Magnesium dichloride-alcohol adducts and catalyst components obtained therefrom

Abstract

Solid adducts comprising MgCl.sub.2, ethanol and water characterized in that the amount of ethanol ranges from 50% to less than 57% by weight, the amount of water is ranges from 0.5 to 5% by weight, the ethanol/water weight ratio is lower than 60 and the porosity determined with Hg method due to pores with radius up to 1 m and expressed in cm.sup.3/g, is lower than 0.2.

Claims

1. A catalyst precursor comprising a solid adduct comprising MgCl.sub.2, ethanol and water, wherein the amount of ethanol ranges from 52-55% by weight, with respect to the adduct, the amount of water ranges from 0.5-5% by weight, with respect to the adduct, the ethanol/water weight ratio is less than 60 and the porosity of the adduct determined with the Hg method due to pores with radii up to 1 m and expressed in cm.sup.3/g, is lower than 0.1; wherein the catalytic precursor has a main melting temperature peak of about 971 C. and a highest temperature peak of less than 108 C. as determined using differential scanning calorimetry (DSC).

2. A catalyst component comprising the catalyst precursor of claim 1, wherein the catalyst component is obtained by reacting the catalyst precursor with a transition metal compound of one of the groups IV to VI of the Periodic Table of Elements.

3. The catalyst component of claim 2, wherein the component is reacted with an Al-alkyl compound, optionally in the presence of an external electron donor compound.

4. The catalyst component of claim 3, wherein the Al-alkyl compound is triethylaluminum.

5. The catalyst component of claim 3, wherein the external electron donor compound is cyclohexylmethyldimethoxysilane.

Description

EXAMPLES

(1) General Procedure for the Preparation of the Catalyst Component for Propylene Polymerization

(2) Into a 11 steel reactor provided with stirrer, 800 cm.sup.3 of TiCl.sub.4 at 0 C. were introduced; at room temperature and whilst stirring 24 g of the adduct were introduced together with an amount of diisobutylphthalate as internal donor so as to give a donor/Mg molar ratio of 8. The whole was heated to 100 C. over 90 minutes and these conditions were maintained over 60 minutes. The stirring was stopped and after 30 minutes the liquid phase was separated from the sedimented solid maintaining the temperature at 100 C. A further treatment of the solid was carried out adding 750 cm3 of TiCl.sub.4 and heating the mixture at 110 C. over 10 min. and maintaining said conditions for 30 min under stirring conditions (500 rpm). The stirring was then discontinued and after 30 minutes the liquid phase was separated from the sedimented solid maintaining the temperature at 110 C. A further treatment of the solid was carried out adding 750 cm.sup.3 of TiCl.sub.4 and heating the mixture at 120 C. over 10 min. and maintaining said conditions for 30 min under stirring conditions (500 rpm). The stirring was then discontinued and after 30 minutes the liquid phase was separated from the sedimented solid maintaining the temperature at 120 C. A further treatment of the solid was carried out adding 750 cm.sup.3 of TiCl.sub.4 and heating the mixture at 120 C. over 10 min. and maintaining said conditions for 30 min under stirring conditions (500 rpm). The stirring was then discontinued and after 30 minutes the liquid phase was separated from the sedimented solid maintaining the temperature at 120 C. Thereafter, 3 washings with 500 cm.sup.3 of anhydrous hexane at 60 C. and 3 washings with 500 cm.sup.3 of anhydrous hexane at room temperature were carried out. The solid catalyst component obtained was then dried under vacuum in nitrogen environment at a temperature ranging from 40-45 C. General procedure for the preparation of the catalyst component for ethylene polymerization

(3) Into a 2L four-necked round flask, purged with nitrogen, 1 L of TiCl.sub.4 was introduced at 0 C. Then, at the same temperature, 70 g of a spherical MgCl.sub.2/EtOH adduct obtained by dealcoholating the adduct of the invention up to 23% wt of ethanol, were added under stirring. The temperature was raised to 130 C. in 1 h and maintained for 60 min. Then, the stirring was discontinued, the solid product was allowed to settle (at the same temperature) and then, the supernatant liquid was siphoned off. A new volume of fresh TiCl.sub.4 was added into the glass reactor in order to have the same solid concentration as in the first treatment. The temperature was then raised to 110 C. and maintained for 15. After the stop of stirring and the solid settling (at the same temperature), the product was washed 5 times with anhydrous hexane (51L) at 50 C. and two times at room temperature. Then, a volume of anhydrous hexane was added into the reactor in order to have (once more) 1 L of total liquid. Under stirring, the temperature was raised to 50 C. and an amount of ethyl acetate corresponding to a molar ratio Mg/Acetate of 1.5 was added drop-wise. The temperature was kept at 50 C. and the mixture was stirred for 2 hours. Then, the stirring was discontinued, the solid product was allowed to settle and the supernatant liquid was siphoned off The solid was washed 2 times with anhydrous hexane (21 L) at 25 C., recovered, dried under vacuum and analyzed.

(4) Fraction soluble in xylene. (XS) The solubility in xylene at 25 C. was determined according to the following method: About 2.5 g of polymer and 250 ml of o-xylene were placed in a round-bottomed flask provided with cooler and a reflux condenser and kept under nitrogen. The mixture obtained was heated to 135 C. and was kept under stirring for about 60 minutes. The final solution was allowed to cool to 25 C. under continuous stirring, and was then filtered. The filtrate was then evaporated in a nitrogen flow at 140 C. to reach a constant weight. The content of said xylene-soluble fraction is expressed as a percentage of the original 2.5 grams. The xylene insoluble fraction is given by the expression 100-XS.

