Polymer composition

Abstract

The invention relates to a composition comprising i) a first heterophasic propylene copolymer (a) and / or a second heterophasic propylene copolymer (b), ii) a high melt strength polypropylene, iii) a polyolefin based elastomer and iv) an inorganic filler, wherein the first heterophasic propylene copolymer (a) has a melt flow index (MFI) in the range of at least 5.6 dg / min and less than 50.0 dg / min as determined according to ISO1133-1:2011 at 230°C with 2.16 kg load and a xylene soluble part in the range from 18.1 to 27.6 wt% as determined by ISO16152:2005 based on the total amount of the first heterophasic propylene copolymer (a), wherein the xylene soluble part of the first heterophasic propylene copolymer (a) has an intrinsic viscosity in the range from 2.9 to 4.8 dl / g as measured according to ISO1628-1:2009 in decalin at 135 °C; wherein the second heterophasic propylene copolymer (b) has a melt flow index (MFI) in the range from 50.0 to 100 dg / min as determined according to ISO1133-1:2011 at 230°C with 2.16 kg load and a xylene soluble part in the range from 12.1 to 20.6 wt% as determined by ISO16152:2005 based on the total amount of the second heterophasic propylene copolymer (b), wherein the xylene soluble part of the second heterophasic propylene copolymer (b) has an intrinsic viscosity in the range from 3.6 to 6.2 dl / g as measured according to ISO1628-1:2009 in decalin at 135 °C.

Description

[0001] POLYMER COMPOSITION

[0002] The present invention relates to a polymer composition and a foamed article comprising such composition. The invention also relates to a process for the preparation of said foamed article and to the use of the foamed article for the preparation of automotive parts.

[0003] Foamed articles, especially polypropylene based foamed articles are widely used in automotive industry because of their low density and superior balance between impact resistance and stiffness.

[0004] WO2013178509A1 discloses a foamed article prepared from a composition comprising (A) from 30 to 85% by weight of a propylene-based component being selected from propylene homopolymers, propylene copolymers or heterophasic propylene polymer, such first propylene -based component having a flexural modulus determined in accordance with ISO 178 higher than 800 MPa; (B) from 1 to 20% by weight of a heterophasic propylene polymer; (C) from 1 to 30% by weight of an ethylene-based plastomer having a hardness (Shore A, ASTM D- 2240) value equal to or lower than 90 points; (D) from 5 to 30% by weight of talc.

[0005] WO2021130140A1 discloses a foamed article comprising a polymer composition comprising a first and a second heterophasic propylene copolymer, an inorganic filler and a polyolefin based elastomer. WO2021130140A1 mentions that the foamed article has a superior surface quality and an excellent stiffness preservation comparing to the solid article prepared from the same material.

[0006] It is an objective of the invention to provide a polymer composition that can be used for preparing a foamed article having a combination of good puncture impact behavior and good stiffness.

[0007] Accordingly, the invention provides a polymer composition comprising i) a first heterophasic propylene copolymer (a) and / or a second heterophasic propylene copolymer (b), ii) a high melt strength polypropylene, iii) a polyolefin based elastomer and iv) an inorganic filler, wherein the first heterophasic propylene copolymer (a) has a melt flow index (MFI) in the range of at least 5.6 dg / min and less than 50.0 dg / min as determined according to ISO1133-1 :2011 at 230°C with 2.16 kg load and a xylene soluble part in the range from 18.1 to 27.6 wt% as determined by ISO16152:2005 based on the total amount of the first heterophasic propylene copolymer (a), wherein the xylene soluble part of the first heterophasic propylene copolymer (a) has an intrinsic viscosity in the range from 2.9 to 4.8 dl / g as measured according to IS01628- 1 :2009 in decalin at 135 °C; wherein the second heterophasic propylene copolymer (b) has a melt flow index (MFI) in the range from 50.0 to 100 dg / min as determined according to ISO1133-1 :2011 at 230°C with 2.16 kg load and a xylene soluble part in the range from 12.1 to 20.6 wt% as determined by ISO16152:2005 based on the total amount of the second heterophasic propylene copolymer (b), wherein the xylene soluble part of the second heterophasic propylene copolymer (b) has an intrinsic viscosity in the range from 3.6 to 6.2 dl / g as measured according to IS01628- 1 :2009 in decalin at 135 °C.

[0008] It was surprisingly found that the addition of a high melt strength polypropylene in making the composition was found to significantly improve the puncture impact behavior while maintaining good stiffness.

[0009] The polymer composition according to the invention comprises a first heterophasic propylene copolymer (a) and / or a second heterophasic propylene copolymer (b). Preferably, the total amount of the first heterophasic propylene copolymer (a) and the second heterophasic propylene copolymer (b) is in the range from 30 to 80 wt%, for example 50 to 75 wt%, based on the total amount of the polymer composition.

[0010] In some embodiments, the polymer composition according to the invention comprises the first heterophasic propylene copolymer (a) and optionally the second heterophasic propylene copolymer (b).

[0011] In some embodiments, the polymer composition according to the invention comprises the second heterophasic propylene copolymer (b) and optionally the first heterophasic propylene copolymer (a). In some embodiments, the polymer composition according to the invention comprises the first heterophasic propylene copolymer (a) and comprises the second heterophasic propylene copolymer (b). This results in a very high surface quality of the foamed article according to the invention. Preferably, the weight ratio between the first heterophasic propylene copolymer (a) and the second heterophasic propylene copolymer (b) is 1 :10 to 10:1 , for example 1 :10 to 1 :1 or 1 :1 to 10:1. In some embodiments, the weight ratio between the first heterophasic propylene copolymer (a) and the second heterophasic propylene copolymer (b) is 1 :2 to 2:1 , for example 2:3 to 3:2.

[0012] The amount of the first heterophasic propylene copolymer (a) may e.g. be in the range from 30 to 80 wt%, for example 50 to 75 wt%, based on the total amount of the polymer composition. This results in a particularly good puncture impact behavior of the foamed article according to the invention.

[0013] The amount of the second heterophasic propylene copolymer (b) may e.g. be in the range from 30 to 80 wt%, for example 50 to 75 wt%, based on the total amount of the polymer composition. This is advantageous for the processibility of the polymer composition for making the foamed article according to the invention.

[0014] First heterophasic propylene copolymer (a)

[0015] The first heterophasic propylene copolymer (a) preferably comprises a first propylene polymer (a1) as matrix and a first ethylene-a-olefin copolymer (a2) as dispersed phase.

[0016] The amount of the first propylene polymer (a1) is preferably in the range from 68 to 92 wt%, preferably in the range from 70 to 87 wt%, even more preferably in the range from 72 to 83 wt% based on the total amount of the first heterophasic propylene copolymer (a).

[0017] The first propylene polymer (a1) in the first heterophasic propylene copolymer (a) can be a propylene homopolymer or / and a propylene-a-olefin copolymer wherein the a- olefin has 2 or 4 to 20 carbon atoms, for example the propylene-a-olefin can be a propylene-ethylene copolymer or a propylene-butene copolymer. Preferably the first propylene polymer (a1) in the first heterophasic propylene copolymer (a) is a propylene homopolymer. The melt flow index (MFI) of the first propylene polymer (a1) in the first heterophasic propylene copolymer (a) is preferably in the range from 20 to 120 dg / min, preferably from 40 to 110 dg / min, more preferably from 60 to 90 dg / min as determined according to ISO1133-1 :2011 at 230 °C with 2.16 kg load.

[0018] The amount of the first ethylene-a-olefin copolymer (a2) is preferably in the range from 8 to 32 wt%, preferably in the range from 13 to 30 wt%, more preferably in the range from 17 to 28 wt% based on the total amount of the first heterophasic propylene copolymer (a).

[0019] In the first heterophasic propylene copolymer (a), the amount of the moiety derived from ethylene is preferably in the range from 35 to 49 wt%, more preferably in the range from 40 to 49 wt% based on the total amount of the first ethylene-a-olefin copolymer (a2).

