CA2038330C - Supported catalyst for ethylene polymerization and the copolymerization of ethylene with alpha-olefins, its preparation and use - Google Patents
Supported catalyst for ethylene polymerization and the copolymerization of ethylene with alpha-olefins, its preparation and use Download PDFInfo
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Abstract
A supported Ziegler-Natta catalyst active in ethylene polymerization and in the copolymerization of ethylene with alpha-olefins consists of:
(A) a cocatalyst in the form of an organometallic compound of aluminium, and (b) a solid catalyst component obtained by:
- (i) impregnating a granular solid support with a solution of a titanium alcaholate and magnesium chloride in a liquid aliphatic hydrocarbon, followed by evaporation of the hydrocarbon solvent;
- (ii) impregnating the support treated in (i) with a solution of magnesium chloride in a liquid aliphatic ester, followed by evaporation of the ester solvent; and - (iii) activating the support treated in (ii) by contact with an alkyl aluminium halide.
In a preferred embodiment, measured quantities of a silicon halide are introduced in stage (i) and/or (ii), this considerably improving catalytic activity.
In a particular embodiment, zirconium or hafnium are introduced into the solid catalyst component (B) in addition to titanium, to obtain catalysts able to produce polyethylenes with a widened molecular weight distribution.
(A) a cocatalyst in the form of an organometallic compound of aluminium, and (b) a solid catalyst component obtained by:
- (i) impregnating a granular solid support with a solution of a titanium alcaholate and magnesium chloride in a liquid aliphatic hydrocarbon, followed by evaporation of the hydrocarbon solvent;
- (ii) impregnating the support treated in (i) with a solution of magnesium chloride in a liquid aliphatic ester, followed by evaporation of the ester solvent; and - (iii) activating the support treated in (ii) by contact with an alkyl aluminium halide.
In a preferred embodiment, measured quantities of a silicon halide are introduced in stage (i) and/or (ii), this considerably improving catalytic activity.
In a particular embodiment, zirconium or hafnium are introduced into the solid catalyst component (B) in addition to titanium, to obtain catalysts able to produce polyethylenes with a widened molecular weight distribution.
Description
SUPPORTER CATALYST FOR ETHYLENE POLYMERIZATION AND THE
COPOLYMERIZATION OF ETHYLENE WITH ALPHA-OLEFINS, ITS PREPARATION
AND USE
This invention relates to a supported catalyst for ethylene polymerization and the copolymerization of ethylene with alpha-olefins, its preparation and use.
It is known that ethylene or general alpha-olefins can be polymerized by the low pressure process using Ziegler-Natter catalysts. These catalysts are generally formed from a compound of group IV to group III elements of the periodic table (transition metal compounds) mixed with an organometallic compound or hydride of group I to group III elements of the periodic table.
The known art comprises Ziogler-Natter catalysts in which the transition metal Compound is fixed to a solid support, such as a magnesium halide. For example, US patent 4,296,223 describes a solid catalyst component obtained by interacting magnesium dichloride, a titanium alcoholate and an aluminium chloride, and US patent 4,192,772 describes a solid catalyst component obtained by interacting a magnesium compound, a titanium compound, a zirconium compound and an aluminium halide.
These catalysts normally allow olefinic polymers to be obtained with a narrow and wide molecular weight distribution respectively, but do not enable the polymer to be obtained directly in the form of flowable granules. Solid catalyst components are also known in the art obtained by activating with an aluminium halide a complex containing magnesium, titanium, halogen, alkoxy groups and an electron donor. Such a complex can be deposited on a support, particularly a porous support, and then activated to provide solid catalyst components particularly suitable for the polymerization or copolymerization of ethylene in the gaseous phase. For this known art reference should be made to the descriptive part of US
patents 4,354,009, 4,359,561, 4,390,456, 4,379,958 and 4,3$3,095.
These supported catalysts enable polyethylenes to be obtained in flowable granular form, however problems often arise deriving from the poor rheology of the polymer because of the presence of fines, and the friability of the granules. A further problem is the unsatisfactory productivity in terms of the quantity of polymer obtained per unit weight of catalyst. This probably derives from the difficulty of depositing the catalyst components on the support in highly active form. Finally, known catalysts are generally insufficiently flexible for use in the production of olefinie polymers with differing characteristics ,according to requirements.
According to the present invention it has now been found possible to obtain a solid catalyst component and a catalyst which are highly active in suspension or gaseous--phase polymerization, and are able to produce ethylene polymers and copolymers of ethylene with alpha-olefins in the form of flowable granules having _ g _ excellent morphology. Specifically, the present invention is based on the discovery that magnesium chloride can be deposited in highly active amorphous form on a porous support by two separate partial impregnations, from a solution of magnesium chloride in aliphatic hydrocarbon and in aliphatic ester respectively. It has also been found that such a catalyst can produce ethylene polymers with a molecular weight distribution varying from narrow to wide by simple modifications introduced into the catalyst, In accordance therewith the present invention provides a supported Ziegler-Natta catalyst active in ethylene polymerization and in the copolymerization of ethylene with alpha-olefins, consisting of:
(A) a cocatalyst in the form of an organometallic compound of aluminium, and (B) a solid catalyst component containing titanium, magnesium, chlorine and alkoxy groups on a support, with a molar ratio of titanium to magnesium of between l:l and l:6 and a titanium content of between 1 and 9% by weight (expressed as metal), obtainod by:
- (i) impregnating a granular porous solid support with a solution of magnesium chloride MgCl2 and a titanium tetraalcoholate Ti(OR)4 (where R is a linear or branched Ca-Cs alkyl radical) in a molar ratio of between 0.1:1 and 0.5:1, in a liquid aliphatic hydrocarbon, followed by evaporation of the hydrocarbon solvent, in order to deposit on the support a complex of formula Ti(OR)4.(O.I-0.5)MgClz;
- (i.i) impregnating the support treated in (i) with a solution 'A t .. l~ ., , ~of magnesium chloride in a liquid aliphatic ester, followed by evaporation of the solvent, to obtain on completion of the operation the deposition on the support of a compley of formula Ti(OR)4.(1-6)MgClz; and - (iii) activating the support treated in (ii) by contact with an alkylaluminium chlorine, operating at a temperature of between and 100°C for a time of between 10 minutes and 24 hours.
According to a preferred embodiment, in stage (i) and/or (ii) a silicon halide is additionally added in a quantity to obtain an 10 atomic ratio of the silicon in said silicon halide to the titanium in the titanium tetraalcoholate of between 0.5:1 and 8:1. In the best embodiment the silicon halide is added in stage (ii) in a quantity to obtain a silicon: titanium atomic ratio of between 2.0:1 and 6.0:1. The use of the silicon halide unexpectedly improves the catalyst activity, even in polymerizations conducted with very large hydrogen quantities, in the production of polyethylenes with a high melt flow index.
The organometallic aluminium compound Forming the cocatalyst (A) is conveniently chosen from trialkylaluminiums, alkylaluminium hydrides and alkylaluminium halides (especially chlorides) containing from 1 to 5 carbon atoms in the alkyl portion.
Trialkylaluminiums with from 2 to 4 carbon atoms in the alkyl portion are preferred, such as triethylaluminium, tributyl-aluminium and triisobutylaluminium.
The support for the solid catalyst component (B) is chosen from granular, preferably spherical, porous solids with a mean particle size of the order of microns and a narrow particle size i~~x.~ "~~~
distribution. The Supports can be organic, such as olefinic or styrene polymers, or inorganic such as silica or aluminium, Microspheroidal silica (size 20-100 p) is preferred with a BBT
surface area of between 150 and 400 m2/g, a total porosity > 80%
and a mean pore radius of between 50 and 200 R. Such a silica can be either used as such or be previously activated. The activation can be effected by heating the silica in an inert atmosphere to a temperature of between about 100°C and about 650°C for a time of between 1 and 20 hours, or by bringing the silica into contact with an organometallic compound such as an alkylmagnesium or an alkylaluminium, such as butylmagnesium, butyl octylmagnesium or triethylaluminium, operating at ambient or higher than ambient temperature, for example 60°C. According to a preferred embodiment the silica is activated by treatment with butyl octylmagnesium in a quantity of the order of 10-20% of the silica by weight.
According to the present invention such a support is impregnated [stage (i)J with a solution of titanium tetraalcoholate Ti(OR)d and magnesium chloride dissolved in a liquid aliphatic hydrocarbon solvent. Preferred examples of of titanium tetraalcoholates 1'i(OR)~ are tetra n-propoxytitanium, tetra n-butoxytitanium, 'tetra i-propoxytitanium and tetra i-butoxytitanium, The magnesium chloride used for the purpose is an anhydrous or substantially anhydrous magnesium chloride (water content less.than 1% by weight). Solvents suitable for the purpose are aliphatic hydrocarbons liquid under normal temperature conditions, such as pentane, hexane, heptane, octane, nonane and decane. The lower-~al~~~9~
boiling solvents such as pentane, hexane and heptane are preferred, as they can be removed by evaporation at relatively low temperature.
According to the present invention, a solution containing between 0>1 and 0.5 moles of magnesium chloride per mole of titanium tetraalcoholate is prepared. The solution concentration is not critical, but a total concentration of the two compounds of the order of 5-10% by weight is convenient. The support is impregnated with the solution at a temperature between 40 and 100°C and preferably at the solvent reflux temperature (for solvents with a suitable boiling point), for a time normally of between 1 and 5 hours. The solution quantity used in the impregnation is such as to have on the support between 1 and 9% by weight and preferably between 3 and 9% by weight of titanium (considered as metal) in the solid catalyst component finally obtained.
After impregnation the hydrocarbon solvent is remaved by evaporation, operating at a temperature not exceeding about 60"C, possibly under reduced pressure. After this treatment a granular solid is obtained consisting of the support an which a complex definable by the formula Ti(OF~)4.(0.1-0.5)MgCl2 is deposited.
This solid is impregnated [stage (ii)] with a solution of magnesium chloride in an aliphatic ester. Aliphatic esters suitable for this purpose are chlorinated or non-chlorinated methyl and ethyl aliphatic esters of lower aliphatic carboxylic acids, such as ethyl formate, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate and ethyl chloroacetate. The preferred solvent is ethyl acetate. Specifically, a solution with a magnesium chloride content preferably of the order of 5 g/1 is used, the impregnation being carried out at a temperature of 50-75°C for a time of the order of I-5 hours. The quantity of solution used is such that the complex deposited on the support is definable by the formula Ti(OR)4.(1-5)MgCl2 after eliminating the solvent. In the preferred.embodiment the deposited complex is definable as Ti(OR)4.(1-3)MgCl2, so that the molar ratio of titanium to magnesium in the solid catalyst component is between 1:1 and 1:3. The aliphatic ester is conveniently evaporated at a temperature not exceeding about 50°C, possibly under reduced pressure. The evaporaticn is preferably controlled to only partly evaporate the ester, to maintain in the deposited complex an ester quantity of up to ZOX and preferably of the order of 5-10% of the weight of the magnesium chloride. It has been found that, on X-ray diffractometer analysis, using for this purpose a power diffractometer with CuKag radiation transmission, the solid obtained at the end of stage (ii) shows a clear characteristic peak at about 7 degrees 28. It is considered that this peak originates Prom a product of crystallographic interaction of the ester on the magnesium chloride lattice. This peak is still present in the solid catalyst component (B) obtained at the end of stage (iii). It has been found that solid catalyst components (B) having the described peak are highly active in ethylene polymerization and in the copolymerization of ethylene with alpha-olefins, whereas the catalyst components without this peak show a lesser polymerization activity.
_, g _ In preparing the solid catalyst component (B) of the present invention, the order of execution of stages (i) and (ii) can be reversed, while still obtaining useful results.
