IE912163A1

IE912163A1 - Process for the preparation of a polyolefin

Info

Publication number: IE912163A1
Application number: IE216391A
Authority: IE
Inventors: Gerhard Thum
Original assignee: Hoechst Ag
Priority date: 1990-06-22
Filing date: 1991-06-21
Publication date: 1992-01-01
Also published as: WO1992000332A1; JPH05502053A; DE4019925A1; DK0535023T3; JPH07107084B2; DE59102518D1; ZA914789B; PT98069B; KR930701492A; KR950009109B1; BR9106583A; ES2061250T3; PT98069A; ATE109800T1; EP0535023B1; EP0535023A1; AU7908291A; IE65299B1; AU640488B2

Abstract

Prodn. of polyolefins (I) by polymerisation of alpha-olefins at 50-150 deg.C and 1-40 bar in the presence of a catalyst consisting of a transition metal component (A) and an organometallic cpd. (component B); the novelty is that (A) is prepd. without sepn. of intermediates, by (a) reaction of an organomagnesium cpd. of formula (n-Bu)x(n-octyl)yMg (II) (with x = 1.2-1.7; y = 0.3-0.8) with 0.5-2.5 mols. chlorinated hydrocarbon (III) (w.r.t. 1 mol. II) at 30-110 deg.C, (b) treatment of the suspension obtd. with 0.1-1 mol. electron donor (IV) (per g-atom Mg in the solid) at 0-100 deg.C and (c) reaction of the support material obtd. with 0.5-2 mols. (per g-atom Mg in the support) of a cpd. of formula TiXm(OR)4-m (V), at 30-120 deg.C (with R = 2-10C alkyl; X = Hal; m = 0-4). Pref. (IV) is diethyl sulphite (IVA) or Me2Si(OEt)2 (IVE), and (V) is TiCl4.

Description

Process for the preparation of a polyolefin The present invention relates to a process for the 5 preparation of a polyolefin having spherical particles by means of a highly active, spherical Ziegler catalyst, with which considerable simplifications and advantages in the handling and processing of the products are achieved.

A multiplicity of catalysts of the Ziegler type for the polymerization of alpha-olefins are already known. Many of these catalysts are based on magnesium chloride as support material, which is obtained by reaction of an organomagnesium compound R2Mg, such as, for example, butylethylmagnesium, with a chlorinated hydrocarbon com15 pound R'-Cl, such as, for example, carbon tetrachloride (cf. US 4 442 225, US 4 439 539, DE 30 10 202).

However, with these catalysts it is not possible to obtain a magnesium chloride of spherical shape.

On the other hand, it is known that spherical magnesium chloride is formed on the reaction of an organomagnesium compound R2Mg with a chloro-organic compound R'-Cl in the presence of an organoaluminum compound, such as triethylaluminum, and an electron donor compound, such as diisoamyl ether (cf. EP 99284).

Restrictions which apply here are that R' must be a hydrocarbon radical having three or more carbon atoms and that the carbon atom adjacent to the chlorine must be either a secondary or tertiary carbon atom.

A process is known for the preparation of a polyolefin by polymerization of alpha-olefins in the presence of a catalyst, the transition metal component A of which has been formed by a) reaction of an organomagnesium compound of the formula R1MgR2 with an organoaluminum compound of the formula AlR3n(OR*)3_n, or the reaction product of aluminum trialkyls or aluminum dialkylhydrides with diolefins, and an aliphatic primary chlorinated hydrocarbon, b) treatment of the resulting solid with an electron donor, and c) reaction of the support material thus obtained with a titanium or zirconium compound of the formula MeXffi(OR5)^m (cf. DE 36 20 060).

It has now been found that a highly active and at the same time spherical catalyst, with which spherical polymers of alpha-olefins can be obtained, which are distinguished by a narrow particle size distribution coupled with a large average particle diameter, can be obtained in a simple manner if a very specific magnesium compound is used.

