Heterophasic propylene copolymers with improved stiffness and stress whitening

Abstract

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

Description

[0001] The present invention relates to a composition comprising a multiphase propylene copolymer, a method for obtaining such a composition, the use of such a composition, and articles comprising such a composition.

[0002] Multiphase propylene copolymers, also known as impact-resistant propylene copolymers or propylene block copolymers, are an important class of polymers due to their attractive mechanical properties, such as impact strength over a wide temperature range, and their low cost. These copolymers have a variety of applications, including the consumer goods industry (such as packaging and household goods), the automotive industry, and electrical applications. For applications such as electrical equipment, parts made of multiphase propylene copolymers are prone to whitening after being subjected to mechanical impact. This phenomenon, known as stress whitening, is undesirable for applications requiring aesthetically pleasing surfaces. Improving stress whitening performance often compromises other properties of multiphase propylene copolymers, such as mechanical properties.

[0003] Therefore, there remains a need for multiphase propylene copolymers that exhibit improved stress whitening properties without degrading mechanical properties. Specifically, it is desirable to provide multiphase propylene copolymers that offer improved stress whitening properties while also possessing, or even improved, stiffness without compromising low-temperature impact resistance.

[0004] The above requirements need to be met by a multiphase propylene copolymer comprising a propylene matrix and an ethylene copolymer as a dispersed phase, wherein the amount of ethylene copolymer is in the range of 8.5 to 12.5 wt% based on the total weight of the multiphase propylene copolymer, wherein the amount of ethylene in the ethylene copolymer is in the range of 32.0 to 40.0 wt% based on the total weight of the ethylene copolymer, and wherein the melt flow index of the multiphase propylene copolymer is in the range of 15 to 35 g / 10 min, determined according to ISO 1133 using a weight of 2.16 kg and a temperature of 230 °C.

[0005] Acrylic matrix

[0006] The propylene-based matrix can be a propylene homopolymer or a random copolymer of propylene with ethylene or a C4-C20 α-olefin. Preferably, the propylene-based matrix is ​​a propylene homopolymer.

[0007] Ethylene copolymer as the dispersed phase

[0008] The ethylene copolymer of the present invention is preferably an ethylene-α-olefin copolymer, wherein the α-olefin is selected from C3-C8 α-olefins. Most preferably, the ethylene copolymer is an ethylene-propylene copolymer.

[0009] Ethylene copolymers differ from propylene-based matrices in forming dispersed phases.

[0010] The amount of ethylene in the ethylene copolymer is in the range of 32.0 to 40.0 wt%, preferably in the range of 34.0 to 40.0 wt%, more preferably in the range of 35.0 to 39.0 wt%, based on the total weight of the ethylene copolymer.

[0011] nucleating agent

[0012] Preferably, the multiphase propylene copolymer contains a nucleating agent, wherein the nucleating agent comprises talc and a cyclic dicarboxylate compound.

[0013] Cyclic dicarboxylate compounds have formula (I):

[0014]

[0015] Such nucleating compositions are described in WO2014202603 and WO2014202604.

[0016] Milliken's commercial Hyperform ® HPN-20E™ nucleating agent contains a calcium cis-hexahydrophthalate compound of formula (I) and a stearate-containing compound as an acid scavenger such as zinc stearate.

[0017] Preferably, the ratio between the amount of talc and the amount of the cyclic dicarboxylate compound is in the range of 13 to 26, more preferably in the range of 15 to 23, and even more preferably in the range of 18 to 22.

[0018] Multiphase propylene copolymer

[0019] The amount of ethylene copolymer is in the range of 8.5 to 12.5 wt%, preferably in the range of 8.5 to 11.5 wt%, more preferably in the range of 8.5 to 10.4 wt%, and most preferably in the range of 8.5 to 9.5 wt%, based on the total weight of the multiphase propylene copolymer. In the context of this invention, the amount of ethylene copolymer in the multiphase propylene copolymer and the amount of ethylene comonomer in the ethylene copolymer can be determined by FT-IR during polymerization.

[0020] The amount of the cyclic dicarboxylate compound can be from 0.0025 to 0.1 wt%, based on the total weight of the multiphase propylene copolymer; preferably at least 0.004, 0.005, 0.008, 0.01 wt% and / or at most 0.08, 0.06, 0.05, 0.03 wt%, based on the total weight of the multiphase propylene copolymer. The amount of talc in the polymer composition is preferably from 0.1 to 5 wt%, more preferably from 0.2 to 4 wt%, even more preferably from 0.3 to 3 wt%, and most preferably from 0.3 to 1 wt%, based on the total composition and the total weight of the multiphase propylene copolymer.

