Heterophasic propylene copolymer with improved impact resistance at low temperature and dimensional stability

Abstract

The invention relates to a composition comprising a heterophasic propylene copolymer, to a process for obtaining such composition, to the use of such composition and an article comprising such composition.

Description

[0001] HETEROPHASIC PROPYLENE COPOLYMER WITH IMPROVED IMPACT RESISTANCE AT LOW TEMPERATURE AND DIMENSIONAL STABILITY

[0002] This application claims priority to European Application No. EP24184304.4, filed June 25, 2024, which is incorporated herein by reference in its entirety.

[0003] The invention relates to a composition comprising a heterophasic propylene copolymer, to a process for obtaining such composition, to the use of such composition and an article comprising such composition.

[0004] Heterophasic propylene copolymer, also known as impact propylene copolymers or propylene block copolymers, are an important class of polymers due to their attractive combination of mechanical properties, such as impact strength over a wide temperature range and their low cost. These copolymers find a wide range of applications ranging from the consumer industry (for example packaging and housewares), the automotive industry to electrical applications. For applications e.g. electrical application and electrical appliance. However a shortcoming of any semicrystalline material - including heterophasic propylene copolymer suffers from dimensional unstability - shrinkage.

[0005] Therefore, there is still a need to have a heterophasic propylene copolymer having improved impact resistance at low temperature and dimensional stability.

[0006] This need is satisfied by a heterophasic propylene copolymer comprising a propylene based matrix and an ethylene copolymer as dispersed phase, wherein the amount of ethylene copolymer is in the range of 22.5 to 32.5 wt% basing on the total amount of the heterophasic propylene copolymer, wherein the amount of ethylene in the ethylene copolymer is in the range of 45.0 to 56.4 wt% basing on the total amount of the ethylene copolymer, wherein the melt flow index of the heterophasic propylene copolymer is in the range from 5.6 to 25 g / lOmin as measured according to ISO1133 using a 2.16 kg weight and a temperature of 230 °C.

[0007] Propylene based matrix The propylene based matrix may be a propylene homopolymer or a propylene random copolymer of ethylene or a C4 -C20 a-olefin. Preferably the propylene based matrix is a propylene homopolymer.

[0008] Ethylene copolymer as dispersed phase

[0009] The ethylene copolymer according to the invention is preferably an ethylene-a-olefin copolymer wherein the a-olefin is selected from C3-C8 a-olefin. Most preferably the ethylene copolymer is an ethyl ene-propylene copolymer.

[0010] The ethylene copolymer differs from the propylene based matrix to form as dispersed phase.

[0011] The amount of ethylene in the ethylene copolymer is in the range of 45.0 to 56.4 wt%, preferably 48.3 to 56.3 wt%, more preferably 50.0 to 56.3 wt% basing on the total amount of the ethylene copolymer. The amount of ethylene in the ethylene copolymer can be determined e.g. by NMR.

[0012] Nucleating agent

[0013] Preferably the heterophasic propylene copolymer comprises a nucleating agent, wherein the nucleating agent comprises talc and a sodium salt comprising phosphate group.

[0014] Preferably the sodium salt comprising phosphate group is sodium bis(2,2-methylene-bis(4,6-di- tert-butylphenyl)phosphate) which is a commercial product e.g. NA 11 from ADEKA.

[0015] Preferably ratio between the amount of talc and the amount of the sodium salt comprising phosphate group is in the range between 3 to 15, more preferably from 4 to 8.

[0016] Heterophasic propylene copolymer

[0017] The amount of ethylene copolymer is in the range of 22.5 to 32.5 wt%, preferably 26.5 to 31.5 wt% basing on the total amount of the heterophasic propylene copolymer.

[0018] The amount of talc is preferably of from 0.1 to 5 wt%, more preferably from 0.2 to 4 wt%, more preferably from 0.3 to 3 wt%, most preferably from 0.3 to 1 wt% based on the total composition based on the total amount of the heterophasic propylene copolymer. Preferably the total amount of the propylene based matrix, the ethylene copolymer and the nucleating agent is at least 96 wt%, preferably at least 98 wt%, even more preferably at least 99 wt% basing on the total amount of the heterophasic propylene copolymer.

[0019] The melt flow index of the heterophasic propylene copolymer is in the range from 5.6 to 25 g / lOmin, preferably from 8 to 18 g / lOmin, more preferably from 9 to 12 g / lOmin as measured according to ISO1133 using a 2.16 kg weight and a temperature of 230 °C.