[0020] Preferably, the moiety of a-olefin in the first ethylene-a-olefin copolymer (a2) in the first heterophasic propylene copolymer (a) is derived from at least one a-olefin having 3 to 20 carbon atoms, for example the first ethylene-a-olefin copolymer (a2) can be an ethylene-propylene copolymer, for example the first ethylene-a-olefin copolymer (a2) can be an ethylene-butene copolymer, for example the first ethylene-a-olefin copolymer (a2) can be an ethylene-hexene copolymer, for example the first ethylene-a- olefin copolymer (a2) can be an ethylene-octene copolymer, for example the first ethylene-a-olefin copolymer (a2) can be an ethylene-propylene-butene copolymer, for example the first ethylene-a-olefin copolymer (a2) can be an ethylene-propylene- hexene copolymer. Preferably the first ethylene-a-olefin copolymer (a2) in the first heterophasic propylene copolymer (a) is an ethylene-propylene copolymer.

[0021] The MFI of the first heterophasic propylene copolymer (a) is in the range of at least 5.6 dg / min and less than 50.0 dg / min, preferably in the range from 8.6 to 45.1 dg / min, preferably in the range from 11 .2 to 25.3 dg / min, more preferably in the range from 12.3 to 18.2 dg / min, as determined according to ISO1133-1 :2011 at 230 °C with a 2.16 kg load.

[0022] The first heterophasic propylene copolymer (a) can be divided into a first xylene- soluble portion (First CXS) and a first xylene-insoluble portion (First CXI). The amount of the xylene-soluble portion is in the range from 18.1 to 27.6 wt%, preferably from 20.3 to 24.2 wt%, based on the total amount of the first heterophasic propylene copolymer (a) as determined according to ISO16152:2005. The amount of the first xylene- insoluble portion based on the total amount of the first heterophasic propylene copolymer is calculated by the following equation: First CXI = 100 wt% - First CXS

[0023] The intrinsic viscosity of the first xylene-insoluble part (First CXI) of the first heterophasic propylene copolymer (a) IVFirst cxi is preferably in the range from 1.0 to 2.0 dl / g, more preferably from 1 .0 to 1 .8 dl / g, more preferably from 1 .2 to 1 .5 dl / g, as measured according to ISO1628-3:2010.

[0024] The intrinsic viscosity of the first xylene-soluble part (First CXS) of the first heterophasic propylene copolymer (a) IVFirstcxs is in the range from 2.9 to 4.8 dl / g, preferably in the range of at least 3.3 dl / g and less than 4.5 dl / g, preferably in the range from 3.8 to 4.3 dl / g, as measured according to IS01628-1 :2009.

[0025] Preferably, the ratio between the intrinsic viscosity of the xylene-soluble part (First CXS) of the first heterophasic propylene copolymer (a) IVFirstcxs and the intrinsic viscosity of the xylene-insoluble part (First CXI) of the first heterophasic propylene copolymer (a) IVFirstcxi is in the range from 2.0 to 3.5, preferably from 2.2 to 3.0.

[0026] The first heterophasic propylene copolymer (a) is preferably a non-visbroken heterophasic propylene copolymer. The term non-visbroken is known in the art, yet for the avoidance of doubt it means that the materials was not treated such as to modify the molecular weight and / or the molecular weight distribution of the polymer directly after polymerisation. In other words, non-visbroken polymers are not treated with peroxides, radiation, or any other initiating source for chain breaking reactions to occur. An advantage of non-visbroken polypropylenes over vis-broken polypropylenes is that the former generally suffer less from the release of low molecular weight materials, such materials inherently being produced upon visbreaking and is not desired for automotive application. For the avoidance of doubt, the term reactor grade indicates that the copolymer is non-visbroken. The first heterophasic propylene copolymer (a) is preferably a reactor grade heterophasic propylene copolymer.

[0027] The process to produce the first heterophasic propylene copolymer (a) is known in the art. Preferably the first heterophasic propylene copolymer (a) is produced in a sequential polymerization process comprising at least two reactors, more preferably the polypropylene of the present invention is produced in a sequential polymerization process comprising at least three reactors.

[0028] The catalyst used in the preparation of the first heterophasic propylene copolymer (a) is also known in the art, for example a Ziegler-Natta catalyst, or a metallocene catalyst. Preferably the catalyst used to produce the first heterophasic propylene copolymer is free of phthalates, for example the catalyst comprises compounds of a transition metal of Group 4 to 6 of IUPAC, a Group 2 metal compound and an internal donor wherein said internal donor include but are not limited to 1 ,3-diethers, for example 9,9-bis (methoxymethyl) fluorene, optionally substituted malonates, maleates, succinates, glutarates, benzoic acid esters, cyclohexene-1 ,2-dicarboxylates, benzoates, citraconates, aminobenzoates, silyl esters and derivatives and / or mixtures thereof.. For example the catalyst used in the preparation of the first heterophasic propylene copolymer (a) is a Ziegler-Natta catalyst comprising a procatalyst, at least one external donor, a co-catalyst and an optional internal donor wherein the external electron donor is chosen from the group consisting of a compound having a structure according to Formula III (R90)2N-Si(OR91)3, a compound having a structure according to Formula IV: (R92)Si(OR93)3and 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 a linear unsubstituted alkyl having between 1 and 8 carbon atoms, preferably ethyl, methyl or n-propyl.

[0029] In one embodiment, R90and R91are each ethyl (compound of Formula III is diethylaminotriethoxysilane, DEATES). In another embodiment, R92is n-propyl and R93are each ethyl (compound of Formula IV is n-propyl triethoxysilane, nPTES) or in another embodiment R92is n-propyl and R93are each methyl (compound of Formula IV is n-propyl trimethoxysilane, nPTMS).

[0030] Preferably, the first heterophasic propylene copolymer (a) is prepared by a catalyst system comprising a Ziegler-Natta catalyst and at least one external electron donor chosen from the group of a compound having a structure according to Formula III (R90)2N-Si(OR91)3, a compound having a structure according to Formula IV: (R92)Si(OR93)3and mixtures thereof.

[0031] A "co-catalyst" is a term well-known in the art in the field of Ziegler-Natta catalysts and is recognized to be a substance capable of converting the procatalyst to an active polymerization catalyst. Generally, the co-catalyst is an organometallic compound containing a metal from group 1 , 2, 12 or 13 of the Periodic System of the Elements (Handbook of Chemistry and Physics, 70th Edition, CRC Press, 1989- 1990). The cocatalyst may include any compounds known in the art to be used as “co-catalysts”, such as hydrides, alkyls, or aryls of aluminum, lithium, zinc, tin, cadmium, beryllium, magnesium, and combinations thereof. The co-catalyst may be a hydrocarbyl aluminum co-catalyst, such as triisobutylaluminum, trihexylaluminum, diisobutylaluminum hydride, dihexylaluminum hydride, isobutylaluminum dihydride, hexylaluminum dihydride, diisobutylhexylaluminum, isobutyl dihexylaluminum, trimethylaluminum, triethylaluminum, tripropylaluminum, triisopropylaluminum, tri-n- butylaluminum, trioctylaluminum, tridecylaluminum, tridodecylaluminum, tribenzylaluminum, triphenylaluminum, trinaphthylaluminum, and tritolylaluminum. In an embodiment, the cocatalyst is selected from triethylaluminum, triisobutylaluminum, trihexylaluminum, di-isobutylaluminum hydride and dihexylaluminum hydride. More preferably, trimethylaluminium, triethylaluminium, triisobutylaluminium, and / or trioctylaluminium. Most preferably, triethylaluminium (abbreviated as TEAL). The co- catalyst can also be a hydrocarbyl aluminum compound such as tetraethyl- dialuminoxane, methylaluminoxane, isobutylaluminoxane, tetraisobutyl-dialuminoxane, diethyl-aluminumethoxide, diisobutylaluminum chloride, methylaluminum dichloride, diethylaluminum chloride, ethylaluminum dichloride and dimethylaluminum chloride, preferably TEAL.

