AU658984B2 - Process for the preparation of a spherical catalyst component - Google Patents

Abstract

The invention relates to a process for the preparation of a spherical catalyst component based on magnesium chloride for the polymerisation of olefins, which has high stability to mechanical stress during the polymerisation, so that considerable simplifications and advantages are achieved in the handling and processing of the polymeric products produced therewith. This is achieved by coating a specific component with a thin protective layer of polyethylene by prepolymerisation before the actual polymerisation.

Description

Roguiation 3.2!2)

AUSTRALIA

Patents Act 1990 658984

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Application Number: Lodged: 0* 9. .9 Invention Title: PROCESS FOR THE PREPARATION OF A SPHERICAL CATALYST

COMPONENT

9* 09 *9 The following statement is a full description of this invention, including the best method of performing it known to :-US HOECHST AKTIENGESELLSCHAFT HOE 92/F 085 Dr.DA/- Description Process for the preparation of a spherical catalyst component The present invention relates to a process for the preparation of a spherical catalyst component based on magnesium chloride, by means of which considerable simplification and advantages are achieved in the handling and processing of the polymeric products produced therewith.

It is known that round magresium chloride exhibits, when the catalysts prepared therefrom are used, low stability to mechanical effects, as occur, for example, on continuous introduction of the catalyst in a continuous polymerization process via the catalyst pump necessary for this purpose. This causes destruction of the spherical structure of the catalyst particles. In the polymerization of olefins (in particular ethylene), uniform, spherical polymer particles are not obtained, rather a powder of irregular structure and a high proportion of fine particles. Furthermore, the known spherica\l catalyst components can only metered with difficulty the dry state, for example in gas-phase polymerization.

It is furthermore known that a spherical po3ymerization catalyst formed by reaction of an organomagnesium compound with an electron donor, an organochlorine compound and a transition-metal compound can be protectod against disintegration by enveloping the catalyst particles with a polyolefin by prepolymerization (cf, EP 232 643).

However, the performance of this catalyst system is unsatisfactory. In addition, the prepolymer must be subjected to complex aftertreatment with a "sph6roprotecteur".

2 Also known is a process for the preparation of a polyolefin by polymerization of alpha-olefins in the presence of a catalyst whose transition-metal component A is formed by a) reaction of an organomagnesium compound of the formula R 2 MgR 1 with an organoaluminum compound of the formula A1R 3 n(OR4) 3 s- or with the product of a reaction of trialkylaluminum compounds or dialkylaluminum hydrides with diolefins, and an aliphatic primary chlorinated hydrocarbon, b) treatment of the resultant solid with an electron donor, and c) reaction of the resultant support material with a compound of titanium or zirconium of the formula MeX.(OR 5 (cf. DE 36 20 060).

However, this transition-metal component has only low stability to mechanical load.

S. Finally, a process is known for the preparation of a polyolefin in which alpha-olefins are polymerized in the presence of a catalyst whose component A has been prepared, without removal of intermediates, by a) reaction of a specific organomagnesium compound with an aliphatic chlorinated hydrocarbon, b) treatment of the resultant suspension with an electron donor at a temperature of from 0 to 100 0

C,

and c) reaction of the resultant support material with a titanium compound, spherical particles being obtained which give polymers with spherical 30 particles (cf. DE 40 19 925).

This component A likewise has only low stability to mechanical effects.

It has now been found that a highly active, spherical and simultaneously mechanically stable catalyst component A can be obtained if a specific catalyst solid is 3 enveloped, before the actual polymerization, with a thin P0 7 '0def protective layer of pely-thy.e- by a prepolymerization.

The invention thus relates to a process for the preparation of a spherical, transition metal-containing catalyst component (component A of the catalyst) based on an organomagnesium compound, an organochlorine compound, if desired an organoaluminum compound, an electron donor and a transition-metal compound, and enveloping of the catalyst particles with a polyolefin by prepolymerization, which comprises carrying out the prepolymerization using a catalyst solid which has been prepared, without removal of intermediates, by a) reaction of an organomagnesium compound of the formula R 1 MgR 2 in which R 1 and R 2 are identical or different alkyl radicals having 2 to 12 carbon atoms, with from 0.5 to 2.5 mol of an aliphatic primary chlorinated hydrocarbon, based on 1 mol of S" the organomagnesium compound, at a temperature of from 30 to 110 0

