Polypropylene composition

Abstract

A polypropylene composition having i) xylene soluble fraction at 25°C ranging from 33 wt% to 44 wt%; ii) intrinsic viscosity of the fraction soluble in xylene at 25°C, ranging from 19 to 2.7 dl / g; iii) melt flow rate, MFR, ranging from 40 g / 10 min to 80 g / 10 min; iv) ethylene derived units content, ranging from 14.0 wt% to 19.5 wt%; v) the ethylene derived units content, on the fraction soluble in xylene at 25°C ranging from 35.0 wt% to 42.0 wt%; the polypropylene composition comprising: A) from 50 wt% to 72 wt% of a propylene homopolymer, and B) from 28 wt% to 50 wt% of a propylene ethylene copolymer having a content of ethylene derived units ranging from 39.0 wt%

Description

TITLEPOLYPROPYLENE COMPOSITIONFIELD OF THE INVENTION

[0001] The present disclosure relates to a polypropylene composition to be used for producing articles such as injection molded articles in view of the low shrinkage.BACKGROUND OF THE INVENTION

[0002] Polypropylene can be injection molded into a variety of desired articles. An advantage of using propylene ethylene copolymer composition is that it can be added to many different kinds of polyolefins to achieve a final composition ready for production of articles such as automobile bumpers. The compositions usually exhibit a good balance of properties. However there is still the need to improve the properties and in particular to reduce the thermal shrinkage.

[0003] WO 2019 / 141546 describes a heterophasic polypropylene composition comprising obtained in the presence of a single-site catalyst comprising:(A) from 20 to 55 wt% of a crystalline fraction (CF), measured by Crystex QC in tri chlorobenzene, which is a propylene homopolymer fraction or a copolymer fraction of propylene monomer units and comonomer units of ethylene or alpha-olefins with 4 to 12 carbon atoms with an amount of comonomer units of up to 6.0 wt%; and(B) from 45 to 80 wt% of a soluble fraction (SF), measured by Crystex QC in trichlorobenzene, which is a copolymer of propylene monomer units and comonomer units of ethylene or alphaolefins with 4-12 carbon atoms, with an amount of comonomer units of from 17 to 55 wt% and an intrinsic viscosity IV of from 1.2 to 7.0 dl / g, wherein the heterophasic polypropylene composition has a tensile modulus of not more than 700 MPa.The amount of component B of this composition is quite high and the MFR of the polymer of the examples range from about 1 to 2.2 g / 10 min being product developed for films.

[0004] EP0472946 relates to a flexible elastoplastic polyolefin compositions comprising, in parts by weight: A) 10-50 parts of an isotactic propylene homopolymer or copolymer; B) 5-20parts of an ethylene copolymer, insoluble in xylene at room temperature; and C) 40-80 parts of an ethylene / propylene copolymer containing less than 40% by weight of ethylene and being soluble in xylene at room temperature; the intrinsic viscosity of said copolymer is preferably from 1.7 to 3 dl / g. Said compositions are relatively flexible and have good elastic properties, as demonstrated by flexural modulus lower than 150 MPa values, Shore D hardness from 20 to 35, and Shore A hardness of about 90, associated with good tension set values (of 20-50% at 75% elongation, and about 33-40% at 100% elongation); nevertheless, such values are not fully satisfactory for many applications.

[0005] More flexible elastoplastic polyolefin compositions have been described in the International Application WO03 / 01 1962, and comprise, by weight:A) 8 to 25% of a crystalline polymer fraction selected from propylene homopolymer and propylene copolymers with a C4-8 alpha-olefin;B) 75 to 92% of an elastomeric fraction comprising two different propylene elastomeric copolymers, and more specifically: (1) a first elastomeric copolymer of propylene with 15 to 32% of ethylene and / or a C4-8 alpha-olefin, and (2) a second elastomeric copolymer of propylene with more than 32% up to 45% of ethylene and / or a C4-8 alpha-olefin, the (l) / (2) weight ratio ranging from 1 : 5 to 5: 1.These polyolefin compositions have flexural modulus lower than 60 MPa, Shore A lower than 90, and tension set at 100% elongation lower than 35%.