[0032] For example, the procatalyst may be prepared by a process comprising the steps of providing a magnesium-based support, contacting said magnesium-based support with a Ziegler-Natta type catalytic species, an internal donor, and an activator, to yield the procatalyst. For example, the Examples of US 5,093,415 of Dow discloses an improved process to prepare a procatalyst. Preferably, the procatalyst is a chemical compound comprising titanium.

[0033] In the context of the present invention, the molar ratio between Si and Ti element in the catalyst system is preferably in the range from 0.1 to 40, preferably from 0.1 to 20, even more preferably from 1 to 20 and most preferably from 2 to 10. Preferably the molar ratio between Al and Ti element in the catalyst system is in the range from 5 to 500, preferably from 15 to 200, more preferably from 30 to 160, most preferably from 50 to 140. In one embodiment, the molar ratio between Si and Ti element is the molar ratio between the external donor and the procatalyst.

[0034] In one embodiment, the molar ratio between Al and Ti element is the molar ratio between the co-catalyst and the procatalyst.

[0035] Second heterophasic propylene copolymer (b)

[0036] The second heterophasic propylene copolymer (b) preferably comprises a second propylene polymer (b1) as matrix and a second ethylene-a-olefin copolymer (b2) as dispersed phase.

[0037] The amount of the second propylene polymer (b1) is preferably in the range from 65 to 90 wt%, preferably from 79 to 88 wt% based on the total amount of the second heterophasic propylene copolymer (b).

[0038] The second propylene polymer (b1) in the second heterophasic propylene copolymer (b) can be a propylene homopolymer or / and a propylene-a-olefin copolymer wherein the a-olefin has 2 or 4 to 20 carbon atoms, for example the propylene-a-olefin can be a propylene-ethylene copolymer or a propylene-butene copolymer. Preferably the second propylene polymer (b1) in the second heterophasic propylene copolymer (b) is a propylene homopolymer.

[0039] The MFI (melt flow index) of the second propylene polymer (b1) in the second heterophasic propylene copolymer (b) is preferably in the range from 20 to 52.0 dg / min, preferably from 50 to 31 .0 dg / min, more preferably from 14.0 to 26.0 dg / min as measured according to ISO1133-1 :2011 at 230 °C with a 2.16 kg load.

[0040] The amount of the second ethylene-a-olefin copolymer (b2) is in the range from 10 to 35 wt%, preferably from 12 to 21 wt% based on the total amount of the second heterophasic propylene copolymer (b).

[0041] In the second heterophasic propylene copolymer (b), the amount of the moiety derived from ethylene is preferably in the range from 35 to 49 wt% based on the total amount of the second ethylene-a-olefin copolymer (b2).

[0042] The moiety of a-olefin in the second ethylene-a-olefin copolymer (b2) in the second heterophasic propylene copolymer (b) is preferably derived from at least one a-olefin having 3 to 20 carbon atoms, for example the second ethylene-a-olefin copolymer (b2) can be an ethylene-propylene copolymer, for example the second ethylene-a-olefin copolymer (b2) can be an ethylene-butene copolymer, for example the second ethylene-a-olefin copolymer (b2) can be an ethylene-hexene copolymer, for example the second ethylene-a-olefin copolymer (b2) can be an ethylene-octene copolymer, for example the second ethylene-a-olefin copolymer (b2) can be an ethylene-propylene- butene copolymer, for example the second ethylene-a-olefin copolymer (b2) can be an ethylene-propylene-hexene copolymer. Preferably the second ethylene-a-olefin copolymer (b2) in the second heterophasic propylene copolymer (b) is an ethylenepropylene copolymer.

[0043] Preferably the MFI of the second heterophasic propylene copolymer (b) is in the range from 50.0 to 100 dg / min, preferably in the range from 55.0 to 90.0 dg / min, preferably in the range from 60.0 to 83.0 dg / min, as determined according to ISO1133-1 :2011 at 230 °C with a 2.16 kg load.

[0044] The second heterophasic propylene copolymer (b) can be divided into a second xylene-soluble portion (Second CXS) and a second xylene-insoluble portion (Second CXI). The amount of the second xylene-soluble portion is preferably in the range from 12.1 to 20.6 wt%, preferably in the range from 12.5 to 20.0 wt%, preferably from to 13.0 to 18.0 wt%, based on the total amount of the second heterophasic propylene copolymer (b) as determined according to ISO16152:2005.

[0045] The intrinsic viscosity of the second xylene-insoluble part (Second CXI) of the second heterophasic propylene copolymer (a) ISecondcxi is preferably in the range from 1.0 to 2.0 dl / g, more preferably from 1 .0 to 1 .8 dl / g, more preferably from 1 .2 to 1 .5 dl / g, as measured according to ISO1628-3:2010.

[0046] The intrinsic viscosity of the second xylene-soluble part (Second CXS) of the second heterophasic propylene copolymer (b) ISecondcxs is preferably in the range from 3.6 to 6.2 dl / g, preferably in the range from 4.5 to 5.8 dl / g, as measured according to IS01628- 1 :2009 in decalin at 135 °C.

[0047] Preferably, the ratio between the intrinsic viscosity of the xylene-soluble part (Second CXS) of the first heterophasic propylene copolymer (a) ISecond cxs and the intrinsic viscosity of the xylene-insoluble part (Second CXI) of the second heterophasic propylene copolymer (a) ISecond cxi is in the range from 3.1 to 7.2, preferably from 3.2 to 5.1.

[0048] The second heterophasic propylene copolymer (b) is preferably a reactor grade heterophasic propylene copolymer.

[0049] The second heterophasic propylene copolymer (b) can be produced with process and catalyst known in the art.

[0050] In one embodiment, the second heterophasic propylene copolymer (b) is produced with the same process as the first heterophasic propylene copolymer (a).

[0051] In one embodiment, the second heterophasic propylene copolymer (b) is produced with the same catalyst as the first heterophasic propylene copolymer (a).

[0052] Optional third heterophasic propylene copolymer

[0053] The polymer composition according to the present invention can comprise a third heterophasic propylene copolymer (c).

[0054] The third heterophasic propylene copolymer (c) preferably comprises a third propylene polymer (c1) as matrix and a third ethylene-a-olefin copolymer (c2) as dispersed phase.

[0055] The amount of the third propylene polymer (c1) is preferably in the range from 65 to 81 wt% based on the total amount of the third heterophasic propylene copolymer (c).

[0056] The third propylene polymer (c1) in the third heterophasic propylene copolymer (c) can be a propylene homopolymer or / and a propylene-a-olefin copolymer wherein the a- olefin has 2 or 4 to 20 carbon atoms, for example the propylene-a-olefin can be a propylene-ethylene copolymer or a propylene-butene copolymer. Preferably the third propylene polymer (c1) in the third heterophasic propylene copolymer (c) is a propylene homopolymer.

[0057] The MFI (melt flow index) of the third propylene polymer (c1) in the third heterophasic propylene copolymer (c) is preferably in the range from 20 to 150 dg / min, preferably from 50 to 100 dg / min, more preferably from 60 to 85 dg / min as measured according to ISO1133-1 :2011 at 230 °C with a 2.16 kg load. The amount of the third ethylene-a-olefin copolymer (c2) is in the range from 19 to 35 wt%, preferably from 25 to 30 wt% based on the total amount of the third heterophasic propylene copolymer (c).

[0058] In the third heterophasic propylene copolymer (c), the amount of the moiety derived from ethylene is preferably in the range from 55 to 68 wt% based on the total amount of the third ethylene-a-olefin copolymer (c2).

