Polypropylene compositions exhibiting high multiaxial impact resistance and improved tiger stripe behavior

Abstract

This invention relates to polymer compositions comprising multiphase propylene copolymers, butene-ethylene copolymers, and optionally inorganic fillers. The invention also relates to methods for preparing said polymer compositions. Furthermore, the invention relates to articles comprising said polymer compositions. The polymer compositions of the present invention exhibit high multiaxial impact resistance and improved tiger-stripe behavior.

Description

Technical Field

[0001] This invention relates to polymer compositions comprising multiphase propylene copolymers, butene-ethylene copolymers, and optionally inorganic fillers. The invention also relates to methods for preparing said polymer compositions. Furthermore, the invention relates to articles comprising said polymer compositions. Background Technology

[0002] Polymer compositions, particularly polypropylene-based polymer compositions, are widely used in the automotive industry due to their excellent mechanical and chemical properties. For automotive applications, it is preferable that the polymer composition exhibits improved tiger-stripe behavior.

[0003] The tiger stripe technique used here refers to the color and gloss variations on the surface of injection-molded parts, resulting from the unstable mold filling properties of the molten polymer as it is injected into the mold and forms the desired shape. These variations are typically observed as alternating areas of low and high gloss and / or light and dark color, where these areas are generally perpendicular to the flow direction of the injection-molded part. Tiger stripes can also be referred to as tiger stripe markings or tiger stripe (flow) markings.

[0004] Examples of this appearance and a more scientific discussion of the causes of tiger stripes can be found in the publication *Journal of Applied Polymer Science*, Vol. 104, 192-199 (2007), by Hirano et al. Another publication, entitled “Morphological Analysis of Tiger-Stripe and Stripe Pattern Determination on Injection Moulding of Polypropylene / Rubber / Talc Blends,” published under the names K. Hirano, Y. Suetsugu, S. Tamura, and T. Kanai, provides further background on this issue.

[0005] For example, improved tiger-stripe behavior in polypropylene-based polymer compositions is known in the prior art:

[0006] US 2002 / 0035209 discloses a polypropylene resin composition comprising two specific propylene-ethylene block copolymers with different structures. More specifically, the reference discloses a polypropylene resin composition that, when formed into a molded article, provides a molded article with excellent appearance due to the almost absence of flow marks (in other words, high mold expansion and very few fisheyes).

[0007] EP3083819B1 discloses a polymer composition containing two multiphase propylene copolymers that has improved tiger stripe properties.

[0008] WO02 / 28958, WO2004 / 087805 and WO2010 / 0108866 provide a solution that typically includes providing a masterbatch that can be diluted with an additional polyolefin, thereby providing a compound with the desired tiger stripe properties and mechanical properties.

[0009] EP 2495280 discloses a polyolefin composition comprising:

[0010] a. 35-90 wt% of a multiphase polypropylene composition, based on the weight of the polyolefin composition, comprising:

[0011] i. 10-50 wt% of the first propylene homopolymer (PPH1) with an MFR2 of 30-80 g / 10 min as measured according to ISO 1133 (230°C, 2.16 kg), based on the weight of the multiphase polypropylene composition.

[0012] ii. 20-65 wt% of a second propylene homopolymer (PPH2) with an MFR2 of 100-250 g / 10 min as measured according to ISO 1133 (230°C, 2.16 kg), based on the weight of the multiphase polypropylene composition; iii. 5-30 wt% of a first xylene cold soluble fraction (XS1) with an intrinsic viscosity IVXS1 of 2.0-3.0 dl / g, based on the weight of the multiphase polypropylene composition.

[0013] iv. The second xylene cold soluble fraction (XS2) with an intrinsic viscosity of 1.5-2.8 dl / g, based on 5-25 wt% of the multiphase polypropylene composition, under the condition that IVXS1 ≠ IVXS2.

[0014] b. 5-40 wt% inorganic filler, based on the weight of the polyolefin composition, and

[0015] c. 5-25 wt% ethylene / 1-butene elastomer based on the weight of the polyolefin composition.

[0016] However, the aforementioned prior art does not solve another known problem for many polypropylene-based polymer compositions: poor low-temperature multiaxial impact resistance.

[0017] Therefore, the object of the present invention is to provide a polymer composition that combines excellent low-temperature multiaxial impact resistance and improved tiger-stripe behavior. The polymer composition should also have sufficient flowability to make it suitable for injection molding applications. Summary of the Invention

