Random propylene-ethylene copolymers

Abstract

The propylene ethylene copolymers of the present disclosure are characterized by the following features: - Melt Flow Rate (MFR 230°C 2,16kg) ranging from 0.2 g / 10 min to 10.0 g / 10 min; - ethylene derived units, measured by 13C-NMR content of between 1.5 wt% and 6.5 wt%; - the ethylene derived units content of the fraction insoluble in xylene at 25°C, measured by 13C-NMR ranging from 1.5 wt% to 5.5 wt%; - the ethylene derived units content of the fraction soluble in xylene at 25°C, measured by 13C-NMR ranging from 12.0 wt% to 25.0 wt%..

Description

RANDOM PROPYLENE-ETHYLENE COPOLYMERSFIELD OF THE INVENTION

[0001] The present disclosure relates to random propylene / ethylene copolymers having excellent properties in terms of mechanical and thermal properties. Random propylene / ethylene copolymer are especially fit for films having enhanced properties.BACKGROUND OF THE INVENTION

[0002] Propylene / ethylene copolymers containing from 0.1 to 10 by weight of ethylene, in which the comonomer is randomly distributed in the polypropylene chain, are generally known as random propylene copolymers. Compared with propylene homopolymers, the said copolymers have a molecular structure which is modified by the presence of the comonomer, leading to a substantially lower degree of crystallinity therein. As a result, random copolymers have a lower melting temperature with respect to propylene homopolymers and also lower sealing temperature and a modulus of elasticity.

[0003] As a downside, the introduction of the comonomer into the polypropylene chain leads to a significant increase in the fraction of polymer which is soluble in xylene at 25 °C, the said soluble polymer being mainly composed of low molecular weight chains and containing percentages of comonomer which are higher than the average content of comonomer calculated on the basis of the whole polymer. The amount of soluble fraction generally increases as the content of comonomer in the copolymer increases and, beyond defined limits, precludes the use of the copolymers in certain sectors, for example in the preparation of films for wrapping food, unless recourse is made to a burdensome stage of elimination of the soluble fraction. The presence of relevant amounts of the said fractions decreases the flowability of the polymer granules, thereby making operations such as discharging and transferring the polymer difficult and giving rise to operation problems in the polymerization plant. Moreover, the presence of the said soluble fractions in significant amounts leads, over the time, to phenomena of deterioration of the optical properties and of the organoleptic properties owed to migration of these fractions to the surface (blooming).

[0004] W02007 / 45600 relates to propylene random copolymers having high melt flow rates for injection molding and melt blow applications.

[0005] The described copolymers have a melt flow rate ranging from 90 to 3000 g / lOmin and a distribution of molecular weight lower than 4. This material is obtained by using metallocene- based catalyst system. Even if the xylene solubles of this material is less than 2.2, the other features such as the high melt flow rate and the narrow distribution of molecular weight make this material not perfectly fit for the production of cast film.

[0006] W02006 / 120190 relates to random propylene / ethylene copolymer having an ethylene content ranging from 4.5 to 7 wt% and Mw / Mn lower than 4. The copolymers described in this document shows a very low level of xylene solubles after visbreaking, however the xylene solubles of the ex reactor polymer are quite high.

[0007] WO2015 / 169653 relates to random propylene / ethylene copolymer having:-ethylene content of between 1.8 and 10.0% by weight;-molecular weight distribution (MWD), expressed in terms of Mw / Mn, greater than 4.0;-the content of xylene soluble fraction (XS) and ethylene content (C2) fulfill the following relationXS<(C2x2.1)-2.4 where:XS = % by weight of the fraction soluble in xylene at 25°C determined according to the method given in the characterization section;C2 = % by weight of ethylene units in the copolymer determined via NMR according to the method given in the characterization section.

[0008] However in these polymers are the xylene soluble fraction is too low for certain applications.SUMMARY OF THE INVENTION

[0009] Now it has surprisingly been found improved propylene / ethylene copolymers, obtained by heterogeneous catalysts, having good thermic and mechanical properties.