[0059] The moiety of a-olefin in the third ethylene-a-olefin copolymer (c2) in the third heterophasic propylene copolymer (b) is preferably derived from at least one a-olefin having 3 to 20 carbon atoms, for example the third ethylene-a-olefin copolymer (c2) can be an ethylene-propylene copolymer, for example the third ethylene-a-olefin copolymer (c2) can be an ethylene-butene copolymer, for example the third ethylene-a- olefin copolymer (c2) can be an ethylene-hexene copolymer, for example the third ethylene-a-olefin copolymer (c2) can be an ethylene-octene copolymer, for example the third ethylene-a-olefin copolymer (c2) can be an ethylene-propylene-butene copolymer, for example the third ethylene-a-olefin copolymer (c2) can be an ethylene- propylene-hexene copolymer. Preferably the third ethylene-a-olefin copolymer (c2) in the third heterophasic propylene copolymer (c) is an ethylene-propylene copolymer.

[0060] Preferably the MFI of the third heterophasic propylene copolymer (c) is in the range from 10 to 100 dg / min, preferably in the range from 15 to 80 dg / min, preferably in the range from 23 to 65 dg / min, as determined according to ISO1133-1 :2011 at 230 °C with a 2.16 kg load.

[0061] The third heterophasic propylene copolymer (c) can be divided into a third xylene- soluble portion (third CXS) and a third xylene-insoluble portion (third CXI). The amount of the third xylene-soluble portion is preferably in the range from 10 to 27 wt%, preferably in the range from 15 to 23 wt%, based on the total amount of the third heterophasic propylene copolymer (c) as determined according to ISO16152:2005.

[0062] The intrinsic viscosity of the third xylene-insoluble part (third CXI) of the third heterophasic propylene copolymer (a) I VThird cxi is preferably in the range from 1 .0 to 2.0 dl / g, more preferably from 1 .0 to 1 .8 dl / g, more preferably from 1 .2 to 1 .5 dl / g, as measured according to ISO1628-3:2010. The intrinsic viscosity of the third xylene-soluble part (third CXS) of the third heterophasic propylene copolymer (c) IThird cxs is preferably in the range from 1.7 to 2.8 dl / g, more preferably in the range from 1 .9 to 2.7 dl / g, more preferably from 2.0 to 2.5 dl / g, as measured according to IS01628-1 :2009 in decalin at 135 °C.

[0063] The ratio between the intrinsic viscosity of the xylene-soluble part (third CXS) of the third heterophasic propylene copolymer (a) IThird cxs and the intrinsic viscosity of the xylene-insoluble part (Third CXI) of the third heterophasic propylene copolymer (a) I V-rhird cxi is in the range from 1.1 to 1.9, preferably from 1 .5 to 1.8.

[0064] The third heterophasic propylene copolymer (c) is preferably a reactor grade heterophasic propylene copolymer.

[0065] The third heterophasic propylene copolymer (c) can be produced with process and catalyst known in the art.

[0066] In one embodiment, the third heterophasic propylene copolymer (c) is produced with the same process as the first heterophasic propylene copolymer (a).

[0067] In one embodiment, the third heterophasic propylene copolymer (c) is produced with the same catalyst as the first heterophasic propylene copolymer (a).

[0068] The amount of the third heterophasic propylene copolymer (c) may e.g. be in the range from 5.0 to 40 wt%, for example 10 to 35 wt%, based on the total amount of the polymer composition.

[0069] Preferably, the total amount of the first heterophasic propylene copolymer (a) and the second heterophasic propylene copolymer (b) and the third heterophasic propylene copolymer (c) is at least 45 wt%, preferably at least 50 wt%, more preferably at least 55 wt%, based on the total amount of the polymer composition.

[0070] In some preferred embodiments, the polymer composition according to the present invention comprises the first heterophasic propylene copolymer (a) and the third heterophasic propylene copolymer (c). Preferably, the total amount of the first heterophasic propylene copolymer (a) and the third heterophasic propylene copolymer (c) is at least 45 wt%, preferably at least 50 wt%, more preferably at least 55 wt%, based on the total amount of the polymer composition. In some preferred embodiments, the polymer composition according to the present invention comprises the second heterophasic propylene copolymer (b) and the third heterophasic propylene copolymer (c). Preferably, the total amount of the second heterophasic propylene copolymer (b) and the third heterophasic propylene copolymer (c) is at least 45 wt%, preferably at least 50 wt%, more preferably at least 55 wt%, based on the total amount of the polymer composition.

[0071] High melt strength polypropylene

[0072] The polymer composition comprises a high melt strength polypropylene (HMS-PP). Preferably, the amount of the high melt strength polypropylene is 1.0 to 10 wt%, for example 3.0 to 7.0 wt%, based on the total amount of the polymer composition.

[0073] A high melt strength polypropylene is branched and, thus, differs from a linear polypropylene in that the polypropylene backbone covers side chains whereas a nonbranched polypropylene, i.e. a linear polypropylene, does not cover side chains. The side chains have significant impact on the rheology of the polypropylene. Accordingly linear polypropylenes and high melt strength polypropylenes can be clearly distinguished by their flow behaviour under stress.

[0074] Branching can be generally achieved by using specific catalysts, i.e. specific single-site catalysts, or by chemical modification. Concerning the preparation of a branched polypropylene obtained by the use of a specific catalyst reference is made to EP 1 892 264. With regard to a branched polypropylene obtained by chemical modification it is referred to EP 0 879 830 A1 . In such a case the branched polypropylene is also called high melt strength polypropylene.

[0075] Suitable examples of commercially available products of the high melt strength polypropylene are commercially available from Borealis AG under the trade name Daploy™, for example Daploy™ WB140HMS.

[0076] Another suitable example of commercially available products of the high melt strength polypropylene is Achieve™ Advanced PP6302E1 from Exxon Mobil.

[0077] Preferably, the high melt strength polypropylene has a branching index g’ of less than 1 .00, more preferably less than 0.90, more preferably less than 0.80, more preferably less than 0.75. The branching index g' is explained e.g. in EP1847555A1. The branching index g' defines the degree of branching and correlates with the amount of branches of a polymer. The branching index g' is defined as g'=[IV]br / [l V]iinin which g' is the branching index, [IVbr] is the intrinsic viscosity of the branched polypropylene and [IV]iinis the intrinsic viscosity of the linear polypropylene having the same weight average molecular weight (within a range of ±10 %) as the branched polypropylene. Thereby, a low g'-value is an indicator for a high branched polymer. In other words, if the g'-value decreases, the branching of the polypropylene increases. Reference is made in this context to B.H. Zimm and W.H. Stockmeyer, J. Chem. Phys. 17,1301 (1949). This document is herewith included by reference. The intrinsic viscosity needed for determining the branching index g' is measured according to DIN ISO 1628 / 1 , October 1999 (in Decalin at 135 °C).

[0078] Preferably, the high melt strength polypropylene has a melt strength of > 30 cN. The melt strength of the high melt strength polypropylene is herein determined in accordance with ISO 16790:2005 at a temperature of 200°C, using a cylindrical capillary having a length of 20mm and a width of 2mm, a starting velocity vO of 9.8mm / s and an acceleration of 6mm / s2.

[0079] High melt strength polypropylene having a melt strength > 30 cN can for example be obtained by the process as disclosed in W02009 / 003930A1. W02009 / 003930A1 discloses an irradiated polymer composition comprising at least one polyolefin resin and at least one non-phenolic stabilizer, wherein the irradiated polymer composition is produced by a process comprising mixing the polyolefin resin with the non-phenolic stabilizer and irradiating this mixture in a reduced oxygen environment. In addition, a high melt strength polypropylene having a melt strength > 45 cN is available from SABIC as SABIC® PP UMS 561 P as of 18 February 2021 .

[0080] Preferably, the high melt strength polypropylene is prepared by a) irradiation of a polypropylene with at least one non-phenolic stabilizer, preferably wherein the non-phenolic stabilizer is chosen from the group of hindered amines, wherein the irradiation is performed with > 2.0 and < 20 Megarad electron-beam radiation in a reduced oxygen environment, wherein the amount of active oxygen is < 15% by volume with respect to the total volume of the reduced oxygen environment for a time sufficient for obtaining a long chain branched polypropylene and b) deactivation of the free radicals in the long chain branched polypropylene to form the high melt strength polypropylene.