[0021] Preferably, the total amount of the propylene-based matrix, ethylene copolymer, and nucleating agent is at least 96 wt%, more preferably at least 98 wt%, and even more preferably at least 99 wt%, based on the total weight of the multiphase propylene copolymer.

[0022] The melt flow index of the multiphase propylene copolymer is in the range of 15 to 35 g / 10 min, preferably in the range of 17 to 29 g / 10 min, more preferably in the range of 18 to 25 g / 10 min, and even more preferably in the range of 19 to 22 g / 10 min, as determined by ISO 1133 using a weight of 2.16 kg and a temperature of 230 °C.

[0023] To concentrate the rubber content of the multiphase propylene copolymer, preparative temperature rise elution fractionation (p-TREF) was performed. Approximately 1 gram of material was completely dissolved in 150 mL of xylene at 130 °C, and the solution was then slowly cooled to 30 °C at a rate of 0.1 °C / min. After cooling, the solution was reheated, and the rubber fraction was collected at 98 °C, while a second fraction (mainly iPP) was collected by further raising the temperature to 130 °C. Each fraction was dried to constant weight and measured.

[0024] The first fraction collected at 98 °C was further measured using high-temperature two-dimensional liquid chromatography (HT-2D-LC). HT-2D-LC provides information on the chemical composition and molar mass distribution (CCD and MMD) of the sample components. Although these two microstructural parameters can be obtained independently, HT-2D-LC directly correlates them in a single experiment. The two dimensions are converted from the first dimension (solvent gradient interaction chromatography, SGIC) to the second dimension (size exclusion chromatography, SEC) using a modulation valve.

[0025] In the first dimension, separation is based on chemical composition, specifically short-chain branching in this case. Copolymer composition is retained based on ethylene segment length (i.e., from random copolymers to block copolymers with long ethylene sequence lengths). Therefore, this method quantifies the differences in ethylene binding within the EPR phase. In the second dimension, separation is based on copolymer chain size.

[0026] Using GPC-1 software, data calculated from HT-2D-LC results were converted into projected profile information. The profile was plotted as the elution volume response to the IR5 detector in the first dimension. First-dimensional calibration was then used to convert the elution volume dimension into chemical composition distribution information.

[0027] Preferably, the C2 (ethylene) content of the multiphase propylene copolymer of the present invention at the peak elution volume is at least 3.5 mol%, more preferably at least 4.5 mol%, even more preferably at least 5 mol%, and still more preferably at least 5.5 mol%. The elution volume can be determined, for example, by high-temperature two-dimensional liquid chromatography (HT-2D-LC). A suitable device for the measurement can be, for example, a PolymerChar (Valencia, Spain) solvent gradient chromatograph equipped with an integrated IR5 detector, a binary gradient pump, and an isocratic pump (both model 1260, Agilent, Waldbronn, Germany). In the context of the present invention, the elution volume of the multiphase propylene copolymer is determined as follows: using a sample concentration of approximately 4.2 mg / mL (solvent 1-decyl alcohol). For dissolution, the sample is first heated by shaking at 160°C in an offline autosampler until dissolved. The sample is allowed to dissolve further by shaking for 1 hour before injection. The following experimental parameters were selected: elution temperature, 160℃; SGIC flow rate, 0.01 mL / min; injection loop, 200 μL; SGIC stationary phase, Hypercarb. ® (Particle size, 5 μm; column size, 100 × 4.6 mm (LxI.D.) (Thermofisher Scientific, Dreieich, Germany)). A 1-decyl alcohol → TCB conversion was used as the eluent, with the following procedure: linear conversion from 1-decyl alcohol to TCB from 0–1000 min, followed by pure TCB from 1000–1200 min. The column was then washed with 1-decyl alcohol at a flow rate of 0.8 mL / min for 40 min to re-establish the original adsorption equilibrium in the column. (Source: Hypercarb) ® The mobile phase from the column was collected in 100 μL sample loops. These were injected into the SEC column (PLGel Olexis, 300 × 7.8 mm (L × ID) (Agilent Technologies, Waldbronn, Germany)) every 10 minutes. SEC analysis in the second dimension was performed in a TCB at 160 °C using a flow rate of 1.5 mL / min. Calibration for the first dimension was based on a narrowly distributed set of ethylene-propylene copolymers with varying amounts of ethylene. Calibration for the second dimension was based on a narrowly distributed set of polystyrene standards (PolymerChar, (Valencia, Spain)). Data collection and analysis were performed using PolymerChar software and processed in GPC1 software and OriginPro version 2019b.

