does not disclose fog values for 2 mm plates. Furthermore, the examples do not contain an alpha nucleating agent. Furthermore, no pelletization steps are disclosed in D1.

[0012] Document WO2012/126759 refers to thermoplastic polyolefin compositions that have a good balance of mechanical and optical properties. The propylene random copolymer composition comprises 60 to 85% by weight of a propylene copolymer and from 0.1 to 2% by weight of ethylene-derived units and 15 to 40% by weight of a propylene copolymer and from 7 to 17% by weight of ethylene-derived units, with said composition having a total ethylene content of 3 to 4.5% by weight, a melt flow rate value in accordance with ISO 1133 (230/2.16 ) from 10 to 120 g/10 min10 min. It does not describe the presence of a propylene polymer (PP-c) with a comonomer content of 0.5 to 2.5% by weight.

[0013] Document WO2016/116606 refers to bimodal polypropylene random copolymer compositions with a good balance of mechanical and optical properties. It differs from the present invention in that it does not comprise a propylene polymer (PP-c) with a comonomer content of 0.5 to 2.5% by weight.

[0014] The present invention is based on the finding that the needs discussed above for a balanced combination of high fluidity, high rigidity and impact and high level of optical properties (low haze value) can be achieved by a process for producing a composition specific polypropylene. Thus, the present invention provides a specific process for producing a specific polypropylene composition, the process comprising the steps of: a) polymerizing in a first reactor, preferably a slurry reactor, monomers comprising propylene and, optionally , one or more comonomers selected from ethylene and C4-C10 alpha-olefins, to obtain a first propylene polymer fraction having a comonomer content in the range of 0.0 to 1.0% by weight, b) polymerize in a second reactor, preferably a gas phase reactor, monomers comprising propylene and one or more comonomers selected from ethylene and C4-C10 alpha-olefins, in the presence of the first propylene polymer fraction to obtain a second fraction of propylene polymer having comonomer content in the range of 4.5 to 20.0% by weight, c) pelletizing the second propylene polymer fraction, d) melt mixing the second pelletized propylene polymer fraction in the presence of i . a propylene polymer (PP-c) containing one or more comonomers selected from ethylene and C4-C10 alpha-olefins wherein the comonomer content is in the range of 0.5 to 2.5% by weight and ii. at least one alpha nucleating agent,

[0015] wherein the polypropylene composition has: i- an MFR2 in the range of 11.0 to 60.0 g/10min, measured in accordance with ISO 1133 at 230 °C under a load of 2.16 kg, ii - a haze value < 20%, measured according to ASTM D1003 on 1 mm thick injection molded plates produced as described in EN ISO 1873-2.

[0016] The first and second propylene polymer fractions, according to the present invention, are produced in a sequential polymerization process, in the presence of an olefin polymerization catalyst.

[0017] The term "polymerization process comprises at least two reactors connected in series. In a preferred embodiment, the term "sequential polymerization process" indicates, in the process for producing the first and second propylene polymer fractions, that the reaction mixture from the first reactor, i.e. the first propylene polymer fraction with unreacted monomers, is transported, preferably transported directly; into a second reactor where a second propylene polymer fraction is obtained.

[0018] Therefore, in the sequential polymerization process to produce the first and second propylene polymer fractions, according to the invention: iii- the first propylene polymer fraction obtained in the first reactor generally comprises a first polymer of propylene (PP-a) which is produced in said first reactor, iv- the second propylene polymer fraction obtained in the second reactor generally comprises a second propylene polymer (PP-b) which is produced in said second reactor.

[0019] Therefore, the present process comprises at least a first reactor and a second reactor. The process may comprise at least one additional polymerization reactor subsequent to the second reactor. In a specific embodiment, the process according to the invention consists of two polymerization reactors, that is, a first reactor and a second reactor. The term "polymerization reactor" should indicate that the main polymerization occurs. Thus, in the event that the process consists of two or more polymerization reactors, this definition does not exclude the option that the overall process comprises, for example, a prepolymerization step in a prepolymerization reactor. The term "consists of" is just a closing formulation in view of the main polymerization reactors. If the general process according to the invention comprises a prepolymerization reactor, the term "first propylene polymer fraction" means the sum of the (co)polymer produced in the prepolymerization reactor and the (co)polymer produced in the first reactor.

[0020] Reactors are generally selected from slurry and gas phase reactors.

[0021] The first reactor is preferably a slurry reactor and can be any batch tank reactor with simple or continuous stirring or closed circuit reactor that operates in bulk polymerization or slurry polymerization. By "bulk polymerization" is meant a process in which polymerization is conducted in a liquid monomer essentially in the absence of an inert diluent. However, it is known to one skilled in the art that the monomers used in commercial production are never pure, but always contain aliphatic hydrocarbons as impurities. For example, propylene monomer can contain up to 5% propane as an impurity. Thus, "bulk polymerization" preferably means a polymerization process in a reaction medium comprising at least 60% (w/w) of the monomer. According to the present invention, the first reactor is more preferably a closed loop reactor.

[0022] The second reactor is preferably a gas phase reactor. Said gas phase reactor may be any mechanically mixed or fluidized bed reactor or settled bed reactor. Preferably, the gas phase reactor comprises a mechanically agitated fluidized bed reactor with gas velocities of at least 0.2 m/s. The gas phase reactor of a fluidized bed type reactor may further include a mechanical stirrer to facilitate mixing in the fluidized bed.

[0023] The potentially subsequent polymerization reactor or reactors is/are preferably a gas phase reactor.

[0024] A preferred polymerization process is a "closed loop gas phase" process, developed by Borealis and known as BORSTARTM technology. Examples of this polymerization process are described in documents EP0887379, WO92/12182, WO2004/000899, WO2004/111095, WO99/24478, WO99/24479 and

[0025] When the general process according to the invention comprises a pre-polymerization reactor, said pre-polymerization step occurs before polymerization in the first reactor. The pre-polymerization step takes place in a pre-polymerization reactor in which the pre-(co)polymerization of propylene is carried out. The prepolymerization reactor is smaller in size compared to the first reactor, the second reactor and the subsequent polymerization reactor or reactors according to the invention, respectively. The reaction volume of the prepolymerization reactor can be, for example, between 0.001% and 10% of the reaction volume of the first reactor, such as the closed loop reactor. In said pre-polymerization reactor, the pre-(co)polymerization of propylene is carried out in bulk or slurry, producing a propylene (co)polymer.

[0026] The operating temperature in the prepolymerization reactor is in the range of 0 to 60 °C, preferably in the range of 15 to 50 °C, more preferably in the range of 18 to 35 °C.

[0027] The pressure in the prepolymerization reactor is not critical, but it must be high enough to maintain the reaction mixture in the liquid phase. Thus, the pressure in the prepolymerization reactor can be in the range of 20 to 100 bar, preferably in the range of 30 to 70 bar.

[0028] Hydrogen may be added to the prepolymerization reactor in order to control the molecular weight and therefore the MFR2 melt flow rate of the propylene (co)polymer produced in the prepolymerization reactor.

[0029] In the first reactor of the process according to the invention, a monomer feed composed of propylene and, optionally, one or more comonomers selected from ethylene and C4-C10 alpha-olefins are fed. If the pre-polymerization step is present in the process, the propylene (co)polymer produced in the pre-polymerization reactor is also fed into the first reactor. In the first reactor, a first propylene polymer fraction is obtained.