[0010] The propylene ethylene copolymers of the present disclosure are characterized by the following features:- Melt Flow Rate (MFR ISO 1133 230°C 2,16kg) ranging from 0.2 g / 10 min to 10.0 g / 10 min;- content of ethylene derived units, measured by13C-NMR according to the method given in the characterization section,, ranging between 1.5 wt% and 6.5 wt%;- ethylene derived units content of the fraction insoluble in xylene at 25°C, measured by13C- NMR according to the method given in the characterization section,, ranging from 1.5 wt% to 5.5 wt%;- ethylene derived units content of the fraction soluble in xylene at 25°C, measured by13C-NMR according to the method given in the characterization section, ranging from 12.0 wt% to 25.0 wt%;- sequences PEP , measured by13C-NMR according to the method given in the characterization section, ranging from 1.5 mol% to 7.0 mol%;- sequences PEP of the fraction soluble in xylene at 25°C, measured by13C-NMR according to the method given in the characterization section, ranging from 9.0 mol% to 17.0 mol%;- molecular weight distribution (MWD) measured according to the method given in the characterization section,, expressed in terms of Mw / Mn, greater than 4.5.Preferably the ethylene derived units content C2 fulfills the following relation: t-0.3<C2<t+0.3 wherein t = XS*0.176+Tm*0.009+Tc*0.012; whereinXS = % by weight of the fraction soluble in xylene at 25°C determined according to the method given in the characterization section;C2 = % by weight of ethylene units in the copolymer determined via NMR according to the method given in the characterization section;Tm is the melting point of the propylene ethylene random copolymer measured according to the method given in the characterization section.Tc is the crystallization temperature of the propylene ethylene random copolymer measured according to the method given in the characterization section.DETAILED DESCRIPTION OF THE INVENTION

[0011] The propylene ethylene copolymers of the present disclosure are characterized by the following features:- Melt Flow Rate (MFR ISO 1133 230°C 2,16kg) ranging from 0.2 g / 10 min to 10.0 g / 10 min; preferably from 0.5 g / 10 min to 8.0 g / 10 min, more preferably from 0.8 g / 10 min to 5.0 g / 10 min;- content of ethylene derived units, measured by13C-NMR ranging between 1.5 wt% and 6.5 wt%; preferably comprised between 2.2 wt% and 5.5 wt% more preferably comprised between 2.5 wt% and 4.5 wt%;- ethylene derived units content of the fraction insoluble in xylene at 25°C, measured by13C- NMR according to the method given in the characterization section, ranging from 1.5 wt% to 5.5 wt%; preferably ranging from 2.0 wt% to 5.0 wt%; more preferably ranging from 2.2 wt% to 4.5 wt%- ethylene derived units content of the fraction soluble in xylene at 25°C, measured by13C-NMR according to the method given in the characterization section, ranging from 12.0 wt% to 25.0 wt%;; preferably ranging from 14.0 wt% to 22.0 wt%; ranging from 16.0 wt% to 19.8 wt%- The sequences PEP , measured by13C-NMR according to the method given in the characterization section, ranging from 1.5 mol% to 7.0 mol%; preferably rom 2.0 mol% to 6.0 mol%; more preferably from 2.5 mol% to 5.5 mol%;- The sequences PEP of the fraction soluble in xylene at 25°C, measured by13C-NMR according to the method given in the characterization section, ranging from 8.0 mol% to 16.0 mol%; preferably from 9.0 mol% to 15.5 mol%; more preferably from 10.0 mol% to 15.0 mol%; even more preferably from 12.3 mol% to 15.0 mol%; even more preferably from 12.5 mol% to 15.0 mol%;- molecular weight distribution (MWD) measured according to the method given in the characterization section,, expressed in terms of Mw / Mn, greater than 4.5;preferably greater than 5.0; the molecular weight distribution is lower than 10.

[0012] Preferably the ethylene derived units content C2 fulfills the following relation: t-0.3<C2<t+0.3; wherein t = XS*0.176+Tm*0.009+Tc*0.012; whereinXS = % by weight of the fraction soluble in xylene at 25°C determined according to the method given in the characterization section;C2 = % by weight of ethylene units in the copolymer determined via NMR according to the method given in the characterization section;Tm is the melting point of the propylene ethylene random copolymer measured according to the method given in the characterization section.Tc is the crystallization temperature of the propylene ethylene random copolymer measured according to the method given in the characterization section.