[0028] For chromatographic evaluation, the peaks and center of distribution (COD) of the eluted rubber component are selected. Peak elution volume is often used as a typical characteristic of the eluted substance in chromatography, where the peak shape is symmetrical. On the other hand, when the peaks show a lack of symmetry or skewness, the center of mass (COG), center of mass (COM), or COD becomes a better descriptor. After calibrating the first dimension using a narrowly distributed ethylene-propylene copolymer, the following linear calibration equation is established for this system:

[0029] Calibration equation

[0030] [C]mol.% = 21.6996 × (first-dimensional elution volume) - 65.9464

[0031] Intercept -65.9464 ± 1.1325 mol.%

[0032] Slope 21.6996±0.2108

[0033] Therefore, the ethylene content at the peak elution volume is a parameter associated with the bonding mode of the ethylene comonomers in the multiphase propylene copolymer. Surprisingly, multiphase propylene copolymers with a preferred ethylene content at the peak elution volume have been found to exhibit improved mechanical properties and stress whitening behavior.

[0034] Preferably, the flexural modulus of the multiphase propylene copolymer is at least 1700 MPa, more preferably at least 1750 MPa, as determined according to ASTM D790.

[0035] Preferably, the notched Izod value of the multiphase propylene copolymer is at least 2.5 kJ / m. 2 According to ISO 180 / 4A.

[0036] Preferably, the stress whitening value of the multiphase propylene copolymer is at most 210 mm. 2 Preferably up to 200mm 2 .

[0037] Polymerization reaction

[0038] Multiphase propylene copolymers can be prepared by a method including the following steps:

[0039] - Polymerize propylene in the presence of a catalyst to obtain a propylene-based matrix; and

[0040] Subsequently, ethylene is polymerized with α-olefins in a propylene-based matrix in the presence of a catalyst to obtain a multiphase propylene copolymer. These steps are preferably carried out in different reactors. The catalysts for the first and second steps may be different, but are preferably the same.

[0041] catalyst

[0042] The catalyst used for preparing the polypropylene composition of the present invention is the catalyst described in detail in WO2021 / 063930, which is incorporated herein by reference. The catalyst comprises a main catalyst, a cocatalyst and an optional external electron donor.

[0043] The main catalyst can be obtained by a method including contacting a magnesium-containing support with a halogen-containing titanium compound and an internal electron donor of formula I:

[0044] Formula I

[0045] where R 1 is a secondary alkyl group and 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 further positions.

[0046] The method for providing the main catalyst comprises the following steps:

[0047] 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, i.e., solid Mg(OR a ) x X 1 2-x , where: R a is a straight-chain, branched or cyclic hydrocarbon group independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl groups and combinations of one or more 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 or cyclic hydrocarbon group independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl groups and combinations of one or more thereof, where the hydrocarbon group may be substituted or unsubstituted, may contain one or more heteroatoms, and preferably has 1-20 carbon atoms, R 4 is preferably 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 between 0 and 2;

[0048] ii) optionally contacting the solid Mg(ORa ) x X 1 2-x With activated electron donors and formula M 1 (OR b ) v-w (OR 3 ) w Or M 2 (OR b ) v-w (R 3 ) w The metal alkoxide compound is contacted with at least one activated compound to obtain a second intermediate; wherein: M 1 ν is a metal selected from Ti, Zr, Hf, Al, or Si; ν is M 1 The valence state of M; 2 For metal Si; for metal M. 2 The valence state 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 groups 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, and v is preferably 3 or 4;

[0049] iii) Contact the first or second intermediate reaction product obtained in step i) or ii) with the halogen-containing Ti compound and the compound represented by formula I as an internal electron donor.

[0050] In one embodiment, during step ii), an alcohol is used as an active electron donor and tetraalkoxytitanium is used as a metal alkoxide compound.

[0051] In one embodiment, an activator is present. In one embodiment, the activator is ethyl benzoate. In one embodiment, the activator is benzamide of formula X:

[0052] Formula X

[0053] 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 R70 and R 71 Both are methyl groups and R. 72 R 73 R 74 and R 75 Both are hydrogen, and are N,N'-dimethylbenzamide (Ba-2Me).

[0054] In some preferred embodiments, the activating compound is N,N-dimethylbenzamide.

