FI89928C - FOERFARANDE FOER FRAMSTAELLNING AV EN FAST PROKATALYSATORKOMPOSITION TILLETT KATALYSATORSYSTEM AVSETT FOER POLYMERISATION AV OLEFINER OCH EN PROKATALYSATORKOMPOSITION FRAMSTAELLD MEDELST FOERFARANDET - Google Patents

Description

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A process for preparing a solid procatalyst composition for a catalyst system for the polymerization of olefins, and a procatalyst composition prepared by the process

The invention relates to a process for preparing a solid procatalyst composition for a catalyst system for the polymerization of olefins. The invention also relates to a procatalyst composition prepared by such a process and its use. 15

A "Ziegler-Natta" catalyst system consisting of a procatalyst and a cocatalyst is commonly used for the polymerization of olefins. The procatalyst is based on one of the transition metal compounds of Groups IVB-VIII of the Periodic Table of the Elements and the cocatalyst is based on an organometallic compound of a metal of Groups IA-IIIA of the Periodic Table of the Elements. The catalyst system generally also includes electron donor compounds that improve and modify catalytic properties.

In the preparation of heterogeneous polymerization catalysts, it is customary to use a support compound on which the transition metal compound is deposited as a component for improving the polymerization activity of the procatalysts. Common support compounds include silica, alumina, magnesium oxide, titanium oxide, carbon in various forms, and various types of polymers. Magnesium compounds such as alkoxides, hydroxides, hydroxy-halides and halides, of which the latter, in particular magnesium dichloride, have recently become the most important carrier components of procatalyst compositions, have proven to be important support compounds.

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Since magnesium halides in their basic crystal form are not activated optimally efficiently by the transition metal compound, their crystal structure must be deformed. Traditionally, this is done by grinding, e.g. in a ball mill, which results in a fine powder with a high specific surface area, the crystal lattices of the particles of which are strongly deformed. When such a powder is activated to a procatalyst composition by deposition with a transition metal compound, and then reduced with an organometallic compound acting as a cocatalyst, a highly active polymerization catalyst is obtained. However, the conventional magnesium halide grinding method has the disadvantage that it consumes a great deal of energy, causes wear and corrosion of the equipment, and is only suitable for the preparation of a catalyst by a laborious batch process.

The crystallinity of magnesium halides has also been reduced by chemical modification. In this case, the magnesium halide, the electron donor and the transition metal compound are reacted with each other, often in solution, to form easily isolated procatalyst compositions. As the electron donors dissolving magnesium halides, for example, alcohols and aliphatic alkyl esters can be mentioned.

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The chemical modification can be performed in the presence of an inert support, whereby a low-crystalline magnesium halide and an associated transition metal compound are deposited on the inert support. In this case, the irregular structure of the inert carrier compound prevents the crystallization of the magnesium halide, whereby the magnesium halide has a very high ability to be activated by the transition metal compound.

This latter category includes GB-2 028 347, 35 which discloses a carrier mixture for carrying a Ziegler catalyst for olefin polymerization comprising a substantially inert, inorganic or organic first component (A) and a magnesium chloride component (3 3 ') 9 2 3 tin (B ) deposited on component (A) from a solution of a solvent which has been substantially removed by evaporation. The patent also relates to a process for preparing a catalyst support mixture on which a Ziegler catalyst for the polymerization of ole-5-fines is supported by impregnating a substantially inert inorganic or organic first component (A) with a solution of magnesium chloride and a solvent and then removing the solvent by evaporation.

The protection defined by 10 GB also applies to the incorporation of such a carrier mixture into a transition metal compound and an organometallic cocatalyst and, of course, to homo or copolymerization processes and products obtained using such a carrier. The publication thus protects all catalyst systems in which the substantially inert inorganic component is impregnated with a solution of magnesium chloride and dried by removing the solvent. The substantially inert inorganic component may be based on alumina, aluminosilicate, silica, magnesium oxide, magnesium carbonate, magnesium hydroxide, silica-aluminum, zeolite or a porous organic support. The carrier can and is rendered inert in all working examples by calcination before use. It can be seen from Examples 1, 3 and 4 that when alumina and silica-alumina are used, they are always calcined before use. These inorganic compounds are known to have reactive hydroxyl groups which are removed only at high calcination temperatures.