[0018] It has been found that the object of the present invention can be achieved by a polymer composition containing a multiphase propylene copolymer and a butene-ethylene copolymer, wherein the melt flow index (MFI) of the polymer composition, measured according to ISO 1133-1:2011 at 230°C with a load of 2.16 kg, is 20-100 dg / min, wherein the amount of the multiphase propylene copolymer, based on the total amount of the polymer composition, is 62.3-93.4 wt%, wherein the melt flow index (MFI) of the multiphase propylene copolymer, measured according to ISO 1133-1:2011, is 20-100 dg / min. 1. At 230°C, the viscosity was measured with a 2.16 kg load of 29-103 dg / min, wherein the xylene-soluble portion of the multiphase propylene copolymer, measured according to ISO 16152:2005, was 12.9-27.8 wt% based on the total amount of the multiphase propylene copolymer; the intrinsic viscosity of the xylene-soluble portion of the multiphase propylene copolymer, measured according to ISO 1628-3:2010, was 1.53-1.89 dl / g; and the amount of butene-ethylene copolymer, based on the total amount of the polymer composition, was 2.5-31.0 wt%. Detailed Implementation

[0019] It has been surprisingly discovered that the polymer compositions of the present invention exhibit high impact resistance and a good balance between impact resistance and warpage.

[0020] To avoid any confusion, "excellent low-temperature multiaxial impact resistance" refers to a multiaxial impact resistance of the polymer composition of at least 42 J as measured at -20°C according to ISO 6603-2:2000A2. For the purposes of this invention, other impact resistance testing methods such as Izod or Charpy are not suitable because these methods measure impact resistance along one axis. Therefore, the results of Izod or Charpy do not reflect multiaxial impact resistance.

[0021] Multiphase propylene copolymer

[0022] Multiphase propylene copolymers typically have a two-phase structure, comprising a propylene-based semi-crystalline polymer as the matrix and a dispersed elastomer phase, typically an ethylene-α-olefin rubber. Multiphase propylene copolymers are usually prepared in a polymerization process.

[0023] The multiphase propylene copolymer preferably comprises a propylene polymer as a matrix and an ethylene-α-olefin copolymer as a dispersed phase, wherein the α-olefin portion of the ethylene-α-olefin copolymer is derived from at least one α-olefin having 3-20 carbon atoms. For example, the ethylene-α-olefin copolymer can be an ethylene-propylene copolymer, an ethylene-butene copolymer, an ethylene-hexene copolymer, an ethylene-octene copolymer, an ethylene-propylene-butene copolymer, or an ethylene-propylene-hexene copolymer.

[0024] In the ethylene-α-olefin copolymer, the amount of the ethylene-derived portion is preferably 40-52 wt%, more preferably 45-50 wt%, based on the total weight of the ethylene-α-olefin copolymer. The ethylene-α-olefin copolymer is preferably an ethylene-propylene copolymer.

[0025] The propylene polymer in the multiphase propylene copolymer can be a propylene homopolymer or / and an ethylene-propylene copolymer, wherein the amount derived from the ethylene portion is 0.3-3.9 wt% of the total ethylene-propylene copolymer. The propylene polymer in the multiphase propylene copolymer is preferably a propylene homopolymer, as this increases the stiffness of the compositions of the present invention.

[0026] The amount of propylene polymer is preferably 65-85 wt%, more preferably 70-80 wt%, and more preferably 73-78 wt%, based on the total amount of the multiphase propylene copolymer.

[0027] The amount of ethylene-α-olefin copolymer is preferably 15-35 wt%, more preferably 20-30 wt%, and more preferably 22-27 wt%, based on the total amount of multiphase propylene copolymer.

[0028] Preferably, based on the multiphase propylene copolymer, the sum of the propylene polymer and the ethylene-α-olefin copolymer is 100 wt%.

[0029] The multiphase propylene copolymer can be divided into a xylene-soluble portion and a xylene-insoluble portion. Based on the total amount of the multiphase propylene copolymer, the amount of the xylene-soluble portion, measured according to ISO 16152:2005, is 12.9-27.8 wt%, preferably 14.3-24.8 wt%, and more preferably 18.9-22.6 wt%. The amount of the xylene-soluble portion, based on the total amount of the multiphase propylene copolymer, can be calculated using the following formula:

[0030] CXI = 100wt% - CXS

[0031] The intrinsic viscosity of the xylene soluble fraction, as measured according to ISO 1628-1:2009, is 1.53-1.89 dl / g, preferably 1.68-1.87 dl / g.

[0032] The intrinsic viscosity of the insoluble portion of xylene, as measured according to ISO 1628-3:2010, is preferably 0.91-1.56 dl / g, more preferably 1.12-1.34 dl / g, and even more preferably 1.20-1.29 dl / g.

[0033] The term "viscosity reduction cracking" is a well-known technique in the field of this invention, such as the viscosity reduction cracking methods for polypropylene disclosed in US4282076 and EP0063654.

[0034] To avoid confusion, in the context of this invention, "viscosity-reducing cracking," "controlled rheology," and "conversion" or "peroxide conversion" refer to the same method; "viscosity-reducing cracking," "produced by controlled rheology," "converted," or "peroxide-converted" are used as adjectives to describe multiphase propylene copolymers prepared by this method.

[0035] Multiphase propylene copolymers are preferably viscous-reducing cracked copolymers.