[0055] Preferably, the internal electron donor used is of formula I:

[0056] Formula I

[0057] Where R 1 For secondary alkyl groups having at least three carbon atoms (C3) 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 seven carbon atoms (C7), preferably at most six carbon atoms (C6), and is preferably isopropyl, isobutyl, isopentyl, cyclopentyl, n-pentyl, and isohexyl, preferably R. 2 Branching occurs at positions 3 or further.

[0058] In another embodiment, the internal electron donor is 3,3-bis(methoxymethyl)-2,6-dimethylheptane, according to Formula I, wherein R 1 It is a secondary alkyl isopropyl, and R 2 It is an isopentyl group (non-secondary alkyl group with a branched chain on the third carbon atom) (abbreviated as iPiPen, where iP represents isopropyl and iPen represents isopentyl, also known as 3-methylbutyl). This compound iPiPen has the chemical formula C0. 13 H 28 O2, with a precise mass of 216.21 and a molecular weight of 216.37. In a more preferred embodiment of the invention, iPiPen is used as an internal donor and N,N-dimethylbenzamide is preferably used as an activator.

[0059] iPiPen

[0060] In another embodiment, the internal electron donor is (1-methoxy-2-(methoxymethyl)-5-methylhexane-2-yl)cyclopentane, according to formula I, wherein R 1 It is a secondary alkylcyclopentyl group, and R 2 It is a secondary cyclopentyl group (abbreviated as CPiPen, where CP represents cyclopentyl and iPen represents isopentyl, also known as 3-methylbutyl). This compound CPiPen has the chemical formula C2. 15 H30 O2, with a precise mass of 242.22 and a molecular weight of 242.40. In a more specific embodiment, CPiPen is used as an internal donor and N,N-dimethylbenzamide is preferably used as an activator.

[0061] CPiPen

[0062] 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, and R 2 It is a non-secondary isohexyl group with a branched chain on the third carbon atom (abbreviated as iPiHex, where iP represents isopropyl and iHex represents isohexyl, also known as 4-methylpentyl). This compound iPiHex has the chemical formula C1. 14 H 30 O2, with a precise mass of 230.22 and a molecular weight of 230.39. In a more specific embodiment, iPiHex is used as an internal donor and N,N-dimethylbenzamide is preferably used as an activator.

[0063] iPiHex

[0064] 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). This compound iPnPen has the chemical formula C2. 13 H 28 O2, with a precise mass of 216.21 and a molecular weight of 216.37. In a more specific embodiment, iPnPen is used as an internal donor and N,N-dimethylbenzamide is preferably used as an activator.

[0065] iPnPen

[0066] 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 The compound iPiHex is a non-secondarily branched isohexyl group with a branched chain at the third carbon atom (abbreviated as iPiHex, where iP represents isopropyl and iHex represents isohexyl, also known as 3-methylpentyl). This compound iPiHex has the chemical formula C1. 14 H 32O2, with a precise mass of 230.22 and a molecular weight of 230.39. In a more specific embodiment, iPiHex is used as an internal donor and N,N-dimethylbenzamide is preferably used as an activator.

[0067] iPiHex

[0068] 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 shows the above embodiments, including their abbreviations and R. 1 and R 2 Groups and whether these groups are secondary groups and whether they are branched.

[0069] 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 branched at the 3-position or further.

[0070]

[0071] In some preferred embodiments, the co-catalyst is selected from trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, diisobutylaluminum hydride, trioctylaluminum, dihexylaluminum hydride, and mixtures thereof.

[0072] Preferably, the external electron donor is selected from compounds having the following structures and mixtures thereof:

[0073] Formula III: (R 90 )2N-Si(OR 91 )3,

[0074] Formula IV: (R) 92 )Si(OR 93 )3,

[0075] Formula V: Si(OR) a ) 4-n R b n

[0076] Where R 90 R 91 R 92 and R 93 Each group is independently a linear, branched, or cyclic, substituted or unsubstituted alkyl group having 1-10 carbon atoms, preferably wherein R 90 R 91 R 92 and R 93Each group is independently a linear, unsubstituted alkyl group having 1-8 carbon atoms.

[0077] Where n can be 0 to 2, and R a and R b Each can be independently represented as alkyl or aryl, optionally containing one or more heteroatoms such as O, N, S or P, and having, for example, 1 to 20 carbon atoms.

[0078] For example, the external electron donor can be ethyl, methyl, or n-propyl, such as diethylaminotriethoxysilane (DEATES), n-propyltriethoxysilane (nPTES), n-propyltrimethoxysilane (nPTMS), 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).