[0020] In the embodiment that the ethylene copolymer is an ethyl ene-propylene copolymer, it is preferably that the ratio between the amount of ethylene-propylene copolymer eluted between 4.4- 6.0mL and the amount of ethylene-propylene copolymer eluted between 6.0-8.5mL is in the range from 1.8 to 4.5, more preferably from 2.3 to 3.7. Preferably the amount of the ethylene-propylene copolymer eluted between 4.4-6.0mL is in the range from 20 to 27 wt%, preferably in the range from 21 to 26 wt% basing on the total amount of the heterophasic propylene copolymer. The amount of ethylene-propylene copolymer eluted between 4.4-6.0mL and the amount of ethylene- propylene copolymer eluted between 6.0-8.5mL according to the invention can for example be measured by high-temperature two-dimensional liquid chromatography (HT-2D-LC). Suitable device to carry out the measurement may for example be PolymerChar (Valencia, Spain) solvent gradient chromatograph equipped with an integrated IR5 detector, a binary gradient pump as well as an isocratic pump (both model 1260, Agilent, Waldbronn, Germany). In the context of the present invention sample concentrations of ~ 4.2 mg / mL (solvent 1 -decanol) were used. For dissolution, the samples (heterophasic propylene copolymers) were first heated in an offline dissolution oven at 160 °C with shaking until dissolution. Prior to injection, the sample was allowed a further one hour of dissolution under shaking. The following experimental parameters were chosen: Elution temperature: 160 °C, SGIC flow rate: 0.01 mL / min, injection loop: 200 pL, SGIC stationary phase: Hypercarb® (particle size: 5 pm, column dimensions: 100 x 4.6 mm (L x I.D.) (Thermofisher Scientific, Dreieich, Germany)). As eluent, a 1-decanol —> TCB gradient was used with the following program: 0-200min pure 1-decanol, 200-700min linear gradient from 1- decanol to TCB, 700-900 min pure TCB. The column was then purged for 40 min with 1-decanol at a flow velocity of 0.8 mL / min in order to establish the original adsorption equilibrium in the column again. The mobile phase coming from the Hypercarb® column was collected in 100 pL sample loops. These were injected into the SEC column (PLGel Olexis, 300 x 7.8 mm (L x I D.) (Agilent Technologies, Waldbronn, Germany) every 10 minutes. SEC was analysis in the second dimension was done in TCB at 160 °C, using a flow rate of 1.5 mL / min. Calibration is based on a set of polystyrene standards (PolymerChar, (Valencia, Spain)). Data collection and analysis was performed using the PolymerChar software and processed in the GPC 1 software as well as OriginPro version 2019b.

[0021] The data captured by IR5 detector is then plotted in function of the elution volume.

[0022] For a typical heterophasic propylene copolymer sample, the volume of elution in the range of 4.4 to 8.5 mL represents the signal from the dispersed ethylene propylene copolymer. With the increase of the elution volume, the ethylene content in the eluted ethylene propylene copolymer increases. Therefore the integration of IR5 response between the volume of elution between 4.4- 6.0mL can be used to identify the amount of ethylene-propylene copolymer which is relatively richer in propylene in comparison with that eluted between 6.0-8.5mL. An ethylene-propylene copolymer relatively richer in propylene means that from the structural perspective, ethylene units are incorporated in a more random manner in the ethylene-propylene copolymer. The sum of the amount of ethylene-propylene copolymer eluted between 4.4-6.0mL and the amount of ethylene- propylene copolymer eluted between 6.0-8.5mL can be considered as the total amount of the ethylene-propylene copolymer in the heterophasic propylene copolymer.

[0023] The inventor of the present invention surprisingly found that in the preferred embodiment that the ratio between the amount of ethylene-propylene copolymer eluted between 4.4-6.0mL and the amount of ethylene-propylene copolymer eluted between 6.0-8.5mL is in the range from 1.8 to 4.5, more preferably from 2.3 to 3.7, the heterophasic propylene copolymer may have lower shrinkage.

[0024] Polymerization

[0025] The heterophasic propylene copolymer may be prepared by a process comprising

[0026] - polymerizing propylene in the presence of a catalyst to obtain the propylene-based matrix and

[0027] - subsequently polymerizing ethylene with a-olefins in the presence of a catalyst in the propylene- based matrix to obtain the heterophasic propylene copolymer. These steps are preferably performed in different reactors. The catalysts for the first step and for the second step may be different, but are preferably the same.

[0028] Catalyst

[0029] The catalyst used for the preparation for the polypropylene composition according to the invention is the catalyst described in detail in W02021 / 063930, incorporated herein by reference. The catalyst comprises a procatalyst, a co-catalyst and optionally an external electron donor.

[0030] The procatalyst is obtainable by a process comprising contacting a magnesium-containing support with a halogen-containing titanium compound, and an internal electron donor according to Formula I:

[0031] Formula I wherein R1is a secondary alkyl group and R2is a non-secondary alkyl group having at least 5 carbon atoms, preferably R2is a non-secondary alkyl group having at least 5 carbon atoms and being branched at the 3 -position or further positions.

