Random propylene-ethylene copolymers

Abstract

The present disclosure relates to a propylene ethylene copolymer comprising: an ethylene content of between 1.8 and 10.0% by weight; a molecular weight distribution (MWD), expressed in terms of Mw/Mn, greater than 4.0; a content of xylene soluble fraction (XS) and ethylene content (C2) that fulfills the following relationship:
XS<(C22.1)2.4
where: XS=% by weight of the fraction soluble in xylene at 25 C.; and C2=% by weight of ethylene units in the copolymer as determined via NMR.

Claims

1. A propylene/ethylene copolymer comprising: an ethylene content of between 2.1 and 7.1% by weight; a molecular weight distribution (MWD), expressed in terms of Mw/Mn, of greater than 4.0; a content of xylene soluble fraction (XS) and ethylene content (C2) that fulfills the following relationship:
XS<(C22.1)2.4 where: XS=% by weight of the fraction soluble in xylene at 25 C.; and C2=% by weight of ethylene units in the copolymer as determined via NMR, wherein propylene/ethylene copolymer has a melt flow rate (MFR, 230 C., 2.16 kg) from 0.5 to 75 g/10 min.

2. The propylene/ethylene copolymer of claim 1, wherein the ethylene content is between 2.7 and 6.3 wt %.

3. The propylene/ethylene copolymer of claim 1, wherein the melt flow rate (MFR, 230 C. 2.16 kg) of the propylene/ethylene copolymer is from 2.0 to 25.0 g/10 min.

4. The propylene/ethylene copolymer of claim 1, wherein the content of the xylene soluble fraction (XS) and the ethylene content (C2) fulfill the following relationship:
XS<(C22.1)2.6 where: XS=% by weight of the fraction soluble in xylene at 25 C.; and C2=% by weight of ethylene units in the copolymer as determined via NMR.

5. A cast film comprising the propylene/ethylene copolymer of claim 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) The propylene ethylene copolymers of the present disclosure are characterized by the following features:

(2) an ethylene content comprised between 1.8 and 10.0% by weight; such as between 2.1 and 7.1 wt %; between 2.7 wt % and 6.3 wt %; and between 2.9 and 5.3 wt %;

(3) a molecular weight distribution (MWD), expressed in terms of Mw/Mn, of greater than 4.0 and lower than 10;

(4) a content of xylene soluble fraction (XS) and ethylene content (C2) that fulfills the following relationship:
XS<(C22.1)2.4
where: XS=% by weight of the fraction soluble in xylene at 25 C. as determined according to the method given in the characterization section; and C2=% by weight of ethylene units in the copolymer as determined via NMR according to the method given in the characterization section;
In certain embodiments, the relationship is defined as:
XS<(C22.1)2.6
alternatively, as:
XS<(C22.1)2.8
and alternatively, as:
XS<(C22.1)3.0.

(5) The propylene ethylene copolymer of the present disclosure comprises propylene and ethylene comonomers.

(6) In some embodiments, in the propylene/ethylene copolymer the melt flow rate (MFR, 230 C. 2.16 kg), referring to the copolymers as a reactor grade (i.e., as copolymers that have not been subjected to chemical or physical visbreaking) ranges from 0.5 to 75 g/10 min; from 2.0 to 25.0 g/10 min; from 3.0 to 20.0 g/10 min; and from 4.0 to 18.0 g/10 min.

(7) In further embodiments, in the propylene/ethylene copolymer the 2,1 propylene insertions cannot be detected via .sup.13C NMR according to the procedure reported in the characterizing section.

(8) In certain embodiments, the propylene ethylene copolymer described herein is beneficial for the production of films such as cast films. The cast film obtained using the propylene ethylene polymer described herein has good optical properties (in a non-nucleated form), including a haze value as measured on a 50 micron cast film of lower than 0.40%, including lower than 0.30%; and lower than 0.25%; and further comprising a low seal initiation temperature (SIT).

