CATALYSTS FOR THE POLYMERIZATION OF OLEFINS

FIELD OF THE INVENTION

[0001] The present disclosure relates to Ziegler-Natta catalysts for the polymerization of olefins comprising a non-aromatic diazo compound as external electron donor compound. The present disclosure further relates to the use of said catalysts in processes for the polymerization of olefins in particular ethylene.

BACKGROUND OF THE INVENTION

[0002] Catalyst components for the stereospecific polymerization of olefins have been disclosed in the art. Concerning the polymerization of propylene, Ziegler-Natta catalysts are used which, in general terms, comprise a solid catalyst component, constituted by a magnesium dihalide on which are supported a titanium compound and, often, an internal electron donor compound, used in combination with an Al-alkyl compound.

[0003] When used in the propylene polymerization for the production of isotactic polypropylene also an external donor (for example an alkylalkoxysilane) is needed in order to increase catalyst stereospecificity.

[0004] When ethylene polymerization is concerned, ZN catalysts may contain ethers as external donors that can impart specific properties to the catalyst.

[0005] In some instances, it is desirable to have available for both ethylene and propylene polymerization, external donors different from alkylalkoxysilane and ethers.

[0006] Consequently, research activities have been devoted to discover alternative classes of donors for use in the preparation of catalyst for olefin polymerization.

[0007] In EP 1058696 is disclosed a catalyst component for the preparation of ethylene homo and copolymers in which an alkyl substituted pyridine is used as internal donor. In addition to not suggesting the use of pyridine derivatives as external donors, the document reports that the pyridine derivatives have a remarkable depressive effect on polymerization activity. SUMMARY OF THE INVENTION

[0008] Surprisingly, the applicant has found that a new class of nitrogen containing non aromatic donors that can be used as external donors for both ethylene and propylene polymerization.

Accordingly, it is an object of the present disclosure a catalyst for the polymerization of olefins comprising (a) a solid catalyst component containing Mg, Ti and optionally an internal electron donor compound (ID), (b) an aluminium alky compound and (c) an external electron donor (ED) of formula (I) where the R ¹ to R ³ groups, equal to, or different from, each other, are selected from hydrogen or C1-C15 hydrocarbon groups, R ⁴ group is selected from hydrogen, C1-C15 hydrocarbon groups, and -NR2 groups in which R groups have the same meaning as R ¹ to R ³ groups, with the proviso that, independently, the couples formed by R'-R ⁴ and R ² -R ³ can be joined together to form non aromatic cyclic structures.

DETAILED DESCRIPTION OF THE INVENTION

[0009] Preferably, the solid catalyst component (a) contains at least one internal electron donor compound (ID) being a molecule containing at least one functional group selected from esters, ethers, ketones, carbamates, carbonates, amines, amides, nitriles, alkoxysilanes and mixtures thereof.

[0010] The ID compound can be mono or multifunctional, meaning that the molecule can contain one or more of the above mentioned functional groups. In case the functional groups are more than one, they can belong to the same or different class. [0011] When the catalyst is to be used in the polymerization of propylene particularly preferred the use of ID containing two or more functional groups selected from esters, ethers, ketones, carbamates and carbonates.

[0012] A particularly preferred class is constituted by IDs containing two functional groups (bidentate) selected from alkyl and aryl esters of mono or polycarboxylic acids such as for example esters of benzoic, phthalic, malonic and succinic acid are preferred. Specific examples of such esters are n-butylphthalate, di-isobutylphthalate, di-n-octylphthalate, diethyl 2,2- diisopropylsuccinate, diethyl 2,2-dicyclohexyl-succinate, ethyl-benzoate and p-ethoxy ethyl- benzoate, diethyl 3,3-di-n-propylglutarate.

[0013] Another class of preferred bidentate IDs is represented by 1,3 diethers of the formula (II) : where R ¹ and R ⁿ are the same or different and are hydrogen or linear or branched Ci-Cix hydrocarbon groups which can also form one or more cyclic structures; R ^m groups, equal or different from each other, are hydrogen or Ci-Cis hydrocarbon groups; R ^,v groups equal or different from each other, have the same meaning of R ^m except that they cannot be hydrogen; each of R ¹ to R ^IV groups can contain heteroatoms selected from halogens, N, O, S and Si.