[0036] Several different types of chemical reactions are known to be used for the viscosity reduction cracking of propylene-based polymers. One example is thermal cracking, which is achieved by exposing the propylene-based polymer to high temperatures, such as 350°C or higher, in an extruder. Another method is to expose the propylene-based polymer to a strong oxidant. Yet another method is exposure to ionizing radiation. However, viscosity reduction cracking is preferably carried out using peroxides, which is why "conversion" is often referred to as "peroxide conversion" in the literature. At high temperatures, such materials initiate free radical chain reactions, leading to β-fracture of the propylene-based polymer molecules. Viscosity reduction cracking can be carried out directly after polymerization and removal of unreacted monomers and before granulation (during extrusion within the extruder where the propylene-based polymer undergoes conversion). However, the invention is not limited to this embodiment; viscosity reduction cracking can also be carried out on already granulated propylene-based polymers, which typically contain stabilizers to prevent degradation.

[0037] Examples of suitable peroxides include organic peroxides with a decomposition half-life of less than 1 minute at the average process temperature during extrusion. Suitable organic peroxides include, but are not limited to, dialkyl peroxides such as diisopropyl peroxide, peroxyketal, peroxycarbonate, diacyl peroxide, peroxyester, and peroxydicarbonate. Specific examples of these include benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl 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. 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.

[0038] 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 used for melt mixing, which in turn depend on the specific composition.

[0039] In multiphase propylene copolymers, during the viscosity reduction cracking process, the type and amount of comonomers in the dispersed phase and matrix of the propylene-based polymer do not change, nor do the amounts of the dispersed phase and matrix of the multiphase propylene copolymer change.

[0040] In one embodiment, the amount of peroxide used to convert the multiphase propylene copolymer is based on the total amount of the multiphase propylene copolymer, for example, 0.01-0.5 wt%, for example, 0.08-0.2 wt%, for example, 0.1-0.2 wt%.

[0041] According to ISO 1133-1:2011, the MFI of the multiphase propylene copolymer is 29-103 dg / min, preferably 41-92 dg / min, and more preferably 45-83 dg / min, measured at 230°C with a load of 2.16 kg.

[0042] Prior to conversion, the MFI of the multiphase propylene copolymer was measured at 230°C with a load of 2.16 kg according to ISO 1133-1:2011. The preferred MFI was 4.9-19.8 dg / 10 min, more preferably 7.8-16.0 dg / min, and even more preferably 10.2-14.3 dg / 10 min.

[0043] Multiphase propylene copolymers can be produced in processes including polymerization steps, such as multi-stage polymerization like bulk polymerization, gas-phase polymerization, slurry polymerization, solution polymerization, or any combination thereof. Any conventional catalyst system can be used, such as Ziegler-Natta or metallocene. These polymerization steps and catalysts are described, for example, in WO 06 / 010414; Ser van der Ven's Polypropylene and other Polyolefins, Studies in Polymer Science 7, Elsevier 1990; WO06 / 010414, US4399054, and US4472524. Multiphase propylene copolymers are preferably prepared using Ziegler-Natta catalysts.

[0044] Multiphase propylene copolymers can be prepared by a method including a polymerization step, said polymerization step comprising:

[0045] - In the presence of a catalyst system, propylene and optionally ethylene and / or α-olefins are polymerized to obtain a propylene-based matrix, and

[0046] - Subsequently, in the presence of a catalyst system, ethylene and α-olefins are polymerized in a propylene-based matrix to obtain a multiphase propylene copolymer consisting of a propylene-based matrix and a dispersed phase.

[0047] These steps are preferably carried out in different reactors. The catalyst systems for the first and second steps can be different or the same.

[0048] Catalysts suitable for the preparation of multiphase propylene copolymers are also well known in the art. Examples include Ziegler-Nat ta catalysts and metallocene catalysts. Catalysts for the production of multiphase propylene copolymers are preferably free of phthalates, for example, catalysts comprising compounds of group 4-6 transition metals of IUPAC, group 2 metal compounds, and internal donors, wherein the internal donors are selected from 1,3-diethers, such as 9,9-bis(methoxymethyl)fluorene, optionally substituted malonates, maleates, succinates, glutarates, benzoates, cyclohexene-1,2-dicarboxylate esters, benzoates, citrates, aminobenzoates, silyl esters, and their derivatives and / or mixtures.

[0049] For example, a catalyst for preparing multiphase propylene copolymers may be a Ziegler-Natta catalyst comprising: a main catalyst, at least one external electron donor, a co-catalyst, and optionally an internal electron donor, wherein the external electron donor is selected from those having the general formula III(R 90 )2N-Si(OR 91 Compounds with the structure IV(R)3, and compounds with the general formula IV(R) 92 )Si(OR 93 Compounds with a )3 structure and mixtures thereof, wherein 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 a straight-chain unsubstituted alkyl group having 1 to 8 carbon atoms, preferably ethyl, methyl, or n-propyl.