C,

20 b} treatment of the resultant suspension with an electron donor in an amount of from 0.1 to 1 mol per mole of the magnesium present in the solid, at a temperature of from 0 to 100 0 C, and c) reaction of the resultant support material with a 25 compound of the formula MXm(OR 5 4 -m in which M is titanium or zirconium, R 5 is an alkyl radical having 2 to 10 carbon atoms, X is a halogen atom and m is an integer from 0 to 4, in an amount of from 0.5 to 2 mol per mole of the magnesium present in the S 30 support material, at a temperature of from 30 to 120 0

C.

First, a spherical solid is formed. To this end, an organomagnesium compound is reacted with an aliphatic primary chlorinated hydrocarbon and, if desired, with an organoaluminum compound.

4 The organomagnesium compound is a dialkylmagnesium compound of the formula R'MgR 2 where R 1 and R 2 are identical or different alkyl radicals having 2 to 12 carbon atoms. Examples are di-n-butylmagnesium, di-n-octylmagnesium, n-butyl-n-octylmagnesium, n-butylethylmagnesium, n-butyl-s-butylmagnesium or mixtures of these compounds. Preference is given to compounds of the formula (n-C4H) 1.2-1.7 (n-CH 17 0.3-08Mg] in particular (n-C 4 H) j.

5 (n-CH 17 0 .sMg Examples of suitable aliphatic primary chlorinated hydrocarbons are tetrachloromethane, chloroform, methylene chloride, 1-chloropropane and 1,1,1-trichloroethane, it also being possible to employ mixtures. Preference is given to chloroform and tetrachloromethane.

A suitable organoaluminur compound is an alkyl- or alkoxyaluminum compound of the formula AIR 3 (OR) in which R 3 and R 4 are identical or different alkyl radicals having 1 to 8 carbon atoms, and n is 0, 1, 2 or 3. Also suitable is the product of reaction of trialkylaluminum compounds or dialkylaluminum hydrides with diolefins containing 1 to 6 carbon atoms, preferably isoprene. A specific example is isoprenylaluminum. In the presence of the organoaluminum compound, the batch contains up to 25 0.15 mol, preferably up to 0.10 mol, of the organoaluminum compound cvcAseO on one v-ol c 5-tf he 94.9 argaooYgnes sm ciorA r>A To form the spherical solid, the organomagnesium compound and, if used, the organoaluminum compound are dissolved in an inert, liquid hydrocarbon under a nitrogen or argon atmosphere. This solution is combined with a solution of the chlorinated hydrocarbon with uniform stirring at a temperature of from 30 to 110 0 C, preferably from 40 to 0 C. The reaction can be carried out by adding the chlorinated hydrocarbon to the solution of the 5 organomagnesium compound and, if used, the organoaluminum compound in the liquid hydrocarbon, or vice versa.

In this reaction, both the reaction time and the degree of dilution of the reactants can be varied within broad limits. The reaction time is from 30 minutes to several hours, preferably from 1 hour to 5 hours. The reactants are employed as from 0.5 to 15 molar solutions. The batch contains up to 2.5 mol, preferably up to 2.0 mol, of the chlorinated hydrocarbon, based on one mole of organomagnesium compound.

The suspended solid formed essentially comprises spherical magnesium chloride and possibly a little aluminum chloride.

To this suspension of the spherical solid, an electron donor is then added. Suitable electron donors are oxygencontaining compounds of silicon, of phosphorus or of :i sulfur, compounds of nitrogen or silicon containing alkyl or aryl radicals having 1 to 8 carbon atoms, such as, for example, triethylamine or hexamethyldisilane, or alipha- 20 tic or aromatic ethers containing identical or different organic radicals. Preference is given to diethyl sulfite and diethoxydimethylsilane.

The electron donor is added to the spherical snlid in a molar ratio of from 0.1 to 1, preferably from 0.1 to 25 0.6 mol, based on one mole of magnesium, at a temperature "of from 0 to 100OC, preferably from 60 to 90 0 C. The reaction time, depending on the reactivity of the reactants, is from 0.5 to 3 hours, preferably up to 1 hour.