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Said GB patent publication therefore relates to a process which begins with a long, energy-consuming and expensive calcination step, if inorganic compounds or mixtures of silicon or aluminum are used as carrier.

U.S. Patent No. 4,467,044 discloses a catalyst component for the polymerization of olefins comprising a silicon-containing support having a magnesium halide and / or manganese halide, a transition metal halide and an electron donor, prepared by the following steps: silica complexed with an alcohol halide and / or manganese halide to form a support, b) reacting the support with an organometallic compound of a metal of groups I-III of the Periodic Table to form an intermediate, c) reacting the intermediate with an electron donor to form an intermediate complex, and reacting the intermediate complex with a liquid comprising a transition metal halide.

No attention has been paid in this publication to whether or not the silica used is inert. Instead, the preparation-20 process is very complex and involves both treatment with an organometallic compound to remove the alcohol and treatment with a separate electron donor11a to form an intermediate complex.

EP-A-296 561 relates to a process for the preparation of a catalyst which a) impregnates a highly porous support consisting of at least 90% by weight of alumina with an internal porosity of at least 0.5 ml / g and wherein said support is calcined at a temperature in the range of 100-1000 ° C, boiled with an alcoholic solution of magnesium chloride to an initial moisture content, b) dried in an inert atmosphere at a temperature between 80-230 ° C, c) treating said dry carrier with a corrosive agent comprising a halide or organometallic compound capable of removing residual alcohol, and d) treating said support with a transition metal compound selected from titanium halides and haloalkoxides.

5 ./ y t 3 It is thus apparent from this publication that, at the beginning of the manufacturing process, the alumina support is calcined inert by heating to a temperature of 100-1000 ° C. Thus, the production process according to said EP application publication, which is based on alumina, requires a long and energy-consuming calcination step before impregnation, removal of alcohol and treatment of the transition metal compound.

It is an object of the present invention to provide a process in which an inorganic support is treated with an alcoholic solution of magnesium halide so that a separate thermal and / or chemical pretreatment of the inorganic support is not required. The invention also seeks to simplify the further processing of the impregnated support prior to its activation with the transition metal compound. These objects have now been achieved by a new process for preparing a solid procatalyst composition for a catalyst system for the polymerization of olefins, which is mainly characterized by the steps set out in the characterizing part of claim 1.

Thus, it has been found that prior art methods of the type mentioned above can be decisively simplified by first contacting hydroxyl-containing silica, magnesium halide and alcohol with each other and drying the mixture thus obtained. The dried mixture is then treated with an alcohol-reactive compound, and finally the treated mixture is reacted with a transition metal compound.

Any hydroxyl-containing silica can be used as a carrier in the invention, but since the untreated silica already contains hydroxyl groups, its use is most preferred. The use of untreated silica saves on additional calcination and / or reaction steps to remove hydroxyl groups.

35

The magnesium halide is preferably magnesium dichloride and most preferably dry magnesium dichloride. This component, which is deposited on hydroxyl-containing silica, is a natural choice of 6,39923, as it is known to be effectively activated by a transition metal compound.

The alcohol used in the first step of the process is preferably a C1-C6 aliphatic alcohol, more preferably n- or i-propanol. The alcohol used is required to form a solution or slurry with the magnesium halide which is absorbed by the hydroxyl-containing silica. It is also preferred that the alcohol form a complex with the magnesium halo-10 genide which is better suited for activating the coated silica particles with a transition metal compound.

In the first step a) of the present invention, the hydroxyl-containing silica, magnesium halide and alcohol are contacted with each other.

In one embodiment, this is accomplished by adding the alcohol to a dry mixture of hydroxyl-containing silica and magnesium halide and stirring and heating the mixture.