[0013] The propylene ethylene copolymer of the present disclosure is defined as containing only propylene and ethylene comonomers.

[0014] Preferably in the propylene / ethylene copolymer of the present disclosure the 2,1 propylene insertions cannot be detected via Cl 3 NMR according to the procedure reported in the characterizing section.

[0015] The propylene ethylene copolymer is particularly fit for the production of films in particular cast film having enhanced mechanical properties. In particular the dart impact test measured on 50 pm cast film measured according to ASTM D 1709 is higher than 400 g; preferably higher than 450 g; more preferably higher than 480 g, the highest value being 1000 g. The Elmendorf measured in the machine direction according to ASTM 1922 on 50 pm cast film is higher than 90 gf, preferably higher than 100 gf; more preferably higher than 105 gf, the highest value being 500 gf. The puncture deformation measured on a on 50 pm cas film of at least 12 mm; preferably at least 14 mm; more preferably at least 17 mm, the highest value being 50 mm (ASTM D 5748).

[0016] Preferably in the fraction insoluble in xylene at 25°C of propylene ethylene copolymer of the present disclosure, the sequence PEP , measured by 13C-NMR ranging from 1.3 mol% to 6.8 mol%; preferably rom 1.9 mol% to 5.9 mol%; more preferably from 2.3 mol% to 5.4 mol%;

[0017] Preferably in the fraction insoluble in xylene at 25°C of propylene ethylene copolymer of the present disclosure, the sequence EEE, measured by 13C-NMR ranges from 0.00 to 0.15; preferably ranges from 0.02 mol% to 0.12 mol%.

[0018] Preferably the fraction insoluble in xylene at 25°C of propylene ethylene copolymer of the present disclosure ranges from 6.2 wt% to 11.0 wt%; more preferably from 6.5 wt% to 9.5 wt%; even more preferably from 6.8 wt% to 9.0 wt%.

[0019] The propylene ethylene copolymer herein disclosed is obtainable by a process comprising polymerizing propylene with ethylene, in the presence of a solid catalyst componentfor the polymerization of olefins comprising a magnesium halide, a titanium compound having at least a Ti-halogen bond and at least an electron donor of formula (I)

[0020] in which R1 and R2 are, independently, C1-C5 alkyl groups, X is Si or C, R3 and R4 groups, independently, are selected from hydrogen, Cl -CIO hydrocarbon groups and halogens with the proviso that at least two R3 are not hydrogen.

[0021] Preferably, R1 and R2 are the same and are selected from C1-C4 linear or branched alkyl groups and more preferably from methyl groups.

[0022] Preferably, R4 groups, independently, are selected from hydrogen, C1-C4 linear or branched alkyl groups and halogens. More preferably, only one or two of R4 groups are C1-C4 linear or branched alkyl groups or halogen. Preferred alkyl groups are methyl, isopropyl or t-butyl, while preferred halogens are Cl and F. The structures in which all R4 groups are hydrogen are also preferred.

[0023] When R3 is a hydrocarbon group it is preferably selected from Cl -C4 linear or branched alkyl groups and more preferably from methyl groups.

[0024] When R3 is a halogen it is preferably selected from Cl and F. More preferably it is F.

[0025] According to a preferred embodiment, X is carbon and R3 is a hydrogen or hydrocarbon group preferably selected from C1-C4 linear or branched alkyl groups more preferably from methyl. Most preferred are the structures in which one R3 is selected from hydrogen and the remaining two from methyl groups.

[0026] Another group of preferred structures are those in which X is carbon and R3 is hydrogen or a halogen group preferably selected from Cl and F more preferably from F. Most preferred arethe structures in which at least two of R3 are selected from F and more preferably those in which all the R3groups are F.

[0027] According to another preferred embodiment, X is Si and R3is a hydrogen or hydrocarbon group preferably selected from C1-C4 linear or branched alkyl groups more preferably from methyl or ethyl. Most preferred are the structures in which all R3groups are selected from methyl.