According to a preferred embodiment of the present invention a silicon halide chosen from silicon tetrahalides and halosilanes is added in stage (i) and/or stage (ii). Conveniently, the silicon halide is added in the form of a solution in the hydrocarbon solvent and/or ester, together with the other components, fn the aforestated quantities. Examples of these components are silicon tetrachloride, trichlorosilane, vinyl trichlorosilane, trichloroethoxy silane and chloroethyl trichlorosilane. Silicon tetrachloride is preferred.
According to the present invention, the support obtained after stages (i) and (ii) is activated (stage (iii)] by contact with an alkylaluminium chloride to obtain the solid catalyst component (B). Conveniently, the treated support from stage (ii) is brought into contact with a solution of an alkylaluminium chloride in an aliphatic hydrocarbon, with a ratio of chlorine atoms in the alkylaluminium chloride to alkoxy groups in 'the solid of between 0.5:1 and 7:1. The procedure is carried out at a temperature of between 10 and 100°C for a time which, depending on the temperature used, varies from 10 minutes to 24 hours. Suitable alkylaluminium chlorides for this purpose include diethylaluminium chloride, ethylaluminium sesquichloride and isobutylaluminium chloride. The solvents can be chosen from the liquid aliphatic hydrocarbons stated in the description of stage (i). The preferred embodiment uses a temperature of between 20 and 90°C
_g_ with a time of between 15 minutes and 2 hours. After treatment the activated solid catalyst component is recovered, then conveniently washed with a liquid aliphatic hydrocarbon solvent until there is no chloride in the wash liquid.
The solid catalyst component (B) of the present invention is a granular solid consisting generally of between 40 and 85% by weight of support, the remainder being the catalytically active part containing titanium, magnesium, chlorine, alkoxy groups and possibly aliphatic ester, with a molar ratio of titanium to magnesium of between 1:1 and 1:6, a titanium content of between about 1 and about 9% of the total weight of component (B}, and an aliphatic ester content of between 0 and 20% of the weight of the magnesium chloride used.
Preferably the support quantity varies from 55 to 80% by weight, the molar ratio of titanium to magnesium varies from I:1 to 1:3, the titanium content varies from 3 to 7% of the weight of component (B) and the aliphatic ester quantity as of the order of 5-10% of the weight of the magnesium chloride. The preferred support is pretreated or non~pretreated microspheroidal silica having the aforesaid characteristics.
The catalysts of the present invention have an atomic ratio of aluminium in the cocatalyst (A) to titanium in the solid catalyst component (B) generally between 200:1 and 20:1, and preferably between 150:1 and 50:1.
Operating in the aforesaid manner, solid catalyst components and catalysts are obtained which are particularly active in the production of high density ethylene polymers with a narrow medium o _ ~~3~~3~~3C) molecular weight distribution, and active in the production of ethylene/alpha~olefin copolymers with low density (LLDPE).
The catalyst of the present invention can also be modified to make it suitable fox the production of polyethylenes with a wider molecular weight distribution. Generally, such a modification consists of introducing into the solid catalyst component active centres of a transition metal other than titanium. Tn practice, such a result is obtained by contacting the support in stage (i) with a solution which in addition to the other components contains a zirconium or hafnium compound, normally chosen from zirconium or hafnium halides, alcoholates and haloalcoholates. Compounds suitable for this purpose are zirconium tetrachloride, hafnium tetrachloride, tetrabutoxy.zirconium, tetrabutoxy hafnium, dichloro dibut gxyzirccrvian and dichloro dibuto.:wy hafnium.. The Z5 treatment conditions for 'the support are those described for stage (i) and the quantity of zirconium or hafnium compound used is such as to obtain a molar ratio of [Ti ~~ Zr (or Hf)J to Mg of between 1:1 and 106 and preferably between 1:1 and 1:3, and a molar ratio of Ti to Zr (or Hf) of between 1:0.5 and 1:2 and preferably between 1:1 and 1:2. At tho and of the treatment the salvent is eliminated in the manner already described in relation to stage (i).
Thus using the catalysts of the present invention, high density ethylene polymers (density between about 0.96 and about 0.95 g/ml) can be prepared with a molecular weight distribution from narrow to wide (Mw/Mn from about 4 to more than 14). In addition the catalysts are sensitive to alpha-olefinic comonomers and allow copolymers of ethylene with an alpha-olefin to be prepared having a density from medium to low (density from about 0.94 to about 0.92 g/ml). Alpha-olefins suitable for this purpose are those containing from 3 to 10 carbon atoms and preferably from 4 to 6 carbon atoms, such as 1-butene, 1-hexene and 4-methyl-1-pentene.
The catalysts are also sensitive to hydrogen, thus allowing simple molecular weight adjustment (melt flow index at 2.1s kg from about 0.0 to about 50 g/10 min).
The catalysts of the present invention can be used in polymerization by the method of suspension in an inert diluent, or by the gaseous phase, fluidized bed or agitated method. The general polymerization conditions are: temperature between 50 and 110°C, total pressure between 5 and 40 bar, and a ratio of hydrogen partial pressure to ethylene partial pressure of between 0 and 10. In all cases a high olefinic polymer productivity is obtained (productivity of the order of 2-10 kg of polymer per gram of solid catalyst component), having an excellent rheology and in particular being in the form of non-friable granules (with a size generally of the order of 1000-1500 p) and free of Yines.
The following experimental examples are provided to batter illustrate the present invention. In these examples the support for the solid catalyst component is a microspheroidal silica in the form of particles with a mean diameter of 40 p, having the following characteristics:
- apparent density: 0.27 g/ml - surface area (BET): 307 m2/g - total porosity:
92.6 ~~~~~;~~c~
1?, - mean pore radius: 132 R
In Examples 1-6, such a silica is activated before use by heating to about 600°C for a time of about 10 hours in a nitrogen atmosphere. In Example 13 the silica is used as such (unactivated). In Examples 14-16 the silica is used activated with magnesium butyloctyl under the stated conditions.
EXAPIPLE 1 (comparison) 5.61 g (16.5 mmoles) of tetra n-butoxytitanium, 0.78 g (8.24 mmoles) of magnesium chloride and 100 ml of anhydrous n-heptane are fed under a nitrogen atmosphere into a 250 ml flask fitted with a reflex condenser, mechanical stirrer and thermometer. The mixture is heated to reflex temperature (about 95°C) for 1 hour to completely dissolve the magnesium chloride.
g of activated silica are introduced into the solution and left 15 in contact for 2 hours under reflex conditions (about 95°C). The system is then evaporated to dryness by evaporating the solvent, to recover a solid which is suspended in 53 m1 of n-hexane and the suspension brought into contact with 13 ml of a 40 wt% solution of aluminium ethyl sesquichloride (4.26 g, 17.2 mmoles) in n-decane.
20 It is loft in contact for 15 minutes at a temperature of 25°C, after which the solid is recovered and washed with anhydrous hexane until no chloride is present in the wash liquid, after which it is dried under reduced pressure. .
16 g of a catalyst component are obtained in the form of microspheroidal solid, containing 61% by weight of SiOz and having a Mg: Ti atomic ratio of 1:2.
EXAMPLE 2 (comparison) i~R~~i~~.~~~
5.61 g (16.5 mmoles) of tetra n-butoxytitanium, 0.78 g ($.24 mmoles) of magnesium chloride and 100 ml of anhydrous n-heptane are fed under a nitrogen atmosphere into a 250 ml flask fitted with a reflux condenser, mechanical stirrer and thermometer. The mixture is heated to reflux temperature for 1 hour to completely dissolve the magnesium chloride.
g of activated silica are introduced into the solution and left in contact for 2 hours under reflux conditions. The system is then evaporated to dryness by evaporating the solvent, to recover 10 a solid which is suspended in 52 ml of a 2 vol% solution of titanium tetrachloride (1.04 g, 5.5 mmoles) in n-hexane and allowed to react for 1 hour at 60°C.
The system is then evaporated to dryness by evaporating the solvent, to recover a solid which is suspended in 53 ml of n-hexane and the suspension brought into contact with l3 ml of a 40 wt% solution of aluminium ethyl sesquichioride (4.26 g, 17.2 mmoles) in n-decane. It is left in contact for 15 minutes at a temperature of 25°C, after which the solid is recovered and washed, after which it is dried under reduced pressure, as described in Example 1.
17 g of a catalyst component are obtained in the form of microspheroidal solid, containing 17.4% by weight of SiOa and having a Mg: Ti atomic ratio of 1:2.5.
EXAMPLE 3 (comparison) Example 2 is repeated but with the difference that 100 ml of titanium tetrachloride are used. After heating to 60°C for 1 hour, the solid is filtered, washed repeatedly with hexane and s~~a.~~~a~~
- :L4 -dried.
A solid catalyst component is obtained with characteristics similar to that of Example 2.
5,63. g (16.5 mmoles) of tetra n-butoxytitanium, 0.78 g (8.24 mmoles) of magnesium chloride and 100 ml of anhydrous n-heptane are fed under a nitrogen atmosphere into a 250 ml flask fatted with a reflex condenser, mechanical stirrer and thermometer. The mixture is heated to reflex temperature for 1 hour to completely dissolve the magnesium chloride.
10 g of hot-activated silica are introduced into the solution and left in contact for 2 hours under reflex conditions. The system is then evaporated to dryness by'evaporating the solvent, to recover a granular solid.
1.04 g (10.9 mmoles) of anhydrous magnesium chloride dissolved in 260 ml of ethyl acetate dried over alumina are fed under a nitrogen atmosphere into a 500 ml flask fitted with a reflex condenser, mechanical stirrer and thermometer. The granular solid obtained as indicated is added to the solution and the mass heated to 60°C for 1 hour. The solvent is then evaporated until a residual ethyl acetate quantity of 5-10% by weight on the magnesium chloride is left, to obtain a solid which is recovered and suspended in 53 ml of n-hexane and the suspension brought into contact with 13 ml of a 40 wt% so.lution of aluminium ethyl sesquichloride (4.26 g, 17.2 mmoles) in n-decane. It is left in contact for 15 minutes at a temperature of 25°C, after which the solid is recovered and washed, and then dried under reduced ~~e~~a~~:~
pressure, as described in Example 1.
17 g of a catalyst component are obtained in the form of microspheroidal solid, containing 5'1.4% by weight of SiOa and having a Mg: Ti atomic ratio of 1.2:1, and which on X-ray analysis shows the characteristic peak of amorphous silica, and a sharp peak at about ? degrees 28.
0.952 g (10.0 mmoles) of anhydrous magnesium chloride dissolved in 300 ml of ethyl acetate dried aver alumina and 14.67 g of activated silica are fed under a stream of nitrogen into a 500 ml flask fitted with a reflex condenser, mechanical stirrer and thermometer and left in contact for 1 hour at 60°C. The ethyl acetate is partially evaparated to recover a granular solid.
4.26 g (12.53 mmoles) of tetra n-butoXytitanium, 2.00 g (6.24 mmoles) oP hafnium tetrachloride, 0.238 g (2.5 mmoles) of anhydrous magnesium chloride and 200 ml of anhydrous n-heptane are fed under a nitrogen stream into a 500 ml flask fitted with a reflex condenser, mechanical stirrer, dropping funnel and thermometer. Reflex conditions are maintained until solubilixation. Then solid prepared as indicated above is added and reacted for 1 hour at 180°C. The system is evaporated to dryness by evaporating the solvent, to recover a granular solid.