[0032] The process for providing said procatalyst comprises the steps of: i) contacting a compound R4zMgX42-z with an alkoxy- or aryloxy-containing silane compound to give a first intermediate reaction product, being a solid Mg(0Ra)xXJ2-x, wherein: Rais 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 said hydrocarbyl group may be substituted or unsubstituted, may contain one or more heteroatoms and preferably has from 1 to 20 carbon atoms; wherein R4is a linear, branched or cyclic hydrocarbyl group independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxy carbonyl or alkylaryl groups, and one or more combinations thereof; wherein said hydrocarbyl group may be substituted or unsubstituted, may contain one or more heteroatoms and preferably has from 1 to 20 carbon atoms, preferably R4is butyl; wherein X4and X1are each independently selected from the group of consisting of fluoride (F-), chloride (C1-), bromide (Br-) or iodide (I-), preferably chloride; z is in a range of larger than 0 and smaller than 2, being 0 < z < 2, x is an integer between 0 and 2; ii) optionally contacting the solid Mg(0Ra)xXJ2-x obtained in step i) with at least one activating compound selected from the group formed by 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: M1is a metal selected from the group consisting of Ti, Zr, Hf, Al or Si; v is the valency of M1; M2is a metal being Si; v is the valency of M2; Rband R3are each 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 said 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 smaller than v, preferably v being 3 or 4; iii) contacting the first or second intermediate reaction product, obtained respectively in step i) or ii), with a halogen-containing Ti-compound and said compound represented Formula I, as the internal electron donor.

[0033] In an embodiment, during step ii) as activating compounds an alcohol is used as activating electron donor and titanium tetraalkoxide is used as metal alkoxide compound.

[0034] In an embodiment, an activator is present. In an embodiment, said activator is ethyl benzoate. In an embodiment, said activator is a benzamide according to formula X:

[0035] Formula X wherein R70and R71are each independently selected from hydrogen or an alkyl, and R72, R73, R74, R75, R76are each independently selected from hydrogen, a heteroatom or a hydrocarbyl group, preferably selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl groups, and one or more combinations thereof, more preferably wherein R70and R71are both methyl and wherein R72, R73, R74, and R75are all hydrogen, being N,N’ -dimethylbenzamide (Ba-2Me).

[0036] In some preferred embodiment the activating compound is N-N-dimethylbenzamide.

[0037] Preferably, the internal electron donors used are according to Formula I:

[0038] Formula I wherein R1is a secondary alkyl group having at least three carbon atoms (C3) and R2is a non-secondary alkyl group having at least 5 carbon atoms, preferably R1et R2is having at most seven carbon atoms (C7), preferably at most six carbon atoms (C6), preferably isopropyl, iso-butyl, iso-pentyl, cyclopentyl, n-pentyl, and iso-hexyl, preferably R2is being branched at the 3 -position or further positions

[0039] In another embodiment, the internal electron donor is 3,3-bis(methoxymethyl)-2,6-dimethyl heptane, according to Formula I wherein R1is iso-propyl being secondary alkyl and R2is isopentyl being non-secondary and having a branch on the third carbon atom (abbreviated as iPiPen, wherein iP stands for iso-propyl and iPen stands for iso-pentyl, also known as 3-methyl-butyl).

[0040] This compound iPiPen has a chemical formula of C13H28O2; an exact mass of 216.21 and a molecular weight of 216.37. In a more preferred embodiment of the invention, iPiPen is used as internal donor and N,N-dimethylbenzamide is preferably used as activator. iPiPen In another embodiment, the internal electron donor is (l-methoxy-2-(methoxymethyl)-5- methylhexan-2-yl)cyclopentane, according to Formula I wherein R1is secondary alkyl cyclopentyl and R2is secondary cyclopentyl (abbreviated as CPiPen, wherein CP stands for cyclopentyl and iPen stands for iso-pentyl, also known as 3-methyl-butyl). This compound CPiPen has a chemical formula of C15H30O2; an exact mass of 242.22 and a molecular weight of 242.40. In a more specific embodiment, CPiPen is used as internal donor and N,N-dimethylbenzamide is preferably used as activator.