[0081] How to deactivate the free radicals is known in the art, for example by heating as described in W02009003930A1 .

[0082] Examples of non-phenolic stabilizers are known in the art and are for example disclosed on pages 37 - 60 of W02009 / 003930A1 , hereby incorporated by reference. Preferably, the non-phenolic stabilizer is chosen from the group of hindered amines. More preferably, the non-phenolic stabilizer comprises at least one hindered amine selected from the group of Chimassorb® 944, Tinuvin® 622, Chimassorb® 2020, Chimassorb® 119, Tinuvin® 770, and mixtures thereof, separate or in combination with at least one hydroxylamine, nitrone, amine oxide, or benzofuranone selected from N.M- dehydrogenated tallow)amine (Irgastab® FS-042), an N,N- di(alkyl)hydroxylamine produced by a direct oxidation of N,N-di(hydrogenated tallow)amine (Irgastab® FS- 042), N-octadecyl-a-heptadecylnitrone, Genox™ EP, a di(C16 -C18 )alkyl methyl amine oxide, 3-(3,4-dimethylphenyl)-5,7-di-tert-butyl-benzofuran-2-one, Irganox® HP- 136 (BFI), and mixtures thereof, and separate or in combination with at least one organic phosphite or phosphonite selected from tris(2,4-di-tert-butylphenyl) phosphite (Irgafos® 168). Even more preferably, the non-phenolic stabilizers of the present subject matter can include those described in U.S. Patents 6,664,317 and 6,872,764, both of which are incorporated herein by reference in their entirety.

[0083] Preferably, the melt strength of the high melt strength polypropylene is > 37 cN, preferably > 40 cN, preferably > 45 cN, > more preferably 50 cN, more preferably > 55 cN, even more preferably > 60 cN, most preferably > 65 cN and / or preferably the melt strength of the high melt strength polypropylene is <100 cN, for example < 95 cN, for example < 90 cN, for example < 87cN.

[0084] With polypropylene as used herein is meant propylene homopolymer, a copolymer of propylene with an a-olefin or a heterophasic propylene copolymer.

[0085] Preferably, the high melt strength polypropylene is polypropylene chosen from the group of propylene homopolymers and propylene copolymers comprising moieties derived from propylene and one or more comonomers chosen from the group of ethylene and alpha-olefins with > 4 and < 12 carbon atoms.

[0086] Preferably, the propylene copolymer comprises moieties derived from one or more comonomers chosen from the group of ethylene and alpha-olefins with > 4 and < 12 carbon atoms in an amount of < 10wt%, for example in an amount of > 1.0 and < 7.0wt% based on the propylene copolymer, wherein the wt% is determined using13C NMR. For example, the propylene copolymer comprises moieties derived from one or more comonomer chosen from the group of ethylene, 1 -butene, 1 -pentene, 1 -hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-decene and 1-dodecene, preferably moieties derived from ethylene.

[0087] Polypropylenes and the processes for the synthesis of polypropylenes are known. A propylene homopolymer is obtained by polymerizing propylene under suitable polymerization conditions. A propylene copolymer is obtained by copolymerizing propylene and one or more other comonomers, for example ethylene, under suitable polymerization conditions. The preparation of propylene homopolymers and copolymers is for example described in Moore, E. P. (1996) Polypropylene Handbook. Polymerization, Characterization, Properties, Processing, Applications, Hanser Publishers: New York.

[0088] Propylene homopolymers, propylene copolymers and heterophasic propylene copolymers can be made by any known polymerization technique as well as with any known polymerization catalyst system. Regarding the techniques, reference can be given to slurry, solution or gas phase polymerizations; regarding the catalyst system reference can be given to Ziegler-Natta, metallocene or single-site catalyst systems. All are, in themselves, known in the art.

[0089] Preferably, the high melt strength polypropylene has a melt flow rate > 0.50 and < 8.0 g / 1 Omin, more preferably > 0.70 and < 5.0 g / 1 Omin, most preferably > 1 .0 and < 4.0 g / 10min as determined in accordance with ASTM D1238 (2013) at a temperature of 230°C under a load of 2.16 kg.

[0090] Preferably, the high melt strength polypropylene has a VOC value as determined in accordance with VDA278 (2011-10) < 250 pg / g, preferably a VOC value < 50 pg / g and / or an FOG value as determined in accordance with VDA278 (2011-10) < 500 pg / g, preferably an FOG-value < 100 pg / g.

[0091] Preferably, the high melt strength polypropylene has a molecular weight distribution

[0092] Mw / Mn of 5 to 20, preferably 7 to 17, most preferably 10 to 15. Mw and Mn may be measured by universal size exclusion chromatography (SEC), as described in ASTM D6474-12, using:

[0093] • Chromatography: PolymerChar GPC-IR system running at 160°C

[0094] • Detection: Polymer Char IR5 infrared detector; PolymerChar viscometer

[0095] • IR5 is used as concentration detector.

[0096] • Column set: three Polymer Laboratories 13 pm PLgel Olexis, 300 x 7.5 mm

[0097] • PE molar mass calibration was performed with linear PE standards (narrow and broad (Mw / Mn = 4 to 15)) in the range of 0.5 - 2800 kg / mol

[0098] • Concentration of samples injected are 0.03 % m / m stabilized with Irgafos 168 and Topanol CA (weight ratio sample: Irgafos: Topanol = 1 :1 :1)

[0099] • Solvent and Eluent is 1 ,2,4-trichlorobenzene stabilized with 1 g / L BHT

[0100] Polyolefin based elastomer

[0101] The polymer composition according to the present invention comprises a polyolefin based elastomer. Preferably, the amount of the polyolefin based elastomer is 3.0 to 20 wt%, for example 3.0 to 9.0 wt% or 9.0 wt% to 20 wt%, based on the total amount of the polymer composition.

[0102] The polyolefin based elastomer is preferably an ethylene-a-olefin copolymer wherein the a-olefin has 3 to 20 carbon atoms, for example the ethylene-a-olefin copolymer is an ethylene-propylene copolymer, for example the ethylene-a-olefin copolymer is an ethylene-butene copolymer, for example the ethylene-a-olefin copolymer is an ethylene-hexene copolymer, for example the ethylene-a-olefin copolymer is an ethylene-octene copolymer or a combination thereof.

[0103] Preferably the polyolefin based elastomer is an ethylene-butene copolymer or / and an ethylene-octene copolymer.

[0104] Preferably the amount of moiety derived from ethylene in the polyolefin based elastomer is in the range from 45 to 90 wt%, preferably from 50 to 87 wt%, more preferably from 55 to 85 wt%, more preferably from 57 to 70 wt% based on the total amount of the polyolefin based elastomer.

[0105] The polyolefin based elastomer according to the present invention preferably has a shore A hardness in the range from 40 to 85, more preferably in the range from 51 to 79, more preferably in the range from 54 to 68 as measured according to ASTM D2240-15. The density of the polyolefin based elastomer according to the present invention is preferably in the range from 0.853 to 0.905 g / cm3, preferably from 0.859 to 0.896 g / cm3, more preferably from 0.860 to 0.882 g / cm3, more preferably from 0.860 to 0.876 g / cm3as measured according to ASTM D792-13.

[0106] The MFI of the polyolefin based elastomer is preferably in the range from 0.20 to 20.0 dg / min, preferably from 0.30 to 14.3 dg / min, more preferably from 0.40 to 7.2 dg / min as measured according to ASTM D1238-13 with a 2.16 kg load at 190°C.

[0107] The polyolefin based elastomer may be prepared using methods known in the art, for example by using a single site catalyst, i.e., a catalyst the transition metal components of which is an organometallic compound and at least one ligand of which has a cyclopentadienyl anion structure through which such ligand bondingly coordinates to the transition metal cation. This type of catalyst is also known as "metallocene" catalyst. Metallocene catalysts are for example described in U.S. Patent Nos. 5,017,714 and 5,324,820. The polyolefin based elastomer may also be prepared using traditional types of heterogeneous multi-sited Ziegler-Natta catalysts.