[0079] Preferably, the external electron 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, cyclopentylpyrrollinedimethoxysilane, bis(pyrrolline)-dimethoxysilane, and mixtures thereof, preferably di(isopropyl)dimethoxysilane (DiPDMS).

[0080] The aforementioned compounds, as examples of external electron donors, are sometimes referred to as selective control agents (SCAs). External electron donors may consist of SCAs. Alternatively, in addition to SCAs, external electron donors may also include compounds known as activity limiting agents (ALAs). Preferably, the activity limiting agent (ALA) is selected from ethyl acetate, ethyl benzoate, p-ethoxyethyl benzoate, methyl trimethylacetate, isopropyl myristate, di-n-butyl sebacate, (poly(alkylene glycol) mono- or diacetate, (poly(alkylene glycol) mono- or dimyristate, (poly(alkylene glycol) mono- or dilaurate, (poly(alkylene glycol) mono- or dioleate), glyceryl triacetate, linoleic acid, oleic acid, palmitic acid and stearic acid mixed glycerides, and mixtures thereof. More preferably, the activity limiting agent (ALA) is isopropyl myristate.

[0081] The ratio of selective control agent (SCA) to activity limiter (ALA) is not critical in principle, but the best results are obtained when the SCA / ALA ratio is 0.010-100, preferably 0.10-20.

[0082] The molar ratio of Al in the co-catalyst to Si in the external electron donor can be, for example, 1-120.

[0083] In a preferred embodiment, the molar ratio of Al in the co-catalyst to Si in the external electron donor is 1-25, preferably 1-15, more preferably 3-10, and even more preferably 3.5-8. The relatively low Al / Si molar ratio results in higher stiffness of the composition.

[0084] It has been surprisingly found that using the preferred catalyst results in ethylene content at peak elution within the desired range.

[0085] Peroxide conversion

[0086] Preferably, the multiphase propylene copolymer is prepared by a method including a peroxide conversion step.

[0087] The terms "peroxide conversion" or "viscosity reduction cracking" are well known in the field of this invention. For example, methods for viscosity reduction cracking of polypropylene have been disclosed in US 4,282,076 and EP 0063654.

[0088] Several different types of chemical reactions are known to be used for viscosity-reducing cracking of propylene polymers. One example is thermal cracking, which is achieved by exposing the polymer to high temperatures, such as 350°C or higher, in an extruder. Another method is exposure to strong oxidants. Yet another method is exposure to ionizing radiation. However, the application of peroxides for viscosity-reducing cracking is preferred. At high temperatures, such materials initiate free radical chain reactions, leading to β-fracture of polypropylene molecules. Viscosity-reducing cracking can be carried out directly after polymerization and removal of unreacted monomers and before granulation (during extrusion within an extruder where the intermediate multiphase propylene copolymer undergoes transformation). However, the invention is not limited to this embodiment; viscosity-reducing cracking can also be carried out on already granulated polypropylene, which typically contains stabilizers to prevent degradation.

[0089] Examples of suitable peroxides include organic peroxides with a decomposition half-life of less than 1 minute at the average process temperature during the viscous cracking step. Suitable organic peroxides include, but are not limited to, dialkyl peroxides such as diisopropyl peroxide, peroxy ketal, peroxy carbonate, diacyl peroxide, peroxy ester, and peroxy dicarbonate. Specific examples of these include benzoyl peroxide, dichlorobenzoyl peroxide, diisopropylbenzene peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(benzoyl peroxide)-3-hexene, 1,4-bis(tert-butylperoxyisopropyl)benzene, lauroyl peroxide, tert-butyl peracetate, and α,a'-bis(tert-butylperoxy)diisopropylbenzene (Luperco®). The peroxide comprises 802), 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-hexene, 2,5-dimethyl-2,5-di(tert-butylperoxy)-hexane, tert-butyl peroxybenzoate, tert-butylperacetic acid phenyl ester, tert-butylperoxy-sec-octanoate, tert-butylperoxyneopentate, isopropylphenylperoxyneopentate, cumene hydroperoxide, dipropylphenyl hydroperoxide, 1,3-bis(tert-butylperoxy-isopropyl)benzene, diisopropylphenyl peroxide, tert-butylperoxyisopropyl carbonate, and any combination thereof. Dialkyl peroxides are preferably used in the method of the present invention. More preferably, the peroxide is α,a'-bis(tert-butylperoxy)diisopropylbenzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)-hexane, or 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxynonane. The peroxide is preferably selected from non-aromatic peroxides.