[0006] In the international Application WO2012 / 152803, polyolefin compositions of improved softness and ductility at low temperatures suitable for applications in membrane for roofing are disclosed wherein a flexible heterophasic composition (I) with broad molecular weight distribution obtainable by blending heterophasic compositions of different melt flow indexes is further blended with an elastomeric component and highly filled with a flame retardant.

[0007] It is still felt the need of polypropylene compositions showing an improved balance of properties in particular an optimum shrinkage to be used to produce in injection molded object in particular in the automotive field.SUMMARY OF THE INVENTION

[0008] Thus, the present disclosure provides a polypropylene composition having: i) xylene soluble fraction at 25°C ranging from 33 wt% to 44 wt%; ii) intrinsic viscosity of the fraction soluble in xylene at 25°C, measured in tetrahydronaphthalene at 135 °C, ranging from 1.9 to 2.7 dl / g; iii) melt flow rate, MFR, measured according to ISO 1133-1 :2012 at 230 °C with a load of 2.16 kg, ranging from 40 g / 10 min to 80 g / 10 min; iv) ethylene derived units content, measured by13C-NMR ranging from 14.0 wt% to 19.5 wt%; v) the ethylene derived units content, measured by13C-NMR on the fraction soluble in xylene at 25°C ranging from 35.0 wt% to 42.0 wt%; the polypropylene composition comprising:A) from 50 wt% to 72 wt% of a propylene homopolymer, andB) from 28 wt% to 50 wt% of a propylene ethylene copolymer having a content of ethylene derived units ranging from 39.0 wt% to 48.2 wt%;The sum of the amount of A) and B) being 100 wt%.DETAILED DESCRIPTION OF THE INVENTION

[0009] Thus, the present disclosure provides a polypropylene composition having: i) xylene soluble fraction at 25°C ranging from from 33 wt% to 44 wt%; preferably from 34 wt% to 42 wt%; more preferably from 35 wt% to 40 wt%; ii) intrinsic viscosity of the fraction soluble in xylene at 25°C, measured in tetrahydronaphthalene at 135 °C, ranging from 1.9 to 2.7 dl / g dl / g; preferably from 2.0 to 2.6 dl / g; more preferably from 2.1 to 2.5 dl / g; iii) melt flow rate, MFR, measured according to ISO 1133-1:2012 at 230 °C with a load of 2.16 kg, ranging from 40 g / 10 min to 80 g / 10 min; preferably from 45 g / 10 min to 70 g / 10 min; more preferably from 49 g / 10 min to 65 g / 10 min; iv) an ethylene derived units content, measured by13C-NMR ranging from 14.0 wt% to 19.5 wt% ; preferably from 14.5 wt% to 19.0 wt%; more preferably from 15.2 wt% to 18.4 wt%;v) the ethylene derived units content, measured by13C-NMR on the fraction soluble in xylene at 25°C ranging from 35.0 wt% to 42.0 wt%; preferably ranging from 36.6 wt% to 41.3 wt%; more preferably ranging from 37.3 wt% to 40.2 wt%; the polypropylene composition comprising:A) from 50 wt% to 72 wt% preferably from 55 wt% to 67 wt% more preferably from of a58 wt% to 65 wt% of a propylene homopolymer, andB) from 28 wt% to 50 wt% preferably from 33 wt% to 45 wt% more preferably from of a35 wt% to 42 wt% of a propylene ethylene copolymer having a content of ethylene derived units ranging from 39.0 wt% to 48.2 wt% preferably from 42.0 wt% to 47.2 wt%; more preferably from 43.5 wt% to 46.3 wt%;The sum of the amount of A) and B) being 100 wt%

[0010] For the present disclosure, the term “copolymer” is referred to polymers containing only two kinds of comonomers, such as propylene and ethylene.

[0011] Preferably the polypropylene composition of the present disclosure is endowed with one or more of the following properties:

[0012] Flexural modulus ranging from 300 MPa to 800 Mpa, preferably from 450 MPa to 680 MPa;

[0013] Charpy impact at 23°C ranging from 50.0 KJ / m2to 80.0 KJ / m2; preferably from 55.0 KJ / m2to 75.0 KJ / m2;

[0014] Melting point comprised between 150°C and 160°C; preferably comprised between 155 °C and 159°C.