[0028] Preferably the electron donor of formula (I) is 2-cyclohexyl-2-isopentyl-l,3- dim ethoxypropane; or 2-cyclohexyl-2-(3 ,3,3 -trifluoro -n-propyl)- 1 ,3 -dimethoxypropane.

[0029] By using the described catalyst component is possible to obtain The propylene ethylene copolymer herein disclosed having the reported particular properties.

[0030] The preparation of the solid catalyst component can be carried out according to several methods.

[0031] According to one method the solid catalyst component can be prepared by reacting a titanium compound of formula Ti(OR)q-yXy, where q is the valence of titanium and y is a number between 1 and q, preferably TiC14, with a magnesium chloride deriving from an adduct of formula MgC12»pROH, where p is a number between 0.1 and 6, preferably from 2 to 3.5, and R is a hydrocarbon radical having 1-18 carbon atoms. The adduct can be suitably prepared in spherical form by mixing alcohol and magnesium chloride, operating under stirring conditions at the melting temperature of the adduct (100-130°C). Then, the adduct is mixed with an inert hydrocarbon immiscible with the adduct thereby creating an emulsion which is quickly quenched causing the solidification of the adduct in form of spherical particles. Examples of spherical adducts prepared according to this procedure are described in USP 4,399,054 and USP 4,469,648. The so obtained adduct can be directly reacted with Ti compound or it can be previously subjected to thermal controlled dealcoholation (80-130°C) so as to obtain an adduct in which the number of moles of alcohol is generally lower than 3, preferably between 0.1 and 2.5. The reaction with the Ti compound can be carried out by suspending the adduct (dealcoholated or as such) in cold TiC14 (generally 0°C); the mixture is heated up to 80-130°C and kept at this temperature for 0.5-2 hours. The treatment with TiC14 can be carried out one or more times. The electron donor compound can be added in the desired ratios during the treatment with TiC14.

[0032] Suitable external electron-donor compounds include silicon compounds, ethers, esters, amines, heterocyclic compounds and particularly 2,2,6,6-tetramethylpiperidine and ketones.

[0033] A preferred class of external donor compounds is that of silicon compounds of formula (R6)a(R7)bSi(OR8)c, where a and b are integers from 0 to 2, c is an integer from 1 to 4 and the sum (a+b+c) is 4; R6, R7, and R8, are alkyl, cycloalkyl or aryl radicals with 1-18 carbon atoms optionally containing heteroatoms. Particularly preferred are the silicon compounds in which a is 1, b is 1, c is 2, at least one of R6 and R7 is selected from branched alkyl, cycloalkyl or aryl groups with 3-10 carbon atoms optionally containing heteroatoms and R8 is a C1-C10 alkyl group, in particular methyl. Examples of such preferred silicon compounds are methylcyclohexyldimethoxysilane (C donor), diphenyldimethoxysilane, methyl-t- butyldimethoxysilane, dicyclopentyldimethoxysilane (D donor), diisopropyldimethoxysilane, (2- ethylpiperidinyl)t-butyldimethoxysilane, (2-ethylpiperidinyl)thexyldimethoxysilane, (3,3,3- trifluoro-n-propyl)-(2-ethylpiperidinyl)-dimethoxysilane, methyl(3,3,3-trifluoro-n- propyl)dimethoxysilane. Moreover, the silicon compounds in which a is 0, c is 3, R7 is a branched alkyl or cycloalkyl group, optionally containing heteroatoms, and R8 is methyl are also preferred. Examples of such preferred silicon compounds are cyclohexyltrimethoxysilane, t- butyltrimethoxysilane and thexyltrimethoxysilane.

[0034] The electron donor compound (iii) is used in such an amount to give a weight ratio between the organoaluminum compound and said electron donor compound (iii) of from 2.5 to 500, preferably from 3 to 300 and more preferably from 3.5 to 100.

[0035] The polymerization process can be carried out according to known techniques for example slurry polymerization using as diluent an inert hydrocarbon solvent, or bulk polymerization using the liquid monomer (for example propylene) as a reaction medium. Moreover, it is possible to carry out the polymerization process in gas-phase operating in one or more fluidized or mechanically agitated bed reactors.