[0030] The first propylene polymer fraction generally has a comonomer content selected from ethylene and C4-C10 alpha-olefins in the range of 0.0 to 1.0% by weight, preferably in the range of 0.0 to 0.8% by weight, more preferably in the range of 0.0 to 0.7% by weight, relative to the total amount of monomers present in the first propylene polymer fraction.

[0031] Generally, the first propylene polymer fraction has a melt flow rate (MFR2) in the range of 11 to 60 g/10min, preferably in the range of 15 to 40 g/10min, more preferably in the range of 17 to 35g/10min. MFR2 is determined according to ISO 1133 at a temperature of 230 °C and a load of 2.16 kg.

[0032] The operating temperature in the first reactor is generally in the range of 62 to 85 °C, preferably in the range of 65 to 82 °C, more preferably in the range of 67 to 80 °C.

[0033] Typically, the pressure in the first reactor is in the range of 20 to 80 bar, preferably in the range of 30 to 70 bar, more preferably in the range of 35 to 65 bar.

[0034] Hydrogen may be added in the first reactor to control the molecular weight and thus the MFR2 melt flow rate of the first propylene polymer fraction obtained in said first reactor.

[0035] Generally, the hydrogen/propylene (H2/C3) ratio in the first reactor is in the range of 1.5 to 6.0 mol/kmol, preferably in the range of 1.6 to 5.5 mol/kmol, more preferably in the range of 1.7 to 5.0 mol/kmol.

[0036] Generally, the ratio of one or more comonomers (selected from ethylene and C4-C10 alpha-olefins) with C3 in the first reactor is less than 10.0 mol/kmol, preferably in the range of 0.0 to 8 .0 mol/kmol, more preferably in the range of 0.0 to 7.5 mol/kmol.

[0037] Generally, the reaction mixture from the first reactor is transported, preferably directly transported; in the second reactor. By "directly conveyed" is meant a process in which the reaction mixture from the first reactor is conveyed directly to the next polymerization step, i.e. the second reactor. Monomers comprising propylene and one or more comonomers selected from ethylene and C4-C10 alpha-olefins are introduced into the second reactor. In the second reactor, a second propylene polymer fraction is obtained.

[0038] The second propylene polymer fraction generally has a comonomer content selected from ethylene and C4-C10 alpha-olefins in the range of 4.5 to 20.0% by weight, preferably in the range of 4.7 to 17 .0% by weight, more preferably in the range of 4.9 to 15.0% by weight, relative to the total amount of monomers present in the second propylene polymer fraction.

[0039] Generally, the second propylene polymer fraction has a melt flow rate (MFR2) in the range of 12 to 60 g/10min, preferably in the range of 15 to 40 g/10min, more preferably in the range of 17 to 35 g/10min. MFR2 is determined according to ISO 1133 at a temperature of 230 °C and a load of 2.16 kg.

[0040] The operating temperature in the second reactor is generally in the range of 70 to 95 °C, preferably in the range of 75 to 90 °C, more preferably in the range of 78 to 88 °C.

[0041] Typically, the pressure in the second reactor is in the range of 5 to 50 bar, preferably in the range of 15 to 40 bar.

[0042] Hydrogen can be added in the second reactor in order to control the molecular weight and thus the MFR2 melt flow rate of the second propylene polymer fraction obtained in said second reactor.

[0043] Generally, the hydrogen/propylene (H2/C3) ratio in the second reactor is in the range of 15.0 to 80.0 mol/kmol, preferably in the range of 17.0 to 70.0 mol/kmol, more preferably in the range of 19.0 to 60.0 mol/kmol.

[0044] Generally, the ratio of one or more comonomers (selected from ethylene and C4-C10 alpha-olefins) with C3 in the second reactor is in the range of 45.0 to 200.0 mol/kmol, preferably in the range of 50.0 to 180.0 mol/kmol, more preferably in the range of 55.0 to 170.0 mol/kmol.

[0045] In the process according to the invention, the propylene polymer produced in the first reactor, that is, the first propylene polymer (PP-a) is generally produced in an amount in the range of 20 to 90% by weight, of preferably in an amount in the range of 25 to 85% by weight, more preferably in an amount in the range of 30 to 80% by weight.

[0046] In the process according to the invention, the propylene polymer produced in the second reactor, that is, the second propylene polymer (PP-b) is generally produced in an amount in the range of 10 to 80% by weight, preferably in an amount in the range of 15 to 75% by weight, more preferably in an amount in the range of 20 to 70% by weight. The amount of the first propylene polymer (PP-a) and the second propylene polymer (PP-b) is relative to the total sum of the first propylene polymer (PP-a) and the second propylene polymer (PP-b) comprised in the second fraction of propylene polymer.

[0047] In the process according to the invention, the one or more comonomers are selected from ethylene and C4-C10 alpha-olefins, preferably selected from ethylene and C4-C8 alpha-olefins, more preferably selected from ethylene and C4-C6 alpha-olefins, even more preferably, selected from one or more comonomers that comprise ethylene, more even more preferably the comonomer is selected from solely ethylene, through the present invention.

[0048] After polymerization in the second stage of the reactor, the second propylene polymer fraction obtained in the second reactor is recovered by conventional procedures known to those skilled in the art. The second propylene polymer fraction recovered according to the invention is generally in particulate form.

[0049] Propylene polymer (PP-c) is generally produced in a polymerization process, such as the slurry polymerization process, gas phase polymerization process or a mixture thereof, in the presence of a polymerization catalyst. olefins.

[0050] In a preferred embodiment, the propylene polymer (PP-c) is produced in a sequential polymerization process with multiple reactors. The term "sequential polymerization process" indicates that propylene polymer (PP-c) is produced in a process comprising at least two reactors connected in series. Reactors are generally selected from slurry and gas phase reactors.

[0051] A more preferred polymerization process is a "closed loop gas phase" process, developed by Borealis and known as BORSTARTM technology. Examples of this polymerization process are described in documents EP0887379, WO92/12182, WO2004/000899, WO2004/111095, WO99/24478, WO99/24479 and WO00/68315.

[0052] Generally, the olefin polymerization catalyst is a Ziegler Natta catalyst. Generally, the Ziegler Natta polymerization catalyst comprises one or more compounds of a transition metal (TM) of Group 4 to 6, as defined in the IUPAC version 2013, such as titanium, in addition to a Group 2 metallic compound, such as a magnesium compound and an internal donor (ID).

[0053] The catalyst components can be supported on a particle support, such as an inorganic oxide, such as silica or alumina. Alternatively, a magnesium halide can form the solid support. It is also possible that the catalyst components are not supported on an external support, but the catalyst is prepared by an emulsion solidification method or by a precipitation method, as is well known to those skilled in the art of catalyst preparation.

[0054] Preferably, the olefin polymerization catalyst is a specific type of Ziegler-Natta catalyst. In this specific type of Ziegler-Natta catalyst, it is essential that the internal donor is a non-phthalic compound. Preferably, throughout the specific type of Ziegler-Natta catalyst preparation, no phthalate compound is used; thus, the final specific type of Ziegler-Natta catalyst does not contain any phthalic compounds. Thus, the specific type of Ziegler-Natta catalyst is free of phthalic compounds. Therefore, the second propylene polymer fraction and the propylene polymer (PP-c), produced in the presence of the specific type of Ziegler-Natta catalyst, are free of phthalic compounds.

[0055] Generally, the specific type of Ziegler-Natta catalyst comprises an internal donor (ID) that is chosen to be a non-phthalic compound; In this way, the specific type of Ziegler-Natta catalyst is completely free of phthalic compounds. Furthermore, the specific type of Ziegler-Natta catalyst may be a solid catalyst preferably free of any external support material, such as silica or MgCl2, and thus the solid catalyst is self-supporting.