[0015] In particular the polypropylene composition of the present disclosure show a low shrinkage in injection molding. Preferably the shrinkage at 25 °C room temperature after 48h can be lower than 0.95 wt% in the longitudinal direction and lower than 1.10 % in the transversal direction.

[0016] The polypropylene composition of the present disclosure is obtained with a polymerization process in two or more stages in which component A) is obtained in the first stages and then component B) is obtained in the second stages in the presence of component A), each stage is in gas-phase. Component B) is polymerized in a gas phase process , operating in one or more fluidized or mechanically agitated bed reactors in the presence of component A) The polymerization is generally carried out at temperature of from 20 to 120°C, preferably of from 40to 80°C. When the polymerization is carried out in gas-phase the operating pressure is generally between 0.5 and 5 MPa, preferably between 1 and 4 MPa. In the bulk polymerization the operating pressure is generally between 1 and 8 MPa, preferably between 1.5 and 5 MPa. Hydrogen is typically used as a molecular weight regulator.,

[0017] Component A) is obtained in a reactor having two interconnected polymerization zones, a riser and a downcomer, wherein the growing polymer particles:(a) flow through the first of said polymerization zones, the riser, under fast fluidization conditions in the presence of propylene and of ethylene;(b) leave the riser and enter the second of said polymerization zones, the downcomer, through which they flow downward in a densified form in the presence of propylene and of ethylene, wherein the concentration of ethylene in the downcomer is higher than in the riser;(c) leave the downcomer and are reintroduced into the riser, thus establishing a circulation of polymer between the riser and the downcomer.

[0018] In the first polymerization zone (riser), fast fluidization conditions are established by feeding a gas mixture comprising one or more alpha-olefins at a velocity higher than the transport velocity of the polymer particles. The velocity of said gas mixture is generally comprised between 0.5 and 15 m / s, preferably between 0.8 and 5 m / s. The terms “transport velocity” and “fast fluidization conditions” are well known in the art; for a definition thereof, see, for example, "D. Geldart, Gas Fluidisation Technology, page 155 et seq., J. Wiley & Sons Ltd., 1986".

[0019] In the second polymerization zone (downcomer), the polymer particles flow under the action of gravity in a densified form, so that high values of density of the solid (mass of polymer per volume of reactor) are achieved, said density of solid approaching the bulk density of the polymer. Throughout the present description a "densified form" of the polymer implies that the ratio between the mass of polymer particles and the reactor volume is higher than 80% of the "poured bulk density" of the obtained polymer. The "poured bulk density" of a polymer is a parameter well known to the person skilled in the art. In view of the above, it is clear that in thedowncomer the polymer flows downward in a plug flow and only small quantities of gas are entrained with the polymer particles.

[0020] According to the process of the present disclosure, the two interconnected polymerization zones are operated in such a way that the gas mixture coming from the riser is totally or partially prevented from entering the downcomer by introducing into the upper part of the downcomer a liquid and / or gas stream, denominated “barrier stream”, having a composition different from the gaseous mixture present in the riser. In order to comply with this process feature, one or more feeding lines for the barrier stream are placed in the downcomer close to the upper limit of the volume occupied by the polymer particles flowing downward in a densified form.

[0021] This liquid / gas mixture fed into the upper part of the downcomer partially replaces the gas mixture entrained with the polymer particles entering the downcomer. The partial evaporation of the liquid in the barrier stream generates in the upper part of the downcomer a flow of gas, which moves counter- currently to the flow of descendent polymer, thus acting as a barrier to the gas mixture coming from the riser and entrained among the polymer particles. The liquid / gas barrier fed to the upper part of the downcomer can be sprinkled over the surface of the polymer particles: the evaporation of the liquid will provide the required upward flow of gas.

[0022] The feed of the barrier stream causes a difference in the concentrations of monomers and / or hydrogen (molecular weight regulator) inside the riser and the downcomer, so that a bimodal polymer can be produced.