[0014] Preferably, R ^IV is a 1-6 carbon atom alkyl radical and more particularly a methyl while the R ^m radicals are preferably hydrogen. In a preferred embodiment, R ¹ and R ¹¹ are joined to form cyclic structure as described in EP728769A1.

[0015] Mixtures of 1,3-diethers may also be employed in the solid catalyst component. Particularly preferred are the internal electron donor mixtures of esters of aliphatic dicarboxylic acids such as malonates, succinates and glutarates with the 1,3-diethers of formula (II) as disclosed for example in WO2012/139897. [0016] Moreover, another preferred class of bidentate IDs is constituted by dicarbamates belonging to of formula (III):

Where R ⁵ and R ⁶ , independently, are selected from hydrogen and C1-C15 hydrocarbon groups, optionally contain a heteroatom selected from halogen, P, S, N, O and Si, which can be fused together to form one or more cycles and A is a bivalent bridging group.

[0017] Dicarbamate structures of formula (III) are described in WO2014048861 the relevant part of which is herein included by reference.

[0018] When the catalyst is to be used in the polymerization of ethylene the use of monofuntional IDs is preferred. Among them, preferred are Ci-Cx alkyl esters of aliphatic mono carboxylic acids in particular selected from such as ethylacetate, methyl formiate, ethylformiate, methylacetate, propylacetate, i-propylacetate, n-butylacetate, i-butylacetate; ethylactetate being the most preferred.

[0019] Another class of preferred monofuntional IDs is that of C2-C20 aliphatic ethers and in particular cyclic ethers, preferably having 3-5 carbon atoms, such as tetrahydrofurane and dioxane. Among linear C2-C20 aliphatic ethers particularly preferred are dimethyl ether, diethyl ether and isoamyl ether.

[0020] In a preferred embodiment, two or more monofunctional IDs are present in the solid catalyst component (a). In this case, it is preferable to use one ID selected from aliphatic ethers and one selected from aliphatic acid esters. Particularly preferred is the use of ethyl acetate as aliphatic acid ester and tetrahydrofurane as aliphatic ether. When used in said mixture the molar ratio between the aliphatic acid ester and the ether present in the final solid catalyst component ranges from 0.2:1 to 16:1 and, more preferably, from 0.5:1 to 10:1.

[0021] In a particular embodiment, the amount of magnesium present in the solid catalyst component ranges from 5 to 25%wt, preferably from 13 to 21%wt based upon the total weight of the solid catalyst component. [0022] The amount of chlorine present in the solid catalyst component is greater than 30%wt, preferably greater than 40% and more preferably ranging from 40 to 80%wt, with respect to the total weight of said catalyst component

[0023] In a particular embodiment, the amount of titanium atoms present in the solid catalyst component is greater than 1% preferably greater than 1.5%wt and more preferably ranging from 1.5 to 6%wt with respect to the total weight of the solid catalyst component.

[0024] In a particular embodiment, the ID is present in the solid catalyst component in an amount which ranges from 1 to 30% by weight preferably in the range from 3 to 20% by weight with respect to the total weight of the solid catalyst component.

[0025] Preferably, the molar ratio of the ID with respect to the Ti atoms ranges from 0.2:1 to to 15:1, preferably, from 0.5:1 to 13:1.

[0026] Preferably, in the ED of formula (I) R ¹ is selected from Ci-Cis hydrocarbon groups.

[0027] In a preferred embodiment, in the external donor ED of formula (I) R ¹ and R ² are selected from Ci-Cio, preferably C1-C5 alkyl groups; R ³ is selected from hydrogen or C1-C5 alkyl groups and R ⁴ is selected from -NR2 groups where R is preferably selected from hydrogen or C1-C5 alkyl groups. Non-limiting examples of structures of formulas (I) within this embodiment are the following: 1,1-dipropylguanidine, 1 -ethyl- 1 -propylguani dine, 1-methyl- 1-propylguanidine, 1 -butyl- 1 -propylguani dine, 1 -ethyl- 1 -methylguani dine, 1,1- dimethylguanidine, 1 -butyl- 1 -methylguanidine, 1 , 1 -diethylguanidine, 1 -butyl- 1- ethylguanidine, 1,1-dibutylguanidine, l-butyl-3,3-dimethyl-l-propylguanidine, 1-butyl-l- ethyl-3,3-dimethylguanidine, l-butyl-l,3,3-trimethylguanidine, 1,1 -dibutyl-3, 3- dimethylguanidine, l-butyl-3,3-diethyl-l-propylguanidine, l-butyl-l,3,3-triethylguanidine, 1- butyl-3 ,3-di ethyl- 1 -methylguanidine, 1 , 1 -dibutyl-3,3 -diethylguanidine, 1 -ethyl-3,3 -dimethyl- 1 -propylguani dine, l,l,3-triethyl-3-propylguanidine, l,l-diethyl-3,3-dimethylguanidine, 1- ethyl-1 ,3,3-trimethylguanidine, 1 , 1 ,3,3-tetraethylguanidine, 1 , 1 ,3,3-tetramethylguanidine,