[0050] In one implementation, R 90 and R 91 All are ethyl (the compound of general formula III is diethylaminotriethoxysilane, DEATES). In another embodiment, R 92 For n-propyl and R 93 All are ethyl (the compound of general formula IV is n-propyltriethoxysilane, nPTES), or in another embodiment, R 92 For n-propyl and R 93 All are methyl (the compound of general formula IV is n-propyltrimethoxysilane, nPTMS).

[0051] The multiphase propylene copolymer of the present invention is preferably prepared by a method for producing multiphase propylene copolymers, wherein step I) is carried out in the presence of a catalyst system comprising a Ziegler-Natta catalyst and at least one electron donor selected from nPTES, nPTMS, DEATES and mixtures thereof.

[0052] The multiphase propylene copolymers of the present invention are preferably prepared using a catalyst system comprising a Ziegler-Natta catalyst and at least one external electron donor selected from the group consisting of general formula III(R 90 )2N-Si(OR 91 Compounds with the structure IV(R)3, and compounds with the general formula IV(R) 92 )Si(OR 93 Compounds with a 3-structure and their mixtures.

[0053] "Procatalyst" is a well-known term in the field of Ziegler-Natta catalysts, and is considered to be a substance capable of converting a main catalyst into an active polymerization catalyst. Procatalysts are typically organometallic compounds containing metals from Groups 1, 2, 12, or 13 of the periodic system (Handbook of Chemistry and Physics, 70th edition, CRC Press, 1989-1990). Procatalysts can include any compound known in the art as a "procatalyst," such as hydrides, alkyl compounds, or aryl compounds of aluminum, lithium, zinc, tin, cadmium, beryllium, and magnesium, as well as combinations thereof. The co-catalyst can be a hydrocarbon-based aluminum co-catalyst, such as triisobutylaluminum, trihexylaluminum, diisobutylaluminum hydride, dihexylaluminum hydride, isobutylaluminum dihydride, hexylaluminum dihydride, diisobutylhexylaluminum, isobutyldihexylaluminum, trimethylaluminum, triethylaluminum, tripropylaluminum, triisopropylaluminum, tri-n-butylaluminum, trioctylaluminum, tridecylaluminum, tri(dodecyl)aluminum, triphenylmethylaluminum, triphenylaluminum, trinaphthylaluminum, and trimethylmethylaluminum. In one embodiment, the co-catalyst is selected from triethylaluminum, triisobutylaluminum, trihexylaluminum, diisobutylaluminum hydride, and dihexylaluminum hydride. More preferably, it is trimethylaluminum, triethylaluminum, triisobutylaluminum, and / or trioctylaluminum. Most preferably, it is triethylaluminum (abbreviated as TEAL). The cocatalyst can also be a hydrocarbon-based aluminum compound, such as tetraethylaluminoxane, methylaluminoxane, isobutylaluminoxane, tetraisobutylaluminoxane, diethyl-aluminum ethoxide, diisobutylaluminum chloride, methylaluminum chloride, diethylaluminum chloride, ethylaluminum chloride, and dimethylaluminum chloride, preferably TEAL.

[0054] For example, the main catalyst can be prepared by a method comprising the steps of providing a magnesium-based support, contacting the magnesium-based support with a Ziegler-Natta-type catalyst, an internal donor, and an activator to produce the main catalyst. For example, an improved method for preparing the main catalyst is disclosed in Dow's US 5,093,415. The main catalyst is preferably a titanium-containing compound.

[0055] In the context of this invention, the molar ratio of Si to Ti in the catalyst system is preferably 0.1-40, more preferably 0.1-20, even more preferably 1-20, and most preferably 2-10. The molar ratio of Al to Ti in the catalyst system is preferably 5-500, more preferably 15-200, more preferably 30-160, and most preferably 50-140.

[0056] In one implementation, the molar ratio of Si to Ti is the same as the molar ratio of the external donor to the main catalyst.

[0057] In one implementation, the molar ratio of Al to Ti is the same as the molar ratio of the co-catalyst to the main catalyst.

[0058] Butene-ethylene copolymer

[0059] The polymer composition of the present invention comprises a butene-ethylene copolymer.

[0060] The butene-ethylene copolymer is preferably a 1-butene-ethylene copolymer.

[0061] According to ASTM D2240-15, the Shore A hardness of the butene-ethylene copolymer of the present invention is preferably 44-101, preferably 48-92, more preferably 51-79, and even more preferably 54-68.

[0062] According to ASTM D792-13, the density of the butene-ethylene copolymer of the present invention is preferably 0.857-0.901 g / cm³. 3 The preferred value is 0.861-0.888 g / cm³. 3 More preferably, it is 0.866-0.875 g / cm³. 3 .

[0063] According to ASTM D1238-13, the MFI of butene-ethylene copolymer is preferably 0.1-19.8 dg / min, more preferably 0.3-11.3 dg / min, and more preferably 0.4-3.4 dg / min, measured at 190°C with a load of 2.16 kg.