40 ml of n-decane dried over alumina and this latter solid are fed under a nitrogen atmosphere into a 100 ml flask fitted with a reflex condenser, mechanical stirrer, dropping funnel and thermometer. 40 ml of a 40 wt% solution of diisobutylaluminium chloride (13.22 g;84.6 mmoles) in n-decane are fed dropwise into the mixture thus obtained, maintaining the temperature between 40 and 45°C.
After the addition the temperature is raised to 90°C and contact is maintained for a further two hours.
The solid is finally separated, washed firstly with anhydrous n-decane until no chloride is present in the wash liquid, and then with n-pentane, and finally dried under a nitrogen stream at 40"G, to recover 22 g of catalyst component in 'the form of microspheroidal solid, containing 66% by weight of SiOa and having a Mg: Ti:Hf atomic ratio of 1:1:0.5, and which on X-ray analysis shows the characteristic peak of amorphous silica, and a sharp peak at about.? degrees 28.
5.61 g (16.5 mmoles) of tetra n-butoxy titanium, 0.78 g (8.24 mmoles) of anhydrous magnesium chloride and 100 mI of anhydrous n-heptane are fed under a nitrogen stream into a 500 ml flask fitted with a,reflux condenser, mechanical stirrer and thermometer. The mixture is reacted under reflux Par 1 hour to completely dissolve the magnesium chloride. 10 g of activated silica are then introduced and left in contact for 2 hours under reflux conditions to recover a solid granulate.
1.04 g (10.2 mmoles) of anhydrous magnesium chloride dissolved in 260 ml of ethyl acetate dried over alumina are fed under a nitrogen stream into a 500 ml flask fitted with a reflux condenser, mechanical stirrer and thermometer, The solid prepared as indicated above is added and reacted for 1 hour at 60°C. The solvent is then evaporated until a residual ethyl acetate quantity ~a ~~a~ ~ x.~a~
_ 17 -of 5-10% by weight on the magnesium chloride is left, to recover a granular solid.
30 ml of n-decane dried over alumina and this latter solid are fed under a nitrogen atmosphere into a 100 ml flask fitted with a reflux condenser, mechanical stirrer, dropping funnel and thermometer. 51 ml of a 40 wt% solution of diisobutylaluminium chloride (16:73 g;108 mmoles) in n-decan~e are fed dropwise into the mixture thus obtained, maintaining the temperature between 40 and 45'C.
After the addition the temperature is raised to 90°C and contact is maintained for a further two hours. The solid is finally separated, washed firstly with anhydrous n-decane until no chloride is present in the wash liquid, and then with n-pentane, and finally dried under a nitrogen stream at 40°C, to recover 17 g of catalyst component in the form of microspheroidal solid, containing 57.4% by weight of 9i0z and having a Mg: Ti atomic ratio of 1.2:1, and which on X-ray analysis shows the characteristic Beak of amorphous silica, and a sharp peak at about 7 degrees 2~.
The solid catalyst components prepared in Examples Z to 4 are used in ethylene golymerization tests (tests 1 to 4?~ The polymerization is conducted in a 5 litre pressure vessel containing 2 litres of n-hexane, operating at a pressure of 10 bar in the presence of hydrogen, with a ratio of hydrogen gressure to ethylene pressure of 0.57:1 at a temperature of 90°C for a 'time of 4 hours, using 300 mg of solid catalyst companent and triethylaluminium as cocatalyst, with a molar ratio of triethylaluminium to titanium in the solid component of 100:1. Table 1 shows for each test the titanium content (%
by weight) of the solid catalyst component, the polyethylene yield expressed as kg of polyethylene per g of solid catalyst component, the polymer density (ASTM D 1505) expressed in g/ml, the melt flow index (MFI) of the polymer (ASTM D 1238; 2.16 kg and 21.6 kg) expressed in g/10 min, and the apparent density of the polymer (ASTM D 1895) expressed in g/ml. In Table 1 tests la to 4a are conducted under the aforesaid conditions with the solid catalyst components of Examples 1 and 4 respectively, but with a hydrogen pressure/ethylene pressure ratio of 0.72:1.
Table 2 shows the particle size distribution in % by weight for each ~, range, of the polyethylenes obtained in the polymerization tests of Table 1.
Test Ti Yield Density MFI App. D
No. (o p) (kg/g) (g/ml) (g/10 min) (g/ml) 1 4.8 1.67 0.9653 10.7 0.30 la 4.8 0.87 ND 52.1 0.26 2 5.8 1.61 0.9647 8.5 0.31 3 4.2 0.83 ND ND ND
COPOLYMERIZATION OF ETHYLENE WITH ALPHA-OLEFINS, ITS PREPARATION
AND USE
This invention relates to a supported catalyst for ethylene polymerization and the copolymerization of ethylene with alpha-olefins, its preparation and use.
It is known that ethylene or general alpha-olefins can be polymerized by the low pressure process using Ziegler-Natter catalysts. These catalysts are generally formed from a compound of group IV to group III elements of the periodic table (transition metal compounds) mixed with an organometallic compound or hydride of group I to group III elements of the periodic table.
The known art comprises Ziogler-Natter catalysts in which the transition metal Compound is fixed to a solid support, such as a magnesium halide. For example, US patent 4,296,223 describes a solid catalyst component obtained by interacting magnesium dichloride, a titanium alcoholate and an aluminium chloride, and US patent 4,192,772 describes a solid catalyst component obtained by interacting a magnesium compound, a titanium compound, a zirconium compound and an aluminium halide.
These catalysts normally allow olefinic polymers to be obtained with a narrow and wide molecular weight distribution respectively, but do not enable the polymer to be obtained directly in the form of flowable granules. Solid catalyst components are also known in the art obtained by activating with an aluminium halide a complex containing magnesium, titanium, halogen, alkoxy groups and an electron donor. Such a complex can be deposited on a support, particularly a porous support, and then activated to provide solid catalyst components particularly suitable for the polymerization or copolymerization of ethylene in the gaseous phase. For this known art reference should be made to the descriptive part of US
patents 4,354,009, 4,359,561, 4,390,456, 4,379,958 and 4,3$3,095.
These supported catalysts enable polyethylenes to be obtained in flowable granular form, however problems often arise deriving from the poor rheology of the polymer because of the presence of fines, and the friability of the granules. A further problem is the unsatisfactory productivity in terms of the quantity of polymer obtained per unit weight of catalyst. This probably derives from the difficulty of depositing the catalyst components on the support in highly active form. Finally, known catalysts are generally insufficiently flexible for use in the production of olefinie polymers with differing characteristics ,according to requirements.
According to the present invention it has now been found possible to obtain a solid catalyst component and a catalyst which are highly active in suspension or gaseous--phase polymerization, and are able to produce ethylene polymers and copolymers of ethylene with alpha-olefins in the form of flowable granules having _ g _ excellent morphology. Specifically, the present invention is based on the discovery that magnesium chloride can be deposited in highly active amorphous form on a porous support by two separate partial impregnations, from a solution of magnesium chloride in aliphatic hydrocarbon and in aliphatic ester respectively. It has also been found that such a catalyst can produce ethylene polymers with a molecular weight distribution varying from narrow to wide by simple modifications introduced into the catalyst, In accordance therewith the present invention provides a supported Ziegler-Natta catalyst active in ethylene polymerization and in the copolymerization of ethylene with alpha-olefins, consisting of:
(A) a cocatalyst in the form of an organometallic compound of aluminium, and (B) a solid catalyst component containing titanium, magnesium, chlorine and alkoxy groups on a support, with a molar ratio of titanium to magnesium of between l:l and l:6 and a titanium content of between 1 and 9% by weight (expressed as metal), obtainod by:
- (i) impregnating a granular porous solid support with a solution of magnesium chloride MgCl2 and a titanium tetraalcoholate Ti(OR)4 (where R is a linear or branched Ca-Cs alkyl radical) in a molar ratio of between 0.1:1 and 0.5:1, in a liquid aliphatic hydrocarbon, followed by evaporation of the hydrocarbon solvent, in order to deposit on the support a complex of formula Ti(OR)4.(O.I-0.5)MgClz;
- (i.i) impregnating the support treated in (i) with a solution 'A t .. l~ ., , ~of magnesium chloride in a liquid aliphatic ester, followed by evaporation of the solvent, to obtain on completion of the operation the deposition on the support of a compley of formula Ti(OR)4.(1-6)MgClz; and - (iii) activating the support treated in (ii) by contact with an alkylaluminium chlorine, operating at a temperature of between and 100°C for a time of between 10 minutes and 24 hours.
According to a preferred embodiment, in stage (i) and/or (ii) a silicon halide is additionally added in a quantity to obtain an 10 atomic ratio of the silicon in said silicon halide to the titanium in the titanium tetraalcoholate of between 0.5:1 and 8:1. In the best embodiment the silicon halide is added in stage (ii) in a quantity to obtain a silicon: titanium atomic ratio of between 2.0:1 and 6.0:1. The use of the silicon halide unexpectedly improves the catalyst activity, even in polymerizations conducted with very large hydrogen quantities, in the production of polyethylenes with a high melt flow index.
The organometallic aluminium compound Forming the cocatalyst (A) is conveniently chosen from trialkylaluminiums, alkylaluminium hydrides and alkylaluminium halides (especially chlorides) containing from 1 to 5 carbon atoms in the alkyl portion.
Trialkylaluminiums with from 2 to 4 carbon atoms in the alkyl portion are preferred, such as triethylaluminium, tributyl-aluminium and triisobutylaluminium.
The support for the solid catalyst component (B) is chosen from granular, preferably spherical, porous solids with a mean particle size of the order of microns and a narrow particle size i~~x.~ "~~~
distribution. The Supports can be organic, such as olefinic or styrene polymers, or inorganic such as silica or aluminium, Microspheroidal silica (size 20-100 p) is preferred with a BBT
surface area of between 150 and 400 m2/g, a total porosity > 80%
and a mean pore radius of between 50 and 200 R. Such a silica can be either used as such or be previously activated. The activation can be effected by heating the silica in an inert atmosphere to a temperature of between about 100°C and about 650°C for a time of between 1 and 20 hours, or by bringing the silica into contact with an organometallic compound such as an alkylmagnesium or an alkylaluminium, such as butylmagnesium, butyl octylmagnesium or triethylaluminium, operating at ambient or higher than ambient temperature, for example 60°C. According to a preferred embodiment the silica is activated by treatment with butyl octylmagnesium in a quantity of the order of 10-20% of the silica by weight.
According to the present invention such a support is impregnated [stage (i)J with a solution of titanium tetraalcoholate Ti(OR)d and magnesium chloride dissolved in a liquid aliphatic hydrocarbon solvent. Preferred examples of of titanium tetraalcoholates 1'i(OR)~ are tetra n-propoxytitanium, tetra n-butoxytitanium, 'tetra i-propoxytitanium and tetra i-butoxytitanium, The magnesium chloride used for the purpose is an anhydrous or substantially anhydrous magnesium chloride (water content less.than 1% by weight). Solvents suitable for the purpose are aliphatic hydrocarbons liquid under normal temperature conditions, such as pentane, hexane, heptane, octane, nonane and decane. The lower-~al~~~9~
boiling solvents such as pentane, hexane and heptane are preferred, as they can be removed by evaporation at relatively low temperature.
According to the present invention, a solution containing between 0>1 and 0.5 moles of magnesium chloride per mole of titanium tetraalcoholate is prepared. The solution concentration is not critical, but a total concentration of the two compounds of the order of 5-10% by weight is convenient. The support is impregnated with the solution at a temperature between 40 and 100°C and preferably at the solvent reflux temperature (for solvents with a suitable boiling point), for a time normally of between 1 and 5 hours. The solution quantity used in the impregnation is such as to have on the support between 1 and 9% by weight and preferably between 3 and 9% by weight of titanium (considered as metal) in the solid catalyst component finally obtained.