[0023] It is known that in a gas-phase polymerization process the reaction mixture comprises, besides the gaseous monomers, also inert polymerization diluents and chain transfer agents, such as hydrogen, useful to regulate the molecular weight of the obtained polymeric chains. The polymerization diluents are preferably selected from C2-C8 alkanes, preferably propane, isobutane, isopentane and hexane. Propane is preferably used as the polymerization diluent in the gas-phase polymerization of the disclosure, so that liquid propane is unavoidably contained in the barrier stream, which is fed to the upper part of the downcomer.

[0024] In one embodiment, the barrier steam comprises: i. from 10 to 100% by mol of propylene; n. from 0 to 80% by mol of ethylene;iii. from 0 to 30% by mol of propane; iv. from 0 to 5% by mol of hydrogen.

[0025] The above indicated compositions of barrier stream can be obtained from the condensation of a part of the fresh monomers and propane, said condensed part being fed to the upper part of the downcomer in a liquid form. According to an embodiment, the above suitable compositions of barrier stream derive from condensation and / or distillation of part of a gaseous stream continuously recycled to the reactor having two interconnected polymerization zones.

[0026] Additional liquid and / or gas of suitable composition can be fed along the downcomer at a point below the barrier stream.

[0027] The recycle gas stream is generally withdrawn from a gas / solid separator placed downstream the riser, cooled by passage through an external heat exchanger and then recycled to the bottom of the riser. Of course, the recycle gas stream comprises, besides the gaseous monomers, also the inert polymerization components, such as propane, and chain transfer agents, such as hydrogen. Moreover, the composition of the barrier stream deriving from condensation and / or distillation of the gas recycle stream may be suitably adjusted by feeding liquid make-up monomers and propane before its introduction into the upper part of downcomer.

[0028] The operating parameters of temperature and pressure are those that are usual in gasphase catalytic polymerization processes. For example, in both riser and downcomer the temperature is generally comprised between 60°C and 120°C, while the pressure can range from 5 to 40 bar.

[0029] The process for preparing the polypropylene composition of the present disclosure is carried out in presence of a highly stereospecific heterogeneous Ziegler-Natta catalyst. The Ziegler-Natta catalysts suitable for producing the polypropylene composition of the disclosure comprise a solid catalyst component comprising at least one titanium compound having at least one titanium-halogen bond and at least an electron-donor compound (internal donor), both supported on magnesium chloride. The Ziegler-Natta catalysts systems further comprise an organo-aluminum compound as essential co-catalyst and optionally an external electron-donor compound.

[0030] Suitable catalysts systems are described in the European patents EP45977, EP361494, EP728769, EP 1272533 and in the international patent application W000163261.

[0031] The organo-aluminum compound is preferably an alkyl-Al selected from the trialkyl aluminum compounds such as for example triethylaluminum, triisobutylaluminum, tri-n- butylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum. It is also possible to use mixtures of trialkylaluminum's with alkylaluminum halides, alkylaluminum hydrides or alkylaluminum sesqui chlorides such as AlEt2Cl and AhEtsCh.

[0032] Preferred external electron-donor compounds include silicon compounds, ethers, esters such as ethyl 4-ethoxybenzoate, amines, heterocyclic compounds and particularly 2, 2,6,6- tetramethyl piperidine, ketones and the 1,3 -di ethers. Another class of preferred external donor compounds is that of silicon compounds of formula Ra5Rb6Si(OR7)cwhere a and b are integer from 0 to 2, c is an integer from 1 to 3 and the sum (a+b+c) is 4; R5, R6, and R7, are alkyl, cycloalkyl or aryl radicals with 1-18 carbon atoms optionally containing heteroatoms. Particularly preferred are methylcyclohexyldimethoxysilane, diphenyldimethoxysilane, methyl-t-butyldimethoxysilane, dicyclopentyldimethoxysilane, 2-ethylpiperidinyl-2-t-butyldimethoxysilane and 1,1,1 ,trifluoropropyl-2-ethylpiperidinyl-dimethoxysilane and 1,1,1 ,trifluoropropyl-metil- dimethoxysilane. The external electron donor compound is used in such an amount to give a molar ratio between the organo-aluminum compound and said electron donor compound of from 0.1 to 500; preferably from 1 to 100; more preferably from 2 to 50.