1 , 1 ,3-triethyl-3 -methylguanidine, 1 , 1 ,3-trimethyl-3-propylguanidine, 1 , 1 -diethyl-3 -methyl-3 - propylguanidine, 1,1 -diethyl-3, 3-dimethylguanidine, 1,1 -dimethyl-3, 3-diproylguanidine, 1,1- di ethyl-3, 3 -dipropylguani dine]. Among them, 1,1,3,3-tetramethyl guanidine (TMG) is the most preferred. [0028] When the ED is selected within structures belonging to this embodiment, it is preferably coupled with solid catalyst component (a) which include a difunctional ID as disclosed above.

[0029] In another preferred embodiment, in the external donor ED of formula (I) the couples formed by R'-R ⁴ and R ² -R ³ are joined together to form non-aromatic ring structures. Preferably, they are joined to form ring structures, which, preferably, are made of five or more members. In a still preferred embodiment, the couple R'-R ⁴ forms a 5-7 members saturated ring structure and the couple R ² -R ³ forms a six-member unsaturated ring because of the C=N double bond present in the formula (I). In view the backbone of the ED of formula (I), when the R'-R ⁴ and R ² -R ³ are joined together to form non-aromatic cyclic structures, EDs having fused heterocyclic rings are obtained. Non-limiting examples of structures of formulas (I) within this embodiment are the following: 2,5,6,7-tetrahydro-3H-pyrrolo[l,2-a]imidazole, 2,3,5,6,7,8-hexahydroimidazo[l,2-a]pyridine, 2,5,6,7,8,9-hexahydro-3H-imidazo[l,2- a]azepine, 2,3,4,6,7,8,9,10-octahydropyrimido[l,2-a]azepine, 1.8-diazabicyclo[5.4.0]undec- 7-ene, 3,4,6,7,8,9-hexahydro-2//-pyrido[l ,2-a]pyrimidine, l,5-diazabicyclo[4.3.0]non-5- ene], 2,3,4,6,7,8-hexahydropyrrolo[l,2-a]pyrimidine. Among them, 1.8- diazabicyclo[5.4.0]undec-7-ene (DBU) and l,5-diazabicyclo[4.3.0] non-5-ene (DBN) are most preferred.

[0030] When the ED is selected within structures belonging to this embodiment, it is preferably coupled with solid catalyst component (a) which include a monofunctional ID as disclosed above.

[0031] The solid catalyst components (a) preferably comprises a titanium compound, having at least a Ti-halogen bond and, when present the ID compound, supported on a Mg halide. The magnesium halide is preferably MgCh in active form which is described as a support for Ziegler-Natta catalysts. Patents USP 4,298,718 and USP 4,495,338 were the first to describe the use of these compounds in Ziegler-Natta catalysis. It is known from these patents that the magnesium dihalides in active form used as support or co-support in components of catalysts for the polymerization of olefins are characterized by X-ray spectra in which the most intense diffraction line that appears in the spectrum of the non-active halide is diminished in intensity and is replaced by a halo whose maximum intensity is displaced towards lower angles relative to that of the more intense line. [0032] The preferred titanium compounds used in the catalyst component of the present disclosure are TiCU and TiCU; furthermore, also Ti-haloalcoholates of formula Ti(OR ⁶ )m-yXy can be used, where m is the valence of titanium, y is a number between 1 and m-1, X is halogen and R ⁶ is a hydrocarbon radical having from 1 to 10 carbon atoms.

[0033] The preparation of the solid catalyst component can be carried out according to several methods. One method comprises the reaction between magnesium alcoholates or chloroalcoholates (in particular chloroalcoholates prepared according to USP 4,220,554) and an excess of TiCU in the presence of the electron donor compounds at a temperature of about 80 to 120°C.