The invention thus relates to a process for the preparation of a polyolefin by polymerization of alpha-olefins at a temperature of 50 to 150’C and a pressure of 1 to 40 bar in the presence of a catalyst composed of a transition metal component (component A) and an organo25 metallic compound (component B), the component A of which has been formed by reaction of an organomagnesium compound with an electron donor, an organic chlorine compound and a transition metal compound, wherein the polymerization is carried out in the presence of a catalyst, the component A of which has been prepared by a) reaction of an organomagnesium compound of the formula [ (n-C4H8) x 2-1.7( n-C8H17)0 3_0 8Mg] with an aliphatic primary chlorinated hydrocarbon in an amount of 0.5 to 2.5 mol of the chlorinated hydrocarbon, based on 1 mol of the organomagnesium compound, at a temperature of 30 to 110’C, b) treatment of the resulting solid with an electron donor in an amount of 0.1 to 1 mol per gram atom of magnesium contained in the solid at a temperature of 0 to 100°C, and c) reaction of the support material thus obtained with 5 a compound of the formula TiX^OR1)^, in which R1 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 0.1 to 2 mol per gram atom of magnesium contained in the support material, at a temperature of 30 to 120’C.

Initially a spherical solid is formed. For this purpose an organomagnesium compound is reacted with an aliphatic primary chlorinated hydrocarbon.

The organomagnesium compound is a magnesium dialkyl of 15 the formula [ (n—C4Hg)1.2-1.7(n—CgH^)0.3-0.8^931 particular [ (n-C4H9) j 5(n-C8H17)0 5Mg].

A suitable aliphatic primary chlorinated hydrocarbon is, for example, carbon tetrachloride, chloroform, methylene chloride, 1-chloropropane or 1,1,1-trichloroethane, it also being possible for mixtures to be employed. Chloroform and carbon tetrachloride are preferably used.

In order to prepare the spherical solid, the organomagnesium compound is dissolved in an inert, liquid hydrocarbon under nitrogen or argon atmosphere. This solution is brought into contact, with uniform stirring at a temperature of 30 to 110°C, preferably of 40 to 80°C, with a solution of the chlorinated hydrocarbon. The reaction can be carried out by adding the chlorinated hydrocarbon to the solution of the organomagnesium compound in the liquid hydrocarbon, or vice versa.

In the case of this reaction, both the reaction time and the degree of dilution of the reactants can be varied within wide limits. The reaction time is 30 min to several hours, preferably 1 hour to 5 hours. The reactants are employed in the form of 0.5 to up to 15 molar solutions.

The batch contains up to 2.5 mol, preferably up to 2.0 mol, of the chlorinated hydrocarbon, based on 1 mol of organomagnesium compound.

The suspended solid formed essentially consists of spherical magnesium chloride.

An electron donor is now added to this suspension of the spherical solid. Suitable electron donors are oxygen10 containing silicon, phosphorus or sulfur compounds, nitrogen compounds or silicon compounds containing alkyl or aryl radicals having 1 to 8 carbon atoms, such as, for example, triethylamine or hexamethyldisilane, or aliphatic or aromatic ethers containing identical or different organic radicals.

Diethyl sulfite and diethoxydimethylsilane are preferably used.

The electron donor is added to the spherical solid in a molar ratio of 0.1 to 1, preferably 0.1 to 0.6, based on one gram atom of magnesium, at a temperature of 0 to 100°C, preferably of 60 to 90"C.

The reaction time is 0.5 to 3 hours, preferably up to 1 h, depending on the reactivity of the reactants.

The spherical support material obtained in this way is immediately reacted under nitrogen or argon atmosphere with a compound of the formula TiX^OR1)^, in which R1 is an alkyl radical having 2 to 10 carbon atoms, X is a halogen atom, preferably chlorine, and m is an integer from 0 to 4, but preferably is 2 or 4. A mixture of several of these compounds can be employed.

Preferred compounds are, for example, TiCl^, TiCl3(OEt), TiCl3 (O-iPr), TiCl2(OEt)2, TiCl2 (O-iPr)2 and TiCl2(O-CH2C6H5)2.