[0041] CPIPen

[0042] In another embodiment, the internal electron donor is 3,3-bis(methoxymethyl)-2,7-dimethyloctane, according to Formula I wherein R1is the secondary alkyl iso-propyl and R2is non-secondary isohexyl with a branch on the third carbon atom (abbreviated as iPiHex, wherein iP stands for isopropyl and iHex stands for iso-hexyl, also known as 4-methyl-pentyl). This compound iPiHex has a chemical formula of C14H30O2; an exact mass of 230.22 and a molecular weight of 230.39. In a more specific embodiment, iPiHex is used as internal donor and N,N-dimethylbenzamide is preferably used as activator. iPiHex

[0043] In another embodiment, the internal electron donor is 3,3-bis(methoxymethyl)-2-methyloctane, according to Formula I wherein R1is secondary alkyl iso-propyl and R2is non-secondary nonbranched n-pentyl (abbreviated as iPnPen, wherein iP stands for iso-propyl and nPen stands for n- pentyl). This compound iPnPen has a chemical formula of C13H28O2; an exact mass of 216.21 and a molecular weight of 216.37. In a more specific embodiment, iPnPen is used as internal donor and N,N-dimethylbenzamide is preferably used as activator. iPnPen

[0044] In another embodiment, the internal electron donor is 3,3-bis(methoxymethyl)-2,6-dimethyloctane, according to Formula I wherein R1is secondary alkyl iso-propyl and R2is non-secondary branched iso-hexyl having a branch at the third carbon atom (abbreviated as iPiHex, wherein iP stands for iso-propyl and wherein iHex stands for iso-hexyl, also known as 3-methyl-pentyl). This compound iPiHex has a chemical formula of C14H32O2 ; an exact mass of 230.22 and a molecular weight of 230.39. In a more specific embodiment, iPiHex is used as internal donor and N,N-dimethylbenzamide is preferably used as activator. iPiHex

[0045] In an embodiment, the substituent R1is isopropyl or cyclopentyl. In an embodiment, the substituent R2is isopentyl or isohexyl. The below table shows the embodiments above with their abbreviations and the R1and R2groups as well if these groups are secondary or not and branched or not.

[0046] According to the present invention, it is further preferred that R1is a secondary alkyl group and R2is a non-secondary alkyl group being branched at the 3-position or further positions. In some preferred embodiment, the co-catalyst is selected from the group consisting of trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, diisobutylaluminum hydride, trioctylaluminium, dihexylaluminum hydride and mixtures thereof.

[0047] Preferably, the external electron donors are chosen from the group of compounds having a structure according to:

[0048] - Formula III : (R90)2N— Si(OR91)3,

[0049] - Formula IV: (R92)Si(OR93)3,

[0050] Formula V: Si(ORa)4-nRbn, and

[0051] - mixtures thereof, wherein each of R90, R91, R92and R93groups are each independently a linear, branched or cyclic, substituted or unsubstituted alkyl having between 1 and 10 carbon atoms, preferably wherein R90, R91, R92and R93groups are each independently a linear unsubstituted alkyl having between 1 and 8 carbon atoms, wherein n can be from 0 up to 2, and each of Raand Rb, independently, represents an alkyl or aryl group, optionally containing one or more hetero atoms for instance O, N, S or P, with, for instance, 1-20 carbon atoms.

[0052] For example the external electron donors maybe ethyl, methyl or n-propyl, for example diethylaminotriethoxysilane (DEATES), n-propyl triethoxysilane, (nPTES), n-propyl trimethoxysilane (nPTMS), diisobutyl dimethoxysilane (DiBDMS), t-butyl isopropyl dimethyxysilane (tBuPDMS), cyclohexyl methyldimethoxysilane (CHMDMS), dicyclopentyl dimethoxysilane (DCPDMS) or di(iso-propyl) dimethoxysilane (DiPDMS). More preferably, the external electron donor is chosen from the group of di(iso-propyl) dimethoxysilane (DiPDMS) or diisobutyl dimethoxysilane (DiBDMS).

[0053] Preferably, the external donor comprises or consists of a compound selected from the list comprising organo-silicon compounds, silanes, alkoxy silanes, alkyl silane, alkyl alkoxy silane and aliphatic / aromatic ester, for example dicyclopentyldimethoxysilane, di-tert- butyldimethoxysilane, methylcyclohexyldimethoxysilane, ethylcyclohexyldimethoxysilane, diphenyldimethoxysilane, diisopropyldimethoxysilane, di-n-propyldimethoxysilane, diisobutyldimethoxysilane, di-n-butyldimethoxysilane, cyclopentyltrimethoxysilane, isopropyltrimethoxysilane, npropyltrimethoxysilane, n-propyltriethoxysilane, ethyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, cyclopentylpyrrolidinodimethoxysilane, bis(pyrrolidino )- dimethoxysilane, and mixtures thereof, preferentially di(iso-propyl) dimethoxysilane (DiPDMS)

[0054] The compounds mentioned above as examples of the external electron donor are sometimes referred as Selectivity Control Agent (SCA). The external electron donor may consist of SCA. Alternatively, in addition to SCA, the external electron donor may further comprise compounds known as an activity limiting agent (ALA). Preferably, the Activity Limiting Agent (ALA) is selected from the group consisting of: ethyl acetate, ethyl benzoate, p-ethoxy ethyl benzoate, methyl trimethylacetate, isopropyl myristate, di-n-butyl sebacate, (poly)(alkylene glycol) mono- or diacetates, (poly)(alkylene glycol) mono- or di-myristates, (poly)(alkylene glycol) mono- or dilaurates, (poly)(alkylene glycol) mono- or di-dioleates, glyceryl tri(acetate), mixed glycerides of linoleic, oleic, palmitic and stearic acids, and mixtures thereof. More preferably, the Activity Limiting Agent (ALA) is isopropyl myristate.