[0034] According to a preferred method, the solid catalyst component can be prepared by reacting a titanium compound of formula Ti(OR ⁷ )m- _y Xy, where m is the valence of titanium and y is a number between 1 and m, preferably TiCU, with a magnesium chloride deriving from an adduct of formula MgCh*pR ^s OH, where p is a number between 0.1 and 6, preferably from 2 to 3.5, and R ⁸ is a hydrocarbon radical having 1-18 carbon atoms. The adduct can be suitably prepared in spherical form by mixing alcohol and magnesium chloride in the presence of an inert hydrocarbon immiscible with the adduct, operating under stirring conditions at the melting temperature of the adduct (100-130°C). Then, the emulsion is quickly quenched, thereby 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 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 TiCU (about 0°C); the mixture is heated up to 80-130°C and kept at this temperature for 0.5-2 hours. The treatment with TiCU can be carried out one or more times. The electron donor compound is preferably added during the treatment with TiCU. The preparation of catalyst components in spherical form are described for example in European Patent Applications EP-A-395083, EP-A-553805, EP-A-553806, EPA601525 and

W098/44009.

[0035] According to variation of the method, in a first step (i) carried out at a temperature ranging from 0 to 150°C, a Mg based compound, for example from an adduct of formula MgCh*pR ^s OH, is reacted with a a Ti compound, having at least a Ti-Cl bond, in an amount such that the Ti/Mg molar ratio is greater than 3 so as to generate an intermediate solid catalyst component containing Mg and Ti and, in a following step (ii) the intermediate solid catalyst component is contacted with is contacted with an electron donor compound ID.

[0036] The solid catalyst components obtained according to the above method may show a surface area (by B.E.T. method) may range between 20 and 500 m ² /g and preferably between 50 and 400 m ² /g, and a total porosity (by B.E.T. method) higher than 0.2 cnr'/g preferably between 0.2 and 0.6 cnr'/g. The porosity (Hg method) due to pores with radius up to lO.OOOA may range from 0.15 to 1.5 cm ³ /g, preferably from 0.25 to 1 cm ³ /g.

[0037] The solid catalyst component has an average particle size ranging from 5 to 120 pm and more preferably from 10 to 100 pm.

[0038] The alkyl-Al compound (b) is preferably chosen among 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 alkylaluminum halides, alkylaluminum hydrides or alkylaluminum sesquichlorides, such as AlEt2Cl and AbEtAh, possibly in mixture with the above cited trialkylaluminums.

[0039] The ED electron donor compound of formula (I) is used in such an amount to give a molar ratio between the organoaluminum compound and said ED of from 0.1 to 500, preferably from 1 to 300 and more preferably from 3 to 100.

[0040] Therefore, it constitutes a further object of the present disclosure a process for the (co)polymerization of olefins CH2=CHR, in which R is hydrogen or a hydrocarbyl radical with 1-12 carbon atoms, carried out in the presence of the catalyst of the present disclosure.

[0041] The polymerization process can be carried out according to available 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.

[0042] The polymerization may be 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 may range between 0.5 and 5 MPa, preferably between 1 and 4 MPa. In the bulk polymerization the operating pressure ranges between 1 and 8 MPa, preferably between 1.5 and 5 MPa.

[0043] The following examples are given in order to further illustrate the disclosure without being intended as limiting it.

CHARACTFRT7ATTONS

Determination of X.I.

[0044] 2.5 g of polymer and 250 ml of o-xylene were placed in a round-bottomed flask provided with a cooler and a reflux condenser and kept under nitrogen. The obtained mixture was heated to 135°C and was kept under stirring for about 60 minutes. The final solution was allowed to cool to 25°C under continuous stirring, and the insoluble polymer was then filtered. The filtrate was then evaporated in a nitrogen flow at 140°C to reach a constant weight. The content of said xylene-soluble fraction is expressed as a percentage of the original 2.5 grams and then, by difference, the X.I. %.

Determination of donors.

[0045] The content of electron donor has been carried out via gas-chromatography. The solid component was dissolved in acidic water. The solution was extracted with ethyl acetate, an internal standard was added, and a sample of the organic phase was analyzed in a gas chromatograph, to determine the amount of donor present at the starting catalyst compound.