[0064] Butene-ethylene copolymers can be prepared using methods known in the art, such as using single-site catalysts, where the transition metal component of the catalyst is an organometallic compound and at least one of its ligands has a cyclopentadienyl anionic structure, through which the ligand coordinates with the transition metal cation. This type of catalyst is also called a "metallocene" catalyst. Metallocene catalysts are described, for example, in US 5,017,714 and US 5,324,820. Butene-ethylene copolymers can also be prepared using conventional heterogeneous multisite Ziegler-Nat ta catalysts.

[0065] Inorganic packing

[0066] The polymer compositions of the present invention may also contain inorganic fillers.

[0067] Suitable examples of inorganic fillers include, but are not limited to, talc, calcium carbonate, wollastonite, barium sulfate, kaolin, glass flakes, layered silicates (bentonite, montmorillonite, saponite) and mica.

[0068] For example, the inorganic filler is selected from talc, calcium carbonate, wollastonite, mica and mixtures thereof.

[0069] The inorganic filler is more preferably talc. According to Stockes' law for precipitation analysis (ISO 13317-3:2001), the average particle size (D50) of talc is preferably 0.1-10.2 micrometers, more preferably 0.6-7.1 micrometers, more preferably 1.3-4.5 micrometers, and even more preferably 1.6-2.5 micrometers.

[0070] Optional additives

[0071] The polymer compositions of the present invention may further comprise additives, such as nucleating and clarifying agents, stabilizers, release agents, plasticizers, antioxidants, lubricants, antistatic agents, crosslinking agents, anti-scratch agents, high-performance fillers, pigments and / or colorants, flame retardants, foaming agents, acid scavengers, recycling additives, antimicrobial agents, antifogging additives, antislip additives, anti-clogging additives, polymer processing aids, etc. These additives are well known in the art. The amount of additives, based on the total amount of the polymer composition, is preferably up to 5.0 wt%, preferably up to 4.5 wt%, more preferably up to 4 wt%, and more preferably up to 3.8 wt%. The reason for preferring a small amount of additives is that, at this point, the additives will not negatively affect the desired properties of the polymer compositions of the present invention.

[0072] In a preferred embodiment, the polymer composition comprises a small amount or substantially no coupling agent, wherein the amount of coupling agent, based on the total amount of the polymer composition, is preferably up to 0.46 wt%, more preferably up to 0.40 wt%, more preferably up to 0.36 wt%, and even more preferably up to 0.31 wt%, wherein the coupling agent is maleic anhydride-grafted polypropylene. For example, the maleic anhydride-grafted polypropylene may be Exxelor, commercially available from ExxonMobil. TM PO 1020. The reason for preferring to use a small amount of coupling agent is that the combination of inorganic filler and a large amount of coupling agent may lead to a deterioration in the impact resistance of the polymer composition of the present invention.

[0073] polymer composition

[0074] The amount of multiphase propylene copolymer in the polymer composition is 62.3-93.4 wt%, preferably 17.3-86.5 wt%, and more preferably 70.4-80.2 wt%, based on the total amount of the polymer composition.

[0075] The amount of butene-ethylene copolymer in the polymer composition is 2.5-31.0 wt%, preferably 8.3-27.1 wt%, more preferably 12.0-23.5 wt%, and even more preferably 15.4-21.7 wt%, based on the total amount of the polymer composition.

[0076] The amount of the optional inorganic filler is preferably up to 10 wt%, more preferably up to 7.5 wt%, based on the total amount of the polymer composition.

[0077] The total amount of the multiphase propylene copolymer, butene-ethylene copolymer, and optional inorganic filler is preferably at least 95 wt%, preferably at least 97 wt%, and preferably at most 99.5 wt%, based on the total amount of the polymer composition.

[0078] According to ISO 1133-1:2011, the MFI of the polymer composition is 20-100 dg / min, preferably 21-70 dg / min, and more preferably 22-48 dg / min, measured at 230°C with a load of 2.16 kg. Within the preferred MFI range, the polymer composition exhibits an optimal balance between impact resistance and processability.

[0079] For example, the polymer compositions of the present invention can be prepared in an extrusion method by melt-mixing a multiphase propylene copolymer, a butene-ethylene copolymer, optional inorganic fillers, and optional additives in an extruder.

[0080] This invention also relates to a method for preparing an article, preferably an automotive component, comprising the following sequential steps:

[0081] - Provides the polymer composition of the present invention;

[0082] - The polymer composition of the present invention is molded into articles, preferably by injection molding.

[0083] The present invention also relates to the use of the polymer compositions of the present invention in the preparation of articles, preferably automotive parts, such as automotive interior parts or automotive exterior parts.

[0084] The present invention also relates to an article, preferably an injection-molded article, more preferably an injection-molded automotive article obtained or obtainable by the method of the present invention, wherein the amount of the polymer composition of the present invention is at least 95 wt%, preferably at least 98 wt%, based on the total amount of the article.