After impregnation the hydrocarbon solvent is remaved by evaporation, operating at a temperature not exceeding about 60"C, possibly under reduced pressure. After this treatment a granular solid is obtained consisting of the support an which a complex definable by the formula Ti(OF~)4.(0.1-0.5)MgCl2 is deposited.
This solid is impregnated [stage (ii)] with a solution of magnesium chloride in an aliphatic ester. Aliphatic esters suitable for this purpose are chlorinated or non-chlorinated methyl and ethyl aliphatic esters of lower aliphatic carboxylic acids, such as ethyl formate, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate and ethyl chloroacetate. The preferred solvent is ethyl acetate. Specifically, a solution with a magnesium chloride content preferably of the order of 5 g/1 is used, the impregnation being carried out at a temperature of 50-75°C for a time of the order of I-5 hours. The quantity of solution used is such that the complex deposited on the support is definable by the formula Ti(OR)4.(1-5)MgCl2 after eliminating the solvent. In the preferred.embodiment the deposited complex is definable as Ti(OR)4.(1-3)MgCl2, so that the molar ratio of titanium to magnesium in the solid catalyst component is between 1:1 and 1:3. The aliphatic ester is conveniently evaporated at a temperature not exceeding about 50°C, possibly under reduced pressure. The evaporaticn is preferably controlled to only partly evaporate the ester, to maintain in the deposited complex an ester quantity of up to ZOX and preferably of the order of 5-10% of the weight of the magnesium chloride. It has been found that, on X-ray diffractometer analysis, using for this purpose a power diffractometer with CuKag radiation transmission, the solid obtained at the end of stage (ii) shows a clear characteristic peak at about 7 degrees 28. It is considered that this peak originates Prom a product of crystallographic interaction of the ester on the magnesium chloride lattice. This peak is still present in the solid catalyst component (B) obtained at the end of stage (iii). It has been found that solid catalyst components (B) having the described peak are highly active in ethylene polymerization and in the copolymerization of ethylene with alpha-olefins, whereas the catalyst components without this peak show a lesser polymerization activity.
_, g _ In preparing the solid catalyst component (B) of the present invention, the order of execution of stages (i) and (ii) can be reversed, while still obtaining useful results.
According to a preferred embodiment of the present invention a silicon halide chosen from silicon tetrahalides and halosilanes is added in stage (i) and/or stage (ii). Conveniently, the silicon halide is added in the form of a solution in the hydrocarbon solvent and/or ester, together with the other components, fn the aforestated quantities. Examples of these components are silicon tetrachloride, trichlorosilane, vinyl trichlorosilane, trichloroethoxy silane and chloroethyl trichlorosilane. Silicon tetrachloride is preferred.
According to the present invention, the support obtained after stages (i) and (ii) is activated (stage (iii)] by contact with an alkylaluminium chloride to obtain the solid catalyst component (B). Conveniently, the treated support from stage (ii) is brought into contact with a solution of an alkylaluminium chloride in an aliphatic hydrocarbon, with a ratio of chlorine atoms in the alkylaluminium chloride to alkoxy groups in 'the solid of between 0.5:1 and 7:1. The procedure is carried out at a temperature of between 10 and 100°C for a time which, depending on the temperature used, varies from 10 minutes to 24 hours. Suitable alkylaluminium chlorides for this purpose include diethylaluminium chloride, ethylaluminium sesquichloride and isobutylaluminium chloride. The solvents can be chosen from the liquid aliphatic hydrocarbons stated in the description of stage (i). The preferred embodiment uses a temperature of between 20 and 90°C
_g_ with a time of between 15 minutes and 2 hours. After treatment the activated solid catalyst component is recovered, then conveniently washed with a liquid aliphatic hydrocarbon solvent until there is no chloride in the wash liquid.
The solid catalyst component (B) of the present invention is a granular solid consisting generally of between 40 and 85% by weight of support, the remainder being the catalytically active part containing titanium, magnesium, chlorine, alkoxy groups and possibly aliphatic ester, with a molar ratio of titanium to magnesium of between 1:1 and 1:6, a titanium content of between about 1 and about 9% of the total weight of component (B}, and an aliphatic ester content of between 0 and 20% of the weight of the magnesium chloride used.
Preferably the support quantity varies from 55 to 80% by weight, the molar ratio of titanium to magnesium varies from I:1 to 1:3, the titanium content varies from 3 to 7% of the weight of component (B) and the aliphatic ester quantity as of the order of 5-10% of the weight of the magnesium chloride. The preferred support is pretreated or non~pretreated microspheroidal silica having the aforesaid characteristics.
The catalysts of the present invention have an atomic ratio of aluminium in the cocatalyst (A) to titanium in the solid catalyst component (B) generally between 200:1 and 20:1, and preferably between 150:1 and 50:1.
Operating in the aforesaid manner, solid catalyst components and catalysts are obtained which are particularly active in the production of high density ethylene polymers with a narrow medium o _ ~~3~~3~~3C) molecular weight distribution, and active in the production of ethylene/alpha~olefin copolymers with low density (LLDPE).
The catalyst of the present invention can also be modified to make it suitable fox the production of polyethylenes with a wider molecular weight distribution. Generally, such a modification consists of introducing into the solid catalyst component active centres of a transition metal other than titanium. Tn practice, such a result is obtained by contacting the support in stage (i) with a solution which in addition to the other components contains a zirconium or hafnium compound, normally chosen from zirconium or hafnium halides, alcoholates and haloalcoholates. Compounds suitable for this purpose are zirconium tetrachloride, hafnium tetrachloride, tetrabutoxy.zirconium, tetrabutoxy hafnium, dichloro dibut gxyzirccrvian and dichloro dibuto.:wy hafnium.. The Z5 treatment conditions for 'the support are those described for stage (i) and the quantity of zirconium or hafnium compound used is such as to obtain a molar ratio of [Ti ~~ Zr (or Hf)J to Mg of between 1:1 and 106 and preferably between 1:1 and 1:3, and a molar ratio of Ti to Zr (or Hf) of between 1:0.5 and 1:2 and preferably between 1:1 and 1:2. At tho and of the treatment the salvent is eliminated in the manner already described in relation to stage (i).
Thus using the catalysts of the present invention, high density ethylene polymers (density between about 0.96 and about 0.95 g/ml) can be prepared with a molecular weight distribution from narrow to wide (Mw/Mn from about 4 to more than 14). In addition the catalysts are sensitive to alpha-olefinic comonomers and allow copolymers of ethylene with an alpha-olefin to be prepared having a density from medium to low (density from about 0.94 to about 0.92 g/ml). Alpha-olefins suitable for this purpose are those containing from 3 to 10 carbon atoms and preferably from 4 to 6 carbon atoms, such as 1-butene, 1-hexene and 4-methyl-1-pentene.
The catalysts are also sensitive to hydrogen, thus allowing simple molecular weight adjustment (melt flow index at 2.1s kg from about 0.0 to about 50 g/10 min).
The catalysts of the present invention can be used in polymerization by the method of suspension in an inert diluent, or by the gaseous phase, fluidized bed or agitated method. The general polymerization conditions are: temperature between 50 and 110°C, total pressure between 5 and 40 bar, and a ratio of hydrogen partial pressure to ethylene partial pressure of between 0 and 10. In all cases a high olefinic polymer productivity is obtained (productivity of the order of 2-10 kg of polymer per gram of solid catalyst component), having an excellent rheology and in particular being in the form of non-friable granules (with a size generally of the order of 1000-1500 p) and free of Yines.
The following experimental examples are provided to batter illustrate the present invention. In these examples the support for the solid catalyst component is a microspheroidal silica in the form of particles with a mean diameter of 40 p, having the following characteristics:
- apparent density: 0.27 g/ml - surface area (BET): 307 m2/g - total porosity:
92.6 ~~~~~;~~c~
1?, - mean pore radius: 132 R
In Examples 1-6, such a silica is activated before use by heating to about 600°C for a time of about 10 hours in a nitrogen atmosphere. In Example 13 the silica is used as such (unactivated). In Examples 14-16 the silica is used activated with magnesium butyloctyl under the stated conditions.
EXAPIPLE 1 (comparison) 5.61 g (16.5 mmoles) of tetra n-butoxytitanium, 0.78 g (8.24 mmoles) of magnesium chloride and 100 ml of anhydrous n-heptane are fed under a nitrogen atmosphere into a 250 ml flask fitted with a reflex condenser, mechanical stirrer and thermometer. The mixture is heated to reflex temperature (about 95°C) for 1 hour to completely dissolve the magnesium chloride.
g of activated silica are introduced into the solution and left 15 in contact for 2 hours under reflex conditions (about 95°C). The system is then evaporated to dryness by evaporating the solvent, to recover a solid which is suspended in 53 m1 of n-hexane and the suspension brought into contact with 13 ml of a 40 wt% solution of aluminium ethyl sesquichloride (4.26 g, 17.2 mmoles) in n-decane.
20 It is loft in contact for 15 minutes at a temperature of 25°C, after which the solid is recovered and washed with anhydrous hexane until no chloride is present in the wash liquid, after which it is dried under reduced pressure. .
16 g of a catalyst component are obtained in the form of microspheroidal solid, containing 61% by weight of SiOz and having a Mg: Ti atomic ratio of 1:2.
EXAMPLE 2 (comparison) i~R~~i~~.~~~
5.61 g (16.5 mmoles) of tetra n-butoxytitanium, 0.78 g ($.24 mmoles) of magnesium chloride and 100 ml of anhydrous n-heptane are fed under a nitrogen atmosphere into a 250 ml flask fitted with a reflux condenser, mechanical stirrer and thermometer. The mixture is heated to reflux temperature for 1 hour to completely dissolve the magnesium chloride.
g of activated silica are introduced into the solution and left in contact for 2 hours under reflux conditions. The system is then evaporated to dryness by evaporating the solvent, to recover 10 a solid which is suspended in 52 ml of a 2 vol% solution of titanium tetrachloride (1.04 g, 5.5 mmoles) in n-hexane and allowed to react for 1 hour at 60°C.
The system is then evaporated to dryness by evaporating the solvent, to recover a solid which is suspended in 53 ml of n-hexane and the suspension brought into contact with l3 ml of a 40 wt% solution of aluminium ethyl sesquichioride (4.26 g, 17.2 mmoles) in n-decane. It is left in contact for 15 minutes at a temperature of 25°C, after which the solid is recovered and washed, after which it is dried under reduced pressure, as described in Example 1.
17 g of a catalyst component are obtained in the form of microspheroidal solid, containing 17.4% by weight of SiOa and having a Mg: Ti atomic ratio of 1:2.5.
EXAMPLE 3 (comparison) Example 2 is repeated but with the difference that 100 ml of titanium tetrachloride are used. After heating to 60°C for 1 hour, the solid is filtered, washed repeatedly with hexane and s~~a.~~~a~~
- :L4 -dried.
A solid catalyst component is obtained with characteristics similar to that of Example 2.
5,63. g (16.5 mmoles) of tetra n-butoxytitanium, 0.78 g (8.24 mmoles) of magnesium chloride and 100 ml of anhydrous n-heptane are fed under a nitrogen atmosphere into a 250 ml flask fatted with a reflex condenser, mechanical stirrer and thermometer. The mixture is heated to reflex temperature for 1 hour to completely dissolve the magnesium chloride.
10 g of hot-activated silica are introduced into the solution and left in contact for 2 hours under reflex conditions. The system is then evaporated to dryness by'evaporating the solvent, to recover a granular solid.