[0033] Without to be bound by a theory it is believed that the particular polymerization process used for obtaining the polypropylene composition gives rise to a polymer having a particular crystallinity due to the distribution of ethylene in the xylene soluble and insoluble fraction at 25°C.

[0034] The polypropylene composition of the present disclosure can be added with additives common known in the art.

[0035] The polypropylene composition of the present disclosure can be used for producing injection molding articles in particular for automotive injection molding articles.

[0036] The polypropylene composition of the present disclosure can also be used in blend with other polymers in particular polypropylene polymers for producing injection molded articles.

[0037] Thus a further object of the present invention is a polypropylene composition comprising :

[0038] a) from 20 wt% to 36 wt% preferably from 25 wt% to 33 wt% of the polypropylene composition above described;

[0039] b) from 4 wt% to 12 wt% preferably from 5 wt% to 10 wt% of an high density polyethylene having a density ranging from 0.950 to 0.970 g / cm3preferably from 0.955 to 0.965 g / cm3;

[0040] c) from 10 wt% to 18 wt%, preferably from 13 wt% to 18 wt% of a propylene homopolymer having a melt flow rate, MFR, measured according to ISO 1133-1:2012 at 230 °C with a load of 5 kg, ranging from 15 g / 10 min to 40 g / 10 min; preferably ranging from 17 g / 10 min to 30 g / 10 min;

[0041] d) from 20 wt% to 40 wt%, preferably from 23 wt% to 35 wt% of an heterophasic propylene ethylene copolymer.

[0042] The polypropylene composition of the present disclosure is particularly suitable for producing injection molding articles in particular automotive injection molding articles in view of the reduced shrinkage value.

[0043] Conventional additives, filler and dyes commonly used in the state of the art may be polypropylene composition and the polypropylene composition of the present invention.

[0044] The following examples are given to illustrate, not to limit, the present disclosure:EXAMPLESXylene-soluble (XS) Fraction at 25 °C

[0045] Xylene Solubles at 25°C have been determined according to ISO 16 152.DSC method for melting point

[0046] Melting point has been measured according to ISO 11357-3, at scanning rate of 20C / min both in cooling and heating, on a sample of weight between 5 and 7 mg., under inert N2 flow. Instrument calibration made with indiumMelt Flow Rate (MFR)

[0047] Measured according to ISO 1133-1 :2012 at 230 °C with a load of 2.16 kg, unless otherwise specified.Intrinsic Viscosity (IV)Ethylene content in the copolymers

[0048] 13C NMR spectra were acquired on a Bruker AV-600 spectrometer equipped with cry oprobe, operating at 160.91 MHz in the Fourier transform mode at 120 °C.The peak of the SPP carbon (nomenclature according to “Monomer Sequence Distribution in Ethylene-Propylene Rubber Measured by13C NMR. 3. Use of Reaction Probability Mode ” C. J. Carman, R. A. Harrington and C. E. Wilkes, Macromolecules, 1977, 10, 536) was used as an internal reference at 29.9 ppm. The samples were dissolved in 1 , 1 ,2,2-tetrachloroethane-<72 at 120 °C with a 8 % wt / v concentration. Each spectrum was acquired with a 90° pulse, and 15 seconds of delay between pulses and CPD to removeJH-13C coupling. 512 transients were stored in 32K data points using a spectral window of 9000 Hz.

[0049] The assignments of the spectra, the evaluation of triad distribution and the composition were made according to Kakugo (“Carbon- 13 NMR determination of monomer sequence distribution in ethylene-propylene copolymers prepared with 8-titanium trichloride- diethylaluminum chloride” M. Kakugo, Y. Naito, K. Mizunuma and T. Miyatake, Macromolecules, 1982, 15, 1150) using the following equations:PPP = 100 Tpp / S PPE = 1OO TP8 / S EPE = 100 T88 / SPEP = 100 SPP / S PEE= 100 SP5 / S EEE = 100 (0.25 Sy8+0.5 S88) / S S = TPP + TP8 + T88 + SPP + Sp8 + 0.25 Sy8 + 0.5 S88

[0050] The molar percentage of ethylene content was evaluated using the following equation: E% mol = 100 * [PEP+PEE+EEE]The weight percentage of ethylene content was evaluated using the following equation:100 * E% mol * MWEE% wt. = E% mol * MWE + P% mol * MWP where P% mol is the molar percentage of propylene content, while MWE and MWP are the molecular weights of ethylene and propylene, respectively.