[0056] The solid catalyst can be obtained by the following general procedure: v- provide a solution of a1) at least one Group 2 alkoxy metal compound (Ax) which is the product of the reaction of a Group 2 metal compound and an alcohol (A) comprising, in addition to the hydroxyl chemical moiety, at least one ether chemical moiety, optionally in a liquid organic reaction medium; or organic liquid reaction; or a3) a mixture of the Group 2 metal alkoxy compound (Ax) and a Group 2 metal alkoxy compound (Bx) being the reaction product of a Group 2 metal compound and the monohydric alcohol (B) , optionally in a liquid organic reaction medium; or a4) Group 2 metal alkoxy compound of formula M(OR1)n(OR2)mX2-n-m or mixture of Group 2 alkoxides M(OR1)n'X2-n' and M(OR2)m'X2-m ', where m is a Group 2 metal, n-m) = 2, as long as n and m are not 0 simultaneously, 0<n'<2 and 0<m'<2; and vi- adding said solution from step a) to at least one compound of a transition metal from Groups 4 to 6 and vii- obtaining solid particles of catalyst components,

[0057] and adding a non-phthalic internal electron donor (ID) at least in one step prior to step c).

[0058] The internal donor (ID) or its precursor is preferably added to the solution from step a) or to the transition metal compound before adding the solution from step a).

[0059] According to the above procedure, the solid catalyst can be obtained by a precipitation method or by an emulsion solidification method, depending on the physical conditions, especially the temperature used in steps b) and c). An emulsion is also called a liquid-liquid two-phase system. In both methods (precipitation or emulsion solidification) the catalyst chemistry is the same.

[0060] In the precipitation method, the solution from step a) is combined with at least one transition metal compound from step b) and the entire reaction mixture is maintained at at least 50 °C, more preferably at a temperature range of 55 to 110 ° C, more preferably in the range of 70 to 100 ° C, to ensure total precipitation of the catalyst component in the form of solid particles of the catalyst component (step c).

[0061] In the emulsion solidification method, in step b) the solution from step a) is typically added to the at least one transition metal compound at a lower temperature, such as from -10 to below 50 °C, preferably from -5 to 30 °C. During stirring of the emulsion, the temperature is typically maintained at -10 to below 40°C, preferably at -5 to 30°C. Drops of the dispersed phase of the emulsion form the active composition of the catalyst. Solidification (step c) of the droplets is suitably carried out by heating the emulsion to a temperature of 70 to 150 °C, preferably 80 to 110 °C. The catalyst prepared by the emulsion solidification method is preferably used in the present invention.

[0062] In step a), preferably, the solution of a2) or a3) is used, that is, a solution of (Ax') or a solution of a mixture of (Ax) and (Bx).

[0063] Preferably, the Group 2 metal is magnesium. The magnesium alkoxy compounds (Ax), (Ax'), (Bx) can be prepared in situ in the first step of the catalyst preparation process, step a), by reacting the magnesium compound with the alcohol (or alcohols), as described above. Another option is to prepare said magnesium alkoxy compounds separately or they may be commercially available as already prepared magnesium alkoxy compounds and used as such in the catalyst preparation process of the invention.

[0064] Illustrative examples of alcohols (A) are glycol monoethers. Preferred alcohols (A) are C2 to C4 glycol monoethers, wherein the ether moieties comprise from 2 to 18 carbon atoms, preferably from 4 to 12 carbon atoms. Preferred examples are 2-(2-ethylhexyloxy) ethanol, 2-butyloxy ethanol, 2-hexyloxy ethanol and 1,3-propylene glycol monobutyl ether, 3-butoxy-2-propanol, with 2-(2-ethyl -hexyloxy) ethanol and 1,3-propylene glycol-monobutyl ether, with 3-butoxy-2-propanol being particularly preferred.

[0065] The illustrative monohydric alcohol (B) is represented by the structural formula ROH in which R is a straight or branched chain C2-C16 alkyl residue, preferably a C4 to C10 alkyl residue, more preferably a C6 residue the C8 alkyl. The most preferred monohydric alcohol is 2-ethyl-1-hexanol or octanol.

[0066] Preferably, a mixture of Mg alkoxy compounds (Ax) and (Bx) or a mixture of alcohols (A) and (B), respectively, are used and employed in a molar ratio of Bx:Ax or B:A from 10:1 to 1:10, more preferably 6:1 to 1:6, even more preferably 5:1 to 1:3, more preferably 5:1 to 3:1.

[0067] The alkoxy magnesium compound may be a reaction product of alcohol (or alcohols), as defined above, and a magnesium compound selected from dialkyl magnesium, alkyl magnesium alkoxide, magnesium dialkoxide, alkoxy magnesium halide and alkyl magnesium halide. In addition, magnesium dialkoxide, magnesium diaryloxide, magnesium aryloxyhalide, magnesium aryloxide and alkyl magnesium aryloxide can be used. Alkyl groups in the magnesium compound can be similar or different C1-C20 alkyl groups, preferably C2-C10 alkyl groups. Typical alkyl-alkoxy magnesium compounds, when used, are Petition 870200054251, dated 04/30/2020, p. 38/79 ethyl magnesium, butyl magnesium pentoxide, octyl magnesium butoxide and octyl magnesium octoxide. Preferably, dialkyl magnesium are used. More preferred, dialkyl magnesium are butyl octyl magnesium or butyl ethyl magnesium.

[0068] It is also possible for the magnesium compound to react in addition to alcohol (A) and alcohol (B) with a polyhydric alcohol (C) of formula R''(OH)m to obtain said magnesium alkoxide compound. Preferred polyhydric alcohols, if used, are alcohols, wherein R'' is a straight, cyclic or branched chain C2 to C10 hydrocarbon residue and m is an integer from 2 to 6.

[0069] The alkoxy magnesium compounds of step a) are thus selected from the group consisting of magnesium dialkoxides, diaryloxy magnesium, alkylaxy magnesium halides, aryloxy magnesium halides, alkyl magnesium alkoxides, aryl magnesium alkoxides and aryl alkyl oxides magnesium or a mixture of magnesium dihalide and magnesium dioxide.

[0070] The solvent to be used for the preparation of the present catalyst can be selected from linear, branched and cyclic chain aromatic and aliphatic hydrocarbons with 5 to 20 carbon atoms, more preferably 5 to 12 carbon atoms or mixtures thereof. Suitable solvents include benzene, toluene, cumene, xylene, pentane, hexane, heptane, octane and nonane. Hexanes and pentanes are particularly preferred.

[0071] The reaction for the preparation of the magnesium alkoxy compound can be carried out at a temperature of 40 to 70 °C. One skilled in the art knows how to select the most appropriate temperature depending on the Mg compound and the alcohol (or alcohols) used.

[0072] The transition metal compound (TM) of Groups 4 to 6, as defined in IUPAC version 2013, is preferably a titanium compound, more preferably a titanium halide, such as TiCl4.

[0073] The internal non-phthalic donor (ID) used in the preparation of the particular type of Ziegler-Natta catalyst used in the present invention is preferably selected from non-phthalic (di)carboxylic acid (di)esters, 1,3-diethers , derivatives and mixtures thereof. An especially preferred donor is a diester of monounsaturated non-phthalic dicarboxylic acids, in particular an ester belonging to a group comprising malonate, maleates, succinates, citraconates, glutarates, cyclohexene-1,2-dicarboxylates and benzoates and derivatives and/or mixtures thereof. Preferred examples are, for example, substituted maleates and citraconates, more preferably citraconates.