[0085] The present invention also relates to automotive parts comprising the polymer composition of the present invention, wherein the amount of the polymer composition is at least 95 wt%, preferably at least 97 wt%, based on the total amount of the automotive part. The automotive part is preferably an airbag cover.

[0086] To avoid any confusion, in the context of this invention, the term "quantity" can be understood as "weight", and "melt flow index (MFI)" and "melt flow rate (MFR)" refer to the same physical property.

[0087] It should be noted that this invention relates to all possible combinations of the features described herein, with particular preference given to those combinations in the claims. Therefore, it should be understood that all combinations of features related to the compositions of the invention, all combinations of features related to the methods of the invention, and all combinations of features related to both the compositions and methods of the invention are described herein.

[0088] It should also be noted that the term 'comprising' does not exclude the presence of other elements. However, it should 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 those components may be advantageous because it provides a simpler and more economical method for preparing said product / composition. Similarly, it should be understood that a description of a method comprising certain steps also discloses a method composed of those steps. A method composed of those steps may be advantageous because it provides a simpler and more economical method. When lower and upper limits are mentioned with respect to parameters, it should be understood that a range formed by the combination of said lower and upper limits is also disclosed.

[0089] The present invention is described below through the following embodiments, but the present invention is not limited thereto.

[0090] Material:

[0091] Multiphase propylene copolymer (HECO):

[0092] PP15 is the same grade available commercially from SABIC. PP5.5 is not an interim grade. The properties of PP15 are shown in Table 3.

[0093] Polymers A, B, C, and D are from Innovene TM The method prepares a multiphase propylene copolymer using a sequential two-reactor setup. A polypropylene homopolymer is produced in the first reactor, and a propylene-ethylene copolymer is produced in the second reactor.

[0094] In the polymerization method, the catalyst system has three components: a main catalyst, an external electron donor, and a co-catalyst. The main catalyst is prepared according to the description in section "Procatalyst III" on page 36 of WO2016198344; the external electron donor for polymers A and B is di(isopropyl)dimethoxysilane (DiPDMS), and the external electron donor for polymers C and D is n-propyltriethoxysilane (nPTES); the co-catalyst is triethylaluminum.

[0095] Table 1 shows the process conditions for polymers A, B, C, and D:

[0096] Table 1: Preparation conditions of polymers A, B, C and D

[0097] polymer A B C D R1 Te(°C) 66 66 69.5 69.5 R1 Pr(Bar) 24 24 24 24 Al / Ti (mol / mol) 135 135 135 135 Si / Ti (mol / mol) 10 10 10 10 R1 H2 / C3 (mol / mol) 0.08 0.05 0.01 0.065 R1 component (wt%) 80 74 76 86 R2 Te(℃) 66 57 66 59 R2 Pr(Bar) 24 24 24 24 R2 H2 / C3 (mol / mol) 0.132 0.005 0.011 0.0042 R2 C2 / C3 (mol / mol) 0.63 0.33 0.3 0.31 R2 component (wt%) 20 26 24 14

[0098] In Table 1, R1 refers to the first reactor, R2 refers to the second reactor, Te refers to the temperature, Pr refers to the pressure, Al / Ti is the molar ratio of the co-catalyst to the main catalyst, Si / Ti is the molar ratio of the external donor to the main catalyst, H2 / C3 is the molar ratio of hydrogen to propylene, C2 / C3 is the molar ratio of ethylene to propylene, and the quantities are the amounts of substances produced in R1 or R2 based on the total amount of polymer A, B, C, or D, respectively.

[0099] Tafmer D605 is a butene-ethylene copolymer, commercially available from Mitsui Chemicals, with a density of 0.861 g / cm³. 3 (ASTM D792-13), MFI is 0.5g / 10min (ASTM D1238-13, 2.16kg, 190℃) and Shore A hardness is 58 (ASTM D2240-15).

[0100] Engage 8200 is a polyolefin elastomer obtained commercially from Dow, with a density of 0.870 g / cm³. 3 (ASTM D792-13), MFI is 5.0 g / 10 min (ASTM D1238-13, 2.16 kg, 190 °C) and Shore A hardness is 66 (ASTM D2240-15).

[0101] Talc HTPultra 5c is an ultrafine talc commercially available from IMI FABIC. Measured according to Stockes' law of sedimentation analysis (ISO 13317-3:2001), the average talc particle size (D50) of Talc HTPultra 5c is 0.65 μm.

[0102] Luzenac HAR T84 is a high aspect ratio talc commercially available from Imerys Talc. Measured according to Stockes' law of sedimentation analysis (ISO 13317-3:2001), the average talc particle size (D50) of Luzenac HAR T84 is 2 μm.

[0103] The additive package consists of 50 wt% color masterbatch, 20 wt% heat and processing stabilizer, 10 wt% UV stabilizer, and 20 wt% processing aids, based on their total amount.