1.04 g (10.9 mmoles) of anhydrous magnesium chloride dissolved in 260 ml of ethyl acetate dried over alumina are fed under a nitrogen atmosphere into a 500 ml flask fitted with a reflex condenser, mechanical stirrer and thermometer. The granular solid obtained as indicated is added to the solution and the mass heated to 60°C for 1 hour. The solvent is then evaporated until a residual ethyl acetate quantity of 5-10% by weight on the magnesium chloride is left, to obtain a solid which is recovered and suspended in 53 ml of n-hexane and the suspension brought into contact with 13 ml of a 40 wt% so.lution of aluminium ethyl sesquichloride (4.26 g, 17.2 mmoles) in n-decane. It is left in contact for 15 minutes at a temperature of 25°C, after which the solid is recovered and washed, and then dried under reduced ~~e~~a~~:~
pressure, as described in Example 1.
17 g of a catalyst component are obtained in the form of microspheroidal solid, containing 5'1.4% by weight of SiOa and having a Mg: Ti atomic ratio of 1.2:1, and which on X-ray analysis shows the characteristic peak of amorphous silica, and a sharp peak at about ? degrees 28.
0.952 g (10.0 mmoles) of anhydrous magnesium chloride dissolved in 300 ml of ethyl acetate dried aver alumina and 14.67 g of activated silica are fed under a stream of nitrogen into a 500 ml flask fitted with a reflex condenser, mechanical stirrer and thermometer and left in contact for 1 hour at 60°C. The ethyl acetate is partially evaparated to recover a granular solid.
4.26 g (12.53 mmoles) of tetra n-butoXytitanium, 2.00 g (6.24 mmoles) oP hafnium tetrachloride, 0.238 g (2.5 mmoles) of anhydrous magnesium chloride and 200 ml of anhydrous n-heptane are fed under a nitrogen stream into a 500 ml flask fitted with a reflex condenser, mechanical stirrer, dropping funnel and thermometer. Reflex conditions are maintained until solubilixation. Then solid prepared as indicated above is added and reacted for 1 hour at 180°C. The system is evaporated to dryness by evaporating the solvent, to recover a granular solid.
40 ml of n-decane dried over alumina and this latter solid are fed under a nitrogen atmosphere into a 100 ml flask fitted with a reflex condenser, mechanical stirrer, dropping funnel and thermometer. 40 ml of a 40 wt% solution of diisobutylaluminium chloride (13.22 g;84.6 mmoles) in n-decane are fed dropwise into the mixture thus obtained, maintaining the temperature between 40 and 45°C.
After the addition the temperature is raised to 90°C and contact is maintained for a further two hours.
The solid is finally separated, washed firstly with anhydrous n-decane until no chloride is present in the wash liquid, and then with n-pentane, and finally dried under a nitrogen stream at 40"G, to recover 22 g of catalyst component in 'the form of microspheroidal solid, containing 66% by weight of SiOa and having a Mg: Ti:Hf atomic ratio of 1:1:0.5, and which on X-ray analysis shows the characteristic peak of amorphous silica, and a sharp peak at about.? degrees 28.
5.61 g (16.5 mmoles) of tetra n-butoxy titanium, 0.78 g (8.24 mmoles) of anhydrous magnesium chloride and 100 mI of anhydrous n-heptane are fed under a nitrogen stream into a 500 ml flask fitted with a,reflux condenser, mechanical stirrer and thermometer. The mixture is reacted under reflux Par 1 hour to completely dissolve the magnesium chloride. 10 g of activated silica are then introduced and left in contact for 2 hours under reflux conditions to recover a solid granulate.
1.04 g (10.2 mmoles) of anhydrous magnesium chloride dissolved in 260 ml of ethyl acetate dried over alumina are fed under a nitrogen stream into a 500 ml flask fitted with a reflux condenser, mechanical stirrer and thermometer, The solid prepared as indicated above is added and reacted for 1 hour at 60°C. The solvent is then evaporated until a residual ethyl acetate quantity ~a ~~a~ ~ x.~a~
_ 17 -of 5-10% by weight on the magnesium chloride is left, to recover a granular solid.
30 ml of n-decane dried over alumina and this latter solid are fed under a nitrogen atmosphere into a 100 ml flask fitted with a reflux condenser, mechanical stirrer, dropping funnel and thermometer. 51 ml of a 40 wt% solution of diisobutylaluminium chloride (16:73 g;108 mmoles) in n-decan~e are fed dropwise into the mixture thus obtained, maintaining the temperature between 40 and 45'C.
After the addition the temperature is raised to 90°C and contact is maintained for a further two hours. The solid is finally separated, washed firstly with anhydrous n-decane until no chloride is present in the wash liquid, and then with n-pentane, and finally dried under a nitrogen stream at 40°C, to recover 17 g of catalyst component in the form of microspheroidal solid, containing 57.4% by weight of 9i0z and having a Mg: Ti atomic ratio of 1.2:1, and which on X-ray analysis shows the characteristic Beak of amorphous silica, and a sharp peak at about 7 degrees 2~.
The solid catalyst components prepared in Examples Z to 4 are used in ethylene golymerization tests (tests 1 to 4?~ The polymerization is conducted in a 5 litre pressure vessel containing 2 litres of n-hexane, operating at a pressure of 10 bar in the presence of hydrogen, with a ratio of hydrogen gressure to ethylene pressure of 0.57:1 at a temperature of 90°C for a 'time of 4 hours, using 300 mg of solid catalyst companent and triethylaluminium as cocatalyst, with a molar ratio of triethylaluminium to titanium in the solid component of 100:1. Table 1 shows for each test the titanium content (%
by weight) of the solid catalyst component, the polyethylene yield expressed as kg of polyethylene per g of solid catalyst component, the polymer density (ASTM D 1505) expressed in g/ml, the melt flow index (MFI) of the polymer (ASTM D 1238; 2.16 kg and 21.6 kg) expressed in g/10 min, and the apparent density of the polymer (ASTM D 1895) expressed in g/ml. In Table 1 tests la to 4a are conducted under the aforesaid conditions with the solid catalyst components of Examples 1 and 4 respectively, but with a hydrogen pressure/ethylene pressure ratio of 0.72:1.
Table 2 shows the particle size distribution in % by weight for each ~, range, of the polyethylenes obtained in the polymerization tests of Table 1.
Test Ti Yield Density MFI App. D
No. (o p) (kg/g) (g/ml) (g/10 min) (g/ml) 1 4.8 1.67 0.9653 10.7 0.30 la 4.8 0.87 ND 52.1 0.26 2 5.8 1.61 0.9647 8.5 0.31 3 4.2 0.83 ND ND ND
4 4.6 2.77 0.965 16.6 0.29 4a 4.6 2.00 ND 57.9 0.30 ND = not determined Test Particle size distribution (p) No. >2000 <2000 >500 <500 >250 <250 1 0.5 95.0 3.9 0.6 1a 0.3 88.0 9.4 2.3 2 0.9 80.9 8.9 9.4 4 0.2 89.6 7.6 2.6 4a 0.3 87.7 10.3 1.7 ND = not determined The catalyst component prepared in Example 4 is used in ethylene polymerization conducted in a 5 litre pressure vessel containing litres of n-hexane,at a total pressure (hydrogen, ethylene and hexane) of 15 bar at 90'C for a time of 2 hours, using 150 mg of solid catalyst component and triethylaluminium as cocatalyst, with a molar ratio of triethylaluminium to titanium in the solid component of 100:1.Table 3 shows the tests 4(a) to 4(e) conducted at various hydrogen pressures.
Test 4(a) 4(b) 4{c) 4(d) 4(e) P Hi (bar) 4.1 4.5 4.9 5.3 5.7 Yield (kg/g) 5.7 4.9 4.5 4.3 3.1 Density (g/ml) 0.961 0.962 0.961 0.964 0.963 MFI (2.16 kg) 2.8 3.4 4.9 6.2 6.3 MFI (21.6 KG) 78.0 95.3 132.0 181.0 189 MFR 27.8 28.0 26.9 29.2 30.0 App. dens. (g/ml) 0.32 0.34 0.31 0.35 0.33 In the table, MFR indicates the melt flow ratio, determined as the ratio MFI (21.6 kg)/MFI (2.16 kg).
Ethylene polymerization tests are conducted with the catalyst of Example 5 [tests 5 (a) , 5 (b) and 5 (c) ] using a 5 litre pressure vessel with 2 litres of n-hexane, with 300 10 mg of solid catalyst component and triisobutylaluminium as cocatalyst in a molar ratio to the titanium in the solid component of 100:1. The polymerization conditions and the test results are given in Table 4. The table also shows for the polyethylenes obtained in tests 5(b) and 5(c) the molecular weight, the molecular weight distribution and the intrinsic viscosity measured at 135°C in trichlorobenzene solution.
Test 5 (a) 5 (b) 5 (c) Temperature (C) 75 75 85 P total (bar) 15 15 15 P H2 (bar) 7.8 8.0 7.2 Time (hours) 4 4 2 Yield (kg/g) 2.1 2.5 1.6 MFI (2.16 kg) 0.05 0.15 0.22 MFI (21.6 kg) 4.9 14.7 9.3 MFR 98 98 84.5 o~~~~a~~~~
Density 0.956 0.950 (g/ml.) 0.95 App. dens. (g/ml) 0.38 0.30 0.27 Mw x 10-3 ND 281 316 Mn x 10-3 ND 21.1 22.3 MwJMn ND 13.3 14.18 Viscosity ND 2.64 2.97 where: Mw = weight-average weight;
molecular Mn = number-average weight;
molecular Nd = not determined.
The procedure of test 4(b) of Example 8 is repeated, adding 160g of 1-butane to the polymerization reactor. An ethylene/1-butane capolymer is obtained, with a yield of 8.9 kg per gram of solid catalyst component, density 0.928 g/ml, MFI (2.16 kg) 22.7 and MFR
8Ø
The procedure of test 4(b) of Example 8 is repeated, adding 100 g of 1-butane to the polymerization reactor. An ethylene/1-butane copolymer is obtained, with a yield of 6.9 kg per gram of solid catalyst component, density 0.941 g/ml, MFI (2.16 kg) 28.2 and MFR
10.16.
The catalyst of example 4 is used in ethylene polymerization conducted in a 5 litre pressure vessel in the gaseous phase, with a total pressure of 20 bar and a hydrogen partial pressure of 8 bar, at 90°C for a time of 2 hours, using 500 mg of solid catalyst component, 270 g of anhydrous sodium chloride and a molar ratio of ~~~~s~~~~
_ 22 _ , triethylaluminium to titanium in the solid component of 60:1. An ethylene polymer is obtained with a yield of 1.3 kg per gram of solid catalyst component, and having an apparent density of 0.38 g/ml, an MFI (2.16 kg) of 6.0 and an MFR of 29.1. The particle size distribution of the polymer in percentage per a range is as follows: >2000 = 0%; <2000 >500 = 82%; <500 >250 = 12.5%; 1250 =
5.5% by weight.
The solid catalyst component is prepared as in Example 4 but with the difference that the silica is used as such (unactivatedj. The solid catalyst component obtained in this manner has s Ti: Mg: CI
ratio of 1.0:1.1:3.6 and a characteristic X-ray peak.
200 mg of the solid catalyst component and triethylaluminium (AI/Ti molar ratio ~ 100:1) are used in the polymerization of ethylene at 15 bar in n-hexane (hydrogen/ethylene molar ratio =
0.47/1) for 2 hours at 90°C.