The spherical support material obtained in this way is immediately reacted, under a nitrogen or argon atmosphere, with a compound of the formula MX(OR 5 )4m in which

R

5 is an alkyl radical having 2 to 10 carbon atoms, M is titanium or zirconium, X is a halogen atom, preferably 6 chlorine, and m is an integer from 0 to 4, but is preferably 2 or 4. It is also possible to employ a mixture of more than one of these compounds. Examples of preferred compounds are TiCl 4 TiC1 3 (OEt), TiC1,(O-iPr), TiCl 2 (OEt) 2 TiCl 2 (O-iPr) 2 and TiCl 2

(O-CHC

6 Hs) 2 Very particular preference is given to TiCl 4 The compound of titanium or zirconium is employed in an amount of from 0.5 to 2 mol, preferably from 0.8 to 1.8 mol, in particular 1 mol, based on one mole of magnesium, of the spherical support material.

The reaction temperature is from 30 to 120 0 C, preferably from 60 to 95°C, and the reaction time, depending on the incorporation rate of the transition metal, is from minutes to several hours, preferably from 1 to 2 hours.

The catalyst solid prepared in this way is finally freed from soluble impurities, such as metal or halogen compounds, by repeated washing with an inert hydrocarbon at a temperature of from 0 to 100°C, preferably from 10 to 500C.

The spherical catalyst solid is then provided with a protective layer of polymer by prepolymerization. To this end, the solid is introduced into a reactor containing a suspension medium and a trialkylaluminum compound.

The suspension medium is a solvent customary in olefin 25 polymerizations, for example a saturated hydrocarbon having 3 to 15 carbon atoms, such as, for example, propane, butanes, pentanes, hexanes, heptanes, cyclohexane or mixtures of such compounds.

The trialkylaluminum compound contains from 1 to carbon atoms in the alkyl radicals.

7 The prepolymerization is carried out at a temperature of from 50 to 110°C, preferably from 50 to 950C, a pressure of from 0.5 to 10 bar, preferably from 0.5 to 6 bar, for a time of from 0.5 to 3 hours, preferably from 0.5 to hours.

The catalyst component A prepared according to the invention is in the form of sphericcl particles whose mean diameter is from 20 to 110 pm, preferably from 40 to pm, and which have a ratio between the weight average diameter, Dm, and the number average diameter, Dn, of less than 1.5, preferably from 1.01 to 1.1.

Component A is employed for the polymerization of alphaolefins in the form of a suspension in an inert hydrocarbon or alternatively in dry form after removal of the suspension medium. Preference is given to the homopolymerization of ethylene or propylene or the copolymerization of ethylene with a C 3 -Co 1 -alpha-olefin or of propylene with ethylene or a C 4

-C

10 -alpha-olefin containing one or more double bonds, such as, for exa&iple, 1-butene, 20 isobutene, 1-hexene or 1,3-butadiene.

The polymerization can be carried out either continuously or batchwise in gas phase or in suspension. In general, hydrogen is additionally employed as molecular weight regulator.

S• 25 Component B (cocatalyst) is an aluminum compound of the o*o formula A1R 6 pY 3 .p in which p is 1, 2 or 3, and R is an alkyl or aryl radical having 1 to 20 carbon atoms, Y is a hydrogen atom, a halogen atom or a Cj-C 20 -alkoxy or S" C 6

-C

20 -aryloxy group. Examples are halogen-containing organoaluminum compounds, such as dialkylaluminum halides, alkylaluminum dihalides or alkylaluminum sesquichlorides, furthermore trialkylaluminum compounds or alkylaluminum hydrides, which can be employed alone or in a mixture. Preference is given to trialkylaluminum 8 compounds, such as, for example, triethylaluminum or triisobutylaluminum.

The polymerization temperature is from 50 to 150°C, preferably from 50 to 100OC, and the pressure is from 1 to 60 bar, preferably from 3 to 25 bar.

The polymers and copolymers prepared by means of the catalyst component A prepared according to the invention are distinguished by a compact, uniform, spherical shape with a very narrow particle size distribution. The ratio between the weight average diameter, and the number average diameter, Dn, is less than 1.5, preferably from 1.02 to 1.3. The D/d rati- is in the range from 1.05 to 1.2. The diameter of the polymer particle is in the range from 100 to 1000 pm, preferably from 300 to 800 pm. The polymers have a high bulk density and excellent processing properties.