According to another embodiment, step a) is performed by dissolving the magnesium halide in alcohol and passing the resulting solution onto hydroxyl-containing silica. According to a third embodiment, the solid complex of magnesium halide and alcohol 25 is melted into a liquid, which is then absorbed into hydroxide-containing silica.

Step a) is preferably carried out with a weight ratio of SiO 2 / MgCl 2 of about 2.5 and a molar ratio of ROH / MgCl 2 of between 1-4, preferably between 2-3. Step a) generally lasts 1 to 10 hours, preferably 1 hour, and has a temperature of generally about 20 to 100 ° C, preferably 80 to 95 ° C.

At the end of step a), a solvent such as a hydrocarbon may be added to the mixture prior to drying. Drying at the end of the step is preferably continued until about 9-15% by weight of the original amount of alcohol remains.

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In the next step b), the dried mixture obtained from step a) is treated with an alcohol-reactive compound. In order that the reaction is not too violent, the support can be cooled to, for example, 0 ° C or the alcohol-reactive compound can be added gradually. The alcohol-reactive compound is preferably aluminum alkyl, aluminum alkyl chloride, other metal alkyl or silicon chloride, alkyl chloride or alkylsilazane. The most preferred alcohol-reactive compound is trialkylaluminum, especially triethylaluminum. In particular, organometallic compounds have the advantage that they can be used stoichiometrically with respect to alcohol and that the resulting catalyst composition has good hydrogen sensitivity.

The molar ratio of step b) between the alcohol-reactive substance and the alcohol is preferably 0.5 to 1.0, in particular about 0.7. The reaction of the alcohol generally takes 0.5 to 2 hours and the temperature is generally about 30 to 50 ° C.

After the treatment, either the solvent is removed simply by evaporation, so that no harmful waste is generated but the solvent can be reused, or the mixture is left in the same solution. After the alcohol reaction step b), only a small amount of the transition metal compound is needed to convert the catalyst to the active catalyst.

Finally, the dried mixture treated with the alcohol-reactive compound is reacted with the transition metal compound in step c). The transition metal compound is a titanium halide such as titanium tetrachloride, or a titanium alkoxy halide such as Ti (OEt) Cl3, Ti (OEt) 2Cl2, Ti (OEt) 3Cl, Ti (i-OPr) Cl3 or a mixture thereof, preferably titanium tetrachloride. In this case, the molar ratio Mg / Ti is between 1 and 10: 1. Activation step c) generally takes about 0.5-8 h and its temperature is generally about 35-100 ° C.

In all steps of the method according to the present invention, i.e. steps a), b) and / or c), 8! 9,928 uses a solvent such as a liquid hydrocarbon as the medium. The preparation of the procatalyst composition thus carried out does not necessarily require washing or siphoning steps. For this reason, the method is very simple and economical.

5

In addition to the new process, the invention relates to a novel procatalyst composition for a catalyst system for the polymerization of olefins. The procatalyst composition is mainly characterized by what is said in the characterizing part of independent product claim 10. The procatalyst composition is further characterized in that it contains 3 to 7% by weight of magnesium, 2 to 6% by weight of titanium and about 3 to 4% by weight of aluminum.

The invention also relates to the use of a procatalyst composition prepared by the above-mentioned process together with an organoaluminum compound acting as a cocatalyst for polymerizing olefins. Typical cocatalysts of the Ziegler-Natta catalyst system, such as trialkylalumines, alkylaluminum halides and alkylaluminum sesquihalides, can then be used as cocatalysts.