(9) In some embodiments, the difference between the melting point and the SIT is higher than 17 C.; such as higher than 18 C. and higher than 19 C.

(10) In some embodiments, the disclosed propylene ethylene copolymer can be prepared by a process comprising polymerizing propylene with ethylene, in the presence of a catalyst comprising the product of the reaction between: (i) a solid catalyst component comprising Ti, Mg, Cl, and an electron donor compound comprising from 0.1 to 50% wt. of Bi with respect to the total weight of the solid catalyst component; (ii) an alkylaluminum compound; and (iii) an electron-donor compound (external donor).

(11) In certain embodiments, in the catalyst component the content of Bi ranges from 0.5 to 40% wt., from 1 to 35% wt., from 2 to 25% wt. and from 2 to 20% wt.

(12) The particles of the solid catalyst component have substantially spherical morphologies and average diameters ranging from 5 and 150 m, from 20 to 100 m and from 30 to 90 m. As defined herein, particles having substantially spherical morphologies means the ratio between the greater axis and the smaller axis is equal to or lower than 1.5, such as lower than 1.3.

(13) In further embodiments, the amount of Mg in the solid catalyst component ranges from 8 to 30% wt., such as from 10 to 25% wt.

(14) Generally, the amount of Ti ranges from 0.5 to 5% wt., including from 0.7 to 3% wt.

(15) In some embodiments, internal electron donor compounds are selected from alkyl and aryl esters of optionally substituted aromatic polycarboxylic acids, such as esters of benzoic and phthalic acids. Specific examples of such esters are n-butylphthalate, di-isobutylphthalate, di-n-octylphthalate, ethyl-benzoate and p-ethoxy ethyl-benzoate.

(16) In certain embodiments, the Mg/Ti molar ratio is equal to, or higher than, 13, such as in the range of 14 to 40 and 15 to 40. Correspondingly, in further embodiments the Mg/donor molar ratio is higher than 16, higher than 17 and ranging from 18 to 50.

(17) The Bi atoms may derive from one or more Bi compounds not having Bi-carbon bonds. In some embodiments, the Bi compounds can be selected from Bi halides, Bi carbonate, Bi acetate, Bi nitrate, Bi oxide, Bi sulfate, and Bi sulfide compounds, including those in which Bi has a valence of +3. In further embodiments, the Bi halides are selected from Bi trichloride and Bi tribromide, such as BiCl.sub.3.

(18) The preparation of the solid catalyst component can be carried out according to several methods.

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

(20) Several ways are available to add one or more Bi compounds in the catalyst preparation. According to the one option, the Bi compound(s) is/are incorporated directly into the MgCl.sub.2.pROH adduct during its preparation. For instance, the Bi compound can be added at the initial stage of adduct preparation by mixing it together with MgCl.sub.2 and the alcohol. Alternatively, it can be added to the molten adduct before the emulsification step. The amount of Bi introduced ranges from 0.1 to 1 mole per mole of Mg in the adduct. In certain embodiments, Bi compound(s) that may be directly formulated into the MgCl.sub.2.pROH adduct are Bi halides such as BiCl.sub.3.

(21) In additional embodiments, the alkyl-Al compound (ii) is chosen from among the trialkyl aluminum compounds such as triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, and tri-n-octylaluminum. It is also possible to use alkylaluminum halides, alkylaluminum hydrides and alkylaluminum sesquichlorides such as AlEt.sub.2Cl and Al.sub.2Et.sub.3Cl.sub.3, optionally in mixtures with the above cited trialkylaluminum compounds. In some embodiments, the Al/Ti ratio is higher than 1 and is generally comprised between 50 and 2000.

(22) External electron-donor compounds for use in the present technology include silicon compounds, ethers, esters, amines, heterocyclic compounds, 2,2,6,6-tetramethylpiperidine and ketones.