[0074] Here and below, the term derivative includes substituted compounds.

[0075] In the emulsion solidification method, the two-phase liquid-liquid system can be formed by simple stirring and, optionally, adding (further) solvent (or solvents) and/or additives, such as a turbulence minimizing agent (TMA). ) and/or an emulsifying agent and/or an emulsion stabilizer, such as a surfactant, which are used in a manner known in the art. These solvents and/or additives are used to facilitate the formation of the emulsion and/or stabilize it. Preferably, the surfactants are acrylic or methacrylic polymers. Particularly preferred are unbranched C12 to C20 (meth)acrylates, such as for example poly(hexadecyl) methacrylate and poly(octadecyl) methacrylate and mixtures thereof. The turbulence minimizing agent (TMA), if used, is preferably selected from polymers of α-olefin monomers having 6 to 20 carbon atoms, such as polyoctene, polynonene, polydecene, polyundecene or polydodecene or mixtures thereof. The most preferable is polydecene.

[0076] The solid particulate product obtained by the precipitation or emulsion solidification method can be washed at least once, preferably at least twice, more preferably at least three times. Washing can occur with an aromatic and/or aliphatic hydrocarbon, preferably with toluene, heptane or pentane. It is also possible to wash with TiCl4 optionally combined with aromatic and/or aliphatic hydrocarbon. Wash liquids may also contain donors and/or Group 13 compounds, such as trialkyl aluminum, halogenated alkylated aluminum compounds, or alkoxyaluminum compounds. Aluminum compounds can also be added during catalyst synthesis. The catalyst may further be dried, for example, by evaporation or nitrogen washing, or it may be mixed with an oily liquid without any drying step.

[0077] The finally obtained specific type of Ziegler-Natta catalyst is desirably obtained in the form of particles with generally an average particle size range of 5 to 200 μm, preferably 10 to 100 μm. The particles are generally compact with low porosity and generally have a surface area of less than 20 g/m2, more preferably less than 10 g/m2. Typically, the amount of Ti present in the catalyst is in the range of 1 to 6 wt%, the amount of Mg is in the range of 10 to 20 wt%, and the amount of internal donor present in the catalyst is in the range of 10 to 40 % by weight of the catalyst composition. A detailed description of the preparation of the catalysts used in the present invention is disclosed in documents WO2012/007430, EP2610271 and EP2610272.

[0078] An external donor (ED) is preferably present as an additional component in the polymerization processes according to the invention. Suitable external donors (DE) include certain silanes, ethers, esters, amines, ketones, heterocyclic compounds and mixtures thereof. It is especially preferred to use a silane. It is more preferred to use silanes of the general formula (I) RapRbqSi(ORc)(4-p-q) (I)

[0079] wherein Ra, Rb and Rc denote a hydrocarbon radical, in particular an alkyl or cycloalkyl group, and wherein p and q are numbers ranging from 0 to 3 with their sum (p+q) being equal to or less than three . Ra, Rb and Rc can be chosen independently of each other and can be the same or different. Specific examples of silanes according to formula (I) are (tert-butyl)2Si(OCH3)2, (cyclohexyl)(methyl)Si(OCH3)2, (phenyl)2Si(OCH3)2 and (cyclopentyl) 2Si(OCH3)2. Another more preferred silane is according to the general formula (II) Si(OCH2CH3)3(NR3R4) (II)

[0080] wherein R3 and R4 can be the same or different and represent a linear, branched or cyclic hydrocarbon group that has 1 to 12 carbon atoms. It is in particular preferred that R3 and R4 are independently selected from the group consisting of methyl, ethyl, n-propyl, n-butyl, octyl, decanyl, iso-propyl, iso-butyl, iso-pentyl, tert-butyl, tert-amyl, neopentyl, cyclopentyl, cyclohexyl, methylcyclopentyl and cycloheptyl. More preferably, ethyl is used.

[0081] Generally, in addition to the Ziegler-Natta catalyst or the specific type of Ziegler-Natta catalyst and the optional external donor (ED), a cocatalyst (Co) may be present in the polymerization processes according to the invention. The cocatalyst is preferably a compound from group 13 of the periodic table (IUPAC, version 2013), such as an aluminum compound, for example, an organoaluminum compound or aluminum halide. An example of a suitable organoaluminum compound is an alkyl aluminum or alkyl aluminum halide compound. Therefore, in a specific embodiment, the cocatalyst (Co) is a trialkylaluminum, such as triethylaluminum (TEAL), dialkyl aluminum chloride or alkyl aluminum dichloride or mixtures thereof. In a specific embodiment, the cocatalyst (Co) is triethyl aluminum (TEAL).

[0082] Generally, the molar ratio between the cocatalyst (Co) and the external donor (ED) [Co/ED] and/or the molar ratio between the cocatalyst (Co) and the transition metal (TM) [Co/TM ] is carefully chosen for each process. The molar ratio between the cocatalyst (Co) and the external donor (ED), [Co/ED] may suitably be in the range of 2.5 to 50.0 mol/mol, preferably in the range of 4.0 to 35.0 mol/mol, more preferably in the range of 5.0 to 30.0 mol/mol. A suitable lower limit may be 2.5 mol/mol, preferably 4.0 mol/mol, more preferably 5.0 mol/mol. A suitable upper limit may be 50.0 mol/mol, preferably 35.0 mol/mol, more preferably 30.0 mol/mol. The indicated lower and upper range values are included.

[0083] The molar ratio between the cocatalyst (Co) and the transition metal (TM), [Co/TM] can suitably be in the range of 20.0 to 500.0 mol/mol, preferably in the range of 50.0 to 400.0 mol/mol, more preferably in the range of 100.0 to 300.0 mol/mol. A suitable lower limit may be 20.0 mol/mol, preferably 50.0 mol/mol, more preferably 100.0 mol/mol. A suitable upper limit may be 500.0 mol/mol, preferably 400.0 mol/mol, more preferably 300.0 mol/mol. The indicated lower and upper range values are included.

[0084] According to the present invention, the second propylene polymer fraction recovered from the polymerization process is generally mixed by melting, in the presence of additives.

[0085] Examples of additives include, but are not limited to, stabilizers such as antioxidants (e.g., sterically hindered phenols, phosphites/phosphonites, sulfur-containing antioxidants, alkyl radical scavengers, aromatic amines, hindered amine stabilizers or mixtures thereof), deactivators of metals (e.g. Irganox® MD 1024) or UV stabilizers (e.g. hindered amine light stabilizers). Other typical additives are modifiers such as antistatic or antifogging agents (e.g. ethoxylated amines and amides or glycerol esters), acid scavengers (e.g. Ca stearate), blowing agents, tackifiers (e.g. polyisobutene), lubricants and resins (e.g. ionomer waxes, polyethylene and ethylene copolymer waxes, Fischer Tropsch waxes, montane-based waxes, fluorine- or paraffin-based compounds) as well as anti-slip and anti-blocking agents (e.g. erucamide, oleamide , talc, natural silica and synthetic silica or zeolites) and mixtures thereof.

[0086] After the melt mixing step, the second propylene polymer fraction resulting from the melt mixing is pelletized, for example, in an underwater pelletizer or after solidifying one or more strands in a water bath, in a pelletizer of wires.

[0087] According to the present invention, the second pelletized fraction of the propylene polymer is melt-mixed in the presence of i. a propylene polymer (PP-c) containing one or more comonomers selected from ethylene and C4-C10 alpha-olefins wherein the comonomer content is in the range of 0.5 to 2.5% by weight and ii. at least one alpha nucleating agent, to produce the inventive polypropylene composition.