[0036] The polymerization is generally carried out at temperature of from 20 to 120°C, preferably of from 40 to 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.

[0037] The following examples are given in order to better illustrate the invention and are not intended to limit it in any way.EXAMPLESOligomer content

[0038] The determination of oligomer content by solvent extraction consists of treating 5g of polypropylene sample with 10 ml of methylenedi chloride (CH2CI2) in an ultrasonic bath at 25°C for 4 hours. 1 rm of the extracted solution is injected into a capillary column and analysed by using FID, without any filtration. For quantitative estimation of oligomer content a calibration based on external standard method has been applied. In particular, a series of hydrocarbons (Cl 2- C22-C28- C40) is used.Determination of X.L

[0039] The Xylene Soluble fraction was measured according to ISO 16152, 2005, but with the following deviations (between brakets what prescribed by the ISO 16152) i- The solution volume is 250 ml (200 ml) ii- During the precipitation stage at 25°C for 30 min, the solution, for the final 10 minutes, is kept under agitation by a magnetic stirrer (30 min, without any stirring at all) iii- The final drying step is done under vacuum at 70°C (100 °C)The content of said xylene-soluble fraction is expressed as a percentage of the original 2.5 grams and then, by difference (complementary to 100), the X.I. %Molecular weight distribution (Mw / Mn)

[0040] Molecular weights and molecular weight distribution were measured at 150°C using a Waters Alliance GPCV / 2000 instrument equipped with four mixed-bed columns PLgel Olexis having a particle size of 13 pm. The dimensions of the columns were 300 * 7.8 mm. The mobile phase used was vacuum distilled 1, 2, 4-tri chlorobenzene (TCB) and the flow rate was kept at 1.0 ml / min. The sample solution was prepared by heating the sample under stirring at 150°C in TCB for one to two hours. The concentration was 1 mg / ml. To prevent degradation, 0.1 g / 1 of 2,6-di- / c / 7-butyl- / ?-cresol were added. 300 pl (nominal value) of solution were injected into the column set. A calibration curve was obtained using 10 polystyrene standard samples (EasiCal kit by Agilent) with molecular weights in the range from 580 to 7 500 000. It was assumed that the K values of the Mark-Houwink relationship were:K= 1.21 x 10'4dl / g and a = 0.706 for the polystyrene standards, K= 1.90 x 10'4dl / g and a = 0.725 for the experimental samples.

[0041] A third order polynomial fit was used for interpolate the experimental data and obtain the calibration curve. Data acquisition and processing was done by using Waters Empowers 3 Chromatography Data Software with GPC option.Melt flow rate (MIL)

[0042] The melt flow rate MIL of the polymer was determined according to ISO 1133 (230°C, 2.16 Kg).13C NMR of propylene / ethylene copolymers

[0043] 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.

[0044] The peak of the Spp carbon (nomenclature according to “Monomer Sequence Distribution in Ethylene-Propylene Rubber Measured by 13C NMR. 3. Use of Reaction Probability Mode ” C. J. Carman, R. A. Harrington and C. E. Wilkes, Macromolecules, 1977, 10, 536) was used as internal reference at 29.9 ppm. The samples were dissolved in 1,1,2,2-tetrachloroethane- d2 at 120°C with a 8 % wt / v concentration. Each spectrum was acquired with a 90° pulse, 15 seconds of delay between pulses and CPD to remove 1H-13C coupling. 512 transients were stored in 32K data points using a spectral window of 9000 Hz.

[0045] 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 trichloridediethylaluminum chloride” M. Kakugo, Y. Naito, K. Mizunuma and T. Miyatake, Macromolecules, 1982, 15, 1150) using the following equations:PPP = 100 Tpp / S PPE = 100 Tps / S EPE = 100 Tss / SPEP = 100 Spp / S PEE= 100 Sps / S EEE = 100 (0.25 Syg+0.5 S55) / SS = Tpp + Tps + Tss + Spp + Sps + 0.25 Syg + 0.5 Sss

[0046] The molar percentage of ethylene content was evaluated using the following equation: E% mol = 100 * [PEP+PEE+EEE]

[0047] 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.