(23) Silicon compounds of the formula (R.sub.6).sub.a(R.sub.7).sub.bSi(OR.sub.8).sub.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; R.sub.6, R.sub.7, and R.sub.8, are alkyl, cycloalkyl or aryl radicals with 1-18 carbon atoms optionally containing heteroatom, may be used as external electron donors. Silicon compounds in which a is 1, b is 1, c is 2, at least one of R.sub.6 and R.sub.7 is selected from branched alkyl, cycloalkyl or aryl groups with 3-10 carbon atoms optionally containing heteroatoms and R.sub.8 is a C.sub.1-C.sub.10 alkyl group, such as a methyl group, may be used. Examples of such 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, and methyl(3,3,3-trifluoro-n-propyl)dimethoxysilane. Moreover, silicon compounds in which a is 0, c is 3, R.sub.7 is a branched alkyl or cycloalkyl group, optionally containing heteroatoms, and R.sub.8 is methyl may be used. Examples of such silicon compounds are cyclohexyltrimethoxysilane, t-butyltrimethoxysilane and thexyltrimethoxysilane.

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

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

(26) In certain embodiments, the polymerization is carried out at a temperature from 20 to 120 C., such as from 40 to 80 C. When the polymerization is carried out in gas-phase, the operating pressure may be between 0.5 and 5 MPa, including between 1 and 4 MPa. In bulk polymerization, the operating pressure may be between 1 and 8 MPa, such as between 1.5 and 5 MPa. Hydrogen may be used as a molecular weight regulator.

(27) The following examples are given in order to better illustrate the present technology and are not intended to limit it in any way.

EXAMPLES

(28) Determination of Mg, Ti

(29) The determination of Mg and Ti content in the solid catalyst component has been carried out via inductively coupled plasma (ICP) emission spectroscopy on an ARL Accuris ICP spectrometer.

(30) The sample was prepared by analytically weighting, in a Fluxy platinum crucible, 0.1-0.3 grams of catalyst and 2 grams of lithium metaborate/tetraborate in a 1:1 mixture. After the addition of some drops of potassium iodide (KI) solution, the crucible is inserted in a special apparatus Claisse Fluxy for the complete burning. The residue is collected with a 5% v/v HNO.sub.3 solution and then analyzed via ICP at the following wavelengths: magnesium279.08 nm; titanium368.52 nm.

(31) Determination of Bi

(32) The determination of Bi content in the solid catalyst component has been carried out via inductively coupled plasma emission spectroscopy (ICP) emission spectroscopy on an ARL Accuris ICP spectrometer.

(33) The sample was prepared by analytically weighing, in a 200 cm.sup.3 volumetric flask, 0.1-0.3 grams of catalyst. After slow addition of both ca. 10 milliliters of 65% v/v HNO.sub.3 solution and ca. 50 cm.sup.3 of distilled water, the sample undergoes a digestion for 4-6 hours. Then the volumetric flask is diluted to the 200 cm.sup.3 mark with deionized water. The resulting solution is directly analyzed via ICP at the following wavelength: bismuth223.06 nm.

(34) Determination of Internal Electron Donor Content

(35) The determination of the content of internal electron donor in the solid catalytic compound was done through gas chromatography. The solid catalytic compound was dissolved in acetone, an internal standard was added, and a sample of the organic phase of the mixture was analyzed in a gas chromatograph to determine the amount of donor present in the starting catalyst compound.

(36) Determination of Xylene Insolubility (X.I.)

(37) The xylene soluble (X.S.) fraction was measured according to ASTM ISO 16152, 2005, but with the following deviations (deviations from the ISO 16152 published method are in brackets): iThe solution volume is 250 ml (200 ml); iiDuring the precipitation stage at 25 C. for 30 min, the solution is kept under agitation by a magnetic stirrer for the final 10 min (30 min, without stirring); and iiiThe final drying step is done under vacuum at 70 C. (100 C.). The content of xylene-soluble fraction is expressed as a percentage of the original 2.5 grams and then, by the difference (complementary to 100%), the xylene insoluble percentage (X.I. %) is determined.