[0090] Those skilled in the art can readily determine, through routine experiments, how much peroxide should be used to obtain a composition with the desired melt flow rate. This also depends on the half-life of the peroxide and the conditions under which it is used for melting, the latter in turn depending on the exact composition.

[0091] Preferably, the MFI of the multiphase propylene copolymer is in the range of 6 to 10 g / 10 min, more preferably in the range of 7 to 9 g / 10 min, and is determined according to ISO 1133 using a weight of 2.16 kg and a temperature of 230 °C before the peroxide conversion step.

[0092] Molding process and suitable applications

[0093] The multiphase propylene copolymer of the present invention can be extruded or injection molded into products.

[0094] The product can be a household appliance, furniture part, or food packaging.

[0095] experiment

[0096] Material

[0097] For the resin portion of the preparation of the Invention Example (IE), the main catalyst is prepared according to the method disclosed in Example 1 of WO2021 / 063930A1. The co-catalyst used to prepare the IE is TEA and the external electron donor is DiPDMS. The Al / Si ratio is 5, where Al / Si is the molar ratio of the co-catalyst (TEA) to the external donor (DiPDMS).

[0098] For the resin portion used to prepare the comparative example (CE), the main catalyst was INcat P420, which is commercially available from INEOS PolyolefinCatalyst and prepared according to the manufacturer's instructions.

[0099] Both IE and CE are multiphase propylene copolymers. These examples were produced during a gas-phase polymerization process carried out in two horizontally stirred gas-phase reactors (R1 and R2), with a downstream powder handling unit (=degassing & catalyst deactivation) to collect the powder. The powder was then fed into an extruder for peroxide conversion and granulation, with the addition of an additive package consisting of 1500 ppm stabilizer, 5250 ppm nucleating agent (5000 ppm talc and 250 ppm HPN20 from Milliken) and 2000 ppm molding agent based on the total amount of the examples.

[0100] Temperature R1 63-73°C, Temperature R2 63°C, Pressure R1 R2 22 bar

[0101] The compositions of IE and CE are shown in Table 1:

[0102]

[0103] Measurement

[0104] Stress whitening

[0105] Stress whitening is a phenomenon where white areas appear on an object when it is subjected to stress due to shallow stamping. The appearance of white areas indicates that the corresponding material has begun to fail.

[0106] According to the PV3905 sample, shallow stamping was performed by dropping a 500-gram ball from a height of 230 mm onto a 65-inch sample. 65 The test piece was injection molded on an Arburg 60T machine according to ISO 37 / 2, with a diameter of 3.2 mm and a mold: 1-1-1-108.

[0107] These test specimens were photographed using an SLR digital camera (Canon 6D; 100mm macro lens, including teleconverter) with fixed settings and lighting conditions, thus eliminating underexposure or overexposure.

[0108] Use the Matlab graphical interface (GUI) to perform image analysis on the photograph in order to determine the value of the parameter "spot size".

[0109] The parameter "spot size" refers to the size and visibility of the white area.

[0110] The spot size is determined as follows:

[0111] The total whiteness of the entire image is calculated as the sum of the whiteness of every pixel in the image. The inherent whiteness of the material is defined as 0. Each pixel constituting the sample has a whiteness of 0-255. The spot size is defined as the size of the area that has 99.5% whiteness of the entire image.

[0112] Stiffness (bending modulus)

[0113] Flexural modulus was measured according to ASTM D790. Test specimens were injection molded to a length of 63.5 mm, a width of 12.7 mm, and a thickness of 3.2 mm. Flexural modulus was determined by measurement in the flow direction. To allow for post-crystallization, test specimens were stored for 14 days under standard conditions of 23°C / 50% RH. Testing was performed using the Zwick-Roell test cell model Z010. The test speed for determining the flexural modulus was 13.5 mm / min. The yield point for determining the modulus was within the range of 0.05%–0.25%.

[0114] Impact resistance

[0115] Notch Izod was measured according to ISO 180 / 4A. Test specimens were injection molded and prepared to be 63.5 mm long, 12.7 mm wide, and 3.2 mm thick. Notch Izod was determined by measurement in a direction perpendicular to the flow direction. To allow for post-crystallization, test specimens were stored for 14 days under standard conditions of 0°C and -20°C / 50% RH.

[0116] Melt flow rate (MFR)

[0117] MFR was measured according to ISO 1133 using a weight of 2.16 kg and a temperature of 230 °C.