The method and product of the present invention have e.g. the following advantages: a) the procatalyst composition is supported on untreated silica, b) the silica can be impregnated with a complex of magnesium dichloride and aliphatic alcohol with a preferred molar ratio of ROH / -

MgCl 2 is at least 2-3, whereby the complex can be absorbed either as a hydrocarbon solution, an alcoholic solution or as such as a melt, 35 c) the alcohol can be treated stoichiometrically or with a small excess of a reactant, preferably aluminum alkyl,

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9 'yyl 3 d) activation with a transition metal compound requires a very small excess of transition metal compound (especially for titanium tetrachloride), i.e. the cost of the expensive transition metal compound is low, 5 e) the preparation can be carried out without washing or siphoning steps, f) by combining 10 organoaluminum compounds, such as aluminum alkyl, and when used together to make homopolymers or copolymers of ethylene, the following advantages are obtained by a very simple method of preparing the catalyst: i) high activity ii) controlled morphology iii) good hydrogen resistance specifically for high melt index HDPE grades.

The following are a few embodiments which are intended solely to illustrate the present invention.

25 EXAMPLES

Example 1 1.0 g of substantially untreated silica (Davison 955) and 0.4 g of anhydrous MgCl 2 (4 mmol) are weighed into a septum flask 30 and nitrogenated. To the flask is added 1.2 mL of i-PrOH (16 mmol) and heated to 80 ° C for 1.5 h, 10 mL of dry n-heptane is added and stirred for 2 h. Finally, the absorbed support is dried by evaporating the solvents. The resulting support contains Mg 6.4% and i-PrOH 13.6%. 35 It is slurried in 10 ml of heptane, 2.6 ml of a 10% solution of TEA (triethylaluminum) (TEA 1.4 mmol, TEA / i-PrOH = 0.7) are added and the mixture is stirred for 1 hour at 40 ° C. The slurry is cooled to room temperature and 0.06 ml of TiCl 4: 39923 ίο (0.5 mmol) is added, stirred for half an hour at 60 ° C. Finally, the product obtained is dried to give 1.1 g of a catalyst composition with Mg 4.3%, Ti 5.0% and Al 3.3%.

Example 2 1.0 g of silica (Davison 955), 0.4 g of anhydrous MgCl 3 and 1.2 ml of n-PrOH are weighed in room air into a septum flask, 10 ml of heptane are added and stirred for 90 minutes at 80 ° C. The resulting mixture is then dried under a stream of nitrogen at a temperature of 80 ° C. The resulting impregnated support is slurried in 10 ml of heptane, 2.1 ml of 10% TEA solution are added and heated at 40 ° C. Next, 0.05 ml of TiCl4 is added to the solution, and finally dried at 100 ° C. 0.77 g of procatalyst composition with Mg 3.7%, Ti 2.8% and Al 3.4% are obtained.

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Example 3

First prepare the impregnated support separately as follows: 25 g of silica (Davison 955) and 10 g of anhydrous MgCl3 are weighed in air into a 500 ml flask. A total of 350 ml of i-PrOH is added and the mixture is heated at 80-95 ° C for 8 hours. Allow to stir overnight, and dry the next day for approx.

At a temperature of 100 ° C.

1.0 g of the impregnated carrier 25 prepared as described above (incl. Mg 6.4% and i-PrOH 13.5%) are slurried in 10 ml of heptane in a septum flask. The mixture is reacted with 2.8 ml of 10% TEA solution for 1.5 hours at 40-50 ° C. Finally, 0.06 ml of TiCl4 are added to the solution, stirred for one hour at 70 ° C and dried at a temperature of about 100 ° C under a stream of nitrogen. 0.95 g of a procatalyst composition with Mg 5.7%, Ti 2.7% and Al 3.4% is obtained.

Testipolvmerointi

The test polymerization of ethylene was carried out on the examples as follows: 1.8 l of isobutane purified with oxygen and dehumidifiers were charged to a 3 l autoclave. 20-50 mg of the procatalyst composition was fed to the reactor together with aluminum alkyl (TEA, Al / Ti = 25-75). Heat-

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The 9 v 2 3 11 state was raised to 95 ° C. A 0.5 l volume pressure vessel, i.e. a bomb, was pressurized to 5 bar with hydrogen and fed to the reactor together with ethylene until the total pressure was 28 bar. The polymerization was carried out for one hour and the total pressure was kept constant by means of an ethylene feed.

