Process for preparing random propylene-ethylene copolymer compositions

Abstract

The present invention relates to a process for preparing a polypropylene composition comprising a propylene-based polymer, the polymer being a propylene-ethylene copolymer having an ethylene content of 2.0 wt% to 5 wt% based on the propylene-ethylene copolymer wherein the polypropylene composition has:-a melt flow rate (MFR) of 1 to 80 g / 10 min; wherein the melt flow rate is determined using ISO 1133-1: 2011, using 2.16 kg at 230 DEG C wherein the process comprises the step of polymerizing propylene and optionally an ethylene comonomer in the gas phase in the presence of a catalyst comprising a procatalyst, a co-catalyst and optionally an external electron donor to obtain the propylene-based polymer, wherein the procatalyst is obtainable by a process comprising the step of contacting a magnesium-containing support with a halogen-containing titanium compound and an internal electron donor according to Formula I: wherein R1 is a secondary alkyl group, R2 is a non-secondary alkyl group having at least 5 carbon atoms, preferably R2 is a non-secondary alkyl group branched in the 3-position or other position; the procatalyst is prepared according to the following steps: i) contacting a compound R4zMgX42-z with an alkoxy or aryloxy-containing silane compound to produce a first intermediate reaction product which is a solid Mg (ORa) xX12-x wherein: Ra is a linear, branched or cyclic hydrocarbyl group independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl groups and one or more combinations thereof; wherein the hydrocarbyl group may be substituted or unsubstituted, may contain one or more heteroatoms, and preferably has from 1 to 20 carbon atoms; wherein R4 is a linear, branched or cyclic hydrocarbyl group independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkaryl groups, and one or more combinations thereof; wherein the hydrocarbyl group may be substituted or unsubstituted, may contain one or more heteroatoms and preferably have from 1 to 20 carbon atoms, preferably R4 is butyl; wherein X4 and X1 are each independently selected from a fluorine ion (F-), a chloride ion (Cl-), a bromide ion (Br-) or an iodide ion (I-), preferably a chloride ion; z is greater than 0 and less than 2, namely 0 lt; zlt, zlt; x is an integer from 0 to 2; ii) optionally contacting the solid Mg (ORa) xX12-x obtained in step i) with at least one activating compound selected from the group consisting of activating electron donors and metal alkoxide compounds of formula M1 (ORb) v-w (OR3) w or M2 (ORb) v-w (R3) w to obtain a second intermediate product; wherein: M1 is a metal selected from Ti, Zr, Hf, Al or Si; v is the valence of M1; m2 is metal Si; v is the valence of M2; rb and R3 are each a linear, branched or cyclic hydrocarbon group, independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkaryl, and one or more combinations thereof; wherein the hydrocarbyl group may be substituted or unsubstituted, may contain one or more heteroatoms, and preferably has from 1 to 20 carbon atoms; wherein w is less than v, preferably v is 3 or 4; iii) bringing the first or second intermediate reaction product obtained in step i) or ii) into contact with a halogen-containing Ti-compound and the compound represented by formula I as the internal electron donor, respectively.

Description

TECHNICAL FIELD

[0001] The present invention relates to a process for preparing a composition comprising a propylene-based polymer, which polymer is a propylene-ethylene copolymer having an ethylene content of 2.0 wt% to 5 wt% based on the propylene-ethylene copolymer.

[0002] Furthermore, the present invention also relates to an article comprising the polypropylene composition of the present invention. Furthermore, the present invention relates to the use of the polypropylene composition and to a process for preparing the article. The present invention also relates to the use of the polypropylene composition of the present invention for compounding with further polymers or for preparing a masterbatch. BACKGROUND

[0003] Polymers, such as polypropylene, are increasingly used in applications with different requirements. At the same time, there is a continuous drive to find tailored polymers that meet the requirements of these applications, such as good transparency and low blooming (e.g. by low CXS). Furthermore, there is a continuous drive for high yield processes, as this is more economically advantageous.

[0004] Therefore, there is a need in the art for a process for preparing a polypropylene composition comprising a propylene-based polymer, which polymer is a propylene-ethylene copolymer having good transparency and low blooming, which propylene-ethylene copolymer has an ethylene content of 2.0 wt% to 5 wt% based on the propylene-ethylene copolymer, which can be produced with a high catalyst yield. SUMMARY

[0005] Therefore, it is an object of the present invention to provide a process for preparing a polypropylene composition comprising a propylene-based polymer, which polymer is a propylene-ethylene copolymer having good transparency and low blooming, which propylene-ethylene copolymer has an ethylene content of 2.0 wt% to 5 wt% based on the propylene-ethylene copolymer, which can be produced with a high catalyst yield.

[0006] This object is achieved by a process for preparing a polypropylene composition comprising a propylene-based polymer, which polymer is a propylene-ethylene copolymer having an ethylene content of 2.0 wt% to 5 wt% based on the propylene-ethylene copolymer,

[0007] wherein the polypropylene composition preferably has at least 95 wt%, more preferably at least 96 wt%, even more preferably at least 97 wt%, even more preferably at least 97.5 wt% of the propylene-based polymer based on the composition, and:

[0008] • a melt flow rate (MFR) of 1-80 g / 10 min, wherein the melt flow rate is determined using ISO 1133-1 :2011 using 2.16 kg at 230 °C, and

[0009] wherein the process comprises the step of polymerizing propylene and ethylene comonomer in the gas phase in the presence of a catalyst to obtain the propylene-based polymer, wherein said catalyst comprises a procatalyst, a cocatalyst and optionally an external electron donor, wherein the procatalyst is obtainable by a process comprising the steps of:

[0010] contacting a magnesium-containing support with a halogen-containing titanium compound and an internal electron donor according to formula I:

[0011]

[0012] wherein R 1 is a secondary alkyl group, R 2 is a non-secondary alkyl group having at least 5 carbon atoms, preferably R 2 is a non-secondary alkyl group branched in the 3-position or other position;