[0118] High-Temperature Two-Dimensional Liquid Chromatography (HT-2D-LC)

[0119] The elution volume of the sample was determined by HT-2D-LC on a PolymerChar (Valencia, Spain) solvent gradient chromatograph equipped with an integrated IR5 detector, a binary gradient pump, and an isocratic pump (both model 1260, Agilent, Waldbronn, Germany). A sample concentration of approximately 4.2 mg / mL (solvent 1-decyl alcohol) was used. For dissolution, the sample was first heated with shaking at 160 °C in an offline autosampler until dissolved. The sample was allowed to dissolve further with shaking for 1 hour before injection. The following experimental parameters were selected: elution temperature, 160 °C; SGIC flow rate, 0.01 mL / min; injection loop, 200 μL; SGIC stationary phase, Hypercarb ® (Particle size, 5 μm; column size, 100 × 4.6 mm (LxI.D.) (Thermofisher Scientific, Dreieich, Germany)). A 1-decyl alcohol → TCB conversion was used as the eluent, with the following procedure: linear conversion from 1-decyl alcohol to TCB from 0–1000 min, followed by pure TCB from 1000–1200 min. The column was then washed with 1-decyl alcohol at a flow rate of 0.8 mL / min for 40 min to re-establish the original adsorption equilibrium in the column. (From Hypercarb) ® The mobile phase from the column was collected in a 100 μL sample loop. These were injected into the SEC column (PLGel Olexis, 300 × 7.8 mm (L × ID) (Agilent Technologies, Waldbronn, Germany)) every 10 minutes. SEC analysis was performed in the second dimension in a TCB at 160 °C using a flow rate of 1.5 mL / min. Calibration was performed using a set of polystyrene standards (PolymerChar, (Valencia, Spain)). Data collection and analysis were performed using PolymerChar software and processed in GPC1 software and OriginProversion 2019b.

[0120] Here, the peaks and center of distribution (COD) of the eluted rubber components are selected to evaluate the differences in ethylene content. Peak elution volume is typically used in chromatography as a typical characteristic of the eluted substance, where the peak exhibits a symmetrical shape. However, when peaks show a lack of symmetry or are skewed, the center of mass (COG), center of mass (COM), or COD becomes a better descriptor.

[0121] Perform 100×4.6mm Hypercarb standard analysis using narrowly distributed ethylene-propylene standards. ® Column calibration. Therefore, based on the elution volume, the peak and distribution center composition of the EPR phase can be calculated. The following equation is obtained from the first-dimensional calibration using a narrowly distributed ethylene-propylene standard:

[0122] [C] mol% = 21.6996 × (first-dimensional elution volume) - 65.9464

[0123] Intercept -65.9464 ± 1.1325 mol%.

[0124] Slope 21.6996±0.2108

[0125] Example: For IE, the peak elution C2 content is calculated as follows:

[0126] [C] mol% = 21.6996 × 3.30 mL - 65.9464

[0127] = 5.66 mol%

[0128] result

[0129] The HT-2D-LC results for IE and CE are shown in Table 2.

[0130] Table 2 HT-2D-LC results for IE and CE

[0131]

[0132] Table 3 Other characterization results for IE and CE

[0133]

[0134] As clearly shown in Table 3, the IE of the present invention maintains the impact resistance at low temperatures, while having improved stiffness and stress whitening properties.

Claims

1. A multiphase propylene copolymer comprising a propylene-based matrix and an ethylene copolymer as a dispersed phase, wherein the amount of the ethylene copolymer is 8.5-12.5 wt% based on the total amount of the multiphase propylene copolymer, wherein the amount of ethylene in the ethylene copolymer is 32.0-40.0 wt% based on the total amount of the ethylene copolymer, and wherein the melt flow index of the multiphase propylene copolymer is in the range of 15-35 g / 10 min, determined according to ISO 1133 using a weight of 2.16 kg and a temperature of 230 °C.

2. The multiphase propylene copolymer according to claim 1, wherein the amount of ethylene copolymer is in the range of 8.5-11.5 wt%, preferably in the range of 8.5-10.4 wt%, and more preferably in the range of 8.5-9.5 wt%, based on the total amount of multiphase propylene copolymer.

3. The multiphase propylene copolymer according to claim 1 or 2, wherein the amount of ethylene in the ethylene copolymer is in the range of 34.0-40.0 wt%, preferably in the range of 35.0-39.0 wt%, based on the total amount of the ethylene copolymer.