[0055] The ratio of Selectivity Control Agent (SCA) to Activity Limiting Agent (ALA) is in principle not critical, best results are obtained for a SCA / ALA ratio in the range from 0.010 to 100, more preferably in the range from 0.10 to 20.

[0056] The molar ratio of Al in the co-catalyst to Si in the external electron donor may e.g. be 1 to 120.

[0057] In a preferred embodiments, the molar ratio of Al in the co-catalyst to Si in the external electron donor is 1 to 25, preferably 1 to 15, preferably 3 to 10, more preferably 3.5 to 8. The relatively low molar ratio of Al / Si results in a higher stiffness of the composition.

[0058] Preferably the molar ratio between the external donor and the pro catalyst is in the range from 15 to 35, more preferably from 18 to 30.

[0059] Peroxide shifting

[0060] Preferably the heterophasic propylene copolymer is prepared in a process comprising a peroxide shifting step. The term “peroxide shifting” or "visbreaking" is well known in the field of the invention. For example methods of visbreaking polypropylene have been disclosed in US 4,282,076 and EP 0063654.

[0061] Several different types of chemical reactions which are well known can be employed for visbreaking propylene polymers. An example is thermal pyrolysis, which is accomplished by exposing a polymer to high temperatures, e.g., in an extruder at 350 °C or higher. Another approach is exposure to powerful oxidizing agents. A further approach is exposure to ionizing radiation. It is preferred however that visbreaking is carried out using a peroxide. Such materials, at elevated temperatures, initiate a free radical chain reaction resulting in beta-scission of the polypropylene molecules. The visbreaking may be carried out directly after polymerisation and removal of unreacted monomer and before pelletisation (during extrusion in an extruder wherein shifting of the intermediate heterophasic propylene copolymer occurs). However, the invention is not limited to such an embodiment and visbreaking may also be carried out on already pelletised polypropylene, which polypropylene generally contains stabilisers to prevent degradation.

[0062] Examples of suitable peroxides include organic peroxides having a decomposition half-life of less than 1 minute at the average process temperature during the visbreaking step. Suitable organic peroxides include but are not limited to dialkyl peroxides, e.g. dicumyl peroxides, peroxyketals, peroxycarbonates, diacyl peroxides, peroxyesters and peroxydicarbonates. Specific examples of these include benzoyl peroxide, dichlorobenzoyi peroxide, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(peroxybenzoato)-3-hexene, l,4-bis(tert- butylperoxyisopropyl)benzene, lauroyl peroxide, tert-butyl peracetate, a,a'-bis(tert- butylperoxy)diisopropylbenzene (Luperco® 802), 2,5- dimethyl-2,5-di(tert-butylperoxy)-3- hexene, 2,5-dimethyl-2,5-di(tert-butylperoxy)-hexane, tert-butyl perbenzoate, tert-butyl perphenylacetate, tert-butyl per-sec-octoate, tert-butyl perpivalate, cumyl perpivalate, cumene hydroperoxide, diisopropyl benzene hydroperoxide, 1 ,3-bis(t-butylperoxy- isopropylbenzene, dicumyl peroxide, tert-butylperoxy isopropyl carbonate and any combination thereof. Preferably, a dialkyl peroxides is employed in the process according to the present invention. More preferably, the peroxide is a,a'-bis-(tert-butylperoxy)diisopropylbenzene, 2,5- dimethyl-2,5-di(tert- butylperoxy)-hexane or 3,6,9-Triethyl-3,6,9-trimethyl-l ,4,7-triperoxonane. Preferably, the peroxide is selected from the group of non-aromatic peroxides.

[0063] It can easily be determined by the person skilled in the art through routine experimentation how much peroxide should be used to obtain a composition having the desired melt flow rate. This also depends on the half-life of the peroxide and on the conditions used for the melt-mixing, which in turn depend on the exact composition.

[0064] Preferably the MFI of the heterophasic propylene copolymer is in the range from 0.4 to 3.3 g / lOmin, preferably from 1.5 to 2.5 g / lOmin as measured according to ISO1133 using a 2.16 kg weight and a temperature of 230 °C prior to the peroxide shifting step.