.A further advantage of the catalyst component A prepared according to the invention is its high mechanical stability and its good metering properties in the dry 20 state. In addition, it has a high catalyst activity, so that only very small amounts of thL catalyst are required for the polymerization. This also means that the polymers need not be subjected to additional aftertreatment, such as, for example, complex washing or purification operations. Furthermore, no undssired discoloration of the product due to catalyst residues occurs, which can frequently result in impairment of the light stability of the polymers.

The residual content of titanium or zirconium in the polymers obtained by means of the catalyst component A prepared according to the invention is less than 5 ppm, frequently less than 3 ppm.

9 In particular, however, the spherical shape and the consequent very good flow properties of the polymers and copolymers mean that considerable simplification and advantages are achieved in handling, drying and processing.

The invention is described in greater detail below by means of the examples.

The melt flow index MFI 190/5 was determined in accordance with DIN 53735 at 190°C and a load of 5 kp.

The ratio between D m and D n was determined in accordance with NF X 11-630 of June 1981: D, [Zn (Di 3 Di]/[Cni(Di) 3 Dn [ZniDJ]/ZEn ni number i of samples of the same diameter

D

i diameter of the i-th sample The particle size distribution D/Dn of component A was determined by image analysis using an IBAS 1.

The particle size distribution D./Dn of the polymer was determined by screen analysis in accordance with 20 DIN 4188.

Comparative Example A 10.5 mmol of triethylaluminum were added to 200 cm 3 of a solution of di-n-butylmagnesium in heptane (corresponding '*to 105 mmol of Mg). The mixture was added dropwise with S 25 vigorous stirring over the course of 90 minutes at 10 0 C to a mixture of 165 mmol of 1-chloropropane and 30 cm 3 of benzine. The batch was stirred at 80°C for a further 3 hours, and the solid was washed five times with a total of 1200 cm 3 of benzine.

A spherical solid having a median diameter d 5 o of 60 pm was obtained.

Mg:Cl:Al 1:2.14:0.04;D,/D n 1.13; D/d 1.1.

10 mmol of aluminum triisopropylate were added at 40°C to 300 cm 3 of a suspension of the abovementioned solid in benzine 100/200 (corresponding to 80 mmol of Mg), the mixture was subsequently stirred at 95 0 C for 2 hours, and the suspension was cooled to 50°C. 120 mmol of titanium tetrachloride dissolved in 20 cm 3 of benzine were added dropwise at this temperature over the course of minutes. The batch was stirred at 90 0 C for a further 4 hours, and the dark violet precipitate was washed five times with 200 cm 3 of benzine each time.

The spherical catalyst solid had a median particle diameter ds 5 of 60 pm.

Mg:Ti:CL;Al 1:0.07:2.68:0.02; Dm/Dn 1.1.

Comparative Example B First, 8.5 mmol of aluminum triisopropylate were added to 200 cm 3 of a solution of butyloctylmagnesium in heptane .";(corresponding to 185 mmol of Mg), and the mixture was stirred at 50°C for 40 minutes. 370 mmol of chloroform were subsequently added dropwise over the course of minutes at 70 5 0 C, the batch was stirred at 85°C for 2 hours, and the spherical solid was washed with 800 cm 3 of benzine.

Mg:Cl:Al 1:2.2:0.06; ds 0 80 pm.

o 25 80 mmol of diethyl sulfite were added at 20 0 C to 500 cm 3 of a suspenrsion of the abovementioned solid in benzine (corresponding to 200 mmol of Mg), and the mixture was stirred at 80°C for 2 hours. The dark-gray suspension was cooled to 50°C, and the solid was washed with 1300 cm 3 of benzine. 230 mmol of titanium tetrachloride were subsequently added dropwise at this temperature over the course of 30 minutes. Subsequent reaction at 95°C gave a violet, spherical catalyst solid, which was washed five 11 times with 200 cm 3 of benzine each time.

Mg:Ti:Cl:Al 1:0.07:2.28:0.02 Dm/Dn 1.1; d 5 s 80 pm.