[0013] said procatalyst is prepared according to the following steps:

[0014] i) contacting a compound R 4 z MgX 4 2-z with an alkoxy- or aryloxy-containing silane compound to produce a first intermediate reaction product which is a solid Mg(OR a ) x X 1 2-x wherein: R a is a linear, branched or cyclic hydrocarbyl group independently selected from an alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl group and one or more combinations thereof; wherein the hydrocarbyl group can be substituted or unsubstituted, can contain one or more heteroatoms and preferably has 1-20 carbon atoms; wherein R 4 is a linear, branched or cyclic hydrocarbyl group independently selected from an alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl group and one or more combinations thereof; wherein the hydrocarbyl group can be substituted or unsubstituted, can contain one or more heteroatoms and preferably has 1-20 carbon atoms, preferably R 4 is a butyl group; wherein X 4 and X 1 are each independently selected from a fluoride (F-), chloride (CI-), bromide (Br-) or iodide (I-) ion, preferably a chloride ion; z is greater than 0 and less than 2, i.e. 0 < z < 2, x is an integer from 0 to 2;

[0015] ii) optionally subjecting the solid Mg(OR a ) x X 1 2-x with at least one activating compound selected from the group consisting of activating electron donors and metal alkoxide compounds of the formula M 1 (OR b ) v-w (OR 3 ) w or M 2 (OR b ) v-w (R 3 ) w ; wherein: M 1 is a metal selected from the group consisting of Ti, Zr, Hf, Al or Si; v is the valence of M 1 ; M 2 is the metal Si; v is the valence of M 2 ; R b and R 3 each is a linear, branched or cyclic hydrocarbyl group independently selected from the group consisting of alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl and one or more combinations thereof; wherein the hydrocarbyl groups can be substituted or unsubstituted, can contain one or more heteroatoms and preferably have 1-20 carbon atoms; wherein w is smaller than v, preferably v is 3 or 4;

[0016] iii) contacting the first or second intermediate reaction product obtained in step i) or ii), respectively, with a halogen-containing Ti compound and said compound of the formula I as the internal electron donor.

[0017] The present application further provides a polypropylene composition obtained or obtainable by the process according to the present application.

[0018] The present application further provides a polypropylene composition comprising a propylene-based polymer which is a propylene-ethylene copolymer having an ethylene content of 2.0 wt% to 5 wt% based on the propylene-ethylene copolymer,

[0019] wherein the polypropylene composition has:

[0020] • a melt flow rate (MFR) of 1-80 g / 10 min, wherein the melt flow rate is determined using ISO 1133-1 :2011 using 2.16 kg at 230 °C, and

[0021] wherein the amount of Ti in the propylene-based polymer is at most 1.4 mg per 1 kg of the propylene-based polymer as determined by inductively coupled plasma mass spectrometry (ICP-MS).

[0022] According to the present invention, it has been surprisingly found that the use of specific catalysts in methods for preparing propylene-based polymers yields a combination of high catalyst yield and low CXS, even at higher MFRs. Due to the use of such a small amount of catalyst, polypropylene compositions having very low amounts of Ti can be produced. Therefore, in another aspect, the present invention provides a polypropylene composition having a low amount of Ti from the catalyst used in preparing the composition, which is advantageous for the high purity of the composition. Detailed Implementation

[0023] propylene-based polymers

[0024] The polypropylene composition according to the invention comprises a propylene-based polymer, which is a propylene-ethylene copolymer having an ethylene content of 2.0 wt% to 5 wt% based on the propylene-ethylene copolymer.

[0025] Preferably, the melt flow rate (MFR) of the polypropylene composition is 1-80 g / 10 min, more preferably 1-60, and more preferably 1-50, which is determined according to ISO 1133-1: 2011 using 2.16 kg at 230°C.

[0026] Preferably, the cold xylene soluble content (CXS) of the random propylene-ethylene copolymer is 3.0-8.0 wt%, more preferably 3.7-6.9 wt%, more preferably 4.6-6.9 wt%, and even more preferably 5.0-6.4 wt%, which is measured by the method described in the "CRYSTEX method for propylene homopolymers" section of the measurement method section of the present invention.

[0027] Preferably, the molecular weight distribution (Mw / Mn) of the polypropylene composition is 1.0-11.0, more preferably 4.0-9.0, wherein Mw represents the weight-average molecular weight and Mn represents the number-average molecular weight, and wherein Mw and Mn are measured according to ISO16014-1(4): 2003.

[0028] Methods for preparing propylene-based polymers

[0029] Those skilled in the art know how to prepare propylene-ethylene copolymers. The preparation of propylene homopolymers and propylene-ethylene copolymers is described, for example, in Moore, EP (1996) Polypropylene Handbook. Polymerization, Characterization, Properties, Processing, Applications, Hanser Publishers: New York.

[0030] Catalyst

[0031] The catalyst for preparing the polypropylene composition according to the present invention is the catalyst detailed in WO2021 / 063930, which is incorporated herein by reference. The catalyst comprises a main catalyst, a cocatalyst and optionally an external electron donor.

[0032] The main catalyst can be obtained by a method comprising contacting a magnesium-containing support with a halogen-containing titanium compound and an internal electron donor according to Formula I:

[0033]

[0034] where R 1 is a secondary alkyl group, R 2 is a non-secondary alkyl group having at least 5 carbon atoms, preferably R 2 is a non-secondary alkyl group having at least 5 carbon atoms and branched at the 3-position or other positions.