Polvmerointitulokset

The polymerization results of the catalyst components according to the above examples are shown in Table 1.

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Table 1 Polymerization results

E.g. cat. Yield Act. MI (21.6) MFR BD

15 _mg g PE_g / g cat g / g Ti _ 1 28 307 10 964 219 000 30.6 30.4 0.38 2 35 316 9 057 322 000 46.2 30.8 0.38 20 3 28 286 10 214 378,000 57.8 32.1 0.37 MI = melt index, ASTM D 1238, condition 190 ° C / 21.6 kg MFR = melt flow ratio, melt index 21.6 kg and 2.16 kg 25 BD = bulk density , g / ml

The comparative example compared eo. the invention and U.S. Patent 4,467,044. 3.3 g of MgCl 2 and 30 ml of anhydrous ethanol were mixed together in a three-way flask equipped with a stirrer at room temperature. The mixture was transferred to another flask containing 4.0 g of silica (Davison 955). The mixture was dried under a stream of nitrogen first at room temperature and then with heat (90 ° C). 13.8 g of carrier were obtained, which by analysis contained Mg 4.6% by weight and EtOH 52.2%. This corresponds to an ethanol i: MgCl 2 ratio of 6.7: 1.

3.55 g of this support was added to a three-necked flask equipped with a stirrer and 30 ml of heptane was added under inert conditions 39923 12, i.e. using a nitrogen atmosphere and dried solvents. The mixture was heated to 100 ° C and 30 ml of a 25% solution of TEA in heptane was added. There was a strong gas evolution. Stirred for 2 hours and cooled to 20 ° C. The solution was siphoned off and the product was washed 4 times with 15 ml of heptane. After drying, 1.7 g of intermediate were obtained.

1.0 g of this intermediate was slurried in a 3-necked flask in 10 mL of heptane, followed by the addition of 16 mL of TiCl 4. Heated to 100 ° C for 2 hours. The dark burgundy product was cooled and washed 4 times with 15 ml of heptane. The solvent was siphoned off and dried. 1.8 g of product were obtained with Mg 4.9%, Ti 14.1% and Cl 54.5%.

The test polymerization under the conditions of the application (IBU 271) gave an activity of 3.2 kg PE / g cat, an MI (21.6) of 7.0 and an MFR (21/2) of 41.6 and a bulk density of 260.

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Tables 2 and 3 compare the production method, metal contents and polymerization result of this catalyst with the results of Example 1 of the invention.

25 Table 2

Comparison of manufacturing methods between the invention and US 4,467,044

Invention US-4,467,044 30 Weight ratio SiO 2 / MgCl 2 2.5 1.2

Molar ratio R0H / MgCl2 2-3 n. 6

Molar ratio TEA / ROH 0.7 0.8

Weight ratio TiCl4 / MgCl2 approx. 0.25 approx. 43 35 It can be seen from the table that in the comparative example presented MgCl2 is used almost as much as silica. Since the function of silica is to act as a support on which MgCl2 is deposited, the use of excess results in a large proportion of

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'' · 'Γ \ Γ.

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Silica does not bind to MgCl2. Using the ratio of the invention, MgCl 2 binds to silica. Further, alcohol is used much more in the comparative example. In this case, the amount of TEA required increases because the molar ratio TEA / ROH is approximately the same in both cases. A significant difference is in titanation: the invention uses such a small amount of TiCl4 that everything binds to the catalyst and not the laundry car Vita. In the comparative example, a considerable excess is used, requiring excess removal and washing steps. In this case, problematic catalyst waste is also produced, which would cause problems, especially in industrial production.

Table 3

Metal concentrations and polymerization results for Examples 1 and 15 for Comparative Example (US-4,467,044)

Pat.julk. Mg Ti Cl Active MI (21) MFR BD

mouth FI 905430/1 4.3 5.0 27.7 10.96 30.6 30.4 0.38 20 US 4,467,044 4.9 14.1 54.8 3.2 7.0 41.6 0 , 26

It is clear from the results that the the comparative example in no way corresponds to the catalyst of our invention in composition and not in performance.