4. The multiphase propylene copolymer according to any one of the preceding claims, wherein the MFI of the multiphase propylene copolymer is in the range of 17-29 g / 10 min, preferably in the range of 18-25 g / 10 min, and even more preferably in the range of 19-22 g / 10 min, as determined according to ISO 1133 using a weight of 2.16 kg and a temperature of 230 °C.

5. The multiphase propylene copolymer according to any one of the preceding claims, wherein the multiphase propylene copolymer comprises a nucleating agent, wherein the nucleating agent comprises talc and a cyclic dicarboxylate compound.

6. The multiphase propylene copolymer according to claim 5, wherein the ratio between the amount of talc and the amount of the cyclic dicarboxylate compound is in the range of 13-26.

7. The multiphase propylene copolymer according to any one of the preceding claims, wherein the multiphase propylene copolymer is prepared in a method including a peroxide conversion step.

8. The multiphase propylene copolymer according to any one of the preceding claims, wherein the MFI of the multiphase propylene copolymer is in the range of 6-10 g / 10 min, preferably in the range of 7-9 g / 10 min, and is determined according to ISO 1133 using a weight of 2.16 kg and a temperature of 230 °C prior to the peroxide conversion step.

9. The multiphase propylene copolymer according to any one of the preceding claims, wherein the multiphase propylene copolymer is prepared in a method comprising the step of polymerizing propylene and ethylene comonomers in the gas phase in the presence of a catalyst, 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 comprising the following steps: Contact the magnesium-containing support with the halogenated titanium compound and the internal electron donor of Formula I: Equation I Where R 1 It is a secondary alkyl group and R 2 It is a non-secondary alkyl group having at least 5 carbon atoms, R 2 Preferably, it is a non-secondary alkyl group having at least 5 carbon atoms and branched at the 3-position or further; 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 to produce the first intermediate product, namely solid Mg(OR) a ) x X 1 2-x ,in: R a is a straight-chain, branched or cyclic hydrocarbon group independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl groups and combinations of one or more 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 or cyclic hydrocarbon group independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl groups and combinations of one or more thereof, wherein the hydrocarbon group may be substituted or unsubstituted, may contain one or more heteroatoms, and preferably has 1-20 carbon atoms, R 4 is preferably butyl; wherein X 4 and X 1 are each independently selected from fluoride ion (F - ), chloride ion (Cl - ), bromide ion (Br - ) or iodide ion (I - ​ ii) Optionally, the solid Mg(OR) obtained in step i) a ) x X 1 2-x With activated electron donors and formula M 1 (OR b ) v-w (OR 3 ) w Or M 2 (OR b ) v-w (R 3 ) w The metal alkoxide compound is contacted with at least one activated compound to obtain a second intermediate; wherein: M 1 ν is a metal selected from Ti, Zr, Hf, Al, or Si; ν is M 1 The valence state of M; 2 For metal Si; for metal M. 2 The valence state 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 groups 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, and v is preferably 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 represented by formula I as an internal electron donor.

10. The multiphase propylene copolymer according to claim 9, wherein the co-catalyst is selected from trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, diisobutylaluminum hydride, trioctylaluminum, dihexylaluminum hydride, and mixtures thereof.

11. The multiphase propylene copolymer according to any one of claims 9 or 10, wherein the catalyst comprises an external donor, wherein the external donor is a silane-containing external donor, preferably wherein the external electron donor is selected from compounds having the following structures and mixtures thereof: 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 Where 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 to 10 carbon atoms, preferably wherein R 90 R 91 R 92 and R 93 Each group is an independent straight-chain unsubstituted alkyl group having 1 to 8 carbon atoms. Where n can be between 0 and 2, R a and R b Each of these groups independently represents an alkyl or aryl group, optionally containing one or more heteroatoms such as O, N, S, or P, and having, for example, 1 to 20 carbon atoms.

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

13. The multiphase propylene copolymer according to any one of claims 9-12, wherein the activator is present in the method for preparing the main catalyst, said activator being preferably a benzamide of 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 All are methyl and R 72 R 73 R 74 and R 75 Both are hydrogen, namely N,N'-dimethylbenzamide (Ba-2Me).

14. The multiphase propylene copolymer according to any one of the preceding claims, wherein the ethylene content of the multiphase propylene copolymer at the peak elution volume is at least 3.5 mol%, preferably at least 4.5 mol%, more preferably at least 5 mol%, and even more preferably at least 5.5 mol%, according to the high-temperature two-dimensional liquid chromatography method described in the specification.

15. An article comprising the multiphase propylene copolymer of any one of the preceding claims, wherein the article is a household appliance, furniture component, or food packaging.

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