[0048] The product of reactivity ratio nr? was calculated according to Carman (C.J. Carman, R.A. Harrington and C.E. Wilkes, Macromolecules, 1977; 10, 536) as:

[0049] The tacticity of Propylene sequences was calculated as mm content from the ratio of the PPP mmTpp (28.90-29.65 ppm) and the whole Tpp (29.80-28.37 ppm)Determination of the regio invertions: determined by means of C13-NMR according to the methodology described by J.C. Randall in "Polymer sequence determination Carbon 13 NMR method", Academic Press 1977. The content of regioinvertions is calculated on the basis of the relative concentration of Sap + Spp methylene sequences.Melting temperature via Differential Scanning Calorimetry (DSC)

[0050] The melting points of the polymers (Tm) were measured by Differential Scanning Calorimetry (D.S.C.) on a Perkin Elmer DSC-1 calorimeter, previously calibrated against indium melting points, and according to ISO 11357-1, 2009 and 11357-3, 2011, at 20°C / min. The weight of the samples in every DSC crucible was kept at 6.0 ± 0.5 mg.

[0051] In order to obtain the melting point, the weighted sample was sealed into aluminium pans and heated to 200°C at 20°C / minute. The sample was kept at 200°C for 2 minutes to allow a complete melting of all the crystallites, then cooled to 5 °C at 20°C / minute. After standing 2 minutes at 5°C, the sample was heated for the second run time to 200°C at 20°C / min. In this second heating run, the peak temperature (Tp,m) was taken as the melting temperature.Flexural modulus

[0052] Flexural Modulus is measured according to ISO 178, and supplemental conditions according to ISO 1873-2.Charpy impact test at 23°C

[0053] Charpy impact test measured according to ISO 179-leA, e ISO 1873-2.Head deflection temperature (HDT)

[0054] measured at 0.45 MPa according to ASTM D 648.Dart impact test

[0055] measured on a 50 gm cast film measured according to ASTM D 1709.Elmendorf

[0056] measured in the machine direction according to ASTM 1922The puncture deformation

[0057] measured on a on 50 gm cast film according to ASTM D 5748Propylene / Ethylene copolymerization Examples 1-2Catalyst system

[0058] The catalyst system has been produced according to the method described in PCT / EP2023 / 068696. The catalyst used in example 1 is described in example 14 of PCT / EP2023 / 068696 without Bismuth. The catalyst used in example 2 is described in example 15 with Bismuth of PCT / EP2023 / 068696.Prepolymerization treatment

[0059] Before introducing it into the polymerization reactors, the solid catalyst component described above have been contacted with triethyl aluminum (TEAL) and methylcyclohexyldimethoxysilane (C donor) in a ratio reported on table 1. Then the resulting mixture is subjected to prepolymerization by maintaining it in suspension in liquid propylene at 20 °C for about 5 minutes before introducing it into the polymerization reactor.Polymerization

[0060] Copolymer are prepared by polymerising propylene and ethylene in the presence of a catalyst under continuous conditions in a plant comprising a polymerisation apparatus as described in EP 1 012 195. The catalyst is sent to the polymerisation apparatus that comprises two interconnected cylindrical reactors, riser and downcomer. Fast fluidisation conditions are established in the riser by recycling gas from the gas-solid separator. In examples 1 -2 no barrier feed has been used. The powder is continuously discharged and dried under a nitrogen flow. The main polymerization conditions are reported in Tablet. The characterization of the polymer is reported on tables 2 and 3Table 1C2=ethylene; C3=propylene; H2=hydrogenTable 2comparative example 1 is grade commercial grade RP241H sold by LYondellbasell comparative example 2 is grade commercial grade RP220M sold by LYondellbasellTable 3XS =fraction soluble in xylene at 25°CXI= fraction insoluble in xylene at 25°C

Claims

CLAIMSWhat is claimed is:

1. A propylene ethylene copolymer characterized by the following features:- Melt Flow Rate (MFR (ISO 1133, 230°C 2,16kg) ranging from 0.2 g / 10 min to 10.0 g / 10 min;- content of ethylene derived units, measured by13C-NMR according to the method given in the characterization section,, ranging between 1.5 wt% and 6.5 wt%;- the ethylene derived units content of the fraction insoluble in xylene at 25 °C, measured by 13C-NMR according to the method given in the characterization section, ranging from 1.5 wt% to 5.5 wt%;- the ethylene derived units content of the fraction soluble in xylene at 25°C, measured by 13C-NMR according to the method given in the characterization section, ranging from 12.0 wt% to 25.0 wt%;- the sequences PEP , measured by13C-NMR according to the method given in the characterization section, ranging from 1.5 mol% to 7.0 mol%;- the sequences PEP of the fraction soluble in xylene at 25°C, measured by13C-NMR according to the method given in the characterization section, ranging from 9.0 mol% to 17.0 mol%;- molecular weight distribution (MWD) measured according to the method given in the characterization section,, expressed in terms of Mw / Mn, greater than 4.0.

2. The propylene ethylene copolymer according to claim 1 wherein the sequences PEP of the fraction soluble in xylene at 25°C, measured by13C-NMR ranging from 12.3 mol% to 15.0 mol%;3. The propylene ethylene copolymer according to to claims 1 or 2 wherein the ethylene derived units content C2 fulfills the following relation: t-0.3<C2<t+0.3 wherein t = XS*0.176+Tm*0.009+Tc*0.012; whereinXS = % by weight of the fraction soluble in xylene at 25°C;C2 = % by weight of ethylene units in the copolymer determined via NMR;Tm is the melting point of the propylene ethylene random copolymer;Tc is the crystallization temperature of the propylene ethylene random copolymer.

4. The propylene ethylene copolymer according to anyone of claims 1-3 wherein the ethylene content is comprised between 2.2 wt% and 5.5 wt%.

5. The propylene ethylene copolymer according to anyone of claims 1-4 wherein The sequences PEP , measured by13C-NMR ranges from 2.0 mol% to 6.0 mol%.

6. The propylene ethylene copolymer according to anyone of claims 1-5 wherein The sequences PEP , measured by13C-NMR ranges from 2.5 mol% to 5.5 mol%..

7. The propylene ethylene copolymer according to anyone of claims 1-6 wherein the 2,1 propylene insertions cannot be detected via C13NMR.

8. The propylene ethylene copolymer according to anyone of claims 1-7 wherein in the fraction insoluble in xylene at 25°C of propylene ethylene copolymer the sequence PEP , measured by13C-NMR ranging from 1.3 mol% to 6.8 mol%.

9. The propylene ethylene copolymer according to anyone of claims 1-8 wherein in the fraction insoluble in xylene at 25°C of propylene ethylene copolymer of the present disclosure, the sequence EEE, measured by13C-NMR ranges from 0.00 to 0.10.

10. The propylene ethylene copolymer according to anyone of claims 1-9 being obtainable by a process comprising polymerizing propylene with ethylene, in the presence of a solid catalyst component for the polymerization of olefins comprising a magnesium halide, a titanium compound having at least a Ti-halogen bond and at least an electron donor of formula (I)in which R1and R2are, independently, C1-C5 alkyl groups, X is Si or C, R3and R4groups, independently, are selected from hydrogen, C1-C10 hydrocarbon groups and halogens with the proviso that at least two R3are not hydrogen.

11. The propylene ethylene copolymer according to claim 10 wherein in the compound of formula (I) R1 and R2 are the same and are selected from C1-C4 linear or branched alkyl groups.

12. The propylene ethylene copolymer according to claims 10 or 11 wherein in the compound of formula (I) R4 groups, independently, are selected from hydrogen, C1-C4 linear or branched alkyl groups and halogens.13 The propylene ethylene copolymer according to claims 11 or 12 wherein in the compound of formula (I) R3 is selected from C1-C4 linear or branched alkyl groups.

14. A film comprising the propylene ethylene copolymer according to claims 1-13.15 The film of claim 14 having the dart impact test measured on 50 pm cast film measured according to ASTM D 1709 higher than 400 g.

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