[0035] The method for providing the main catalyst follows the method described in WO2021 / 063930A1 (which is incorporated by reference) and comprises the following steps:

[0036] i) Contacting the compound R 4 z MgX 4 2-z with a silane compound containing an alkoxy or aryloxy group to produce a first intermediate reaction product, which is a solid Mg(OR a ) x X 1 2-x , where: R a is a straight-chain, branched-chain or cyclic hydrocarbon group, which is independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl and one or more combinations thereof; where the hydrocarbon group may be substituted or unsubstituted, may contain one or more heteroatoms and preferably has 1-20 carbon atoms; where R 4 is a straight-chain, branched-chain or cyclic hydrocarbon group, which is independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkaryl and one or more combinations thereof; where the hydrocarbon group may be substituted or unsubstituted, may contain one or more heteroatoms and preferably has 1-20 carbon atoms, preferably R 4 is butyl; where X 4 and X 1 are each independently selected from fluoride ion (F-), chloride ion (Cl-), bromide ion (Br-) or iodide ion (I-), preferably chloride ion; z is greater than 0 and less than 2, i.e., 0 < z < 2, and x is an integer from 0 to 2;

[0037] ii) Optionally, make the solid Mg(OR) obtained in step i) a ) x X 1 2-x A second intermediate is obtained by contacting with at least one activating compound selected from activated electron donors and formula M. 1 (OR b ) v-w (OR 3 ) w Or M 2 (OR b ) v-w (R 3 ) w Metal alkane oxide compounds; wherein: M 1 It is a metal selected from Ti, Zr, Hf, Al, or Si; v is M 1 The valence of M; 2 It is metal Si; v is M 2 The valence of R; b and R 3 Each is a straight-chain, branched, or cyclic hydrocarbon group, independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl, or alkylaryl and one or more combinations thereof; wherein the hydrocarbon group may be substituted or unsubstituted, may contain one or more heteroatoms, and preferably has 1-20 carbon atoms; wherein w is less than v, preferably v is 3 or 4;

[0038] iii) Contact the first or second intermediate reaction product obtained in step i) or ii) with the halogen-containing Ti compound and the compound of formula I, which is the internal electron donor.

[0039] In one embodiment, during step ii), an alcohol is used as the activating electron donor, and tetraalkoxytitanium is used as the metal alkoxy compound.

[0040] In one implementation, an activator is present.

[0041] In one embodiment, the activator is ethyl benzoate.

[0042] In one embodiment, the activator is benzamide according to formula X:

[0043]

[0044] Where R 70 and R 71 Each is independently selected from hydrogen or alkyl groups, and R 72 R 73 R 74 R 75 R76 Each is independently selected from hydrogen, heteroatoms, or hydrocarbon groups, preferably from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl, or alkylaryl groups and one or more combinations thereof, more preferably wherein R 70 and R 71 They are all methyl groups, and R is one of them. 72 R 73 R 74 and R 75 If both are hydrogen, then the activator is N,N'-dimethylbenzamide (Ba-2Me).

[0045] The preferred internal electron donor is based on Equation I:

[0046]

[0047] Where R 1 It is a secondary alkyl group having at least 3 carbon atoms, and R 2 It is a non-secondary alkyl group having at least 5 carbon atoms, preferably R. 1 and R 2 It has at most 7 carbon atoms, preferably at most 6 carbon atoms, and is preferably isopropyl, isobutyl, isopentyl, cyclopentyl, n-pentyl, and isohexyl, preferably R. 2 Branching at 3-positions or other positions.

[0048] In another embodiment, the internal electron donor is 3,3-bis(methoxymethyl)-2,6-dimethylheptane according to formula I, wherein R 1 It is isopropyl, as a secondary alkyl group, R 2 It is isopentyl, a non-secondary alkyl group, and has a branched chain at the third carbon atom (abbreviated as iPiPen, where iP represents isopropyl and iPen represents isopentyl, also known as 3-methyl-butyl). The compound iPiPen has the chemical formula C 13 H 28 O2; exact mass is 216.21, molecular weight is 216.37. In a more preferred embodiment of the invention, iPiPen is used as an internal donor and / or the activating compound is preferably N,N-dimethylbenzamide.

[0049]

[0050] In another embodiment, the internal electron donor is (1-methoxy-2-(methoxymethyl)-5-methylhex-2-yl)cyclopentane according to formula I, wherein R 1 It is a secondary alkylcyclopentyl group, and R 2 It is secondary cyclopentyl (abbreviated as CPiPen, where CP represents cyclopentyl and iPen represents isopentyl, also known as 3-methyl-butyl). The compound CPiPen has the chemical formula C10.15 H 30 O2; exact mass is 242.22, molecular weight is 242.40. In a more specific embodiment, CPiPen is used as an internal donor, and N,N-dimethylbenzamide is preferably used as an activator.

[0051]

[0052] In another embodiment, the internal electron donor is 3,3-bis(methoxymethyl)-2,7-dimethyloctane according to formula I, wherein R 1 It is a secondary alkyl isopropyl group, and R 2 It is a non-secondary isohexyl group with branches on four carbon atoms (abbreviated as iPiHex, where iP represents isopropyl and iHex represents isohexyl, also known as 4-methyl-pentyl). The compound iPiHex has the chemical formula C 14 H 30 O2; precise mass 230.22, molecular weight 230.39. In a more specific embodiment, iPiHex is used as an internal donor, and N,N-dimethylbenzamide is preferably used as an activator.

[0053]

[0054] In another embodiment, the internal electron donor is 3,3-bis(methoxymethyl)-2-methyloctane according to formula I, wherein R 1 It is a secondary alkyl isopropyl, and R 2 It is a non-secondary, unbranched n-pentyl group (abbreviated as iPnPen, where iP represents isopropyl and nPen represents n-pentyl). The compound iPnPen has the chemical formula C1. 13 H 28 O2; precise mass is 216.21, molecular weight is 216.37. In a more specific embodiment, iPnPen is used as an internal donor, and N,N-dimethylbenzamide is preferably used as an activator.