Melt flow rate fMFR)

[0046] The melt flow rate MIL of the polymer was determined according to ISO 1133 (230°C,

2.16 Kg]

Determination of Melt Index (MIE, MIF, MIP)

[0047] The melt indices are measured at 190 °C according to ASTM D-1238, condition “E” (load of 2.16 kg), “P” (load of 5.0 kg) and “F” (load of 21.6 kg).

The ratio between MIF and MIE is indicated as F/E, while the ratio between MIF and MIP is indicated as F/P.

Determination of comonomer content [0048] 1 -Butene was determined via ¹³ C NMR analysis.

¹³ C NMR spectra were acquired on a Bruker AV-600 spectrometer equipped with cryo-probe, operating at 150.91 MHz in the Fourier transform mode at 120°C.

The peak of the S55 carbon (nomenclature according to C. J. Carman, R. A. Harrington and C. E. Wilkes, Macromolecules, 10, 3, 536 (1977)) was used as internal reference at 29.90 ppm. The samples were dissolved in l,l,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 ¹ H- ¹³ C coupling. About 512 transients were stored in 32K data points using a spectral window of 9000 Hz.

Assignments of the spectra were made according to J.C. Randal, Macromol. Chem Phys., C29, 201 (1989).

Triad distribution and composition were made starting from relations between peaks and triads described by Kakugo et al. modified to consider overlaps of signals in the spectra.

Triads

BBB = 100 Tbb/S

BBE = 100 Tbd/S

EBE = 1002B2 (EBE) /S

BEB = IOO bbb/b

BEE= 100 Sa5/S

EEE = 100 (0.25 Sy5+0.5 S55)/S

Molar composition

B= BBB + BBE+ EBE

E = EEE + BEE + BEB

Determination of fraction soluble in xylene

[0049] 2.5 g of polymer and 250 ml of o-xylene were placed in a round-bottomed flask equipped with a cooler and a reflux condenser and kept under nitrogen. The resulting mixture was heated to 135 °C and was kept under stirring for about 60 minutes. The final solution was allowed to cool to 25 °C under continuous stirring, and the insoluble polymer was then filtered. The filtrate was then evaporated in a nitrogen flow at 140 °C to reach a constant weight. The content of the xylene-soluble fraction is expressed as a percentage of the original 2.5 grams.

Determination of effective density

[0050] Effective density: ASTM-D 1505-10 but referred to MGΈ” 1 g/10’ as corrected by the following equation: density (MIE=1) =density(measured) -0.0024 ln(MI E).

EXAMPLES

General procedure for the polymerization of propylene

[0051] A 4-litre steel autoclave equipped with a stirrer, pressure gauge, thermometer, catalyst feeding system, monomer feeding lines and thermostating jacket, was purged with nitrogen flow at 70°C for one hour. Then, at 30°C under propylene flow, were charged in sequence with 75 mL of anhydrous hexane, 0.76 g of AlEt3, the external electron donor in order to have a Al/Donor molar ratio of 20, and 0.006÷0.010 g of solid catalyst component. The autoclave was closed; subsequently 2.0 NL of hydrogen were added. Then, under stirring, 1.2 kg of liquid propylene was fed. The temperature was raised to 70°C in five minutes and the polymerization was carried out at this temperature for two hours. At the end of the polymerization, the non-reacted propylene was removed; the polymer was recovered and dried at 70°C under vacuum for three hours. Then the polymer was weighed and fractionated with o-xylene to determine the amount of the xylene insoluble (X.I.) fraction. Polymer characteristics are reported in Table 3.