(38) Molecular Weight Distribution (Mw/Mn)

(39) Molecular weights and molecular weight distributions were measured at 150 C. using a Waters Alliance GPCV/2000 instrument equipped with four mixed-bed columns (PLgel Olexis) having an average particle size of 13 m. The dimensions of the columns were 3007.8 mm. The mobile phase used was vacuum distilled 1,2,4-trichlorobenzene (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/l of 2,6-di-tert-butyl-p-cresol were added. 300 l 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=1.2110.sup.4 dl/g and =0.706 for the polystyrene standards, and K=1.9010.sup.4 dl/g and =0.725 for the experimental samples.

(40) A third-order polynomial fit was used for interpolating the experimental data and obtaining the calibration curve. Data acquisition and processing were performed using Waters Empowers 3 Chromatography Data Software with a GPC option.

(41) Melt Flow Rate (MIL)

(42) The melt flow rate (MIL) of the polymer was determined according to ASTM ISO 1133 (230 C., 2.16 kg).

(43) .sup.13C NMR of Propylene/Ethylene Copolymers

(44) .sup.13C NMR spectra were acquired on a Bruker AV-600 spectrometer equipped with a cryoprobe, operating at 160.91 MHz, in Fourier transform mode at 120 C.

(45) The peak of the S.sub. carbon (nomenclature according to Monomer Sequence Distribution in Ethylene-Propylene Rubber Measured by .sup.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 an internal reference at 29.9 ppm. The samples were dissolved in 1,1,2,2-tetrachloroethane-d2 at 120 C. with an 8% w/v concentration. Each spectrum was acquired with a 90 pulse, 15 seconds of delay between pulses and CPD to remove .sup.1H-.sup.13C coupling. 512 transients were stored in 32K data points using a spectral window of 9000 Hz.

(46) 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 -titanium trichloride-diethylaluminum chloride, M. Kakugo, Y. Naito, K. Mizunuma and T. Miyatake, Macromolecules, 1982, 15, 1150) using the following equations:
PPP=100T.sub./S PPE=100T.sub./S EPE=100T.sub./S
PEP=100S.sub./S PEE=100S.sub./S EEE=100(0.25S.sub.+0.5S.sub.)/S
S=T.sub.+T.sub.+T.sub.+S.sub.+S.sub.+0.25S.sub.+0.5S.sub.

(47) 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:

(48) $E\%\mathrm{wt}.=\frac{100*E\%\mathrm{mol}*{\mathrm{MW}}_E}{E\%\mathrm{mol}*{\mathrm{MW}}_{E+}P\%\mathrm{mol}*{\mathrm{MW}}_P}$
where P % mol is the molar percentage of propylene content, while MW.sub.E and MW.sub.P are the molecular weights of ethylene and propylene, respectively.

(49) The product of reactivity ratio r.sub.1r.sub.2 was calculated according to Carman (C. J. Carman, R. A. Harrington and C. E. Wilkes, Macromolecules, 1977; 10, 536) as:

(50) $r_1{r}_2=1+\left(\frac{\mathrm{EEE}+\mathrm{PEE}}{\mathrm{PEP}}+1\right)-\left(\frac{P}{E}+1\right){\left(\frac{\mathrm{EEE}+\mathrm{PEE}}{\mathrm{PEP}}+1\right)}^{0.5}$

(51) The tacticity of propylene sequences was calculated as mm content from the ratio of the PPP mmT.sub. (28.90-29.65 ppm) and the whole T.sub. (29.80-28.37 ppm)

(52) Determination of the Regioinversions:

(53) Determined by means of .sup.13C-NMR according to the methodology described by J. C. Randall in Polymer sequence determination Carbon 13 NMR method, Academic Press, 1977. The content of regioinversions is calculated on the basis of the relative concentration of S.sub.+S.sub. methylene sequences.