[0088] The propylene polymer (PP-c) according to the invention is generally a propylene copolymer.

[0089] The propylene polymer (PP-c) generally contains one or more comonomers selected from ethylene and C4-C10 alpha-olefins, preferably selected from ethylene and C4-C8 alpha-olefins, more preferably selected from of ethylene and C4-C6 alpha-olefins, even more preferably, selected from one or more comonomers comprising ethylene, more even more preferably the comonomer is selected from solely ethylene.

[0090] The propylene polymer (PP-c) according to the invention generally has a comonomer content in the range of 0.5 to 2.5% by weight, preferably in the range of 0.6 to 2.0% by weight. weight, more preferably in the range of 0.7 to 1.8% by weight, in relation to the total amount of monomers present in the propylene polymer. Petition 870200054251, dated 04/30/2020, p. 47/79

[0091] Generally, propylene polymer (PP-c) has a melt flow rate (MFR2) in the range of 11 to 60 g/10min, preferably in the range of 15 to 40 g/10min, more preferably in the range from 17 to 35 g/10 min. MFR2 is determined according to ISO 1133 at a temperature of 230 °C and a load of 2.16 kg.

[0092] The alpha nucleating agent is generally selected from the group consisting of: (i) salts of monocarboxylic acids and polycarboxylic acids, e.g. sodium benzoate or aluminum tert-butylbenzoate, (ii) dibenzylidene sorbitol (e.g. , 1.3:2.4 dibenzylidene sorbitol) and C1-Cθ -alkyl substituted dibenzylidene sorbitol derivatives such as methyldibenzylidene sorbitol, ethyldibenzylidene sorbitol or dimethyldibenzylidene sorbitol (e.g. 1.3:2.4 di(methylbenzylidene) sorbitol) or nonitol derivatives substituted, such as 1,2,3,-trideoxy-4,6:5,7-bis-O-[(4-propylphenyl)methylene]-nonitol, (iii) salts of phosphoric acid diesters, e.g. sodium 2,2'-methylenebis(4,6-di-tert-butylphenyl) or aluminum-hydroxy-bis[2,2'-methylene-bis(4,6-di-t-butylphenyl)phosphate], (v) mixtures thereof.

[0093] Preferably, the alpha nucleating agent is a dibenzylidene sorbitol (e.g., 1.3:2.4 dibenzylidene sorbitol) or a C1-C8-alkyl substituted dibenzylidene sorbitol derivative, such as methyldibenzylidene sorbitol, ethyl dibenzylidene sorbitol or dimethyl dibenzylidene sorbitol (e.g. 1,3:2,4 di(methylbenzylidene)sorbitol) or a substituted nonitol derivative, such as 1,2,3,-trideoxy-4,6:5,7-bis-O-[(4-propylphenyl)methylene ]-nonitol.

[0094] According to the present invention, generally, 15 to 84% by weight of the second pelletized propylene polymer fraction is melt mixed in the presence of 15 to 84% by weight of the propylene polymer (PP-c) and 0 .01 to 1.0% by weight of the at least one alpha nucleating agent, based on the total sum of the second pelletized fraction of propylene polymer, the propylene polymer (PP-c) and the at least one nucleating agent.

[0095] Preferably, 18 to 79.1% by weight of the second pelletized fraction of propylene polymer is melt mixed in the presence of 20 to 81.1% by weight of propylene polymer (PP-c) and 0.03 to 0.90% by weight of the at least one alpha nucleating agent, based on the sum total of the second propylene polymer pelletized fraction, the propylene polymer (PP-c) and at least one alpha nucleating agent.

[0096] More preferably, 20 to 74.2% by weight of the second pelletized fraction of propylene polymer is melt mixed in the presence of 25 to 79.2% by weight of propylene polymer (PP-c) and 0.05 to 0.80% by weight of at least one alpha nucleating agent, based on the sum total of the second pelletized propylene polymer fraction, the propylene polymer (PP-c) and at least one alpha nucleating agent.

[0097] Melt mixing of the second pelletized propylene polymer fraction with the propylene polymer (PP-c) and the at least one alpha nucleating agent is generally carried out in a melt mixing device, such as a extruder or a co-rotating type kneader. The melt mixing device may include a feeding zone, a kneading zone and a die zone.

[0098] Generally, a specific temperature profile is maintained along the screw of the melt mixing device.

[0099] The melt mixing of the pelletized propylene polymer with the second propylene polymer (PP-C) and at least one alpha nucleating agent is preferably carried out in an extruder.

[00100] The extruder can be any extruder known in the art. The extruder may thus be a single screw extruder; a twin screw extruder, such as a co-rotating type twin screw extruder or a counter rotating twin screw extruder; or a multi-screw extruder such as a ring extruder. Preferably, the extruder is a single screw extruder or a twin screw extruder. The especially preferred extruder is a co-rotating type twin screw extruder.

[00101] The extruder typically comprises a feeding zone, a melting zone, a mixing zone and a die zone. The extruder, as one skilled in the art knows, is typically composed of barrels which are comprised in the above-mentioned zones of the extruder.

[00102] The extruder typically has a length to diameter ratio, L/D, of up to 60:1, preferably up to 40:1.

FOOD AREA

[00103] The second pelletized propylene polymer fraction, the propylene polymer (PP-c) and at least one alpha nucleating agent are generally introduced into the extruder through a feed zone. The feed zone directs the mixture of the second pelletized propylene polymer fraction, the propylene polymer (PP-c) and at least one alpha nucleating agent to the melting zone. Typically, the feeding zone is formed by a feeding hopper and a connecting tube that connects the hopper to the melting zone. Typically, the second pelletized propylene polymer fraction, the propylene polymer (PP-C) and at least one alpha nucleating agent flows through the feed zone under the action of gravity, that is, generally downwards.

[00104] In a preferred embodiment, at least one alpha nucleating agent is completely introduced or partially introduced through one or more feed holes comprised in the extruder, for example, through a side feeder.

FUSION ZONE

[00105] Generally, the mixture of the second pelletized fraction of the propylene polymer, the propylene polymer (PP-c) and at least one alpha nucleating agent passes from the feed zone to a melt zone. In the fusion zone, the mixture melts.

MIXING ZONE

[00106] After the melting zone, the molten mixture passes to a mixing zone. The screw in the mixing zone typically comprises one or more mixing sections comprising screw elements that provide a certain degree of backward flow.

[00107] The mixing zone may comprise additional elements, such as a butterfly valve or a gear pump.

MATRIX ZONE

[00108] The matrix zone normally comprises a matrix. No limitations are imposed on the design of the die used in the extruder.

[00109] In the process according to the invention the second pelletized fraction of propylene polymer, the propylene polymer (PP-c) and at least one alpha nucleating agent are generally melted at a temperature in the range of 190 to 260 ° C , preferably in the range of 200 to 250 °C.

[00110] One skilled in the art is well familiar with the screw speed in the extruder and can easily determine the appropriate screw speed. Generally, the screw speed is adjusted to a range of 100 to 750 revolutions per minute (rpm), preferably to a range of 150 to 650 revolutions per minute (rpm).

[00111] The extruder may also have one or more feed ports for introducing other components, such as other polymers or additives, into the extruder. The location of these additional feed ports depends on the type of material added through the port.