[0065] Forming process and suitable applications

[0066] The heterophophasic propylene copolymer according to the invention may be extrusion moulded or injection moulded in to an article.

[0067] The article may be for rigid packaging application or may be an automotive part.

[0068] Experiment

[0069] Material

[0070] For the preparation of the resin part of the inventive example (IE), the procatalyst was prepared according to the method disclosed in W02021 / 063930A1, example 1. The co-catalyst for the preparation of IES is TEA and external electron donor is DiPDMS. The Al / Si ratio is 5, Al / Si is the molar ratio of the co-catalyst (TEA) to the external donor (DiPDMS).

[0071] For the preparation of the resin part of the comparative example (CE), the procatalyst is INcat P420 commercially available from INEOS Polyolefin Catalyst and prepared according to the instructions of the manufacturer.

[0072] Both IE and CE are heterophasic propylene copolymers. The examples were produced in a gasphase polymerization process which was performed in two horizontally stirred gas-phase reactors (R1 and R2) with downstream powder processing units (= degassing & catalyst deactivation) for powder collection. Then the powder was introduced in an extruder for peroxide shifting, adding an additive package consisting of 2000 ppm stabilizers, 4500 ppm talc, 900 ppm Mina 11 from Milliken and 450 ppm light stabilizer basing on the total amount of the example and pelletization. During the pelletization, the MFR of the examples have been peroxide shifted from MFR initial to

[0073] MFR final

[0074] Catalyst compositions of the examples is shown in Table 1.

[0075] Table 1 Catalyst compositions of the examples Si / Ti is the ratio of the external donor (DiPDMS) to the procatalyst. The pressure setting of both reactors for all examples is in the range from 21 to 23 MPa. The temperature of both reactors for all examples is in the range from 62 to 68 °C.

[0076] The composition of IE1, IE2, and and CE1 are shown in Table 2:

[0077] Table 2 Composition of the examples

[0078] Measurement

[0079] MFR

[0080] The MFR hopol, MFR initial and MFR final of the heterophasic propylene copolymer composition, the matrix phase and the dispersed phase measured according to ISO1133 using a

[0081] 2.16 kg load at 230°C.

[0082] RCC2

[0083] RCC2 was determined by13C-NMR spectroscopy. Approximately 150 mg of material was dissolved in l,l,2,2-tetrachloroethane-d2 (TCE-d2). To ensure a homogeneous solution, the sample preparation has been conducted in a heated rotary oven. The NMR measurements were carried out in the solution-state using a Bruker 500 Advance III HD spectrometer operating at

[0084] 500.16 and 125.78 MHz for 1H and 13C, respectively, and equipped with a 10 mm DUAL cryogenically-cooled probe head operating at 125 °C. The 13C-NMR experiments were performed using standard single pulse excitation utilizing the NOE and bi-level WALTZ 16 decoupling scheme (Zhou Z. et al. J. Mag. Reson 187 (2007) 225. A total of 512 transients were acquired per spectrum. The spectra were calibrated by setting the central signal of TCE’s triplet at 74.2 ppm. Quantitative 13C NMR spectra were processed, integrated and relevant quantitative properties determined from the integrals using proprietary computer programs.

[0085] Impact resistance

[0086] The notched Izod was measured in accordance with ISO 180 / 4 A. The test specimen was injection moulded and prepared to a length of 63.5 mm, a width of 12.7 mm and a thickness of 3.2 mm. The notched Izod was determined by measuring in the perpendicular direction on the flow direction. To allow after-crystallization to occur, the test specimen was stored for 14 days under standard conditions of 0 °C, -10 °C and -20 °C / 50% atmospheric humidity.

[0087] High-temperature two-dimensional liquid chromatography (HT-2D-LC) to determine RC and amount of ethyl ene-propylene copolymer eluted between 4.4-6.0mL and between 6.0-8.5 mL