Comparative Example C To 621 cm 3 of a solution of a magnesium compound having the approximate composition [(n-C 4 H) 1 s (n-CS7 7 0 5 Mg], which is commercially available under the name BOMAG-A, in heptane 570 mmol of Mg) were added 55.3 cm 3 570 mmol) of CCl 4 together with 500 cm 3 of benzine 100/120 0 C) over the course of 90 minutes at 70-80 0 C. The batch was subsequently stirred at 85 0 C for 120 minutes. The pale, red-brown, spherical solid had an Mg/Cl ratio of 1:2.08 and was suitable as a catalyst support without further work-up.

31.9 cm 3 250 mmol) of diethyl sulfite were added at 85 0 C over the course of 5 minutes to the resultant MgCl 2 suspension 570 mmol of Mg), and the mixture was subsequently stirred at 85°C for 60 minutes. 62.8 cm 3 570 mmol) of TiCl 4 were added at 85°C over the course S 20 of 20 minutes to the dark-brown suspension, and the batch was stirred at 95 0 C for 120 minutes. The dark-violet catalyst solid was subsequently washed eight times with *to: 150 cm 3 of benzine 100/120 0 C) each time at •until free of titanium.

Mg:Ti:Cl 1:0.130:2.28; dso 60 pm; D,/Dn 1.12.

ee*o Comparative Example D 656 cm 3 of a heptane solution of the Mg compound mentioned o in Comparative Example C 570 mmol of Mg) were added at 70-75 C over the course of 90 minutes to 200 cm 3 of benzine 100/120 0 C) and 98 cm 3 of CHCl 3 1210 mmol), and the mixture was subsequently stirred at 75-77°C for a further 120 minutes. The pale-brown, spherical solid had an Mg/Cl ratio of 1:1.97.

12 17.2 cm 3 135 mmol) of diethyl sulfite were added at 82-84 0 C over the course of 10 minutes to a portion of the resultant suspension 306 mmol of Mg), and the mixture was subsequently stirred at 84-85 0 C for 60 minutes.

33.7 cm 3 306 mmol) of TiC14 were subsequently added dropwise at 85°C over the course of 20 minutes, and the batch was again stirred at 85-88 0 C for 120 minutes. The violet, spherical catalyst solid was washed eight times with a total of 1300 cm 3 of benzine 100/120 0 C) at 55 0

C.

Mg:Ti:Cl 1:0.085:2.10; d 0 s 55 pm; Dm/Dn 1.18.

Example 1 A 1.5 dm 3 steel autoclave was charged with 800 cm 3 of benzine, 20 mmol of triethylaluminum and 10 mmol of titanium of the catalyst solid from Comparative Example C. 2.0 bar of nitrogen and 1.1 bar of hydrogen were then injected. The prepolymerization took place at 65 0 C over the course of 60 minutes. During this time, a total of 69 g of prepolymer having a spherical structure were 20 formed. The polymer was washed with 500 cm 3 of hexane and was dried in a rotary evaporator.

MFI 190/5 750 g/10 min; density 1.061 g/cm 3 BD 326 g/dm 3 d 5 s 53 pm.

1. Example 2 25 Example 1 was repeated, but only 0.5 bar of hydrogen were employed instead of 1.1 bar of hydrogen. A spherical prepolymer having an MFI 190/5 of 95 g/10 min was obtained.

Examples 3 and 4 A 150 dm 3 steel autoclave was charged with 100 dm 3 of benzine and 30 mmol of triethylaluminum, and 0.25 mmol of 13 titanium from the prepolymer from Example 1 or 2 was added. The reactor contents were brought to a temperature of 85°C, and sufficient hydrogen was introduced during the polymerization so that its content in the gas space was 20% by volume. 24 kg of ethylene and 500 cm 3 of 1-butene were then introduced into the reactor over the course of 4 hours. When the polymerization was complete, 24 kg of polyethylene, corresponding to a catalyst yield of 96 kg of polyethylene per mmol of titanium employed or about 65 kg of PE per g of catalyst, were obtained. Both polymers, prepared by means of the two prepolymers, had an MFI 190/5 of 0.41 g/10 min.

ds 5 710 pm; BD 430 g/dm 3 no fine particles 200 pm; Dm/Dn 1.12.