[00112] Examples of additives include, but are not limited to, stabilizers such as antioxidants (e.g., sterically hindered phenols, phosphites/phosphonites, sulfur-containing antioxidants, alkyl radical scavengers, aromatic amines, hindered amine stabilizers or mixtures thereof), metal deactivators (e.g. Irganox® MD 1024) or UV stabilizers (e.g. hindered amine light stabilizers). Other typical additives are modifiers such as antistatic or antifogging agents (e.g. ethoxylated amines and amides or glycerol esters), acid scavengers (e.g. Ca stearate), blowing agents, tackifiers (e.g. polyisobutene), lubricants and resins (e.g. ionomer waxes, polyethylene and ethylene copolymer waxes, Fischer Tropsch waxes, montane-based waxes, fluorine- or paraffin-based compounds) as well as anti-slip and anti-blocking agents (e.g. erucamide, oleamide , talc, natural silica and synthetic silica or zeolites) and mixtures thereof.

[00113] Generally, the total amount of additives introduced into the extruder during the second pelletized fraction of the propylene polymer, the propylene polymer (PP-c) and at least one alpha nucleating agent, according to the present invention, is not more than 5.0% by weight, preferably not more than 2.0% by weight, more preferably not more than 1.5% by weight. The amount of additives is relative to the total amount of polypropylene composition introduced into the extruder.

[00114] At the end of the extruder, a molten polypropylene composition is obtained. The inventive melt polypropylene composition may then be passed through a die in the optional mold zone of the extruder. When the inventive molten polypropylene composition is passed through the die, it is generally further cooled and pelletized.

[00115] The matrix zone typically comprises a matrix plate, which is generally a thick metal disk with multiple holes. The holes are parallel to the screw axis.

[00116] The granulator is generally a wire granulator or an underwater granulator.

[00117] The invention also provides a polypropylene composition obtained, preferably obtained, by the process according to the invention.

[00118] The polypropylene composition that can be obtained, preferably obtained, by the process according to the invention generally has one or more comonomers selected from ethylene and C4-C10 alpha-olefins, preferably selected from ethylene and C4-C8 alpha-olefins, more preferably selected from ethylene, and C4-C6 alpha-olefins, even more preferably, selected from one or more comonomers comprising ethylene, more even more preferably the comonomer is selected from solely of ethylene.

[00119] The obtainable polypropylene composition, preferably obtained by the process according to the invention, generally has a comonomer content in the range of 1.5 to 5.0% by weight, preferably in the range of 1.6 to 4.0 % by weight, more preferably in the range of 1.7 to 3.5 mol%. The comonomer content is relative to the total amount of monomers present in the polypropylene composition.

[00120] Generally, the polypropylene composition that can be obtained, preferably obtained, by the process according to the invention, has a melt flow rate (MFR2) in the range of 12 to 60 g/10min, preferably in the range of 15 to 40 g/10min, more preferably in the range of 17 to 35 g/10min. MFR2 is determined according to ISO 1133 at a temperature of 230 °C and a load of 2.16 kg.

[00121] Generally, the polypropylene composition that can be obtained, preferably obtained, by the process according to the invention has a haze value < 20%, preferably from 2% to 18%, more preferably from 3% to 17% . The haze value is measured according to ASTM D1003 on 1 mm thick injection molded plates produced as described in EN ISO 1873-2.

[00122] Generally, the polypropylene composition obtainable, preferably obtained, by the process according to the invention has a melting temperature > 152 °C, preferably in the range of 153 to 163 °C, more preferably in the range of 154 to 162 °C, even more preferably in the range of 154 to 160 °C. The melting temperature (Tm) is measured by DSC in accordance with ISO 11357/3.

[00123] Generally, the polypropylene composition obtained, preferably obtained by the process according to the invention, has a crystallization temperature > 120 °C, preferably in the range of 122 to 132 °C, more preferably in the range of 123 to 130°C. The melting temperature (Tc) is measured by DSC in accordance with ISO 11357/3.

[00124] Generally, the polypropylene composition that can be obtained, preferably obtained, by the process according to the invention has a xylene soluble content (XCS) in the range of 5.5 to 18.0% by weight, preferably in the range range of 6.0 to 16.0% by weight, more preferably in the range of 6.2 to 15.0% by weight. The xylene-soluble fraction is determined according to ISO 16152 at 25 °C.

[00125] Generally, the polypropylene composition obtained, preferably obtained by the process according to the invention, has a tensile modulus > 950 MPa, preferably in the range of 951 to 1600 MPa, more preferably in the range of 1000 to 1600 MPa, furthermore more preferably in the range of 1050 to 1550 MPa. Tensile modulus is measured in accordance with ISO 527-1:2012/ISO 527-2:2012 at 23°C on injection molded test specimens.

[00126] Generally, the polypropylene composition obtained, preferably obtained by the process according to the invention, has a Charpy notched impact resistance > 4.8 kJ/m2, preferably in the range of 4.9 to 20.0 kJ /m2, more preferably in the range of 5.0 to 15.0 kJ/m2, even more preferably in the range of 5.0 to 13.0 kJ/m2, even more preferably, in the range of 7.0 to 13 kJ /m2. Charpy notched impact strength is measured in accordance with ISO 179/1eA at 23°C on injection molded test specimens as described in EN ISO 1873-2.

[00127] The present invention also provides an article comprising the polypropylene composition obtained, preferably obtained, by the process according to the invention. Suitable articles are films, such as cast films and injection molded articles. A preferred article is a closure lid, a screw cap or a closure system for food or liquid packaging.

[00128] Finally, the present invention relates to the use of the polypropylene composition obtained, preferably obtained by the process according to the invention, in the preparation of a cast film or an injection molded article, preferably a closing lid, a screw cap or closure system for packaging food or liquids. A fluid is commonly defined as a substance that continuously deforms (flows) under an applied shear stress.

EXAMPLES I. MEASUREMENT METHODS A) FLUIDITY INDEX

[00129] The melt flow rate (MFR) is determined in accordance with the ISO 1133 standard and is indicated in g/10min. The MFR is an indication of the fluidity and therefore the processability of the polymer. The higher the melt flow rate, the lower the viscosity of the polymer. The MFR2 of polypropylene is determined at a temperature of 230 °C and a load of 2.16 kg. B) DSC ANALYSIS

[00130] The melting temperature and the crystallization and melting temperature were obtained in a heat/cold/heat cycle with a scan rate of 10 °C/min between 30 °C and 225 °C. The crystallization and melting temperatures were taken as the peaks of the endotherms and exotherms in the cooling stage and the second heating stage, respectively. C) SOLUBLE CONTENT IN XYLENE (XCS, % BY WEIGHT)

[00131] The content of the xylene-soluble polymer is determined in accordance with standard SO 16152; 5th edition; 01/07/2005 at 25 °C. D) TRACTION MODULE

[00132] The tensile modulus is measured in accordance with ISO 527-1:2012/ISO527-2:2012 at 23 °C and at a transverse head speed = 50 mm/min; using injection molded test specimens as described in EN ISO 18732 (dog bone shape, 4 mm thick). E) CHARPY NOTCHED IMPACT

[00133] Charpy notched impact resistance is determined in accordance with ISO 179/1eA at 23 °C on injection molded test specimens as described in EN ISO 1873-2 (80 x 10 x 4 mm). F) MIST

[00134] Haze is determined in accordance with ASTM D1003 on injection molded plates 1 mm thick and 60x60 mm² in area produced as described in EN ISO 1873-2. G) COMMONOMER CONTENT

POLY(PROPYLENE-CO-ETHYLENE) - ETHYLENE CONTENT BY IR SPECTROSCOPY

[00135] Quantitative infrared (IR) spectroscopy was used to quantify the ethylene content of poly(ethylene-co-propene) copolymers through calibration to a primary method.