[0055]

[0056] In another embodiment, the internal electron donor is 3,3-bis(methoxymethyl)-2,6-dimethyloctane according to formula I, wherein R 1 It is a secondary alkyl isopropyl, and R 2 It is a non-secondarily branched hexyl group with a branch at the third carbon atom (abbreviated as iP3Hex, where iP represents isopropyl and 3Hex represents a hexyl group with a branch at the third carbon atom, also known as 3-methyl-pentyl). The compound iPiHex has the chemical formula C 14 H 32O2; exact mass is 230.22, molecular weight is 230.39. In a more preferred embodiment, iP3Hex is used as an internal donor and / or N,N-dimethylbenzamide is preferably used as an activator.

[0057]

[0058] In another embodiment, the polymer yield provided by the main catalyst used according to the invention is based on at least 50 kg of polymer per gram of main catalyst used.

[0059] In one implementation, the base R is replaced 1 It is isopropyl or cyclopentyl. In one embodiment, the substituent R 2 It is isopentyl or isohexyl. The table below uses abbreviations and R. 1 and R 2 The groups indicate the above embodiments, as well as whether these groups are secondary groups and whether they are branched.

[0060] According to the present invention, R is further preferred. 1 It is a secondary alkyl group, and R 2 It is a non-secondary alkyl group that is branched at the 3 position or other positions.

[0061] Preferably, the catalyst includes an external electron donor, and the molar ratio of the co-catalyst to the external electron donor is greater than 1 and at most 160, or greater than 1 and at most 120, or greater than 1 and at most 90, ranging from 1 to 25, or 1 to 15, or 1 to 10, or 2 to 8, or 2 to 5.

[0062] Preferably, the co-catalyst is selected from trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, diisobutylaluminum hydride, trioctylaluminum, dihexylaluminum hydride and mixtures thereof.

[0063] Preferably, the external electron donor is selected from compounds having the following structures:

[0064] - Formula III: (R 90 )2N—Si(OR 91 )3,

[0065] - Formula IV: (R 92 )Si(OR 93 )3,

[0066] - Equation V: Si(OR) a ) 4-n R b n ,

[0067] - and its mixtures,

[0068] Each R 90 R 91 R 92 and R 93 Each group is independently a straight-chain, branched, or cyclic, substituted or unsubstituted alkyl group having 1-10 carbon atoms, preferably wherein R 90 R 91 R 92 and R 93 Each group is independently a straight-chain unsubstituted alkyl group having 1-8 carbon atoms.

[0069] Where n can be 0 up to 2, and each R a and R b Independently representing an alkyl or aryl group, which optionally contains one or more heteroatoms such as O, N, S, or P, and has, for example, 1-20 carbon atoms.

[0070] Preferably, the molar ratio of Al in the co-catalyst to Si in the external electron donor is greater than 1 and at most 160, or greater than 2 and at most 120, or greater than 3 and at most 90.

[0071] For example, ethyl, methyl, or n-propyl, such as diethylaminotriethoxysilane (DEATES), n-propyltriethoxysilane (nPTES), n-propyltrimethoxysilane (nPTMS); and those having the general formula Si(OR) a ) 4-n R b n Organosilicon compounds, where n can be 0 up to 2; and each R a and R b Independently representing an alkyl or aryl group, optionally containing one or more heteroatoms such as O, N, S, or P, having, for example, 1-20 carbon atoms; examples include diisobutyldimethoxysilane (DiBDMS), tert-butylisopropyldimethoxysilane (tBuPDMS), cyclohexylmethyldimethoxysilane (CHMDMS), dicyclopentyldimethoxysilane (DCPDMS), or di(isopropyl)dimethoxysilane (DiPDMS). More preferably, the external electron donor is selected from di(isopropyl)dimethoxysilane (DiPDMS) or diisobutyldimethoxysilane (DiBDMS).

[0072] Preferably, the exogenous donor comprises or consists of compounds selected from or composed of the following: organosilicon compounds, silanes, alkoxysilanes, alkylsilanes, alkylalkoxysilanes, and aliphatic / aromatic esters, such as dicyclopentyldimethoxysilane, di-tert-butyldimethoxysilane, methylcyclohexyldimethoxysilane, ethylcyclohexyldimethoxysilane, diphenyldimethoxysilane, diisopropyldimethoxysilane, di-n-propyldimethoxysilane, diisobutyldimethoxysilane, di-n-butyldimethoxysilane, cyclopentyltrimethoxysilane, isopropyltrimethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, ethyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, cyclopentylpyrrolidinedimethoxysilane, bis(pyrrolyl)-dimethoxysilane, and mixtures thereof, preferably di(isopropyl)dimethoxysilane (DiPDMS).

[0073] The compounds described above as examples of external electron donors are sometimes referred to as selective control agents (SCAs). The external electron donor may consist of an SCA. Optionally, in addition to an SCA, the external electron donor may further comprise a compound called an activity limiting agent (ALA). Preferably, the activity limiting agent (ALA) is selected from: ethyl acetate, ethyl benzoate, ethyl p-ethoxybenzoate, methyl trimethylacetate, isopropyl myristate, di-n-butyl sebacate, (poly(alkylene glycol) monoacetate or diacetate, (poly(alkylene glycol) monomyristate or dimyristate, (poly(alkylene glycol) monolaurate or dilaurate, (poly(alkylene glycol) monodioleate or dioleate), triglycerides, linoleic acid, oleic acid, palmitic acid and stearic acid mixed glycerides, and mixtures thereof. More preferably, the activity limiting agent (ALA) is isopropyl myristate.

[0074] The ratio of selective control agent (SCA) to activity limiter (ALA) is not critical in principle, but the optimal results are obtained when the SCA / ALA ratio is 0.010-100, more preferably 0.10-20.

[0075] The molar ratio of Al in the co-catalyst to Si in the external electron donor can be, for example, 1-25.

[0076] In some preferred embodiments, the molar ratio of Al in the co-catalyst to Si in the external electron donor is 1-15, preferably 1-10, preferably 2-8, and preferably 2-5.

[0077] A relatively low Al / Si molar ratio produces compositions with lower CXS.