[0088] Elution volume of the samples were measured by HT-2D-LC performed on PolymerChar (Valencia, Spain) solvent gradient chromatograph equipped with an integrated IR5 detector, a binary gradient pump as well as an isocratic pump (both model 1260, Agilent, Waldbronn, Germany). Sample concentrations of- 4.2 mg / mL (solvent 1-decanol) were used. For dissolution, the samples were first heated in an offline dissolution oven at 160 °C with shaking until dissolution. Prior to injection, the sample was allowed a further one hour of dissolution under shaking. The following experimental parameters were chosen: Elution temperature: 160 °C, SGIC flow rate: 0.01 mL / min, injection loop: 200 pL, SGIC stationary phase: Hypercarb® (particle size: 5 pm, column dimensions: 100 x 4.6 mm (L x I.D.) (Thermofisher Scientific, Dreieich, Germany)). As eluent, a 1-decanol —> TCB gradient was used with the following program: 0-200min pure 1- decanol, 200-700min linear gradient from 1-decanol to TCB, 700-900 min pure TCB. The column was then purged for 40 min with 1-decanol at a flow velocity of 0.8 mL / min in order to establish the original adsorption equilibrium in the column again. The mobile phase coming from the Hypercarb® column was collected in 100 pL sample loops. These were injected into the SEC column (PLGel Olexis, 300 x 7.8 mm (L x I.D.) (Agilent Technologies, Waldbronn, Germany) every 10 minutes. SEC was analysis in the second dimension was done in TCB at 160 °C, using a flow rate of 1.5 mL / min. Calibration is based on a set of polystyrene standards (PolymerChar, (Valencia, Spain)). Data collection and analysis was performed using the PolymerChar software and processed in the GPC 1 software as well as OriginPro version 2019b. The data captured by IR5 detector is then plotted in function of the elution volume.

[0089] For a typical heterophasic propylene copolymer sample, the volume of elution in the range of 4.4 to 8.5 mL represents the signal from the dispersed ethylene propylene copolymer. With the increase of the elution volume, the ethylene content in the eluted ethylene propylene copolymer increases. Therefore the integration of IR5 response between the volume of elution between 4.4- 6.0mL can be used to identify the a portion of ethyl ene-propylene comonomer which is relatively richer in propylene in comparison with that eluted between 6.0-8.5mL. The amounts of ethylenepropylene copolymer eluted in the range of 4.4-6.0 mL and of ethyl ene-propylene copolymer eluted in the in the range of 6.0-8.5 mL are presented in the result table.

[0090] Shrinkage measurement

[0091] Shrinkage was measured according to ISO 294-4 in two batches, the Samples of Batch 1 have been condition at 23 °C for 24 h after preparation of the samples by injection moulding and prior to the measurement; the Samples of Batch 2 were obtained also by injection moulding, then the samples have been annealed at 90°C for 1 h then conditioned at 23 °C for 24h prior to shrinkage measurement. 10 Samples have been measured in each batch.

[0092] Results

[0093] Table 3. Properties of examples IE1, IE2 and comparative example CE1

[0094] As clearly illustrated in Table 3, IES according to the invention have shown improve improved dimensional stability and impact resistance at low temperature.

Claims

CLAIMS1. A heterophasic propylene copolymer comprising a propylene based matrix and an ethylene copolymer as dispersed phase, wherein the amount of ethylene copolymer is in the range of 22.5 to 32.5 wt% basing on the total amount of the heterophasic propylene copolymer, wherein the amount of ethylene in the ethylene copolymer is in the range of 45.0 to 56.4 wt% basing on the total amount of the ethylene copolymer, wherein the melt flow index of the heterophasic propylene copolymer is in the range from 5.6 to 25 g / lOmin as measured according to ISO1133 using a 2.16 kg weight and a temperature of 230 °C.

2. The heterophasic propylene copolymer according to claim 1, wherein the amount of ethylene copolymer is in the range of 26.5 to 31.5 wt% basing on the total amount of the heterophasic propylene copolymer.

3. The heterophasic propylene copolymer according to claim 1 or 2, wherein the amount of ethylene in the ethylene copolymer is in the range of 48.3 to 56.3 wt%, preferably 50.0 to 56.3 wt% basing on the total amount of the ethylene copolymer.

4. The heterophasic propylene copolymer according to any one of the previous claims wherein the MFI of the heterophasic propylene copolymer is in the range from 8 to 18 g / lOmin, preferably from 9 to 12 g / lOmin as measured according to ISO1133 using a 2.16 kg weight and a temperature of 230 °C.

5. The heterophasic propylene copolymer according to any one of the previous claims wherein the ethylene copolymer is an ethylene-propylene copolymer.

6. The heterophasic propylene copolymer according to claim 5 wherein, wherein the ratio between the amount of ethylene-propylene copolymer eluted between 4.4-6.0mL and the amount of ethylene-propylene copolymer eluted between 6.0-8.5mL is in the range from 1.8 to 4.5, more preferably from 2.3 to 3.7.

7. The heterophasic propylene copolymer according to any one of the previous claims wherein the heterophasic propylene copolymer is prepared in a process comprising a peroxide shifting step.

8. The heterophasic propylene copolymer according to claim 7 wherein the MFI of the heterophasic propylene copolymer is in the range from 0.4 to 3.3 g / lOmin, preferably from 1.5 to 2.5 g / lOmin as measured according to ISO1133 using a 2.16 kg weight and a temperature of 230 °C prior to the peroxide shifting step.