[0104] Sample preparation

[0105] Mixing

[0106] The pellets of the example were prepared by compounding the components in Table 4 in a KraussMaffei Berstorff ZE40A_UTX 43D twin-screw extruder with the following settings: screw speed of 400 rpm, throughput of 150 kg / h, torque of 38%, temperature of 235°C, and head pressure of 13 bar.

[0107] Sample preparation

[0108] The specimens used for measuring MFI are particles obtained in the compounding step. Specimens used for multiaxial impact resistance measurement are prepared by injection molding. The specimen dimensions for multiaxial impact resistance measurement are defined in ISO 6603-2:2000A2. The preparation method for specimens used for tiger stripe evaluation is explained in the test methods section.

[0109] Test methods

[0110] Melt Flow Index

[0111] Melt flow index (MFI) is measured at 230°C with a load of 2.16 kg according to ISO 1133-1:2011.

[0112] Weight percentage of xylene soluble fraction (CXS) and weight percentage of xylene insoluble fraction (CXI).

[0113] The weight percentage of the xylene-soluble portion (CXS) of a multiphase propylene copolymer is measured according to ISO 16152:2005. The weight percentage of the xylene-insoluble portion (CXI) of the multiphase propylene copolymer is calculated using the following formula:

[0114] CXI = 100wt% - CXS

[0115] The xylene-soluble and xylene-insoluble fractions (CXS and CXI) obtained in this test were used for the intrinsic viscosity (IV) test.

[0116] Intrinsic viscosity (IV)

[0117] The intrinsic viscosity (IV) of CXS and CXI was measured in naphthalene at 135 °C according to ISO 1628-1:2009 and ISO 1628-3:2010, respectively.

[0118] Multiaxial impact resistance

[0119] Multiaxial impact resistance was measured at -20°C according to ISO 6603-2:2000A2.

[0120] Tiger Stripes (TS) Review

[0121] like Figure 1As shown, using a feeding system and a mold, the particles of the embodiment were injection molded into two types of ruler-shaped test specimens. Figure 2 and Figure 3 The details of these two types of molds are described. These two types of molds are called fan gates ( Figure 2 ) and pinhole gate ( Figure 3 ).

[0122] Figure 1 The feeding system and mold are described. Molten sample is injected through a gate with an upper diameter of 4 mm and a lower diameter of 7 mm. The lower end of the gate merges with a rectangular channel in the mold, the channel being 6.5 mm wide and 3 mm deep.

[0123] Figure 2 A type of gating system called a fan-shaped gating is described. Following a rectangular channel of 43 mm in length is a fan-shaped section of 25 mm in length. Along the length of the fan-shaped section, the width changes from 6.5 mm to 30 mm, and the thickness changes from 3 mm to 2 mm. Following the fan-shaped section is an elongated section of 30 mm in width and 3 mm in thickness.

[0124] Figure 3 Another type of gating system called a pinhole gating system is described. This pinhole gating system is related to... Figure 2 The fan-shaped gate is the same, except that the rectangular channel has the following three areas: the first area is 32mm long and 6.5mm wide, followed by the second area is 6mm long and 1.2mm wide, and then the third area is 5mm long and 6mm wide.

[0125] The melt temperature was set to 240°C during injection, while the mold was set to room temperature. Three different screw speeds were applied as shown in Table 2. For each sample, five specimens with smooth and textured sides were obtained from the fan-shaped gate, and five specimens with smooth and textured sides were obtained from the pin-shaped gate.

[0126] Table 2 Injection Conditions

[0127]

[0128] Each sample was visually inspected to check for tiger stripes on its textured surfaces. Surface quality was evaluated on a scale of 1-10, with 10 being the best. The average TS score for each sample was as follows:

[0129] The table is provided in Table 4.

[0130] TS score describe 1 From any angle, there is a very clear transition between the glossy and dull areas. 2 *From any angle, there is a clear transition between the glossy and dull areas. 3 From any angle, there is a clearly visible transition between the glossy and dull areas. 4 From any angle, there is a visible transition between the glossy and dull areas. 5 From any angle, the transition between the glossy and dull areas is not very obvious. 6 From a specific angle, there is a visible transition between the glossy and dull areas. 7 From a specific angle, there is a subtle transition between the glossy and dull areas. 8 There is no visible transition between glossy and dull areas, resulting in an uneven surface appearance. 9 There is no visible transition between glossy and dull areas, and the surface appearance is uniform. 10 There is no visible transition between the glossy and dull areas; the surface is flawless.

[0131] result

[0132] Table 3 Performance of HECO

[0133]

[0134] Table 4 Properties of PP compounds

[0135]

[0136] According to the information in Table 4, only the polymer composition of the present invention exemplified by IE 1 simultaneously possesses an MFI of at least 20 dg / min (suitable for injection molding), a multiaxial impact resistance of at least 42 J, and an excellent TS score.