[0078] In some preferred embodiments, the molar ratio of Al in the co-catalyst to Si in the external electron donor is greater than 3 and at most 40.

[0079] A relatively high Al / Si molar ratio results in a higher catalyst yield.

[0080] Furthermore, surprisingly, the method according to the invention allows for maintaining high catalyst yields at high MFRs, whereas known catalyst systems using existing technologies experience a decrease with increasing MFRs.

[0081] Catalyst yield (CY) Ti (KgPP / gcat):

[0082] In a preferred embodiment, the CY Ti (KgPP / gcat) of the method is at least 25, more preferably at least 30, more preferably at least 35, and more preferably at least 40, wherein CY Ti (KgPP / gcat) is calculated according to formula (1):

[0083]

[0084] The Ti content in the catalyst and the Ti content in the obtained polymer were determined by inductively coupled plasma mass spectrometry (ICP-MS).

[0085] Preferably, the amount of Ti in the propylene-based polymer, as determined by inductively coupled plasma mass spectrometry (ICP-MS), is at most 1.4 mg / kg, preferably 1.2 mg / kg, more preferably 1.0 mg / kg, and more preferably 0.5 mg / kg, based on the propylene-based polymer.

[0086] Composition

[0087] The melt flow rate (MFR) of the polypropylene composition is 1-80 g / 10 min, wherein the melt flow rate is determined using ISO 1133-1:2011 with 2.16 kg at 230°C. In some preferred embodiments, the MFR of the polypropylene composition, determined using ISO 1133-1:2011 with 2.16 kg at 230°C, is 1-45 g / 10 min. In some preferred embodiments, the MFR of the polypropylene composition, determined using ISO 1133-1:2011 with 2.16 kg at 230°C, is 45-80 g / 10 min.

[0088] Preferably, the amount of propylene-based polymer is at least 95 wt% based on the polypropylene composition, more preferably at least 96 wt%, even more preferably at least 97 wt%, and even more preferably at least 97.5 wt%.

[0089] Inorganic packing

[0090] The compositions according to the invention may contain inorganic fillers. Suitable examples of such inorganic fillers include, but are not limited to, talc.

[0091] The compositions according to the invention may contain no or substantially no inorganic fillers. For example, the compositions according to the invention may contain less than 1.0 wt%, less than 0.1 wt%, or less than 0.01 wt% of inorganic fillers.

[0092] additive

[0093] In some embodiments, the polypropylene composition further comprises additives, for example, in an amount of 0.10-2.0 wt% based on the polypropylene composition.

[0094] The additives include stabilizers. These stabilizers may be selected, for example, from heat stabilizers, antioxidants, and / or UV stabilizers, all of which are known to those skilled in the art.

[0095] Additives may further include nucleating agents, colorants such as pigments and dyes; clarifying agents; surface tension modifiers; lubricants; flame retardants; release agents; flow improvers; plasticizers; antistatic agents; foaming agents; and slip agents.

[0096] In one aspect, the present invention provides an article comprising the polypropylene composition of the present invention. Preferably, the amount of the polypropylene composition is at least 95 wt% based on the article. The article can be obtained by injection molding, blow molding, extrusion, or compression molding. The article can be a household article such as a vacuum cleaner housing, household chemicals and paints, or a packaging article such as containers, crates, boxes, battery boxes, barrels, flower pots, food containers / packaging, ice cream containers, thin-walled packaging, caps and seals, films, pouches, health care packaging, or health care articles such as pharmaceutical products, laboratory glassware, medical devices, medical diagnostic articles, or automotive interior articles such as dashboard carriers, door panels, front bulkhead panels, front bulkhead carriers, door covers, door fasteners, armrests, pillar covers, seat covers, trunk covers, interior trim, and applications in heating, ventilation, and air conditioning (HVAC) applications.

[0097] In one aspect, the present invention relates to the use of the polypropylene composition of the invention in the preparation of articles. Preferably, the amount of the polypropylene composition is at least 95 wt% based on the article.

[0098] The products can be obtained through injection molding, blow molding, extrusion, or compression molding. These products can be household items such as vacuum cleaner housings, household chemicals and paints, or packaging items such as containers, crates, boxes, battery boxes, barrels, flower pots, food containers / packaging, ice cream containers, thin-walled packaging, caps and seals, films, pouches, health care packaging, or health care products such as pharmaceutical products, laboratory glassware, medical devices, medical diagnostic products, or automotive interior products such as dashboard carriers, door panels, front panel panels, front panel carriers, door cladding, door fasteners, armrests, pillar cladding, seat cladding, trunk cladding, interior trim, and applications in heating, ventilation, and air conditioning (HVAC) applications.

[0099] In one aspect, the present invention provides a method for preparing an article of articles, comprising the following steps:

[0100] a. Providing the polypropylene composition of the present invention, and

[0101] b. Convert the polypropylene composition into an article, for example, by extrusion or injection molding.

[0102] The present invention further relates to the use of the polypropylene compositions of the present invention for blending with other polymers, such as other polypropylenes, or for the preparation of masterbatches.

[0103] It should be further noted that the present invention relates to all possible combinations of the features described herein, with particular preference given to those combinations of features present in the claims. Therefore, it should be understood that this document describes all combinations of features relating to compositions according to the invention; all combinations of features relating to methods according to the invention; and all combinations of features relating to compositions according to the invention and features relating to methods according to the invention.

[0104] It should be further noted that the term "comprising / including" does not exclude the presence of other elements. However, it should also be understood that a description of a product / composition comprising certain components also discloses a product / composition composed of those components. A product / composition composed of these components may be advantageous because it provides a simpler and more economical method for preparing the product / composition. Similarly, it should be understood that a description of a method including certain steps also discloses a method composed of those steps. A method composed of these steps may be advantageous because it provides a simpler and more economical method.

[0105] The invention will now be illustrated by the following embodiments, but is not limited thereto.