Example A continuous polymerization of ethylene was carried out by means of the prepolymer from Example 1. To this end, :ethylene, hydrogen, 1-butene, triethylaluminum and catalyst component A from Example 1 were introduced 20 continuously into the reactor. The polymerization temperature was 85 0 C, the partial pressure of ethylene was bar and the partial pressure of hydrogen was 2.9 bar.

A spherical polymer was obtained. Catalyst yield 33 kg of PE per mmol of titanium, MFI 190/5 2.9 g/10 min.

25 d 5 0 667 pm; fine particles 100 pm Dm/Dn 1.19.

0* *0 '*Comparative Example E Example 5 was repeated, but the catalyst solid from Comparative Example C was used. A polyethylene having a median particle diameter d 50 of 214 pm was obtained, with 22% of fine particles 100 pm. Only some of the polymer had a spherical shape. Yield and melt flow index corresponded to Example 14 Table Comparison of screen analysei Emnple <z63 n <100 gn <00 gm 1 1.2 E 14 22 35 -:3W0 n <50 n <800 m <000 gm 3.3 16 68 93 46 73 99.5 100 e.

*9 *6*t

S

S. S S

S

S.

S S

S

SS

SS S. 55 S S S

S

*SS.

.S

S S 55 6 0 5S S

Claims (4)

1. A process for the preparation of a spherical, transition metal-containing catalyst component based on an organomagnesium compound, an organochlorine compound, if desired an organoaluminum compound, an electron donor and a transition-metal compound, and enveloping of the catalyst particles with a polyolefin by prepolymerization, which comprises carrying out the prepolymerization using a solid part of the transition metal-containing catalyst which has been prepared, without removal of intermediates, by a) reaction of an organomagnesium compound of the formula R1MgR2 in which R1 and R2 are identical or different alkyl radicals having 2 to 12 carbon atoms, with from 0.5 to 2.5 mol of an aliphatic primary chlorinated hydrocarbon, based on 1 mol of the organomagnesium compound, at a temperature of from 30 to 1100C, b) treatment of the resultant suspension with an electron donor in an amount of from 0.1 to 1 mol per mole of the magnesium present in the solid part of the transition metal-containing catalyst at a temperature of from 0 to 1000C, c) reaction of the resultant support material obtained according to b) with a compound of the formula MXm(OR5) 4 -m in which M is titanium or zirconium, R5 is an alkyl radical having 2 to 10 carbon atoms, X is a halogen atom and m is an integer from 0 to 4, in an amount of from 0.5 to 2 mol per mole of the magnesium present in the support material, at a temperature of from 30 to 1200C, and d) providing the resultant support material with a protective layer of polymer by prepolymerization.

2. The process as claimed in claim 1, wherein the reaction between the organomagnesium compound and the aliphatic primary chlorinated hydrocarbon was carried out in the presence of an organoaluminum compound of the formula AIR3n(OR4)3.n in which R3 and 16 HOE 92/F 085 R 4 are identical or different alkyl radicals having 1 to 8 carbon atoms, and n is 0, 1, 2 or 3, or the product of the reaction of trialkylaluminum compounds or dialkylaluminum hydrides with diolefins containing 1 to 6 carbon atoms, in an amount of up to 0.15 mol of organoaluminum compound, based on one mole of the organomagnesium compound.

3. The process as claimed in claim 1, wherein the organomagnesium compound employed was a compound of the formula (n-C 4 H) 1.2-1. 7 (n-C 8 H 17 )0.3-0. 8 Mg].

4. The process as claimed in claim 1, wherein the electron donor employed was diethyl sulfite or diethoxydimethylsilane. The process as claimed in claim 1, wherein TiCl 4 was employed. DATED this 25th day of March 1993. HOECHST AKTIENGESELLSCHAFT WATERMARK PATENT TRADEMARK ATTORNEYS o*as "THE ATRIUM" eae 290 BURWOOD ROAD HAWTHORN. VIC. 3122. HOE 92/F 085 Abstract of the disclosure Process for the preparation of a spherical catalyst component The invention relates to a process for the preparation of a spherical catalyst component based on magnesium chloride for the polymerization of olefins, which has high stability to mechanical load during the polymeriza- tion, so that considerable simplification and advantages are achieved in the handling and processing of the polymeric products produced therewith. This is achieved by enveloping a specific component, before the actual polymerization, with a thin protective layer of poly- ethylene by a prepolymerization. *.I *me