An ethylene polymer is obtained with a yield of 3.6 kg per gram of solid catalyst component, and having a density of 0.962 g/ml, an apparent density of 0.31 g/ml, an MFI (2.16 kg) of 3.72 and an MFR
of 27.9. The particle size distribution of the polymer in percentage per a range is as follows: >2000 = 0.7%; <2000 >1000 =
Test 4(a) 4(b) 4{c) 4(d) 4(e) P Hi (bar) 4.1 4.5 4.9 5.3 5.7 Yield (kg/g) 5.7 4.9 4.5 4.3 3.1 Density (g/ml) 0.961 0.962 0.961 0.964 0.963 MFI (2.16 kg) 2.8 3.4 4.9 6.2 6.3 MFI (21.6 KG) 78.0 95.3 132.0 181.0 189 MFR 27.8 28.0 26.9 29.2 30.0 App. dens. (g/ml) 0.32 0.34 0.31 0.35 0.33 In the table, MFR indicates the melt flow ratio, determined as the ratio MFI (21.6 kg)/MFI (2.16 kg).
Ethylene polymerization tests are conducted with the catalyst of Example 5 [tests 5 (a) , 5 (b) and 5 (c) ] using a 5 litre pressure vessel with 2 litres of n-hexane, with 300 10 mg of solid catalyst component and triisobutylaluminium as cocatalyst in a molar ratio to the titanium in the solid component of 100:1. The polymerization conditions and the test results are given in Table 4. The table also shows for the polyethylenes obtained in tests 5(b) and 5(c) the molecular weight, the molecular weight distribution and the intrinsic viscosity measured at 135°C in trichlorobenzene solution.
Test 5 (a) 5 (b) 5 (c) Temperature (C) 75 75 85 P total (bar) 15 15 15 P H2 (bar) 7.8 8.0 7.2 Time (hours) 4 4 2 Yield (kg/g) 2.1 2.5 1.6 MFI (2.16 kg) 0.05 0.15 0.22 MFI (21.6 kg) 4.9 14.7 9.3 MFR 98 98 84.5 o~~~~a~~~~
Density 0.956 0.950 (g/ml.) 0.95 App. dens. (g/ml) 0.38 0.30 0.27 Mw x 10-3 ND 281 316 Mn x 10-3 ND 21.1 22.3 MwJMn ND 13.3 14.18 Viscosity ND 2.64 2.97 where: Mw = weight-average weight;
molecular Mn = number-average weight;
molecular Nd = not determined.
The procedure of test 4(b) of Example 8 is repeated, adding 160g of 1-butane to the polymerization reactor. An ethylene/1-butane capolymer is obtained, with a yield of 8.9 kg per gram of solid catalyst component, density 0.928 g/ml, MFI (2.16 kg) 22.7 and MFR
8Ø
The procedure of test 4(b) of Example 8 is repeated, adding 100 g of 1-butane to the polymerization reactor. An ethylene/1-butane copolymer is obtained, with a yield of 6.9 kg per gram of solid catalyst component, density 0.941 g/ml, MFI (2.16 kg) 28.2 and MFR
10.16.
The catalyst of example 4 is used in ethylene polymerization conducted in a 5 litre pressure vessel in the gaseous phase, with a total pressure of 20 bar and a hydrogen partial pressure of 8 bar, at 90°C for a time of 2 hours, using 500 mg of solid catalyst component, 270 g of anhydrous sodium chloride and a molar ratio of ~~~~s~~~~
_ 22 _ , triethylaluminium to titanium in the solid component of 60:1. An ethylene polymer is obtained with a yield of 1.3 kg per gram of solid catalyst component, and having an apparent density of 0.38 g/ml, an MFI (2.16 kg) of 6.0 and an MFR of 29.1. The particle size distribution of the polymer in percentage per a range is as follows: >2000 = 0%; <2000 >500 = 82%; <500 >250 = 12.5%; 1250 =
5.5% by weight.
The solid catalyst component is prepared as in Example 4 but with the difference that the silica is used as such (unactivatedj. The solid catalyst component obtained in this manner has s Ti: Mg: CI
ratio of 1.0:1.1:3.6 and a characteristic X-ray peak.
200 mg of the solid catalyst component and triethylaluminium (AI/Ti molar ratio ~ 100:1) are used in the polymerization of ethylene at 15 bar in n-hexane (hydrogen/ethylene molar ratio =
0.47/1) for 2 hours at 90°C.
An ethylene polymer is obtained with a yield of 3.6 kg per gram of solid catalyst component, and having a density of 0.962 g/ml, an apparent density of 0.31 g/ml, an MFI (2.16 kg) of 3.72 and an MFR
of 27.9. The particle size distribution of the polymer in percentage per a range is as follows: >2000 = 0.7%; <2000 >1000 =
6.3%; ~Z000 >500 = 91%; <500 >250 = 1.3%; <250 >125 = 0.1%; <125 >63 = 0.5%; <63 = 0.1% by weight.
6.60 g (19.4 mmoles) of tetra n-butoxytitanium, 0.917 g (9.63 mmoles) of magnesium chloride and 100 ml of anhydrous n-heptane are fed under a nitrogen atmosphere into a 250 ml flask fitted .. 23 ~.
with a reflex condenser, mechanical stirrer and thermometer. The mixture is heated to reflex temperature for 1 hour to completely dissolve the magnesium chloride.
11.4 g of silica hot-activated by contact for 1 hour at 60°C with a solution containing 150 ml of anhydrous n-hexane and 13 ml of a 20 wt% solution of magnesium butyl octyl in n-heptane are introduced into the solution and left in contact for 1 hour under reflex conditions. The system is then evaporated to dryness by evaporating the solvent, to recover a granular solid.
0.966 g (10.1 mmoles) of anhydrous magnesium chloride dissolved in 250 ml of ethyl acetate dried over alumina are fed under a nitrogen atmosphere into a 500 ml flask fitted with a reflex condenser, mechanical stirrer and thermometer. The granular solid obtained as indicated above is added to 'the solution and the mass heated to 60°C for 1 hour. The solvent is then evaporated to obtain a granular solid. 10 g of the solid obtained in this manner are suspended in 60 m1 of anhydrous n-hexane and the suspension brought into oontact with 6.6 ml of a 49.5 wt% solution of aluminium ethyl sesquighloride (2.60 g, 10.6 mmoles)' in n-hexane. zt is left in contact for 15 minutes at a temperature of 25°C, after which the solid is recovered, washed, and then dried.
About 10 g of a catalyst component are obtained in the form of microspheroidal solid, containing 60% by weight of SiOz and having a Mg: Ti atomic ratio of 1.6:1 The solid catalyst component prepared in this manner is used in an ethylene polymerization test. The polymerization is conducted in a 5 litre pressure vessel containing 2 litres of n-hexane, ~~~~~v~~
- 2~ -operating at a pressure of 15 bar in the presence of hydrogen, with a ratio of hydrogen pressure to ethylene pressure of 0.47:1 at a temperature of 90°C for a time of 1.5 hours, using I50 mg of solid catalyst component and triethylaluminium as cocatalyst, with a molar ratio of triethylaluminium to titanium in the solid component of 100:1.
Polyethylene is obtained with a yield of 3.7 kg of polymer per gram of solid catalyst component, the polyethylene obtained having the following characteristics:
Density (ASTM D 1505): 0.9630 g/ml Apparent density (ASTM D 1895): 0.37 g/ml Melt flow index (ASTM D 1238; 2.16 kg): 3.7 g/10 min Melt flow ratio: 30.4 (Melt flow Index ~ MFI (21.6 kg)/MFI (2.16 kg) Particle size distribution (p):
>2000 0.9% by weight <2000 >1000 4,2 11000 >500 84,8 '~
<500 >250 g,4 <250 p, r~ n 6.60 g (19.4 mmoles) of tetra n-butoxytitanium, 0,917 g (9.63 mmoles) of magnesium chloride and 100 ml of anhydrous n-haptane are fed under a nitrogen atmosphere into a 250 ml flask fitted with a reflux condenser, mechanical stirrer and thermometer. The mixture is heated to reflux temperature for 1 hour to completely dissolve the magnesium chloride.
11.4 g of silica hot-activated by contact for 1 hour at 60°C with a solution containing 150 ml of anhydrous n-hexane and 13 ml of a 20 wt% solution of magnesium butyl octyl in n-heptane axe introduced into the solution and left in contact for 1 hour under reflux conditions. The system is then evaporated to dryness by evaporating the solvent, to recover a granular solid.
0.966 g (I0.1 mmoles) of anhydrous magnesium chloride dissolved in 250 ml of ethyl acetate dried over alumina are fed under a nitrog%n atmosphere into a 500 ml flask fitted with a reflux IO condenser, meohanical stirrer and thermometer. The granular solid obtained as indicated above and 9.O m1 (13.2 g; 77.8 mmoles) of silicon tetrachloride are added to the solution and the mass heated to 60°C for 1 hour. The solvent is then evaporated to obtain a granular solid. 10 g of the solid obtained in this I5 manner are suspended in 60 m1 o.f anhydrous n-hexane and the suspension brought into contact with 6.6 ml of a 49.5 wt% solution of aluminium ethyl sesquichloride (2.68 g, 10.8 mmoles) in n-hexane. It is left in contact for 1,5 minutes at a temperature of 25°C, after which the solid is recovered, washed, and then dried.
20 About 10 g of a catalyst component are ohtalned in the form of microspheroidal solid, containing 60% by weight of Si02 and having a Mg: Ti atomic ratio of 2.1:1.0 The solid catalyst component prepared in this manner is used in an ethylene polymerization test. The polymerization is conducted in 25 a 5 litre pressure vessel containing 2 litres of n-hexane, operating at a pressure of 15 bar in the presence of hydrogen, with a ratio of hydrogen pressure to ethylene pressure of 0.47:1 at a temperature of 90°C for a time of 2 hours, using 50 mg of solid catalyst component and triethylaluminium as cocatalyst, with a molar ratio of triethylaluminium to titanium in the solid component of 120:1.
Polyethylene is obtained with a yield of 17 kg of polymer per gram of solid catalyst component, the polyethylene obtained having the following characteristics:
Density (ASTM D 1505): 0.9596 g/ml Apparent density (ASTM D 1895); 0.32 g/ml Melt flow index (ASTM D 1238; 2.16 kg): 1.20 g/10 min Melt flow ratio: 33.7 (Melt flow index = MFI (21. 6 kg) /MFI (2 . 16 kg) Particle size distribution (~.) :
>2000 6.4% by weight <2000 >1000 70.6 "
<1000 > 500 21.6 "
< 500 > 250 0.9 "
<250 0.5 "
The solid catalyst component prepared as described in Example 15 is used in a further ethylene polymerization test. The polymerization is conducted in a 5 litre pressure vessel containing 2 litres of n-hexane, operating at a pressure of 15 bar in the presence of hydrogen, with a ratio of hydrogen pressure to ethylene pressure of 1.3:1 at a temperature of 90°C for a time of 2 hours, using 50 mg of solid catalyst component and triethylaluminium as cocatalyst, with a molar ratio of triethylaluminium to titanium in °
2~ ° ~~~~3~~~.~
the solid component of 120:1.
Polyethylene is obtained with a yield of 8.1 kg of polymer per gram of solid catalyst component, the polyethylene obtained having the following characteristics:
Density (ASTM D 1505): 0.9667 g/ml Apparent density (ASTM D 1895): 0.32 g/ml Melt flow index (ASTM D 1238; 2.16 kg): 12.95 g/10 man Melt flow ratio: 21.9 (Melt flow Index ~MF'I (21.6 kg)/MFI (2.16 kg) Particle size distribution (~):
>2000 1.3% by weight <2000 >1000 50.0 "
<1000 >500 44.2 "
<500 >250 3.6 °' <250 p,g
6.60 g (19.4 mmoles) of tetra n-butoxytitanium, 0.917 g (9.63 mmoles) of magnesium chloride and 100 ml of anhydrous n-heptane are fed under a nitrogen atmosphere into a 250 ml flask fitted .. 23 ~.
with a reflex condenser, mechanical stirrer and thermometer. The mixture is heated to reflex temperature for 1 hour to completely dissolve the magnesium chloride.