[00136] Calibration was facilitated by the use of a set of in-house non-commercial calibration standards, with known ethylene contents, determined by quantitative nuclear magnetic resonance (NMR) spectroscopy in the solution state 13C in the solution state. The calibration procedure was performed in the conventional manner, well documented in the literature. The calibration set consisted of 38 calibration standards with ethylene content ranging from 0.2 to 75.0% by weight produced at pilot scale or full scale under a variety of conditions. The calibration set was selected to reflect the typical range of copolymers encountered by the final quantitative IR spectroscopy method.

[00137] Quantitative IR spectra were recorded in the solid state using a Bruker Vertex 70 FTIR spectrometer. Spectra were recorded on 25x25 mm square films of 300 um thickness, prepared by compression molding at 180 to 210 °C and 4 to 6 mPa. For samples with very high ethylene content (>50 mol%), 100 μm thick films were used. Standard transmission FTIR spectroscopy was employed using a spectral range of 5000 to 500 cm-1, an aperture of 6 mm, a spectral resolution of 2 cm-1, 16 background scans, 16 spectrum scans, a zero fill factor of the interferogram of 64 and Blackmann-Harris apodization in 3 terms.

[00138] The quantitative analysis was carried out using the total area of CH2 balance deformations at 730 and 720 cm-1 (AQ) corresponding to (CH2)>2 structural units (integration method G, limits 762 and 694 cm-1 ). The quantitative band was normalized to the CH band area at 4323 cm-1 (AR) corresponding to structural units (G integration method, limits 4650, 4007 cm-1). The ethylene content in weight percent units was then predicted from the normalized absorption (AQ/AR) using a quadratic calibration curve. The calibration curve was previously constructed by ordinary least squares (OLS) regression of the normalized absorptions and primary comonomer content measured in the calibration set. POLY(PROPYLENE-CO-ETHYLENE) - ETHYLENE CONTENT FOR CALIBRATION USING 13C NMR SPECTROSCOPY

[00139] Quantitative 13C{1H} NMR spectra were recorded in the solution state using a Bruker Avance III 400 operational NMR spectrometer, 400.15 and 100.62 MHz for 1H and 13C, respectively. All spectra were recorded using a 10mm extended temperature probe head optimized for 13C to 125°C using nitrogen gas for all tires. Approximately 200 mg of material was dissolved in 3 ml of 1,2-tetrachloroethane-d2 (TCE-d2) together with chromium (III) acetylacetonate (Cr(acac)3), resulting in a 65 mM solution of relaxing agent in solvent (Singh, G., Kothari, A., Gupta, V., Polymer Testing 28 5 (2009), 475). To ensure a homogeneous solution, after initial sample preparation on a heat block, the NMR tube was further heated in a rotary oven for at least 1 hour. After insertion into the magnet, the tube was rotated at 10 Hz. This configuration was chosen primarily for high resolution and is quantitatively necessary for accurate quantification of ethylene content. Standard single-pulse excitation was employed without NOE, using an optimized tip angle, 1 s recycling delay, and a two-level 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). A total of 6144 (6k) transients were acquired per spectrum. Quantitative 13C{1H} NMR spectra were processed, integrated and relevant quantitative properties determined from the integrals. All chemical shifts were indirectly referenced to the central methylene group of the ethylene block (EEE) at 30.00 ppm using the solvent chemical shift. This approach allowed comparable references even when this structural unit was not present. Characteristic signals corresponding to ethylene incorporation were observed (Cheng, HN, Macromolecules 17 (1984), 1950) and the comonomer fraction calculated as the fraction of ethylene in the polymer relative to all monomers in the polymer: fE = (E/( P+E) The comonomer fraction was quantified by the method of Wang et al. (Wang, WJ., Zhu, S., Macromolecules 33 (2000), 1157) by integrating multiple signals over the entire spectral region of the 13C{1H} spectra. This method was chosen for its robust nature and ability to account for the presence of region defects when necessary. The integral regions have been slightly adjusted to increase applicability across the full range of comonomer content encountered. For systems With very low ethylene content, where only isolated ethylene in the PPEPP sequences was observed, Wang et. al.'s method was modified by reducing the influence of integration of sites that are no longer present. This approach reduced the overestimation of ethylene content of such systems and was achieved by reducing the number of sites used to determine the absolute ethylene content to E = 0.5(Sββ + SβY + Sβδ + 0.5(Sαβ + Say)) through the use of this set of sites from corresponding integral equation becomes E = 0.5(IH +IG + 0.5(IC + ID)) using the same notation used in the paper by Wang et. al. (Wang, W-J., Zhu, S., Macromolecules 33 (2000), 1157). The equations used for the absolute propylene content were not modified. The mol percent incorporation of comonomer was calculated from the mole fraction: E [mol%] = 100 * fE. The percent weight percentage of comonomer incorporation was calculated from the mole fraction: E [wt%] = 100 * (fE * 28.06)/((fE * 28.06) + ((1-fE) * 42.08)).

II. INVENTIVE AND COMPARATIVE EXAMPLES A) CATALYST PREPARATION

[00140] To prepare the catalyst, 3.4 liters of 2-ethylhexanol and 810 ml of glycolbutyl propylene monoether (in molar ratio 4/1) were added to a 20.0 l reactor. Then, 7.8 liters of a 20.0% toluene solution of BEM (butyl ethyl magnesium) supplied by Crompton GmbH, was slowly added to the well-stirred alcohol mixture. During the addition, the temperature was maintained at 10.0 °C. After addition, the temperature of the reaction mixture was increased to 60.0 °C and mixing was continued at this temperature for 30 minutes. Finally, after cooling to room temperature, the obtained Mg alkoxide was transferred to a storage container.

[00141] 21.2 g of Mg alkoxide prepared above were mixed with 4.0 ml of bis(2-ethylhexyl) citraconate for 5 min. After mixing, the Mg complex obtained was immediately used to prepare the catalyst component.

[00142] 19.5 ml of titanium tetrachloride was placed in a 300 ml reactor equipped with a mechanical stirrer at 25.0 °C. The mixing speed was adjusted to 170 rpm. 26.0 g of the Mg complex prepared above was added within 30 minutes, maintaining the temperature at 25.0 °C. 3.0 ml of Viscoplex® 1-254 and 1.0 ml of a toluene solution with 2 mg of Necadd 447™ were added. Then, 24.0 ml of heptane were added to form an emulsion. Mixing was continued for 30 minutes at 25.0 °C, after which the reactor temperature was increased to 90.0 °C in 30 minutes. The reaction mixture was stirred for another 30 minutes at 90.0 °C. Then stirring was stopped and the reaction mixture was allowed to stand for 15 minutes at 90.0 °C. The solid material was washed 5 times: washings were carried out at 80.0 °C under agitation for 30 min at 170 rpm. After stirring was stopped, the reaction mixture was allowed to stand for 20 to 30 minutes and followed by siphoning.

[00143] Wash 1: washing was done with a mixture of 100 ml of toluene and 1 ml of donor.