Claims

1. A polymer composition comprising a multiphase propylene copolymer and a butene-ethylene copolymer, According to ISO 1133-1:2011, the melt flow index of the polymer composition, measured at 230°C with a load of 2.16 kg, is 20-70 dg / min. The amount of the multiphase propylene copolymer, based on the total amount of the polymer composition, is 62.3-93.4 wt%. The melt flow index of the multiphase propylene copolymer, measured according to ISO 1133-1:2011 at 230℃ with a load of 2.16 kg, is 41-92 dg / min. The xylene-soluble portion of the multiphase propylene copolymer, measured according to ISO 16152:2005, is 12.9-27.8 wt% based on the total amount of the multiphase propylene copolymer. The intrinsic viscosity of the xylene-soluble fraction of the multiphase propylene copolymer, measured according to ISO 1628-1:2009, is 1.53-1.89 dl / g. The intrinsic viscosity of the xylene-insoluble fraction of the multiphase propylene copolymer, measured according to ISO 1628-3:2010, is 0.91-1.29 dl / g, and The amount of butene-ethylene copolymer is 8.3-31.0 wt% based on the total amount of the polymer composition.

2. The polymer composition of claim 1, wherein the butene-ethylene copolymer is a 1-butene-ethylene copolymer.

3. The polymer composition of any one of claims 1-2, wherein the amount of butene-ethylene copolymer is 12.0-27.1 wt% based on the total amount of the polymer composition.

4. The polymer composition of any one of claims 1-2, wherein the melt flow index of the multiphase propylene copolymer is 45-83 dg / min, measured at 230°C with a load of 2.16 kg according to ISO 1133-1:2011.

5. The polymer composition of any one of claims 1-2, wherein the amount of the multiphase propylene copolymer is 62.3-86.5 wt% based on the total amount of the polymer composition.

6. The polymer composition of any one of claims 1-2, wherein the amount of the multiphase propylene copolymer is 70.4-80.2 wt% based on the total amount of the polymer composition.

7. The polymer composition of any one of claims 1-2, wherein the polymer composition further comprises an inorganic filler, wherein the amount of the inorganic filler is at most 10 wt% based on the total amount of the polymer composition.

8. The polymer composition of claim 7, wherein the amount of the inorganic filler is at most 7.5 wt% based on the total amount of the polymer composition.

9. The polymer composition of any one of claims 1-2, wherein the melt flow index of the butene-ethylene copolymer is 0.1-19.8 dg / min, as measured by a load of 2.16 kg at 190°C according to ASTM D1238-13.

10. The polymer composition of any one of claims 1-2, wherein the melt flow index of the butene-ethylene copolymer is 0.3-11.3 dg / min, as measured by a load of 2.16 kg at 190°C according to ASTM D1238-13.

11. The polymer composition of any one of claims 1-2, wherein the melt flow index of the butene-ethylene copolymer is 0.4-3.4 dg / min, as measured by a load of 2.16 kg at 190°C according to ASTM D1238-13.

12. The polymer composition of any one of claims 1-2, wherein the density of the butene-ethylene copolymer is 0.857-0.901 g / cm³ as measured by ASTM D792-13. 3 .

13. The polymer composition of any one of claims 1-2, wherein the density of the butene-ethylene copolymer is 0.861-0.888 g / cm³ as measured by ASTM D792-13. 3 .

14. The polymer composition of any one of claims 1-2, wherein the density of the butene-ethylene copolymer is 0.866-0.875 g / cm³ as measured by ASTM D792-13. 3 .

15. The polymer composition of claim 7, wherein the inorganic filler is talc.

16. The polymer composition of claim 7, wherein the average particle size D50 of the inorganic filler is 0.1-10.2 µm, as measured by ISO 13317-3:2001, sedimentation analysis, and Stockes' law.

17. The polymer composition of any one of claims 1-2, wherein the butene-ethylene copolymer has a Shore A hardness of 44-101 as measured by ASTM D2240-15.

18. The polymer composition of any one of claims 1-2, wherein the melt flow index of the polymer composition is 25-70 dg / min, measured at 230°C with a load of 2.16 kg according to ISO 1133-1:2011.

19. The polymer composition of any one of claims 1-2, wherein the melt flow index of the polymer composition is 28-50 dg / min, measured at 230°C with a load of 2.16 kg according to ISO 1133-1:2011.

20. A method for preparing an article, comprising the following sequential steps: Provide a polymer composition according to any one of claims 1-19; The polymer composition of any one of claims 1-19 is molded into an article.

21. The method of claim 20, wherein the polymer composition is molded into an article by injection molding.

22. The method of claim 20 or 21, wherein the article of manufacture is an automotive part.

23. The method of claim 22, wherein the automotive component is an airbag cover.

24. Use of the polymer composition of any one of claims 1-19 for use in automotive parts.

25. The use of claim 24, wherein the automotive component is an airbag cover.

26. An automotive part comprising the polymer composition of any one of claims 1-19, wherein the amount of the polymer composition is at least 95 wt% based on the total amount of the automotive part.

27. The automotive component of claim 26, wherein the amount of the polymer composition is at least 97 wt% based on the total amount of the automotive component.

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