(54) Melting Temperature via Differential Scanning Calorimetry (DSC)

(55) 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 ASTM ISO 11357-1, 2009 and ASTM ISO 11357-3, 2011, at 20 C./min. The weight of the samples in every DSC crucible was kept at 6.00.5 mg. In order to obtain the melting point, the weighted sample was sealed in aluminum 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 for 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.

(56) Seal Initiation Temperature (SIT) and Preparation of the Film Specimens

(57) Films with a thickness of 50 m are prepared by extruding each test composition in a single screw Collin extruder (length/diameter ratio of screw: 1:25) at a film drawing speed of 7 m/min and a melt temperature of 210-250 C. Each resulting film is superimposed on a 1000 m thick film of a propylene homopolymer having a xylene insoluble fraction of 97 wt % and a MFR L of 2 g/10 min. The superimposed films are bonded to each other in a Carver press at 200 C. under a 9000 kg load, which is maintained for 5 minutes. The resulting laminates are stretched longitudinally and transversally, i.e. biaxially, by a factor of 6 with a TOM long film stretcher at 150 C. for obtaining a 20 m thick film (18 m homopolymer+2 m test). 25 cm specimens are cut from the films.

(58) Determination of the SIT

(59) For each test, two of the above specimens are superimposed in alignment, the adjacent layers being layers of the particular test composition. The superimposed specimens are sealed along one of the 2 cm sides with a Brugger Feinmechanik Sealer, Model HSG-ETK 745. The sealing time is 5 seconds at a pressure of 0.1 N/mm.sup.2. The sealing temperature is increased by 2 C. for each seal, starting from about 10 C. less than the melting temperature of the test composition. The sealed samples are left to cool and then their unsealed ends are attached to an Instron machine where they are tested at a traction speed of 50 mm/min.

(60) The SIT is the minimum sealing temperature at which the seal does not break when a load of at least 2 Newtons is applied in the test conditions.

(61) Determination of the Haze

(62) 50 m film specimens prepared as described above for the SIT measure have been used. The haze value is measured using a Gardner photometric unit connected to a Hazemeter Type UX-10 or an equivalent instrument having a G.E. 1209 light source with filter C. Reference samples of known haze are used for calibrating the instrument.

(63) Procedure for the Preparation of the Spherical Adduct

(64) The microspheroidal MgCl.sub.2.pC.sub.2H.sub.5OH adduct was prepared according to the method described in Comparative Example 5 of WIPO Pat. App. Pub. No. WO 98/44009, with the difference that BiCl.sub.3 was in powder form and 3 mol % with respect to the magnesium has been added before feeding of the oil. The adduct contains 11.2 wt. % of Mg.

(65) Procedure for the Preparation of the Solid Catalyst Component

(66) Into a 300 L jacketed reactor, equipped with a mechanical stirrer, condenser and thermocouple, 200 L of TiCl.sub.4 were introduced at room temperature under a nitrogen atmosphere. After cooling to 0 C., while stirring, diisobutylphthalate and 8 kg of the spherical adduct (prepared as described above) were sequentially added. The amount of charged internal donor was such to meet a Mg/donor molar ratio of 8. The temperature was raised to 100 C. and maintained for 1 hour. Thereafter, stirring was stopped, the solid product was allowed to settle and the supernatant liquid was siphoned off at 100 C. After the supernatant was removed, additional fresh TiCl.sub.4 was added to reach the initial liquid volume again. The mixture was then heated to 120 C. and kept at this temperature for 0.5 hours. Stirring was stopped again, the solid was allowed to settle and the supernatant liquid was siphoned off at 120 C. The treatment with TiCl.sub.4 at 120 C. was then repeated again with the same procedure as before but the treatment time was decreased to 15 minutes. The solid was washed with anhydrous hexane six times in a temperature gradient down to 60 C. and one time at room temperature. The solid was then dried under vacuum.