[0106] Example

[0107] Methods for preparing main catalysts

[0108] For Invention Examples E1-E4: The main catalyst was prepared according to the method disclosed in Example 1 of WO2021 / 063930A1.

[0109] For comparative examples CE1 and CE2, the catalysts were prepared using microspheres of MgCl22.1EtOH with an average particle size of 15 micrometers, according to comparative example 1 in EP0728770B1.

[0110] Process conditions for E1-E5 and CE1-CE2

[0111] Gas-phase polymerization is carried out in a horizontally stirred gas-phase reactor with a downstream powder processing unit (=degassing and catalyst deactivation) for powder collection.

[0112] The temperature of the powder bed is measured via a series of internal thermocouples. The data from these thermocouples is used to control the quench flow to individual quench nozzles.

[0113] Hydrogen is fed into the reactor to control the melt flow rate, and ethylene is fed into the reactor to obtain random propylene-ethylene copolymer.

[0114] The obtained random propylene-ethylene copolymers were collected and their properties were measured.

[0115] Table 1 shows the catalysts used in the polymerization method and the different properties of the resulting random propylene-ethylene copolymers.

[0116] Table 1. Reaction conditions and polymer properties of polymerization.

[0117] Al / Ti is the molar ratio of the co-catalyst (TEA) to the main catalyst.

[0118] Si / Ti is the molar ratio of the external donor (DiPDMS) to the main catalyst.

[0119] Al / Si is the molar ratio of the co-catalyst (TEA) to the exogenous donor (DiPDMS).

[0120] NA: Unanalyzed

[0121] It can be seen that, compared with CE1 and CE2 produced using catalysts containing different main catalysts, the method of producing E1-E5 using catalysts containing the main catalyst of the present invention has a higher catalyst yield (represented by CY (ICP / Ti)) while producing compositions with the same C2 content and lower CXS content.

[0122] The comparison of E2-E3 shows that a higher Al / Si molar ratio (lower amount of Si (external donor)) in the catalyst achieves a higher catalyst yield while maintaining a low CXS content.

[0123] The comparison between E2 and E5 shows that as MFR increases, CY remains at a high level, while for CE1 and CE2, it is clear that CY decreases significantly at higher MFR.

[0124] Furthermore, lower Ti levels were detected in E1-E5 than in CE1 and CE2, indicating that the polypropylene of this invention contains fewer impurities than polypropylene produced using other catalysts, such as those used in Comparative Examples 1 and 2 of EP0728770B1, which utilize microspheres of MgCl22.1EtOH supported on an average particle size of 15 micrometers. Therefore, propylene produced by the method according to this invention is suitable for applications requiring fewer impurities without the need for further additional purification processes.

[0125] Measurement methods

[0126] MFR

[0127] MFR was measured according to ISO 1133 (2.16 kg / 230℃).

[0128] CRYSTEX method for atactic propylene-ethylene copolymers

[0129] The following CRYSTEX method can be used to determine the following properties of random propylene-ethylene copolymers:

[0130] - Amount of crystalline insoluble fraction in random propylene-ethylene copolymer (CXI equivalent, whole sample, HT fraction);

[0131] - Amount of amorphous soluble fraction in random propylene-ethylene copolymer (CXS equivalent, whole sample).

[0132] These properties can be measured using the CRYSTEX method with the CRYSTEX QC instrument at CRYSTEX QC Polymer Char (Valencia, Spain). A schematic diagram of the CRYSTEX QC instrument is shown in Del Hierro, P.; Ortin, A.; Monrabal, B.; "Soluble Fraction Analysis in polypropylene, The Column", February 2014, pp. 18-23.

[0133] The CRYSTEX QC instrument includes an infrared detector (IR4) and an online dual-capillary viscometer. Quantification of the HT fraction, LT fraction, TC2 full fraction, TC2-HT fraction, and TC2-LT fraction can be performed using the infrared detector, which measures the IR absorbance at two different wavelengths (CH3 and CH2). The IV full fraction, IV-HT fraction, and IV-LT fraction can be determined using the online dual-capillary viscometer.

[0134] The random propylene-ethylene copolymer sample to be analyzed was weighed at a concentration of 10 mg / mL. After filling the vial with 1,2,4-TCB containing 250 mg / L of 2,6-tert-butyl-4-methylphenol (BHT) as an antioxidant, the sample was dissolved at 170°C until completely dissolved for 60 min, while stirring at a constant speed of 800 rpm.

[0135] A specified volume of sample solution is injected into a column packed with an inert support, where crystallization of the sample and separation of the soluble fraction from the crystalline fraction occur. This process is repeated twice.

[0136] During the first injection, the entire sample was measured at high temperature to determine the IV full fraction [dl / g] and TC2 full fraction (m / m%) of the PP homopolymer. However, TC2 was not related to the random propylene-ethylene copolymer.

[0137] During the second injection, measurements were taken at low temperature to determine the amorphous soluble fraction (CXS equivalent full sample) (m / m%), and then at high temperature to determine the crystalline insoluble fraction (CXI equivalent full sample (m / m%)).

[0138] The crystalline insoluble fraction and the amorphous soluble fraction were separated by temperature cycling of dissolution at 165 °C, crystallization at 40 °C, and redissolution at 165 °C in 1,2,4-trichlorobenzene (1,2,4-TCB).

[0139] The CXS content was determined using different PP polymer calibrated instruments, the PP polymer having a known CXS content determined according to the standard gravimetric method of ISO 16152.

[0140] Catalyst yield (CY) ICP / Ti

[0141] The Ti content in the catalyst and the Ti content in the obtained polymer were measured by ICP. The ICP procedure was as follows: Approximately 250 mg of each sample was digested in 6 mL of concentrated nitric acid (trace metal grade) using an Anton Paar Multiwave PRO equipped with a sealed high-pressure quartz digestion vessel via microwave-assisted acid digestion. After the microwave digestion run, the acid was transferred analytically to a pre-cleaned plastic centrifuge tube containing 1 mL of internal standard solution and diluted with MilliQ water to a labeled 50 mL. Elemental quantification in the samples was performed using an Agilent 8900 ICP-MS system with a multi-element calibration group from Inorganic Ventures.