TiCl4 is very particularly preferred.

In the reaction described above, the titanium compound is 5 employed in an amount of 0.5 to 2 mol, preferably 0.8 to 1.8 mol and in particular 1 mol, based on one gram atom of magnesium in the spherical support material.

The reaction temperature is 30 to 120°C, preferably 60 to 95°C, and the reaction time is 30 min to several hours, preferably 1 to 2 hours, depending on the titanium coverage required.

The catalyst component A prepared in this way is finally freed from soluble impurities, such as metal or halogen compounds, at a temperature of 0 to 100°C, preferably of to 50*C, by repeated washing with an inert hydrocarbon.

The catalyst component A prepared according to the invention is in the form of spherical particles, the average diameter of which is 20 to 110 μαι, preferably 40 to 80 μία, and which have a ratio of mass-average diameter Dm to number-average diameter Dn of less than 1.5, preferably 1.01 to 1.2.

The component A is employed in the form of a suspension in an inert hydrocarbon, or alternatively, after separa25 ting off the suspending agent, dry for the polymerization of alpha-olefins. The polymerization of ethylene or propylene or the copolymerization of ethylene and/or propylene with an alpha-olefin having 4 to 10 carbon atoms and one or more double bonds, such as, for example, but-l-ene, isobutene, hex-l-ene or buta-1,3-diene, is preferred.

The polymerization can be carried out either continuously or discontinuously in the gas phase or in saturated hydrocarbons having 3 to 15 carbon atoms, such as, for example, propane, butanes, pentanes, hexanes, heptanes, cyclohexanes or mixtures of such compounds.

In general, hydrogen, as molar mass regulator, and, as component B (cocatalyst), an aluminum compound of the formula AlR2pY3.p, in which p is 1, 2 or 3 and R2 is an alkyl or aryl radical having 1 to 20 carbon atoms and Y is hydrogen, a halogen atom or an alkoxy or aryloxy group having, in each case, 1 to 20 carbon atoms, are additionally also employed.

Examples are halogen-containing organoaluminum compounds, such as dialkylaluminum halides, alkylaluminum dihalides or alkylaluminum sesquichlorides, and also aluminum tri15 alkyls or aluminum alkylhydrides, which can be employed on their own or as a mixture.

Aluminum trialkyls, such as, for example, aluminum triethyl or aluminum triisobutyl, are preferably used.

The polymerization temperature is 50 to 150’C, preferably 20 50 to 100°C, and the pressure 1 to 40 bar, preferably 3 to 12 bar.

The polymers and copolymers prepared in the process according to the invention are distinguished by a compact, uniform spherical shape with a very narrow particle size distribution. The ratio of mass-average diameter Dn to number-average diameter Dn is less than 1.5, preferably from 1.02 to 1.3. The D/d ratio is in the range from 1.05 to 1.2. The diameter of the polymer particle is in the range from 100 to 1,000 pm, preferably 300 to 800 μτα. The polymers have a high bulk density and an excellent processability.

A further advantage of the catalyst according to the invention lies in the high contact activity, so that only very small amounts of the catalyst are necessary for the polymerization. Consequently, the polymers also do not have to be subjected to an additional after-treatment, such as, for example, laborious washing or purification operations. Furthermore, no undesired discolorations of the product due to catalyst residues, which frequently can lead to an impairment of the stability of the polymers to light, occur.

The residual titanium or zirconium content in the poly10 mers prepared according to the invention is less than ppm, frequently less than 3 ppm.

In particular, however, considerable simplifications and advantages in the handling, drying and processing are achieved as a result of the spherical shape and the associated very good flowability of the polymers and copolymers.

The invention is illustrated in more detail below by the examples.

The MFI (190/5) melt index was determined in accordance 20 with DIN 53735 at 190°C and at a load of 5 kp.

The Dm to Dn ratio was determined in accordance with NF X 11-630 of June 1981: Dm = [Σ ni (Di)3 Di]/[E ni (Di)3] Dn = [Σ ni DiJ/Σ ni ni = number i of the samples of the same diameter Di = diameter of the i-th sample.