General procedure for the LLDPE polymerization test in slurry

[0052] A 4.5 liter stainless-steel autoclave equipped with a magnetic stirrer, temperature, pressure indicator, and feeding line for ethylene, propane, 1 -butene, and hydrogen, and a steel vial for the injection of the catalyst, was purified by fluxing pure nitrogen at 70°C for 60 minutes. The autoclave was then washed with propane, heated to 75°C and finally loaded with 800 grams of propane, 1 -butene (in the amount variable between 160 g and 200 g), ethylene (7.0 bar, partial pressure) and hydrogen (1.5 bar, partial pressure). In a separate 100 cm ³ round bottom glass flask were subsequently introduced 50 cm ³ of anhydrous hexane, the cocatalyst mixture solution composed by triethyl aluminum/di ethyl aluminum chloride, TEA/DEAC 2/1 weight ratio (8.5 mmol of aluminum), tetrahydrofuran or a compound of formula (I) as external donor (Al/ED molar ratio is indicated in Table 2), and 0.010÷0.020 grams of the solid catalyst component; they were mixed together and stirred at room temperature for 10 minutes and then introduced in the reactor through the steel vial by using a nitrogen overpressure. Under continuous stirring, the total pressure was maintained constant at 75°C in order to absorb 150 g of ethylene or for a maximum time of 2 h by continuous ethylene feeding into the system. At the end of the polymerization, the reactor was depressurized and the temperature was reduced to 30°C. The recovered polymer was dried at 70°C under a nitrogen flow and weighted. Polymer characteristics are reported in Table 2.

General procedure for the HDPE polymerization test Polymerizations Conditions for catalyst A

[0053] A 4.5-liter stainless-steel autoclave equipped with a magnetic stirrer, temperature and pressure indicator, and a feeding line for hexane, ethylene, and hydrogen, was used and purified by fluxing pure nitrogen at 70 °C for 60 minutes. Then, a solution of 1550 cm ³ of hexane containing 0.1 g of triethyl aluminum (TEA) was introduced at a temperature of 25 °C under nitrogen flow. In a separate 100 cm ³ round bottom glass flask were subsequently introduced 50 cm ³ of anhydrous hexane, 0.4 g of triethyl aluminum (TEA), 0.025 grams of the solid catalyst component and the amount of external donor reported in Table 1. The components were mixed together, aged 10 minutes at room temperature and introduced under nitrogen flow into the reactor. The autoclave was closed, the temperature was raised to 75 °C, and hydrogen (4 bars partial pressure) and ethylene (7.0 bars partial pressure) were added. Under continuous stirring, the total pressure was maintained at 75 °C for 120 minutes by feeding ethylene. At the end of the polymerization, the reactor was depressurized and the temperature was reduced to 30 °C. The recovered polymer was dried at 40 °C under vacuum and analyzed. Polymer characteristics are reported in Table 1. Polymerizations Conditions for catalyst B

[0054] The procedure for catalyst A is repeated, but using tri isobutyl aluminum (ΉBA) instead of tri ethyl aluminum (TEA), 0.35 g of which into autoclave and 0.15 g in the precontact solution. Furthermore, the polymerization time was 3 h instead of 2 h. Polymer characteristics are reported in Table 1.

General Procedure for the preparation of the solid catalyst component for the LLDPE polymerization test in slurry [0055] An initial amount of microspheroidal MgCh 2.8C2H5OH was prepared according to the method described in Example 2 of W098/44009. The so obtained microspheroidal MgCh- EtOH adduct was subjected to a thermal treatment under nitrogen stream over a temperature range of 50-150°C, to reduce the alcohol content. Using this method, a solid support materials containing 28.5%wt of EtOH, having average particle size of 23 pm was obtained.

Into a 750 mL four-necked round flask, purged with nitrogen, 500 mL of TiCU were introduced at 0°C. Then, at the same temperature, 20 grams of above described spherical adduct were added under stirring. The temperature was raised to 130°C and maintained at that temperature for 1 hours. Then, the stirring was discontinued, the solid product was allowed to settle and the supernatant liquid was siphoned off. A new amount of fresh TiCU was added to the flask, such to reach the initial liquid volume. The temperature was maintained at 110°C for 0.5 hour. Again, the solid was allowed to settle, and the liquid was siphoned off.

The solid was then washed three times with anhydrous hexane (250 mL at each washing) at 60°C and twice at 40°C.

500 mL of anhydrous heptane were added to the solid component and heated under stirring to 50°C. At the same temperature, under stirring, 10.5 ml of THF were added dropwise. The temperature was then raised to 95 °C and the mixture was continuously stirred for 2 hours. Then, the temperature was decreased to 80°C, the stirring was discontinued, the solid product was allowed to settle and the supernatant liquid was siphoned off.

The solid was washed twice with anhydrous hexane (2 x 250 mL) at 40 °C, recovered, dried under vacuum and analyzed. The solid showed the following characteristics: Ti = 1.85% (by weight), Mg = 14.6% (by weight), tetrahydrofuran = 32.6% (by weight).