[0108] Inorganic filler

[0109] The polymer composition according to the present invention comprises an inorganic filler. Preferably, the amount of the inorganic filler in the range from 3.0 to 30 wt%, for example 3.0 to 10 wt% or 10 to 30 wt%, based on the total amount of the polymer composition. Preferably, the ash content of the polymer composition as measured according to ISO 3451-1 :2008 at 600°C for 4 hours is in the range from 3.0 to 30 wt%, for example 3.0 to 10 wt% or 10 to 30 wt%, based on the total amount of the polymer composition.

[0110] Suitable examples of inorganic fillers include but are not limited to talc, calcium carbonate, wollastonite, barium sulfate, kaolin, glass fibers, laminar silicates (bentonite, montmorillonite, smectite) and mica.

[0111] For example, the inorganic filler is selected from the group consisting of talc, calcium carbonate, wollastonite, mica and mixtures thereof.

[0112] Preferably, the inorganic filler is a talc. The mean particle size of talc (D50) of talc is preferably in the range from 0.12 to 10.2 pm, preferably in the range from 0.23 to 5.1 pm, more preferably in the range from 0.36 to 0.86 pm, as determined according to ISO 13317-3:2001 , sedimentation analysis, Stokes’ law.

[0113] Preferably, the total amount of the first heterophasic propylene copolymer (a), the second heterophasic propylene copolymer (b), the high melt strength polypropylene, the polyolefin based elastomer and the inorganic filler and the optional third heterophasic propylene copolymer (c) is at least 95 wt%, preferably at least 97 wt%, preferably at least 98.5 wt%, based on the total amount of the polymer composition.

[0114] In some preferred embodiments, the total amount of the first heterophasic propylene copolymer (a), the second heterophasic propylene copolymer (b), the high melt strength polypropylene, the polyolefin based elastomer and the inorganic filler is at least 95 wt%, preferably at least 97 wt%, preferably at least 98.5 wt%, based on the total amount of the polymer composition.

[0115] Additives

[0116] The polymer composition according to the present invention may further contain additives, for instance nucleating agents and clarifiers, stabilizers, release agents, plasticizers, anti-oxidants, lubricants, antistatics, cross linking agents, scratch resistance agents, pigments and / or colorants, flame retardants, acid scavengers, recycling additives, anti-microbials, anti-fogging additives, slip additives, anti-blocking additives, polymer processing aids and the like. Such additives are well known in the art. For a polymer composition with good properties, the amount of the additives is preferably to be at most 5.0 wt%, preferably at most 4.5 wt%, preferably at most 4 wt%, more preferably at most 3.8 wt% based on the total amount of the polymer composition.

[0117] Preferably, the total amount of the first heterophasic propylene copolymer (a), the second heterophasic propylene copolymer (b), the high melt strength polypropylene, the polyolefin based elastomer and the inorganic filler and the optional third heterophasic propylene copolymer and the optional additives is 100 wt% based on the total amount of the polymer composition.

[0118] In some preferred embodiments, the total amount of the first heterophasic propylene copolymer (a), the second heterophasic propylene copolymer (b), the high melt strength polypropylene, the polyolefin based elastomer and the inorganic filler and the optional additives is 100 wt% based on the total amount of the polymer composition. Foamed article

[0119] The invention further provides a foamed article prepared by foam injection moulding of the polymer composition.

[0120] Preferably, the amount of the polymer composition with respect to the foamed article is at least 90 wt%, at least 95 wt%, at least 98 wt%, at least 99 wt% or 100 wt%.

[0121] The foamed article may be a foamed sheet, e.g. having a thickness of 0.1 to 20 cm, 0.3 to 10 cm or 0.5 to 5.0 cm. For example, the thickness of the foamed sheet may be 0.1 to 3.0 cm, 3.0 to 10 cm or 10 to 20 cm.

[0122] Foam injection moulding

[0123] Generally, to prepare a foamed article, a polymer composition is mixed with a foaming agent. Then the mixture is heated to cause the polymer composition to melt and to cause the foaming agent to yield gas. Instead of first providing a mixture of a foaming agent and the polymer composition and subsequently melting the mixture to obtain a molten mixture, it is also possible to provide a melt of the polymer composition and mix a foaming agent into the melt of the polymer composition to obtain a molten mixture. Depending on the process, the resulting mixture is maintained as a gas laden melt until it is dispensed in a controlled manner through orifices or into shaping cavities. When the foaming is complete, the foamed article is allowed to solidify by cooling. Such processes are known in the art, e.g. from Thermoplastic Foams, by James L. Throne, Sherwood Publishers 1996, hereby incorporated by reference.

[0124] Preferably, the foam injection moulding is performed by expanding a molten mixture having a thickness of to in a mould to the foamed article having a thickness of t1 at an expansion ratio t1 / tO in the range from 1 .05 to 2.14, preferably in the range from 1 .38 to 1 .97, more preferably in the range from 1 .49 to 1 .82.

[0125] Preferably, the foam injection moulding comprises sequential steps of:

[0126] - a) providing a mixture of a foaming agent and the polymer composition and melting the mixture to obtain a molten mixture or b) providing a melt of the polymer composition and mixing a foaming agent into the melt of the polymer composition to obtain a molten mixture;

[0127] - injection moulding the molten mixture into a mould;

[0128] - optionally applying a pressure to the molten mixture in the mould; - opening the mould at least partially to allow the molten mixture to form a soft foamed article; and

[0129] - allowing the soft foamed article to solidify to form the foamed sheet and removing the foamed sheet from the mould.

[0130] This process is sometimes referred as core-back injection moulding process or a mould motion process.

[0131] Preferably, the foamed article has a density of 0.50 to 0.80 g / cm3, for example 0.50 to 0.65 g / cm3or 0.65 to 0.80 g / cm3, wherein the density is determined according to ISO 845 (2006).

[0132] The foaming agent used according to the invention can either be a physical foaming agent or a chemical foaming agent, wherein the chemical foaming agent is a chemical that decomposes at specific temperature to liberate gas(es), wherein physical foaming agent are either volatile liquids or gas(es). Typical chemical foaming agent includes but is not limited to azodicarbonamide, sodium bicarbonate, 5-phenyl tetrazole and citrate derivatives.

[0133] A typical physical foaming agent includes but is not limited to fluids such as nitrogen, carbon dioxide, hydrocarbons (e.g. butane, pentane) in gaseous or supercritical state; and their mixtures.

[0134] The amount of the foaming agent used in the present invention can be varied depending on its nature and the foaming performance of the foaming agent. In some instances, the amount of the foaming agent varies in the range of 0.2-5.0 wt% based on the total weight of the polymer composition.

[0135] The invention further provides use of the foamed article according to the invention or the foamed article obtained or obtainable by the process according to the invention for the preparation of automotive parts, for example automotive exterior parts or automotive interior parts. Examples include door panels, door trims, instrumental panels, interior trims, A / B / C pillars, seat claddings, center console, cup holders, arm, top / lower instrumental panel carrier trim parts, glove compartment and tail gate trim (for example trim trunk covers, cover bezel under the tail gate).

[0136] Experiments Materials

[0137] Polymer A (“third heterophasic propylene copolymer (c)” described above), Polymer B (“first heterophasic propylene copolymer (a)” described above), Polymer D (“second heterophasic propylene copolymer (b)” described above) were used.