(5) General Procedure for the Propylene Polymerization Test

(6) A 4 liter steel autoclave equipped with a stirrer, pressure gauge, thermometer, catalyst feeding system, monomer feeding lines and thermostatting jacket, was used. The reactor was charged with 0.01 gr. of solid catalyst component 0.76 g of TEAL, 0.076 g of cyclohexylmethyldimetoxy silane, 3.2 l of propylene, and 2.0 l of hydrogen. The system was heated to 70 C. over 10 min. under stirring, and maintained under these conditions for 120 min. At the end of the polymerization, the polymer was recovered by removing any unreacted monomers and was dried under vacuum.

(7) General Procedure for Ethylene Polymerization Test.

(8) A 4.5 liter stainless-steel autoclave equipped with a magnetic stirrer, temperature and pressure indicator, feeding line for hexane, ethylene, and hydrogen, was used and purified by fluxing pure nitrogen at 70 C. for 60 minutes. Then, a solution of 1550 cm3 of hexane containing 4 cm3 of 10% by wt/vol TEAL/hexane was introduced at a temperature of 30 C. under nitrogen flow. In a separate 200 cm3 round bottom glass bottle were successively introduced, 50 cm3 of anhydrous hexane, 1 cm3 of 10% by wt/vol, TEAL/hexane solution and 0.020+0.025 g of the solid catalyst of table 1. They were mixed together, aged 10 minutes at room temperature and introduced under nitrogen flow into the reactor. The autoclave was closed, then the temperature was raised to 75 C., hydrogen (4 bars partial pressure) and ethylene (7.0 bars partial pressure) were added. Under continuous stirring, the total pressure was maintained at 75 C. for 120 minutes by feeding ethylene. At the end the reactor was depressurised and the temperature was dropped to 30 C. The recovered polymer was dried at 70 C. under a nitrogen flow and analyzed. The obtained results are reported in table 2.

Example 1

(9) In a reactor containing 51.2 kg of anhydrous EtOH and 1.1 kg of water at room temperature were introduced under stirring 39.9 kg of MgCl.sub.2. Once the addition of MgCl.sub.2 was completed, the temperature was raised up to 125 C. and kept at this value for 12 hours. After that, the melt was continuously fed to a stirred emulsification unit and mixed with OB55 vaseline oil, while stirring was brought to 1100 rpm and keeping the temperature at 128 C. The mixture was discharged into a vessel containing hexane which was kept under stirring and cooled at the temperature of 10 C. After 12 hours, the solid particles of the MgCl.sub.2EtOH adduct recovered were then washed with hexane and dried at 40 C. flash dryer. The compositional analysis showed that the support contained 54.4% by weight of EtOH and 1.35% of water (EtOH/water weight ratio 40). The porosity of said adduct was 0.075 cm.sup.3/g. The DSC profile showed the main peak at 98.1 C. with total associated fusion enthalpy of 97.1 J/g.

Example 2

(10) In a vessel reactor containing 838 g of anhydrous EtOH containing 15 g of water at room temperature were introduced under stirring 673 g of MgCl.sub.2. Once the addition of MgCl.sub.2 was completed, the temperature was raised up to 125 C. and kept at this value for 7 hours. After that, the melt was continuously fed to a stirred emulsification unit, mixed with 5600 cm.sup.3 OB55 vaseline oil, while the stirring was brought to 2800 rpm and kept at that value for ten minutes, keeping the temperature at 130 C. Subsequently, the mixture was discharged into a vessel containing hexane which was kept under stirring and cooled so that the final temperature did not exceed 2 C. After 12 hours, the solid particles of the MgCl.sub.2EtOH adduct recovered were then washed with hexane and dried at 40 C. under vacuum. The compositional analysis showed that they contained 53% by weight of EtOH and 1.65% of water (EtOH/water weight ratio 32). The porosity of said adduct was 0.088 cm.sup.3/g. The DSC profile showed the main peak at 97.85 C. and the highest temperature peak at 103.6 C. with total associated fusion enthalpy of 109.1 J/g. The support was then dealcoholated in a fluidised bed obtaining a dealcoholated support having 22.8% ethanol and 2.5% of water. A catalyst for ethylene polymerization was prepared and tested according to the general methods and the results are reported in table 2.

Example 3

(11) An adduct was prepared according to the procedure of Example 2 with the difference that 15 g of additional water were introduced. The compositional analysis showed that the adduct contained 52% by weight of EtOH and 2.6% of water (EtOH/water weight ratio 20). The porosity of said adduct was 0.082 cm.sup.3/g. The DSC profile showed the main peak at 97.5 C. with total associated fusion enthalpy of 103.2 J/g. The support was then dealcoholated in a fluidised bed obtaining a dealcoholated support having 21% ethanol and 4.3% of water. The catalyst component for ethylene polymerization was prepared and tested according to the general methods and the results are reported in table 2.

Comparison Example 1

(12) The procedure of Example 2 was repeated with the difference that 886 g of anhydrous EtOH at room temperature were used, while 633 g of MgCl2 were introduced under stirring. The compositional analysis showed that the adduct contained 58.2% by weight of EtOH and 0.6% of water (EtOH/water ratio 97). The support was then dealcoholated in a fluidised bed obtaining a dealcoholated support having 22.3% ethanol and 0.8% of water. The catalyst component for ethylene polymerization was prepared and tested according to the general methods and the results are reported in table 2.

(13) TABLE-US-00001 TABLE 1 Propylene Polymerization Activity XI Bulk Density Example Kg/g % cm.sup.3/g 1 68.8 98.0 0.470

(14) TABLE-US-00002 TABLE 2 Ethylene Polymerization Activity Melt Bulk Density Example Cocatalyst Kg/g Index E cm.sup.3/g 2 Teal 8.7 1.1 0.395 3 Teal 9 0.63 0.387 Comp. 1 Teal 7 0.53 0.351