[00144] Wash 2: washing was done with a mixture of 30

[00145] ml of TiCl4 and 1 ml Wash 3: from donor to wash. was made with 100 ml of toluene

[00146] . Wash 4: washing was done with 60 ml of heptane

[00147] . Wash 5: washing was done with 60 ml of heptane

[00148] under 10 minutes of Then stirring. stirring was stopped and the reaction mixture was left to stand for 10 minutes, while decreasing the temperature to 70 °C with subsequent siphoning, followed by N2 bubbling for 20 minutes, to obtain an air-sensitive powder. B) INVENTIVE EXAMPLES (IE1, IE2 AND IE3)

[00149] The second propylene polymer fraction, as well as the propylene polymer (PP-c) in relation to the inventive examples (IE1, IE2 and IE3) were produced in a pilot installation with a prepolymerization reactor, a reactor closed circuit slurry system and a gas phase reactor. The solid catalyst component described above, together with triethyl aluminum (TEAL) as cocatalyst and dicyclopentyl dimethoxy silane (D-donor) as external donor, were used in the preparation of the second propylene polymer fraction and the propylene polymer (PP -c), respectively.

[00150] The conditions of the polymerization process and the properties of the second propylene polymer fraction and the propylene polymer (PP-c) are described in Table 1.

[00151] The inventive polypropylene compositions were prepared by extruding the respective amount of second propylene polymer fraction, propylene polymer (PP-c) and nucleating agent in a Coperion ZSK 40 co-rotating twin-screw extruder (diameter of screw 40 mm, L/D ratio 38). The temperatures in the extruder were in the range of 190 to 230 °C. In each of the examples of the invention 0.05% by weight of Irganox 1010 (pentaerythrityl-tetracys(3-(3',5'-di-tert.butyl-4-hydroxyphenyl)-propionate, CAS number 6683-19-8 , commercially available from BASF AG, Germany), 0.05% by weight of (Tris(2,4-di-t-butylphenyl) Irgafos 168, CAS number 31570-04-4, commercially available from BASF AG , Germany), 0.10% by weight Calcium Stearate (CAS. 159223-0, commercially available under the trade name Ceasit FI from Baerlocher GmbH, Germany) and 0.06% by weight glycerol monostearate (CAS No. . 97593-29-8, commercially available with 90% purity under the trade name Grindsted PS 426 from Danisco A/S, Denmark) were added to the extruder as additives. Petition 870200054251, dated 04/30/2020, page 68 /79

[00152] After the extrusion step and after solidifying the yarns in a water bath, the resulting polypropylene composition was sedimented in a yarn sedimenter.

[00153] The properties of the polypropylene composition are described in Table 2. C) COMPARATIVE EXAMPLES (CE1 AND CE2)

[00154] CE-1 is a random copolymer of C2 propylene with an MFR2 of 13.0 g/10min, produced in a reactor process and distributed by Borealis under the trade name RE420MO.

[00155] CE-2 is a random copolymer of C2 propylene with an MFR2 of 20.0 g/10min, produced in a reactor process and distributed by Borealis under the trade name RF365MO. TABLE 1. PREPARATION AND PROPERTIES OF THE SECOND FRACTION OF PROPYLENE POLYMER AND PROPYLENE POLYMER (PP-C). *Division refers to the amount of propylene polymer produced in each specific reactor. TABLE 2. CONDITIONS OF THE EXTRUSION PROCESS AND THE PROPERTIES OF THE POLYPROPYLENE COMPOSITION. I *measured in pellets obtained after the extrusion process.

[00156] From Table 2, it can be derived that the polypropylene compositions (inventive examples) show an improved balanced combination of high fluidity, high rigidity and impact and high level of optical properties (low haze value), compared to the comparative examples.

Claims (14)

1. Process for producing a polypropylene composition by sequential polymerization characterized by the fact that it comprises the steps: a) polymerizing in a first reactor, preferably a slurry reactor, monomers comprising propylene and, optionally, one or more comonomers selected from ethylene and C4-C10 alpha-olefins, to obtain a first propylene polymer fraction having a comonomer content in the range of 0.0 to 1.0% by weight, b) polymerize in a second reactor , preferably a gas phase reactor, monomers comprising propylene and one or more comonomers selected from ethylene and C4-C10 alpha-olefins, in the presence of the first propylene polymer fraction to obtain a second propylene polymer fraction having comonomer content in the range of 4.5 to 20.0% by weight, c) pelletizing the second propylene polymer fraction, d) melt mixing the second pelletized propylene polymer fraction in the presence of starting ethylene and C4- C10 alpha-olefins in which the comonomer content is in the range of 0.5 to 2.5% by weight and II. at least one alpha nucleating agent, wherein the polypropylene composition has: i- an MFR2 in the range of 11.0 to 60.0 g/10min, measured in accordance with ISO 1133 at 230 °C under a load of 2 .16 kg, ii- a haze value < 20%, measured in accordance with ASTM D1003 on 1 mm thick injection molded plates produced as described in EN ISO 1873-2; iii- from 15 to 84% by weight of the second pelletized polymer fraction in relation to the total amount of polypropylene composition; iv- from 15 to 84% by weight of the propylene polymer (PP-c) with respect to the total amount of the polypropylene composition; v- from 0.01 to 1.0% by weight of at least one alpha nucleating agent with respect to the total amount of the polypropylene composition; and vi- wherein the fraction of the first propylene polymer is produced in an amount of 20 to 90% by weight with respect to the total sum of the first propylene polymer and the second propylene polymer with respect to the total sum of the first propylene polymer and the second propylene polymer comprised in the fraction of the second propylene polymer. 2. Process according to claim 1, characterized by the fact that the polypropylene composition has a comonomer content in the range of 1.5 to 5.0% by weight, in relation to the total amount of monomers present in the composition. polypropylene. 3. Process according to any one of claims 1 or 2, characterized in that the melt mixing of the second pelletized propylene polymer fraction is carried out at a temperature in the range of 190 to 260 ° C. 4. Process according to any one of claims 1 to 3, characterized in that the melt mixing of the second pelletized propylene polymer fraction is carried out in a single screw extruder or twin screw extruder. 5. Process according to any one of claims 1 to 4, characterized by the fact that the second propylene polymer fraction and the propylene polymer (PP-c) are free of a phthalic compound. 6. Polypropylene composition characterized by the fact that it is obtainable by the process as defined in any one of claims 1 to 5. 7. Polypropylene composition according to claim 6, characterized by the fact that the polypropylene composition has a xylene soluble content (XCS) in the range of 5.5 to 18.0% by weight, as determined in accordance with the ISO 16152 standard at 25 °C. 8. Polypropylene composition according to any one of claims 6 or 7, characterized by the fact that the polypropylene composition has a melting temperature > 152 ° C and a crystallization temperature > 120 ° C, as measured in accordance with the ISO 11357/3 standard. 9. Polypropylene composition according to any one of claims 6 to 8, characterized by the fact that the polypropylene composition has a tensile modulus > 950 MPa, as measured in accordance with ISO 527-1: 2012/ISO 527-2:2012 in injection molded specimens at 23 °C. 10. Polypropylene composition according to any one of claims 6 to 9, characterized in that the polypropylene composition has a Charpy notched impact resistance > 4.8 kJ/m2, as measured in accordance with ISO 179 /1eA at 23°C in injection molded test specimens as described in EN ISO 1873-2. 11. Polypropylene composition according to any one of claims 6 to 10, characterized in that the polypropylene composition is free of a phthalic compound. 12. Article characterized by the fact that it comprises the polypropylene composition as defined in any one of claims 6 to 11. 13. Article according to claim 12, characterized in that the article is a cast film, an injection molded article, a closure cap, a screw cap or a closure system for food or fluid packaging. 14. Use of the polypropylene composition as defined in any one of claims 6 to 11, characterized by the fact that it is in the preparation of a cast film, an injection molded article, a closure cap, a screw cap or a sealing system. closure for food or fluid packaging.