[0138] Polymer A, B and D are heterophasic propylene copolymers prepared in an Innovene™ process, wherein a sequential two-reactor setup was employed. Polypropylene homopolymers were produced in first reactor and propylene-ethylene copolymers were produced in the second reactor. There were three component in the catalyst system in the polymerization process: A procatalyst, an external electron donor and a co-catalyst. The procatalyst was prepared according to the description in WO2016198344, page 36, “Procatalyst IN” paragraph; The external electron donor used for Polymer A and B was di(iso-propyl) dimethoxysilane (DiPDMS), the external electron donor used for Polymer D was n- propyltriethoxysilane (nPTES); the co-catalyst was triethylaluminium. The process condition of Polymer A, B and D are given in Table 1 :

[0139] The process condition of Polymer A, B and D are given in Table 1 :

[0140] Table 1 : Preparation condition of Polymer A, B and D

[0141] In Table 1 , R1 refers to the first reactor, R2 refers to the second reactor, Te refers to temperature, Pr refers to pressure, Al / Ti is the molar ratio of the co-catalyst to the procatalyst, Si / Ti is the molar ratio of the external donor to the procatalyst, H2 / C3 is the molar ratio of hydrogen to propylene, C2 / C3 is the molar ratio of ethylene to propylene, split is the amount of substance produced in R1 or R2 based on the amount of the total Polymer A or B or D respectively.

[0142] Engage 8200 is an ethylene- 1 -octene elastomer commercially available from Dow, having a density of 0.870 g / cm3 (ASTM D792-13), an MFI of 5.0 g / 10 min (ASTM D1238-13, 2.16 kg, 190°C) and a shore A hardness of 66 (ASTM D2240-15).

[0143] Tafmer DF605 is an ethylene- 1 -butene elastomer commercially available from Mitsui Chemicals, having a density of 0.861 g / cm3 (ASTM D792-13), an MFI of 0.5 g / 10 min (ASTM D1238-13, 2.16 kg, 190°C) and a shore A hardness of 58 (ASTM D2240-15).

[0144] SABIC® PP-UMS 561 P is a high melt strength polypropylene with a melt strength of more than 65 cN.

[0145] Talc HTPultra 5c is an ultrafine talc commercially available from IMI FABI. The mean particle size of talc (D50) of Talc HTPultra 5c is 0.65 pm as measured according to sedimentation analysis, Stokes’ law (ISO 13317-3:2001).

[0146] The additive package used consists of 70 wt% color masterbatch, 20 wt% heat and process stabilizers, 10 wt% processing aid based on the total amount of the additive package.

[0147] Chemical foaming agent used in the present invention was ORGATER BA.M2.E and is commercially available from ADEKA.

[0148] Sample preparation

[0149] Compounding Pellets of the Examples were prepared by compounding the components in amounts as indicated in Table 3 in a KraussMaffei Berstorff ZE40AJJTX 43D twin-screw extruder with the following setting: 400 rpm screw speed, 150kg / h throughput, 38% torque, 235 °C as temperature and 13 bar as head pressure.

[0150] Foam injection moulding

[0151] Foamed articles were prepared by core-back foam injection. The core-back foam injection moulding process consisted of the following sequential steps:

[0152] - The pellets of an example obtained in the compounding step were dry-blended with a chemical foaming agent to create a mixture of pellets. The amount of the chemical foaming agent used was 4 wt% based on the total amount of the pellets;

[0153] - The mixture of the pellets obtained in the dry-blending step was then added to the hopper of the injection moulding machine. The injection moulding machine settings used were: barrel temperature 240 °C, mould temperature 75 °C. The mould tool used comprises a fixed half and a moveable half. When the two halves are closed, the tool has a mould cavity of 90mm-wide x 160 mm-long rectangular plaque geometry.

[0154] - Then the molten mixture of pellets (melt) were injected into the mould cavity with an injection speed of 250 cm3 / s with a duration of the injection step of 0.2 s;

[0155] - The injected melt was held in the mould for 6.5 s with a pressure of 400 bar, after which the mould was opened at a core-back distance of 1 mm in 1 s to let the injected melt expand into foam from the initial (cavity) thickness to of 2 mm to the final foam thickness t1 of 3 mm. The expansion ratio (t1 / tO) was thus 1 .5.

[0156] - The foam was further cooled in the mould to solidify for 40 s, and subsequently, removed from the mould for characterization.

[0157] Test method

[0158] Melt flow index

[0159] Melt flow index (MFI) was measured according to IS01133-1 :2011 at 230°C with a 2.16kg load.

[0160] Weight percentage of the xylene-soluble portion (CXS) and weight percentage of the xylene- insoluble portion (CXI)

[0161] Weight percentage of the xylene-soluble portion (CXS) of the heterophasic propylene copolymers was determined according to IS016152:2005. Weight percentage of xylene- insoluble portion (CXI) of the heterophasic propylene copolymers was calculated using the following equation: CXI = 100 wt% - CXS Both xylene-soluble and xylene-insoluble portions (CXS and CXI) obtained in this test were used in the intrinsic viscosity (IV) test.

[0162] Intrinsic viscosity (IV)

[0163] Intrinsic viscosity (IV) of CXS and CXI was determined according to IS01628-1 :2009 and IS01628-3:2010 respectively in decalin at 135 °C.

[0164] Flexural properties

[0165] Flexural properties of the foamed articles were measured according to ISO 14125:1998 at 23°C after 7 days.

[0166] Puncture impact behavior

[0167] The puncture impact behavior of the foamed articles was determined in instrumented impact test according to ISO 6603-A2 at an impact speed of 4.4 m / s at 23°C after 7 days and at -10°C after 7 days. The inside diameter of the specimen supporting ring is 40mm and the hemispherical striker used has a diameter of 20mm.

[0168] The ISO 6603-2 curve type evaluation is a common method to characterize the force / deflection data obtained by impact test experiments. It provides four typical types of curve progression that can usually be observed during data evaluation. In general, these range from ductile to brittle and focus on information like yielding, crack initiation and crack propagation. Obtained data has been divided into these four categories, which are summarized below

[0169] Break types:

[0170] YD : Yielding followed by deep drawing (Ductile) - most preferred

[0171] YS : Yielding followed by stable cracking (Semi-ductile) - preferred

[0172] YU : Yielding followed by unstable cracking (Semi-brittle) - least preferred

[0173] NY : No yielding (Brittle) - not preferred

[0174] When the break types are the same, the Energy at 90% F-max can be used to determine the level of puncture impact behavior. The maximum force (F-max) is determined from the force / deflection response measured from the instrument. The Energy at 90% F-max is determined from electronically integrating the force I deflection data to the deflection at which the force has dropped to 90% of F-max after reaching maximum.

[0175] Ash content The ash content of the pellets of the polymer composition obtained in the compounding process was measured according to ISO 3451-1 :2008 at 600°C for 4 hours.

[0176] Surface quality evaluation Foamed injection moulded articles were visually observed for occurrence of surface defect on both sides. The surface quality was evaluated on a rating of 1 to 3, 3 being the best. Results

[0177] Table 2 Properties of HECOs

[0178] Table 3 Composition of polymer compositions and properties

[0179] It can be understood from the comparison of CE-1 to CE-5 versus IE-1 to IE-5 that the addition of high melt strength polypropylene resulted in a better puncture impact behavior (break type improvement or in case of same break type, higher Energy at 90% F-max) and comparable flexural properties. Surface quality is also maintained. IE-1 made using the first heterophasic propylene copolymer (a) (Polymer B) showed a particularly large improvement in the puncture impact behavior. IE-3 made using both the first heterophasic propylene copolymer (a) (Polymer B) and the second heterophasic propylene copolymer (b) (Polymer D) showed a surprisingly good surface quality.