[0142] Then, calculate CY according to equation (1).

[0143]

[0144] ethylene content

[0145] Ethylene content was measured using 13C-NMR spectroscopy. For this purpose, approximately 150 mg of material was dissolved in 1,1,2,2-tetrachloroethane-d2 (TCE-d2). To ensure a homogeneous solution, sample preparation was performed in a heated rotary oven. NMR measurements were performed in solution using a Bruker 500 Advance III HD spectrometer, running at 500.16 and 125.78 MHz for 1H and 13C, respectively, equipped with a 10 mm dual cryogenic probe operating at 125 °C. 13C-NMR experiments were performed using standard single-pulse excitation, decoupled using a NOE and a two-level WALTZ16 decoupling scheme (Zhou Z. et al. J. Mag. Reson 187 (2007) 225). A total of 512 transients were obtained for each spectrum. The spectra were calibrated by setting the center signal of the triplet state of the TCE to 74.2 ppm. The quantitative 13C NMR spectra were processed and integrated, and the relevant quantitative properties were determined from the integration using a proprietary computer program.

Claims

1. A method for preparing a polypropylene composition comprising a propylene-based polymer, the polymer being a random propylene-ethylene copolymer, the ethylene content of the random propylene-ethylene copolymer being 2.0 wt%-5 wt% based on the propylene-ethylene copolymer. The polypropylene composition has the following characteristics: A melt flow rate (MFR) of 1-80 g / 10 min, preferably 1-60, more preferably 1-50, wherein the melt flow rate is determined using ISO 1133-1:2011, with 2.16 kg at 230°C. The method includes the step of polymerizing propylene and ethylene comonomers in the gas phase in the presence of a catalyst to obtain the propylene-based polymer, wherein the catalyst comprises a main catalyst, a cocatalyst, and optionally an external electron donor, wherein the main catalyst can be obtained by a method including the following steps: Contact the magnesium-containing support with the halogen-containing titanium compound and the internal electron donor according to Formula I: Where R 1 It is a secondary alkyl group, R 2 It is a non-secondary alkyl group having at least 5 carbon atoms, preferably R. 2 It is a non-secondary alkyl group having at least 5 carbon atoms and branched at the 3-position or other positions; The main catalyst is prepared according to the following steps: i) Make compound R 4 z MgX 4 2-z Contact with silane compounds containing alkoxy or aryloxy groups yields a first intermediate product, which is solid Mg(OR) a ) x X 1 2-x ,in: R a is a straight-chain, branched-chain or cyclic hydrocarbon group, independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl and one or more combinations thereof; wherein the hydrocarbon group may be substituted or unsubstituted, may contain one or more heteroatoms and preferably has 1-20 carbon atoms; wherein R 4 is a straight-chain, branched-chain or cyclic hydrocarbon group, independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkaryl and one or more combinations thereof; wherein the hydrocarbon group may be substituted or unsubstituted, may contain one or more heteroatoms and preferably has 1-20 carbon atoms, preferably R 4 is butyl; wherein X 4 and X 1 each independently selected from fluoride ion (F-), chloride ion (Cl-), bromide ion (Br-) or iodide ion (I-), preferably chloride ion; z is greater than 0 and less than 2, i.e., 0 < z < 2, and x is an integer from 0 to 2; ii) Optionally, make the solid Mg(OR) obtained in step i) a ) x X 1 2-x A second intermediate is obtained by contacting with at least one activating compound selected from activated electron donors and formula M. 1 (OR b ) v-w (OR 3 ) w Or M 2 (OR b ) v-w (R 3 ) w Metal alkane oxide compounds; wherein: M 1 It is a metal selected from Ti, Zr, Hf, Al, or Si; v is M 1 The valence of M; 2 It is metal Si; v is M 2 The valence of R; b and R 3 Each is a straight-chain, branched, or cyclic hydrocarbon group, independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl, or alkylaryl and one or more combinations thereof; wherein the hydrocarbon group may be substituted or unsubstituted, may contain one or more heteroatoms, and preferably has 1-20 carbon atoms; wherein w is less than v, preferably v is 3 or 4; iii) Contact the first or second intermediate reaction product obtained in step i) or ii) with the halogen-containing Ti-compound and the compound of formula I, which is the internal electron donor.

2. The method according to claim 1, wherein the co-catalyst is selected from trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, diisobutylaluminum hydride, trioctylaluminum, dihexylaluminum hydride and mixtures thereof.

3. The method according to claim 2, wherein the catalyst comprises the external electron donor, and wherein the molar ratio of the co-catalyst to the external electron donor is 1-25, or 1-15, or 1-10, or 2-8, or 2-5.

4. The method according to claim 2 or 3, wherein the catalyst comprises an external electron donor, wherein the external electron donor is a silane-containing external electron donor, preferably wherein the external electron donor is selected from compounds having the following structure: Formula III: (R 90 )2N—Si(OR 91 )3, Formula IV: (R 92 )Si(OR 93 )3, Formula V: Si(OR a ) 4-n R b n , and its mixtures, Each R 90 R 91 R 92 and R 93 Each group is independently a straight-chain, branched, or cyclic, substituted or unsubstituted alkyl group having 1-10 carbon atoms, preferably wherein R 90 R 91 R 92 and R 93 Each group is independently a straight-chain unsubstituted alkyl group having 1-8 carbon atoms. Where n can be 0 up to 2, and each R a and R b Independently representing an alkyl or aryl group, which optionally contains one or more heteroatoms such as O, N, S, or P, and has, for example, 1-20 carbon atoms. and in, The molar ratio of Al in the co-catalyst to Si in the external electron donor is 1-25, or 1-15, or 1-10, or 2-8, or 2-5.