General Procedure for the preparation of the solid catalyst component for propylene polymerization test

Into a 500 ml round bottom flask, equipped with mechanical stirrer, cooler and thermometer 300 ml of TiCU were introduced at room temperature under nitrogen atmosphere. After cooling to 0°C, while stirring, 9,9-bis(methoxymethyl)fluorene and 9.0 g of the spherical adduct (prepared as described above) were sequentially added into the flask. The amount of charged internal donor was such as to have a Mg/donor molar ratio of 6. The temperature was raised to 100°C and maintained for 2 hours. 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 TiCU was added to reach the initial liquid volume again. The mixture was then heated at temperature in the range of 110°C and kept at this temperature for 1 hour. Stirring was stopped again, the solid was allowed to settle and the supernatant liquid was siphoned off. The solid was washed with anhydrous hexane six times in temperature gradient down to 60°C and one time at room temperature. The obtained solid was then dried under vacuum and analyzed. The solid showed the following characteristics: Ti = 4.1% (by weight), Mg = 13.8% (by weight), 9,9- bis(methoxymethyl)fluorene = 12.6% (by weight).

EXAMPLE 1-3 and comparative examples 1-2 Preparation of Solid Catalyst Component A

[0056] A magnesium chloride and alcohol adduct containing about 3 mols of alcohol was prepared following the method described in example 2 of USP 4,399,054, but working at 2000 RPM instead of 10000 RPM. The adduct were subject to a thermal treatment, under nitrogen stream, over a temperature range of 50-150 °C until a weight content of 24.4% of alcohol was reached.

[0057] Into a 2 L four-necked round flask, purged with nitrogen, 1 L of TiCU was introduced at 0°C. Then, at the same temperature, 70 g of a spherical MgCh/EtOH adduct containing 24.4 %wt of ethanol and prepared as described above were added under stirring. The temperature was raised to 130°C in 2 h and maintained for 90 min. Then, the stirring was discontinued, the solid product was allowed to settle and the supernatant liquid was siphoned off. A new amount of fresh TiCU was added to the flask, such to reach the initial liquid volume. The temperature was maintained at 115°C for 90 minutes. Again, the solid was allowed to settle, and the liquid was siphoned off. The solid was then washed three times with anhydrous iso-hexane (400 mL at each washing) at 60°C and twice at 40°C.

[0058] At the end the residual solid was suspended in 600 mL of dry iso-hexane. At the same temperature, under stirring, .ethyl acetate was added dropwise to have a Mg/donor molar ratio of 1.7. [0059] The temperature was raised to 50°C and the mixture was stirred for 2 hours. Then, the stirring was discontinued, the solid product was allowed to settle and the supernatant liquid was siphoned off.

[0060] The solid was washed twice with anhydrous hexane (2 x 100 mL) at 40 °C, recovered, and dried under vacuum. The solid showed the following characteristics: Ti = 2.2% (by weight), Mg = 15.3% (by weight), ethyl acetate = 29.3% (by weight). The so obtained solid catalyst components were tested in polymerization of ethylene for preparing HDPE according to the procedure described above. The results are listed in Table 1.

EXAMPLE 4 and comparative examples 3-4

Procedure for the preparation of the solid catalyst component (B)

[0061] A magnesium chloride and alcohol adduct containing about 3 mols of alcohol was prepared following the method described in example 2 of USP 4,399,054, but working at 2000 RPM instead of 10000 RPM. The adduct were subject to a thermal treatment, under nitrogen stream, over a temperature range of 50-150 °C until a weight content of 25% of alcohol was reached.

Into a 2 L four-necked round flask, purged with nitrogen, 1 L of TiC14 was introduced at 0°C. Then, at the same temperature, 70 g of a spherical MgCb/EtOH adduct containing 25 %wt of ethanol and prepared as described above were added under stirring. The temperature was raised to 140°C in 2h and maintained for 120 minutes. Then, the stirring was discontinued, the solid product was allowed to settle and the supernatant liquid was siphoned off. The solid residue was then washed once with heptane at 80°C and five times with hexane at 25°C and dried under vacuum at 30°C. The solid showed the following characteristics: Ti = 3.0% (by weight), Mg = 8.7% (by weight). The so obtained solid catalyst components were tested in polymerization of ethylene for preparing HDPE according to the procedure described above. The results are listed in Table 1.

Table 1

Table 2

Table 3