Claims

CLAIMS1 . A composition comprising i) a first heterophasic propylene copolymer (a) and / or a second heterophasic propylene copolymer (b), ii) a high melt strength polypropylene, iii) a polyolefin based elastomer and iv) an inorganic filler, wherein the first heterophasic propylene copolymer (a) has a melt flow index (MFI) in the range of at least 5.6 dg / min and less than 50.0 dg / min as determined according to ISO1133-1 :2011 at 230°C with 2.16 kg load and a xylene soluble part in the range from 18.1 to 27.6 wt% as determined by ISO16152:2005 based on the total amount of the first heterophasic propylene copolymer (a), wherein the xylene soluble part of the first heterophasic propylene copolymer (a) has an intrinsic viscosity in the range from 2.9 to 4.8 dl / g as measured according to ISO1628-1 :2009 in decalin at 135 °C; wherein the second heterophasic propylene copolymer (b) has a melt flow index (MFI) in the range from 50.0 to 100 dg / min as determined according to ISO1133-1 :2011 at 230°C with 2.16 kg load and a xylene soluble part in the range from 12.1 to 20.6 wt% as determined by ISO16152:2005 based on the total amount of the second heterophasic propylene copolymer (b), wherein the xylene soluble part of the second heterophasic propylene copolymer (b) has an intrinsic viscosity in the range from 3.6 to 6.2 dl / g as measured according to ISO1628-1 :2009 in decalin at 135 °C.

2. The composition according to any one of the preceding claims, wherein the MFI of the first heterophasic propylene copolymer (a) is in the range from8.6 to 45.1 dg / min, preferably in the range from 11 .2 to 25.3 dg / min, more preferably in the range from 12.3 to 18.2 dg / min, as determined according to ISO1133-1 :2011 at 230°C with 2.16 kg load and / or the xylene soluble part of the first heterophasic propylene copolymer (a) is in the range from 20.3 to 24.2 wt% as determined by ISO16152:2005 based on the total amount of the first heterophasic propylene copolymer (a) and / or the intrinsic viscosity of the xylene soluble part of the first heterophasic propylene copolymer (a) is in the range of at least 3.3 and less than 4.5 dl / g,preferably in the range from 3.8 to 4.3 dl / g, as measured according to ISO1628- 1 :2009 in decalin at 135 °C and / or the ratio between the intrinsic viscosity of the xylene-soluble part of the first heterophasic propylene copolymer (a) and the intrinsic viscosity of the xylene- insoluble part of the first heterophasic propylene copolymer is in the range from 2.0 to 3.5, preferably from 2.2 to 3.0.

3. The polymer composition according to any one of the preceding claims, wherein the MFI of the second heterophasic propylene copolymer (b) is in the range from 55.0 to 90.0 dg / min, preferably in the range from 60.0 to 83.0 dg / min, as determined according to ISO1133-1 :2011 at 230 °C with a 2.16 kg load and / or the xylene soluble part of the second heterophasic propylene copolymer (b) is in the range from to 12.5 to 20.0 wt%, preferably from to 13.0 to 18.0 wt%, as determined by ISO16152:2005 based on the total amount of the second heterophasic propylene copolymer (b) and / or the intrinsic viscosity of the xylene soluble part of the second heterophasic propylene copolymer (a) is in the range from 4.5 to 5.8 dl / g as measured according to ISO1628-1 :2009 in decalin at 135 °C and / or the ratio between the intrinsic viscosity of the xylene-soluble part of the first heterophasic propylene copolymer (a) and the intrinsic viscosity of the xylene- insoluble part of the first heterophasic propylene copolymer is in the range from 3.1 to 7.2, preferably from 3.2 to 5.1 .

4. The polymer composition according to any one of the preceding claims, wherein the high melt strength polypropylene has a melt strength determined in accordance with ISO 16790:2005 at a temperature of 200°C, using a cylindrical capillary having a length of 20mm and a width of 2mm, a starting velocity vO of 9.8mm / s and an acceleration of 6mm / s2of > 30 cN, preferably > 40 cN, more preferably > 45 cN, > even more preferably 50 cN, even more preferably > 55 cN, even more preferably > 60 cN, most preferably > 65 cN and / or the melt strength of the high melt strength polypropylene is <100 cN, for example < 95 cN, for example < 90 cN, for example < 87cN, and / or the high melt strength polypropylene has a branching index g’ of less than 1 .00 wherein g'=[I ]br / [l V]iinin which g' is the branching index, [IVbr] is the intrinsic viscosity of the branched polypropylene and [IV]iinis the intrinsic viscosity of the linear polypropylene having the same weight average molecular weight (within a range of ±10 %) as the branched polypropylene.

5. The polymer composition according to any one of the preceding claims, wherein the high melt strength polypropylene has a molecular weight distribution Mw / Mn of 5 to 20, preferably 7 to 17, most preferably 10 to 15, measured by universal size exclusion chromatography as described in ASTM D6474-12.

6. The polymer composition according to any one of the preceding claims, wherein the polyolefin based elastomer is an ethylene-a-olefin copolymer, preferably wherein the a-olefin has 3 to 20 carbon atoms, for example the ethylene-a-olefin copolymer is an ethylene-propylene copolymer, an ethylene- butene copolymer, an ethylene-hexene copolymer, an ethylene-octene copolymer or a combination thereof.

7. The polymer composition according to any one of the preceding claims, wherein the inorganic filler is a talc.

8. The polymer composition according to any one of the preceding claims, wherein the inorganic filler has a mean particle size (D50) in the range from 0.12 to 10.2 pm, preferably in the range from 0.23 to 5.1 pm, more preferably in the range from 0.36 to 0.86 pm as measured according to 18013317-3:2001 , sedimentation analysis, Stokes’ law.

9. The composition according to any one of the preceding claims, wherein the total amount of the first heterophasic propylene copolymer (a) and the second heterophasic propylene copolymer (b) is in the range from 30 to 80 wt% based on the total amount of the polymer composition, the amount of the high melt strength polypropylene is 1.0 to 10 wt% based on the total amount of the polymer composition, the amount of the polyolefin based elastomer is 3.0 to 20 wt% based on the total amount of the polymer composition, the amount of the inorganic filler in the range from 3.0 to 30 wt% based on the total amount of the polymer composition and / or the ash content of the polymer composition as measured according to ISO 3451-1 :2008 at 600°C for 4 hours is in the range from 3.0 to 30 wt% based on the total amount of the polymer composition.

10. The composition according to any one of the preceding claims, wherein the weight ratio between the first heterophasic propylene copolymer (a) and the second heterophasic propylene copolymer (b) is 1 : 10 to 10: 1 , for example 1 : 10 to 1 : 1 or 1 : 1 to 10:1.11 . The polymer composition according to any one of the preceding claims, wherein the composition optionally further comprises a third heterophasic propylene copolymer, wherein the total amount of the first heterophasic propylene copolymer (a), the second heterophasic propylene copolymer (b), the high melt strength polypropylene, the polyolefin based elastomer and the inorganic filler and the optional third heterophasic propylene copolymer is at least 95 wt%, preferably at least 97 wt%, preferably at least 98.5 wt%, based on the total amount of the polymer composition.

12. A foamed article prepared by foam injection moulding the polymer composition according to any one of the preceding claims.

13. The foamed article according to any one of the preceding claims, wherein the foam injection moulding is performed by expanding a molten mixture having a thickness of to in a mould to the foamed article having a thickness of t1 at an expansion ratio t1 / tO in the range from 1.05 to 2.14, preferably in the range from 1.38 to 1.97, more preferably in the range from 1 .49 to 1 .82.

14. A process for the preparation of a foamed article comprising sequential steps of:- providing a mixture of a foaming agent and the polymer composition according to any one of claims 1 to 11 ;- a) providing a mixture of a foaming agent and the polymer composition and melting the mixture to obtain a molten mixture or b) providing a melt of the polymer composition and mixing a foaming agent into the melt of the polymer composition to obtain a molten mixture;- injection moulding the molten mixture into a mould;- optionally applying a pressure to the molten mixture in the mould;- opening the mould at least partially to allow the molten mixture to form a soft foamed article; and- allowing the soft foamed article to solidify to form the foamed article and removing the foamed article from the mould.

15. Use of the foamed article of claim 12 or 13 or the foamed article obtained or obtainable by the process according to claim 14 for the preparation of automotive parts, for example for the preparation of automotive exterior parts or for the preparation of automotive interior parts.

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