11.4 g of silica hot-activated by contact for 1 hour at 60°C with a solution containing 150 ml of anhydrous n-hexane and 13 ml of a 20 wt% solution of magnesium butyl octyl in n-heptane are introduced into the solution and left in contact for 1 hour under reflex conditions. The system is then evaporated to dryness by evaporating the solvent, to recover a granular solid.
0.966 g (10.1 mmoles) of anhydrous magnesium chloride dissolved in 250 ml of ethyl acetate dried over alumina are fed under a nitrogen atmosphere into a 500 ml flask fitted with a reflex condenser, mechanical stirrer and thermometer. The granular solid obtained as indicated above is added to 'the solution and the mass heated to 60°C for 1 hour. The solvent is then evaporated to obtain a granular solid. 10 g of the solid obtained in this manner are suspended in 60 m1 of anhydrous n-hexane and the suspension brought into oontact with 6.6 ml of a 49.5 wt% solution of aluminium ethyl sesquighloride (2.60 g, 10.6 mmoles)' in n-hexane. zt is left in contact for 15 minutes at a temperature of 25°C, after which the solid is recovered, washed, and then dried.
About 10 g of a catalyst component are obtained in the form of microspheroidal solid, containing 60% by weight of SiOz and having a Mg: Ti atomic ratio of 1.6:1 The solid catalyst component prepared in this manner is used in an ethylene polymerization test. The polymerization is conducted in a 5 litre pressure vessel containing 2 litres of n-hexane, ~~~~~v~~
- 2~ -operating at a pressure of 15 bar in the presence of hydrogen, with a ratio of hydrogen pressure to ethylene pressure of 0.47:1 at a temperature of 90°C for a time of 1.5 hours, using I50 mg of solid catalyst component and triethylaluminium as cocatalyst, with a molar ratio of triethylaluminium to titanium in the solid component of 100:1.
Polyethylene is obtained with a yield of 3.7 kg of polymer per gram of solid catalyst component, the polyethylene obtained having the following characteristics:
Density (ASTM D 1505): 0.9630 g/ml Apparent density (ASTM D 1895): 0.37 g/ml Melt flow index (ASTM D 1238; 2.16 kg): 3.7 g/10 min Melt flow ratio: 30.4 (Melt flow Index ~ MFI (21.6 kg)/MFI (2.16 kg) Particle size distribution (p):
>2000 0.9% by weight <2000 >1000 4,2 11000 >500 84,8 '~
<500 >250 g,4 <250 p, r~ n 6.60 g (19.4 mmoles) of tetra n-butoxytitanium, 0,917 g (9.63 mmoles) of magnesium chloride and 100 ml of anhydrous n-haptane are fed under a nitrogen atmosphere into a 250 ml flask fitted with a reflux condenser, mechanical stirrer and thermometer. The mixture is heated to reflux temperature for 1 hour to completely dissolve the magnesium chloride.
11.4 g of silica hot-activated by contact for 1 hour at 60°C with a solution containing 150 ml of anhydrous n-hexane and 13 ml of a 20 wt% solution of magnesium butyl octyl in n-heptane axe introduced into the solution and left in contact for 1 hour under reflux conditions. The system is then evaporated to dryness by evaporating the solvent, to recover a granular solid.
0.966 g (I0.1 mmoles) of anhydrous magnesium chloride dissolved in 250 ml of ethyl acetate dried over alumina are fed under a nitrog%n atmosphere into a 500 ml flask fitted with a reflux IO condenser, meohanical stirrer and thermometer. The granular solid obtained as indicated above and 9.O m1 (13.2 g; 77.8 mmoles) of silicon tetrachloride are added to the solution and the mass heated to 60°C for 1 hour. The solvent is then evaporated to obtain a granular solid. 10 g of the solid obtained in this I5 manner are suspended in 60 m1 o.f anhydrous n-hexane and the suspension brought into contact with 6.6 ml of a 49.5 wt% solution of aluminium ethyl sesquichloride (2.68 g, 10.8 mmoles) in n-hexane. It is left in contact for 1,5 minutes at a temperature of 25°C, after which the solid is recovered, washed, and then dried.
20 About 10 g of a catalyst component are ohtalned in the form of microspheroidal solid, containing 60% by weight of Si02 and having a Mg: Ti atomic ratio of 2.1:1.0 The solid catalyst component prepared in this manner is used in an ethylene polymerization test. The polymerization is conducted in 25 a 5 litre pressure vessel containing 2 litres of n-hexane, operating at a pressure of 15 bar in the presence of hydrogen, with a ratio of hydrogen pressure to ethylene pressure of 0.47:1 at a temperature of 90°C for a time of 2 hours, using 50 mg of solid catalyst component and triethylaluminium as cocatalyst, with a molar ratio of triethylaluminium to titanium in the solid component of 120:1.
Polyethylene is obtained with a yield of 17 kg of polymer per gram of solid catalyst component, the polyethylene obtained having the following characteristics:
Density (ASTM D 1505): 0.9596 g/ml Apparent density (ASTM D 1895); 0.32 g/ml Melt flow index (ASTM D 1238; 2.16 kg): 1.20 g/10 min Melt flow ratio: 33.7 (Melt flow index = MFI (21. 6 kg) /MFI (2 . 16 kg) Particle size distribution (~.) :
>2000 6.4% by weight <2000 >1000 70.6 "
<1000 > 500 21.6 "
< 500 > 250 0.9 "
<250 0.5 "
The solid catalyst component prepared as described in Example 15 is used in a further ethylene polymerization test. The polymerization is conducted in a 5 litre pressure vessel containing 2 litres of n-hexane, operating at a pressure of 15 bar in the presence of hydrogen, with a ratio of hydrogen pressure to ethylene pressure of 1.3:1 at a temperature of 90°C for a time of 2 hours, using 50 mg of solid catalyst component and triethylaluminium as cocatalyst, with a molar ratio of triethylaluminium to titanium in °
2~ ° ~~~~3~~~.~
the solid component of 120:1.
Polyethylene is obtained with a yield of 8.1 kg of polymer per gram of solid catalyst component, the polyethylene obtained having the following characteristics:
Density (ASTM D 1505): 0.9667 g/ml Apparent density (ASTM D 1895): 0.32 g/ml Melt flow index (ASTM D 1238; 2.16 kg): 12.95 g/10 man Melt flow ratio: 21.9 (Melt flow Index ~MF'I (21.6 kg)/MFI (2.16 kg) Particle size distribution (~):
>2000 1.3% by weight <2000 >1000 50.0 "
<1000 >500 44.2 "
<500 >250 3.6 °' <250 p,g
Claims (17)
1. A supported Ziegler-Natta catalyst active in ethylene polymerization and in the copolymerization of ethylene with alpha-olefins, consisting of:
(A) a cocatalyst in the form of an organometallic compound of aluminium, and (B) a solid catalyst component containing titanium, magnesium, chlorine and alkoxy groups on a support, with a molar ratio of titanium to magnesium of between 1:1 and 1:6 and a titanium content of between 1 and 9% by weight (expressed as metal), obtained by:
- (i) impregnating a granular porous solid support with a solution of magnesium chloride MgCl2 and a titanium tetraalcoholate Ti(OR)4 (where R is a linear or branched C1-C5 alkyl radical) in a molar ratio of between 0.1:1 and 0.5:1, in a liquid aliphatic hydrocarbon, followed by evaporation of the hydrocarbon solvent, in order to deposit on the support a complex of formula Ti(OR)4.(0.1-0.5)MgCl2;
- (ii) impregnating the support treated in (i) with a solution of magnesium chloride in a liquid aliphatic ester, followed by evaporation of the solvent, to obtain on completion of the operation the deposition on the support of a complex of formula Ti(OR)4.(1-6)MgCl2; and - (iii) activating the support treated in (ii) by contact with an alkyl aluminium chloride, operating at a temperature of between and 100°C for a time of between 10 minutes and 24 hours.
(A) a cocatalyst in the form of an organometallic compound of aluminium, and (B) a solid catalyst component containing titanium, magnesium, chlorine and alkoxy groups on a support, with a molar ratio of titanium to magnesium of between 1:1 and 1:6 and a titanium content of between 1 and 9% by weight (expressed as metal), obtained by:
- (i) impregnating a granular porous solid support with a solution of magnesium chloride MgCl2 and a titanium tetraalcoholate Ti(OR)4 (where R is a linear or branched C1-C5 alkyl radical) in a molar ratio of between 0.1:1 and 0.5:1, in a liquid aliphatic hydrocarbon, followed by evaporation of the hydrocarbon solvent, in order to deposit on the support a complex of formula Ti(OR)4.(0.1-0.5)MgCl2;
- (ii) impregnating the support treated in (i) with a solution of magnesium chloride in a liquid aliphatic ester, followed by evaporation of the solvent, to obtain on completion of the operation the deposition on the support of a complex of formula Ti(OR)4.(1-6)MgCl2; and - (iii) activating the support treated in (ii) by contact with an alkyl aluminium chloride, operating at a temperature of between and 100°C for a time of between 10 minutes and 24 hours.
2. A catalyst as claimed in claim 1, characterised in that said cocatalyst (A) is chosen from trialkylaluminiums, alkylaluminium hydrides and alkylaluminium halides containing from 1 to 5 carbon atoms in the alkyl portion, the molar ratio of aluminium in said cocatalyst (A) to titanium in the solid catalyst component (B) varying between 200:1 and 20:1.
3. A catalyst as claimed in claim 2, characterised in that said cocatalyst (A) is chosen from trialkylaluminiums with from 2 to 4 carbon atoms in the alkyl portion.
4. A catalyst as claimed in claim 1, characterised in that the support for the solid catalyst component (B) is chosen from granular, porous solids, chosen from olefinic and styrene polymers, the silica, alumina and said support constituting between 40 and 85% by weight.
5. A catalyst as claimed in claim 1, characterised in that said support is a microspheroidal silica support with a BET surface area of between 150 and 400 m2/g, a total porosity > 80% and a mean pore radius of between 50 and 200 .ANG., said silica being either unactivated, or activated by heating in an inert atmosphere to a temperature of between about 100°C and about 650°C for a time of between 1 and 20 hours, or activated by contact with an alkylmagnesium or an alkylaluminium.
6. A catalyst as claimed in claim 1, characterised in that in stage (i) the support is impregnated with a solution containing magnesium chloride and titanium tetraalcoholate Ti(OR)4 with a total concentration of these compounds of the order of 5-10% by weight, at a temperature of between 40 and 100°C, for a time of between 1 and 5 hours, to deposit on the support a titanium quantity, considered as metal, of between 2 and 10% by weight in the solid catalyst component finally obtained.
7. A catalyst as claimed in claim 6, characterised in that the solvent used is chosen from pentane, hexane and heptane, the titanium alcoholate being chosen from tetra n-propoxytitanium, tetra n-butoxytitanium, tetra i-propoxytitanium and tetra i-butoxytitanium.
8. A catalyst as claimed in claim 1, characterised in that stage (ii) uses a solution of magnesium chloride in a chlorinated or non-chlorinated methyl or ethyl ester of a lower aliphatic carboxylic acid chosen from ethyl formate, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate and ethyl chloroacetate, operating at a temperature of 50-75°C for a time of the order of 1-5 hours until obtaining on the support a complex of formula Ti(OR)4.(1-6)MgCl2, and a residual ester quantity of between 0 and 20%
by weight.
by weight.
9. A catalyst as claimed in claim 8, characterised in that stage (ii) is operated to obtain on the support a complex of formula Ti(OR)4.(1-3)MgCl2.