Propylene/Ethylene Copolymerization Examples 1-2

(67) Prepolymerization Treatment

(68) Before introducing it into the polymerization reactors, the solid catalyst component described above is contacted with triethyl aluminum (TEAL) and methylcyclohexyldimethoxysilane (C donor) in a ratio reported on Table 1. 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.

(69) Polymerization

(70) Copolymers are prepared by polymerizing propylene and ethylene in the presence of a catalyst under continuous conditions in a plant comprising a polymerization apparatus as described in EP Pat. Doc. No. 1 012 195. The catalyst is sent to the polymerization apparatus that comprises two interconnected cylindrical reactors, the riser and the downcomer. Fast fluidization 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 Table 1. The characterization of the polymer is reported in Table 4.

(71) TABLE-US-00001 TABLE 1 Ex 2 Ex. 1 a Catalyst feed g/h 10 10 Catalyst/TEAL g/g 6 6 TEAL/C donor g/g 5 3 Polymerization temperature C. 75 70 Pressure Bar-g 28 27 H.sub.2/C.sub.3 mol/mol 0.019 0.031 C.sub.2/C.sub.2 + C.sub.3 mol/mol 0.023 0.028 Residence time min 66 79 C.sub.2 = ethylene; C.sub.3 = propylene; H.sub.2 = hydrogen

Comparative Examples 3-5

(72) Comparative Examples 3-5 are the repetition of Examples 1, 3 and 4 of U.S. Pat. No. 6,365,685, in which the X.S. of the resulting polymers has been determined according to the method given in the above characterization section. The results are reported in Table 2.

(73) TABLE-US-00002 TABLE 2 Comparative Example 3 4 5 C.sub.2 wt % 2.3 4 6 XS wt % 2.8 6.4 14.0 C2x2.1-2.4 2.4 6.0 10.2

Comparative Example 6

(74) Procedure for the Preparation of the Spherical Adduct

(75) Microspheroidal MgCl.sub.2.pC.sub.2H.sub.5OH adduct was prepared according to the method described in Comparative Example 5 of WIPO Pat. App. Pub. No. WO 98/440091. The adduct contains 11.2 wt. % of Mg.

(76) Procedure for the Preparation of the Solid Catalyst Component

(77) The solid catalyst component has been prepared according to the method described above.

(78) Polymerization

(79) Prepolymerization Treatment

(80) Before introducing it into the polymerization reactors, the solid catalyst component described above is contacted with triethyl aluminum (TEAL) and methylcyclohexyldimethoxysilane (C donor) in the 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.

(81) The polymerization run is conducted in continuous mode in a series of two reactors equipped with devices to transfer the product from one reactor to the one immediately next to it. The two reactors are loop liquid phase reactors. Hydrogen is used as a molecular weight regulator. The gas phase (propylene, ethylene and hydrogen) is continuously analyzed via gas chromatography. The polymerization conditions are reported in Table 3. The characterization of the polymer is reported on Table 4.

(82) TABLE-US-00003 TABLE 3 Loop reactor in liquid phase Catalyst feed g/h 10 Catalyst/TEAL g/g 6 TEAL/C donor 3 Temperature, C. 67 Pressure, bar 34 Residence time, min 81 H.sub.2 feed mol ppm 1500 C2 feed (kg/h) 2.3 C2-loop wt % 3.3 Xylene solubles % 6.2 C2 = ethylene; C3 = propylene; H.sub.2 = hydrogen

(83) TABLE-US-00004 TABLE 4 Ex 1 2 Comp. Ex. 6 MFR g/10 13.2 9.3 11.6 C2 % 3.0 4.0 3.3 XS % 3.2 5.2 6.2 Mw/Mn 4.1 4.4 >4.0 C2x2.1-2.4 3.9 6.0 4.53 Tm C. 144.1 139.1 144.0 Characterization of cast film (50 micron) Haze % 0.19 0.14 0.19 SIT C. 123 118 124

(84) From the results herein it is evident that the film obtained with the random compolymer according to the present disclosure shows a better haze and an higher difference between the melting point and the SIT.