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Claims (22)

A process for the preparation of a solid procatalyst composition in a catalyst system intended for polymerization of olefins, characterized by the steps of: after the mixture is dried, b) the dried mixture is treated with a compound which reacts with the alcohol, and c) the treated mixture is reacted with a titanium compound, the molar ratio Mg / Ti being between 1: 1 - 10: 1. Process according to claim 1, characterized in that the hydroxyl-containing silica is substantially untreated silica. Process according to claim 1 or 2, characterized in that the magnesium halide is magnesium dichloride, preferably dry magnesium dichloride. 20 4. A process according to claim 1, 2 or 3, characterized in that the alcohol is an aliphatic CC-Cg alcohol, preferably n-propanol. . 25 Process according to any of the preceding patent claims, characterized in that step a) is carried out by adding the alcohol to a dry mixture of the hydroxyl-containing silica and the magnesium halide. 30 Process according to any of claims 1-4, characterized in that step a) is carried out by dissolving the magnesium halide in the alcohol and feeding the obtained solution to the hydroxyl-containing silica. 35 Process according to any one of claims 1-4, characterized in that a solid complex of the magnesium halide and the alcohol is melted into a liquid which is absorbed in the hydroxyl-containing silica. 18 · '> - 3 Process according to any of the preceding claims, characterized in that the weight ratio SiO2 / MgCl2 in step a) is about 2-5. 5 Method according to any of the preceding claims, characterized in that the mole ratio ROH / MgCl2 is between 1 and 4, preferably between 2 and 3. Process according to any of the preceding claims, characterized in that step a) lasts for 1-10 hours, preferably 1-4 hours, and its temperature is 20-100 ° C, preferably 80 - 95 ° C. Process according to any of the preceding claims, characterized in that the drying in step a) is continued until 9-15% by weight of the original amount of alcohol remains. Process according to any one of the preceding claims, characterized in that the compound reacting with the alcohol in step b) is an aluminum alkyl, an aluminum alkyl chloride, an alkyl of another metal or a chloride, alkyl chloride. - or alkyl disilazane compound of silicon. 25 Process according to claim 12, characterized in that the compound reacting with the alcohol is a trialkyl aluminum, preferably triethyl aluminum. Process according to any of the preceding claims, characterized in that the molar ratio in step b) between the alcohol-reacting compound and the alcohol is between 0.5 and 1.0, preferably about 0.7. Process according to any of the preceding claims, characterized in that step b) lasts 0.5 - 2 hours and its temperature is about 30-50 ° C. 19 'j j 9 2 8 Process according to any of the preceding claims, characterized in that the titanium compound in step c) is a titanium halide or a titanium alkoxy halide, preferably titanium tetrachloride. 5 Process according to any of the preceding claims, characterized in that step c) takes about 0.5 - 8 hours and its temperature is about 30-100 ° C. 10 A process according to any of the preceding claims, characterized in that hydrocarbons are used as the medium in steps a), b) and / or c). Process according to any of the preceding claims, characterized in that steps a) - c) are carried out without washing or siphoning. A procatalyst composition of a catalyst system for the polymerization of olefins, characterized in that it is prepared such that a) hydroxyl-containing silica, magnesium dichloride and alcohol are contacted and the thus obtained mixture is dried, b) the dried mixture is treated with a compound reacting with the alcohol; and c) the treated mixture is reacted with a titanium compound, the molar ratio Mg / Ti being between 1: 1 and 10: 1. A procatalyst composition according to claim 20, characterized in that it contains 3-7 wt.% Magnesium, 2-6 wt.% Titanium and about 3-4 wt.% Aluminum. Use of a procatalyst composition according to any one of claims 20 or 21 or prepared according to the process of any of claims 1-19 together with an organoaluminum compound acting as a cocatalyst for the polymerization of olefins.