[0051] Preparation of injection molded specimens: test specimens 80 x 10 x 4 mm were obtained according to the method ISO 1873-2:2007.

[0052] Flexural modulus: Determined according to the method ISO 178:2019 on injectionmolded test specimens.

[0053] Tensile Modulus: Determined according to ISO 527-2, on injection molded test specimens.

[0054] Charpy Impact test : measured according to ISO 179-1:2010 on injection molded specimens.Longitudinal and Transversal Thermal Shrinkage

[0055] A plaque of 100x195x2.5 mm is moulded in an injection moulding machine “KM- 160” (where 160 stands for 160 tons of clamping force).

[0056] The injection conditions are:- Melt temperature = 220 °C;- Mold temperature = 35 °C;- Injection speed = 33 mm / sec;- Max pressure of injection = 100 bar;- Interior mould pressure which drives the change to 2ndor holding pressure = 150 bar;2ndholding pressure = 42 bar;2ndholding pressure time = 30 sec;Cool down time = 30 seconds;Screw diameter 45 mm.

[0057] The plaque is measured 48 hours after moulding, kept at 23 ± 2 °C and humidity 50% ±10%, through callipers, and the shrinkage is given by:Longitudinal shrinkage = ((195 - read_value) / 195) x 100Transversal shrinkage = ((100 - read_value) / 100) x 100

[0058] where 195 is the length (in mm) of the plaque along the flow direction, measured immediately after moulding (mold); 100 is the length (in mm) of the plaque crosswise the flow direction, measured immediately after moulding (mold); and the read value is the plaque length in the relevant direction after 48 hours.Example 1

[0059] Preparation of the Ziegler-Natta solid catalyst component

[0060] The Ziegler-Natta catalyst was prepared according to Example 5, lines 48-55, of the European Patent EP728769B 1.

[0061] Preparation of the catalyst system - Precontact

[0062] Before introducing it into the polymerization reactors, the solid catalyst component described above is contacted with aluminum-triethyl (TEAL) and with the dicyclopentyldimethoxysilane (D donor) under the conditions reported in Table 1.

[0063] Prepolymerization

[0064] The catalyst system is then subject to prepolymerization treatment at 20°C by maintaining it in suspension in liquid propylene for a residence time of 8 minutes before introducing it into the polymerization reactor.

[0065] Polymerization

[0066] The homopolymerization of propylene was carried out in gas-phase polymerization reactor comprising two interconnected polymerization zones, a riser and a downcomer, as described in European Patent EP782587. Hydrogen was used as molecular weight regulator. The polymer particles exiting from the polymerization step were transferred to a fluidized bed gas phase reactor to polymerize propylene and ethylene. The resulting polymer were subjected to a steam treatment to remove the unreacted monomers and dried under a nitrogen flow.

[0067] The main precontact, prepolymerization and polymerization conditions and the quantities of monomers and hydrogen fed to the polymerization reactor are reported in Table 1.Table 1H2=hydrogen; C2- = ethylene, C3-= propylene the characterization of the polymers of ex 1 is reported in Table 2.Table 2Comparative example 2 is the propylene copolymer of example 1 of US 7,649,052The polymers of examples 1 and comparative example 2 have been blended with other components according to table 3Table 3WhereinHS GC 7260 is an high density polyethylene commercial grade sold by LyondellBasell having a density of 0.960 (ISO 1183);MP EP548S is a commercial heterophasic propylene ethylene copolymer sold by LyondellBasell;AF HA1152 is a commercial propylene homopolymer sold by LyondellBasell having an MFR , measured according to ISO 1133-1:2012 at 230 °C with a load of 5 kg, of 25 g / 10 minAdditive package is reported in table 4Table 4 additive packageThe properties of composition 1 and comparative composition 2 are reported on table 5Table 5The composition according to the invention shows an improved shrinkage and charpy impact resistance.