9. The heterophasic propylene copolymer according to any one of the previous claims wherein the heterophasic propylene copolymer is produced in a process comprises the step of polymerizing propylene and ethylene comonomers in the presence of a catalyst in a gas phase, wherein said catalyst comprises a procatalyst, a co-catalyst and optionally an external electron donor, wherein the procatalyst is obtainable by a process comprising the steps of: contacting a magnesium-containing support with a halogen-containing titanium compound, and an internal electron donor according to Formula I:Formula I wherein R1is a secondary alkyl group and R2is a non-secondary alkyl group having at least 5 carbon atoms, preferably R2is a non-secondary alkyl group having at least 5 carbon atoms and being branched at the 3 -position or further positions; said procatalyst is prepared according to the following steps: i) contacting a compound R4zMgX42-z with an alkoxy- or aryloxy-containing silane compound to give a first intermediate reaction product, being a solid Mg(ORa)xXJ2-x, wherein: Rais 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 said hydrocarbyl group may be substituted or unsubstituted, may contain one or more heteroatoms and preferably has from 1 to 20 carbon atoms; wherein R4is a linear, branched or cyclic hydrocarbyl group independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxy carbonyl or alkylaryl groups, and one or more combinations thereof; wherein said hydrocarbyl group may be substituted or unsubstituted, may contain one or more heteroatoms and preferably has from 1 to 20 carbon atoms, preferably R4is butyl; wherein X4and X1are each independently selected from the group ofconsisting of fluoride (F-), chloride (C1-), bromide (Br-) or iodide (I-), preferably chloride; z is in a range of larger than 0 and smaller than 2, being 0 < z < 2, x is an integer between 0 and 2; ii) optionally contacting the solid Mg(0Ra)xX12-x obtained in step i) with at least one activating compound selected from the group formed by activating electron donors and metal alkoxide compounds of formula M1(0Rb)v-w(0R3)w or M2(ORb)v-w(R3)w, to obtain a second intermediate product; wherein: M1is a metal selected from the group consisting of Ti, Zr, Hf, Al or Si; v is the valency of M1; M2is a metal being Si; v is the valency of M2; Rband R3are each 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 said 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 smaller than v, preferably v being 3 or 4; iii) contacting the first or second intermediate reaction product, obtained respectively in step i) or ii), with a halogen-containing Ti-compound and said compound represented Formula I, as the internal electron donor.

10. The heterophasic propylene copolymer according to claim 9, wherein the co-catalyst is selected from the group consisting of trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, di -isobutylaluminum hydride, trioctylaluminium, dihexylaluminum hydride and mixtures thereof.

11. The heterophasic propylene copolymer according to any one of claims 9 or 10, the catalyst comprises an external donor, wherein the external electron donor is a silane containing external donor, preferably wherein the external electron donor is selected from the group of compounds having a structure according to:- Formula III : (R90)2N— Si(OR91)3,- Formula IV: (R92)Si(OR93)3, Formula V: Si(ORa)4-nRbn, and- mixtures thereof, wherein each of R90, R91, R92and R93groups are each independently a linear, branched or cyclic, substituted or unsubstituted alkyl having between 1 and 10 carbon atoms, preferably wherein R90,R91, R92and R93groups are each independently a linear unsubstituted alkyl having between 1 and 8 carbon atoms, wherein n can be from 0 up to 2, and each of Raand Rb, independently, represents an alkyl or aryl group, optionally containing one or more hetero atoms for instance O, N, S or P, with, for instance, 1-20 carbon atoms.

12. The heterophasic propylene copolymer according to any one of claims 9 to 11, wherein the molar ratio of co-catalyst to external electron donor is in the range from 1 to 25, preferably 1 to 15, preferably 3 to 10, more preferably 3.5 to 8.

13. The heterophasic propylene copolymer according to any one of claims 9 to 12, wherein an activator is present in the process for the preparation of the procatalyst, the activator preferably being a benzamide according to formula X:wherein R70and R71are each independently selected from hydrogen or an alkyl, and R72, R73, R74, R75, R76are each independently selected from hydrogen, a heteroatom or a hydrocarbyl group, preferably selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl groups, and one or more combinations thereof, more preferably wherein R70and R71are both methyl and wherein R72, R73, R74, and R75are all hydrogen, being N,N’ -dimethylbenzamide (Ba-2Me).

14. The heterophasic propylene copolymer according to any one of the claims 5 to 13 wherein the amount of the ethyl ene-propylene copolymer eluted between 4.4-6.0mL is in the range from 20 to 27 wt%, preferably in the range from 21 to 26 wt% basing on the total amount of the heterophasic propylene copolymer.

15. An article comprising the heterophasic propylene copolymer according to any one of the previous claims wherein the article is rigid packaging application or an automotive part.

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