5. The method according to any one of the preceding claims, wherein during step ii), an alcohol is used as an activating electron donor as the activating compound, and tetraalkoxytitanium is used as a metal alkoxide compound.

6. The method according to any one of the preceding claims, wherein an activator is present, preferably benzamide according to formula X: Where R 70 and R 71 Each is independently selected from hydrogen or alkyl groups, and R 72 R 73 R 74 R 75 R 76 Each is independently selected from hydrogen, heteroatoms, or hydrocarbon groups, preferably from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl, or alkylaryl groups and one or more combinations thereof, more preferably wherein R 70 and R 71 They are all methyl groups, and R is one of them. 72 R 73 R 74 and R 75 If both are hydrogen, then the activator is N,N'-dimethylbenzamide (Ba-2Me).

7. The method according to any one of the preceding claims, wherein the catalyst yield (CY)Ti (KgPP / gcat) of the method is at least 25, more preferably at least 30, more preferably at least 35, more preferably at least 40, wherein CYTi (kgPP / gcat) is calculated according to formula (1): The Ti content in the catalyst and the Ti content in the obtained polymer were determined by inductively coupled plasma mass spectrometry (ICP-MS).

8. The method according to any one of the preceding claims, wherein the cold xylene soluble content (CXS) of the random propylene-ethylene copolymer is 3.0-8.0 wt%, preferably 3.7-6.9 wt%, more preferably 4.6-6.9 wt%, and even more preferably 5.0-6.4 wt%, which is measured by the method described in the "CRYSTEX method for random propylene-ethylene copolymers" section of the measurement method part of the present invention.

9. The method according to any one of the preceding claims, wherein the amount of Ti in the propylene-based polymer, as determined by inductively coupled plasma mass spectrometry (ICP-MS), is at most 1.4 mg / kg of the propylene-based polymer, preferably at most 1.2 mg / kg of the propylene-based polymer, preferably at most 1.0 mg / kg of the propylene-based polymer, and preferably at most 0.5 mg / kg of the propylene-based polymer.

10. The method according to any one of the preceding claims, wherein the internal electron donor is 3,3-bis(methoxymethyl)-2,6-dimethylheptane and / or wherein the activating compound is N,N-dimethylbenzamide.

11. The method according to any one of the preceding claims, wherein the external electron donor comprises or is composed of compounds selected from or formed thereof: Organosilicon Compounds, silanes, alkoxysilanes, alkylsilanes, alkylalkoxysilanes, and aliphatic / aromatic esters, such as dicyclopentyldimethoxysilane, di-tert-butyldimethoxysilane, methylcyclohexyldimethoxysilane, ethylcyclohexyldimethoxysilane, diphenyldimethoxysilane, diisopropyldimethoxysilane, di-n-propyldimethoxysilane, diisobutyldimethoxysilane, di-n-butyldimethoxysilane, cyclopentyltrimethoxysilane, isopropyltrimethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, ethyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, cyclopentylpyrrolidinedimethoxysilane, bis(pyrrolyl)-dimethoxysilane, and mixtures thereof, preferably di(isopropyl)dimethoxysilane (DiPDMS).

12. The method according to any one of the preceding claims, wherein the external electron donor further comprises a compound selected from: ethyl acetate, ethyl benzoate, ethyl p-ethoxybenzoate, methyl trimethylacetate, isopropyl myristate, di-n-butyl sebacate, (poly(alkylene glycol) monoacetate or diacetate, (poly(alkylene glycol) monomyristate or dimyristate, (poly(alkylene glycol) monolaurate or dilaurate, (poly(alkylene glycol) monodioleate or dioleate, tri(acetic acid) glycerides, a mixture of glycerides of linoleic acid, oleic acid, palmitic acid and stearic acid, and mixtures thereof, preferably isopropyl myristate.

13. A polypropylene composition obtained or obtainable by the method according to any one of the preceding claims.

14. Articles comprising the polypropylene composition according to claim 13, The amount of the polypropylene composition is at least 95 wt% based on the article, and / or The product can be obtained by injection molding, blow molding, extrusion or compression molding, and / or The product can be: • Household products, such as vacuum cleaner housings, household chemicals and paints, or • Packaging products, such as containers, crates, boxes, battery boxes, barrels, flower pots, food containers / packaging, ice cream containers, thin-walled packaging, lids and seals, films, pouches, health care packaging, or • Health products, such as pharmaceutical products, laboratory equipment, medical devices, medical diagnostic products, or • Automotive interior products, such as dashboard carriers, door panels, front bulkhead panels, front bulkhead panel carriers, door covers, door fasteners, armrests, pillar covers, seat covers, trunk covers, interior trim, or • Products suitable for heating, ventilation, and air conditioning (HVAC) applications.

15. Use of the polypropylene composition according to claim 13 in the preparation of articles. The amount of the polypropylene composition is at least 95 wt% based on the article, and / or The product can be obtained by injection molding, blow molding, extrusion or compression molding, and / or The product can be: • Household products, such as vacuum cleaner housings, household chemicals and paints, or • Packaging products, such as containers, crates, boxes, battery boxes, barrels, flower pots, food containers / packaging, ice cream containers, thin-walled packaging, lids and seals, films, pouches, health care packaging, or • Health products, such as pharmaceutical products, laboratory equipment, medical devices, medical diagnostic products, or • Automotive interior products, such as dashboard carriers, door panels, front bulkhead panels, front bulkhead panel carriers, door covers, door fasteners, armrests, pillar covers, seat covers, trunk covers, interior trim, or • Products suitable for heating, ventilation, and air conditioning (HVAC) applications.

16. A method for preparing an article, comprising the following steps: a. Providing the polypropylene composition according to claim 13, and b. Convert the polypropylene composition into an article, for example, by extrusion or injection molding.

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