Claims

CLAIMSWhat is claimed is:

1. A polypropylene composition having i) xylene soluble fraction at 25°C ranging from 33 wt% to 44 wt%; ii) intrinsic viscosity of the fraction soluble in xylene at 25°C, measured in tetrahydronaphthalene at 135 °C, ranging from 1.9 to 2.7 dl / g; iii) melt flow rate, MFR, measured according to ISO 1133-1 :2012 at 230 °C with a load of 2.16 kg, ranging from 40 g / 10 min to 80 g / 10 min; iv) ethylene derived units content, measured by13C-NMR, ranging from 14.0 wt% to 19.5 wt%; v) the ethylene derived units content, measured by13C-NMR on the fraction soluble in xylene at 25°C, ranging from 35.0 wt% to 42.0 wt%; the polypropylene composition comprising:A) from 50 wt% to 72 wt% of a propylene homopolymer, andB) from 28 wt% to 50 wt% of a propylene ethylene copolymer having a content of ethylene derived units, measured by 13C-NMR, ranging from 39.0 wt% to 48.2 wt%; the sum of the amount of A) and B) being 100 wt%.

2. The polypropylene composition according to claim 1 wherein xylene soluble fraction at 25°C ranges from 34 wt% to 42 wt%.

3. The polypropylene composition according to anyone of claims 1-2 wherein the intrinsic viscosity of the fraction soluble in xylene at 25 °C, measured in tetrahydronaphthalene at 135 °C, ranges from 2.0 to 2.6 dl / g.

4. The polypropylene composition according to anyone of claims 1-3 wherein the melt flow rate, MFR, measured according to ISO 1133-1 :2012 at 230 °C with a load of 2.16 kg, ranges from 45 g / 10 min to 70 g / 10 min.

5. The polypropylene composition according of claims 1-4 wherein the ethylene derived units content, measured by13C-NMR, ranges from 14.5 wt% to 19.0 wt%.

6. The polypropylene composition according to anyone of claims 1-5 wherein the ethylene derived units content, measured by13C-NMR on the fraction soluble in xylene at 25°C ranges from 36.6 wt% to 41.3 wt%.

7. The polypropylene composition according to anyone of claims 1-6 wherein component A) ranges from 55 wt% to 67 wt% and component B) ranges from 33 wt% to 45 wt%.

8. The polypropylene composition according to anyone of claims 1-7 wherein in component B) the ethylene derived units content of a propylene ethylene copolymer ranges from 42.0 wt% to 47.2 wt%.

9. A polypropylene composition comprising : a) from 20 wt% to 36 wt% of the polypropylene composition of claims 1-8; b) from 4 wt% to 12 wt% of an high density polyethylene having a density ranging from 0.950 to 0.970 g / cm3; c) from 10 wt% to 18 wt% of a propylene homopolymer having a melt flow rate, MFR, measured according to ISO 1133-1:2012 at 230 °C with a load of 5 kg, ranging from 15 g / 10 min to 40 g / 10 min; d) from 20 wt% to 40 wt% of an heterophasic propylene ethylene copolymer.

10. The polypropylene composition according to claim 9 comprising : a) from 25 wt% to 33 wt% of polypropylene composition of claims 1-8; b from 5 wt% to 10 wt% of an high density polyethylene having a density ranging from 0.950 to 0.970 g / cm3; c) from 13 wt% to 18wt% of a propylene homopolymer having a melt flow rate, MFR, measured according to ISO 1133-1:2012 at 230 °C with a load of 5 kg, ranging from 15 g / 10 min to 40 g / 10 min; d) from 23 wt% to 35 wt% an heterophasic propylene ethylene copolymer.

11. The polypropylene composition according to claim 9-10 wherein in component a) the xylene soluble fraction at 25°C ranges from 20 wt% to 40 wt%.

12. The polypropylene composition according to claim 9-11 wherein component b) has density ranging from 0.955 to 0.965 g / cm3.

13. The polypropylene composition according to claim 9-12 wherein component c) has a melt flow rate, MFR, measured according to ISO 1133-1 :2012 at 230 °C with a load of 5 kg, ranging from 17 g / 10 min to 30 g / 10 min.

14. An injection molding article comprising the propylene ethylene copolymer of claims 1-8.

15. An injection molding article comprising the polypropylene composition of claim 9-13.

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