10. A catalyst as claimed in claim 1, characterised in that in stage (i) and/or (ii) a silicon halide chosen from silicon tetrahalides and halosilanes is additionally added in a quantity to obtain an atomic ratio of silicon to titanium of between 0.5:1 and 8:1.
11. A catalyst as claimed in claim 10, characterised in that the silicon halide is added in stage (ii) in a quantity to obtain a silicon:titanium atomic ratio of between 2.0:1 and 6.0:1.
12. A catalyst as claimed in claims 10 and 11, characterised in that said silicon halide is chosen from silicon tetrachloride; trichlorosilane, vinyl trichlorosilane, trichloroethoxy silane and chloroethyl trichlorosilane.
13. A catalyst as claimed in claim 1, characterised in that in stage (iii) the treated support from stage (ii) is brought into contact with a solution of an alkylaluminium chloride in an aliphatic hydrocarbon, with a ratio of chlorine atoms in the alkylaluminium chloride to alkoxy groups in the solid of between 0.5:1 and 7:1.
14. A catalyst as claimed in claim 13, characterised in that said alkylaluminium chloride is chosen from diethylaluminium chloride, ethylaluminium sesquichloride and isobutylaluminium chloride, operating at a temperature of between 20 and 90 ° C for a time of between 15 minutes and 2 hours.
15. A catalyst as claimed in claim 1, characterised in that the support in stage (i) is impregnated with a solution containing additionally a halide, alcoholate or haloalcoholate of zirconium or hafnium, the quantity of zirconium or hafnium compound used being such as to obtain a molar ratio of [Ti + Zr (or Hf)] to Mg of between 1:1 and 1:6 and a molar ratio of Ti to Zr (or Hf) of between 1:0.5 and 1:2.
16. A process for ethylene polymerization or for the copolymerization of ethylene with an alpha-olefin containing from 3 to 10 carbon atoms in the molecule, characterised by being conducted by the method of suspension in an inert diluent, or by the gaseous phase, fluidized bed or agitated method, at a temperature of between 50 and 110°C, a total pressure of between 5 and 40 bar, and a ratio of hydrogen partial pressure to ethylene partial pressure of between 0 and 10, in the presence of a catalyst claimed in any one of claims 1 to 15.
17. A process as claimed in claim 16, characterised in that the alpha-olefin contains from 4 to 6 carbon atoms in the molecule.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IT19698A IT1240611B (en) | 1990-03-16 | 1990-03-16 | Supported catalyst for the polymerization of ethylene and for the copolymerization of ethylene with alpha-olefins, its preparation and its use |
| IT21503A/90 | 1990-09-18 | ||
| IT19698A/90 | 1990-09-18 | ||
| IT02150390A IT1243720B (en) | 1990-09-18 | 1990-09-18 | Solid catalyst component for the (co)polymerisation of ethylene and process for the preparation thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2038330A1 CA2038330A1 (en) | 1991-09-17 |
| CA2038330C true CA2038330C (en) | 2002-01-15 |
Family
ID=26327265
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002038330A Expired - Lifetime CA2038330C (en) | 1990-03-16 | 1991-03-15 | Supported catalyst for ethylene polymerization and the copolymerization of ethylene with alpha-olefins, its preparation and use |
Country Status (15)
| Country | Link |
|---|---|
| US (1) | US5278117A (en) |
| EP (1) | EP0446989B1 (en) |
| JP (1) | JP3223301B2 (en) |
| AT (1) | ATE138392T1 (en) |
| BR (1) | BR9101045A (en) |
| CA (1) | CA2038330C (en) |
| CZ (1) | CZ281369B6 (en) |
| DE (1) | DE69119628T2 (en) |
| DK (1) | DK0446989T3 (en) |
| ES (1) | ES2088455T3 (en) |
| FI (1) | FI99207C (en) |
| GR (1) | GR3020578T3 (en) |
| HU (1) | HU212478B (en) |
| RU (1) | RU2022971C1 (en) |
| SK (1) | SK279445B6 (en) |
Families Citing this family (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT1252041B (en) * | 1990-10-11 | 1995-05-29 | Enimont Anic Srl | SOLID COMPONENT OF CATALYST FOR THE (CO) POLYMERIZATION OF ETHYLENE |
| FI89500C (en) * | 1991-12-31 | 1993-10-11 | Neste Oy | Procatalytic composition for homo- and copolymerization of alpha-olefins, its preparation and use |
| US5583083A (en) * | 1991-12-31 | 1996-12-10 | Neste Oy | Procatalyst composition for homo- and copolymerization of alpha olefins, its preparation and its use |
| US5661097A (en) * | 1994-08-12 | 1997-08-26 | The Dow Chemical Company | Supported olefin polymerization catalyst |
| EP0767183B1 (en) * | 1995-10-02 | 1998-11-18 | PCD Polymere AG | Supported catalyst for olefin polymerization |
| DE69600988T2 (en) * | 1995-10-02 | 1999-07-08 | Borealis Ag | Supported catalyst for olefin polymerization |
| EP0771820A1 (en) * | 1995-11-03 | 1997-05-07 | Union Carbide Chemicals & Plastics Technology Corporation | Supported ziegler-natta catalysts for polyolefin production |
| US6486089B1 (en) | 1995-11-09 | 2002-11-26 | Exxonmobil Oil Corporation | Bimetallic catalyst for ethylene polymerization reactions with uniform component distribution |
| US6417130B1 (en) | 1996-03-25 | 2002-07-09 | Exxonmobil Oil Corporation | One pot preparation of bimetallic catalysts for ethylene 1-olefin copolymerization |
| EP0912244A4 (en) | 1996-07-15 | 2001-09-12 | Mobil Oil Corp | Comonomer pretreated bimetallic catalyst for blow molding and film applications |
| CZ34998A3 (en) * | 1997-02-17 | 1999-08-11 | Pcd Polymere Gesellschaft M. B. H. | Process for preparing solid carrier for olefin polymerization catalysts |
| US6051525A (en) | 1997-07-14 | 2000-04-18 | Mobil Corporation | Catalyst for the manufacture of polyethylene with a broad or bimodal molecular weight distribution |
| US6153551A (en) | 1997-07-14 | 2000-11-28 | Mobil Oil Corporation | Preparation of supported catalyst using trialkylaluminum-metallocene contact products |
| KR20010089884A (en) | 1998-11-17 | 2001-10-12 | 우에하라 아끼라 | Suppositories |
| CA2465647C (en) * | 2001-11-30 | 2010-12-14 | Exxonmobil Chemical Patents, Inc. | Ethylene/alpha-olefin copolymer made with a non-single-site/single-site catalyst combination, its preparation and use |
| EA008985B1 (en) | 2003-11-14 | 2007-10-26 | Полимери Эуропа С.П.А. | Improved solid catalyst component and process for the (co) polymerization of ethylene |
| ITMI20032206A1 (en) * | 2003-11-14 | 2005-05-15 | Polimeri Europa Spa | IMPROVED CATALYST SOLID COMPONENT FOR (C0) POLYMERIZATION OF ETHYLENE AND THE CALLED USING PROCESS. |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| LU65587A1 (en) * | 1972-06-22 | 1973-12-27 | ||
| US4192772A (en) * | 1975-04-14 | 1980-03-11 | Solvay & Cie | Solid catalyst and process for the preparation thereof |
| DE2543181C2 (en) * | 1975-09-27 | 1986-08-28 | Basf Ag, 6700 Ludwigshafen | Process for the polymerisation of ethylene or of its copolymerisation with C 3 to C 1 0 α-monoolefins |
| US4383095A (en) * | 1979-02-16 | 1983-05-10 | Union Carbide Corporation | Process for the preparation of high density ethylene polymers in fluid bed reactor |
| US4359561A (en) * | 1979-06-18 | 1982-11-16 | Union Carbide Corporation | High tear strength polymers |
| US4379758A (en) * | 1980-12-24 | 1983-04-12 | Union Carbide Corporation | Catalyst composition for polymerizing ethylene |
| US4354009A (en) * | 1981-07-30 | 1982-10-12 | Union Carbide Corporation | Catalyst composition for copolymerizing ethylene |
| US4370456A (en) * | 1981-11-23 | 1983-01-25 | Union Carbide Corporation | Catalyst composition for copolymerizing ethylene |
| US4562168A (en) * | 1984-05-17 | 1985-12-31 | Phillips Petroleum Company | Catalyst and olefin polymerization |
| IT1203330B (en) * | 1987-02-06 | 1989-02-15 | Enichem Base Spa | Catalyst and catalyst component for the polymerization of ethylene or the co-polymerization of ethylene with alpha-Olefin |
| US5024982A (en) * | 1988-12-14 | 1991-06-18 | Phillips Petroleum Company | Silica-containing olefin polymerization catalysts and process |
-
1991
- 1991-03-06 AT AT91200481T patent/ATE138392T1/en not_active IP Right Cessation
- 1991-03-06 EP EP91200481A patent/EP0446989B1/en not_active Expired - Lifetime
- 1991-03-06 DE DE69119628T patent/DE69119628T2/en not_active Expired - Fee Related
- 1991-03-06 ES ES91200481T patent/ES2088455T3/en not_active Expired - Lifetime
- 1991-03-06 DK DK91200481.9T patent/DK0446989T3/en active
- 1991-03-08 US US07/666,587 patent/US5278117A/en not_active Expired - Lifetime
- 1991-03-13 CZ CS91655A patent/CZ281369B6/en not_active IP Right Cessation
- 1991-03-13 SK SK655-91A patent/SK279445B6/en not_active IP Right Cessation
- 1991-03-14 HU HU91850A patent/HU212478B/en not_active IP Right Cessation
- 1991-03-15 JP JP07581591A patent/JP3223301B2/en not_active Expired - Fee Related
- 1991-03-15 CA CA002038330A patent/CA2038330C/en not_active Expired - Lifetime
- 1991-03-15 BR BR919101045A patent/BR9101045A/en not_active IP Right Cessation
- 1991-03-15 RU SU914894955A patent/RU2022971C1/en active
- 1991-03-15 FI FI911299A patent/FI99207C/en active
-
1996
- 1996-07-18 GR GR960401935T patent/GR3020578T3/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| DE69119628T2 (en) | 1996-12-05 |
| JPH05140220A (en) | 1993-06-08 |
| FI99207B (en) | 1997-07-15 |
| FI911299A0 (en) | 1991-03-15 |
| HU910850D0 (en) | 1991-09-30 |
| EP0446989A2 (en) | 1991-09-18 |
| SK279445B6 (en) | 1998-11-04 |
| RU2022971C1 (en) | 1994-11-15 |
| EP0446989B1 (en) | 1996-05-22 |
| HUT60295A (en) | 1992-08-28 |
| GR3020578T3 (en) | 1996-10-31 |
| FI99207C (en) | 1997-10-27 |
| US5278117A (en) | 1994-01-11 |
| DE69119628D1 (en) | 1996-06-27 |
| HU212478B (en) | 1996-07-29 |
| CA2038330A1 (en) | 1991-09-17 |
| DK0446989T3 (en) | 1996-09-16 |
| EP0446989A3 (en) | 1992-03-11 |
| CZ281369B6 (en) | 1996-09-11 |
| ATE138392T1 (en) | 1996-06-15 |
| FI911299A (en) | 1991-09-17 |
| BR9101045A (en) | 1991-11-05 |
| CS9100655A2 (en) | 1991-10-15 |
| ES2088455T3 (en) | 1996-08-16 |
| JP3223301B2 (en) | 2001-10-29 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed | ||
| MKEC | Expiry (correction) |
Effective date: 20121202 |