The particle size distribution Dn/Dn of the component A was determined by means of image analysis.

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

Example 1 55.3 cm3 (= 570 mmol) of CC1A together with 500 cm3 of benzine (b.p. 100/120*C) were added in the course of 90 min at 70-80eC to 621 cm3 of a solution of a magnesium compound having the approximate composition [ (n-C4H8) χ 5(n-C8H17)0 jMg], which is available commercially under the name BOMAG-A, in heptane (= 570 mmol of Mg). The batch was then stirred for 120 min at 85 °C. The bright, red-brown, spherical solid had an Mg/Cl ratio of 1 to 2.08 and could be employed as catalyst support without further working up.

Example 2 656 cm3 of a solution of the Mg compound named in Example 1 in heptane (= 570 mmol of Mg) were added in the course of 90 min to 200 cm3 of benzine (b.p. 100/120°C) and 98 cm3 of CHC13 (= 1,210 mmol) at 70-75’C and the mixture was then stirred for a further 120 min at 75-77°C. The pale brown, spherical solid had an Mg/Cl ratio of 1:1.97.

Example 3 17.2 cm3 (= 135 mmol) of diethyl sulfite were added at 82-84°C in the course of 10 min to a portion of the MgCl2 suspension prepared in Example 2 (= 306 mmol of Mg) and the mixture was then stirred for 60 min at 84-85°C. 33.7 cm3 (= 306 mmol) of TiCl4 were then added dropwise in the course of 20 min at 85°C and the batch was stirred for a further 120 min at 85-88"C. The violet, spherical catalyst solid was washed 8 times with in total 1,300 cm3 of benzine (b.p. 100/120’C) at 55eC.

Mg:Ti:Cl = 1:0.085:2.10 d50 = 55 Mm; Dm/Dn = 1.18.

Example 4 31.9 cm3 (= 250 mmol) of diethyl sulfite were added at 85°C in the course of 5 min to the MgCl2 suspension obtained in Example 1 (= 570 mmol of Mg) and the mixture was then stirred for 60 min at 85eC. 62.8 cm3 (= 570 mmol) of TiCl4 were added in the course of 20 min to the dark brown suspension at 85°C and the batch was stirred for 120 min at 95eC. The dark violet catalyst solid was then washed at 60°C 8 times with, in each case, 150 cm3 of benzine (b.p. 100/120eC) until titanium-free.

Mg:TisCl = 1:0.130:2.28 d50= 60 pm; Dm/Dn — 1.12.

Example 5 The procedure was analogous to Example 3 except that 92 mmol of di-n-butyl ether were employed in place of 135 mmol of diethyl sulfite.

Mg:Ti:Cl = 1:0.008:1.95 d50= 50 pro; Dm/Dn= 1.15.

Example 6 The procedure was analogous to Example 4 except that diethoxydimethylsilane was employed in place of diethyl sulfite.

Mg:Ti:Cl = 1:0.06:2.11 d50= 45 pm; Dm/Dn= 1.17.

Examples 7-14 The ethylene polymerization was carried out in accordance with the table in a 1.5 dm3 steel autoclave at a temperature of 85’C and a pressure of 7 bar in 800 cm3 of benzine (b.p. 100/120°C). In each case 3.0 mmol of triethylaluminum (TEA) or triisobutylaluminum (TIBA) were added as component B. The spherical polyethylene particle had a D/d ratio of between 1.1 and 1.3. The proportion of fines < 100 pm was < 0.1%.

Table: Ethylene polymerization Ex. Comp.A Ex. No. Comp.B h2 X by vol. Yield gPE/mmol Ti MFI 190/5 g/10 min d50 pm Bulk density g/i 7 3 TEA 55 14,580 22.5 520 395 8 3 TIBA 45 18,980 6.8 585 360 9 3 TIBA 55 10,110 22.0 475 390 10 4 TIBA 45 14,040 4.3 380 330 11 4 TEA 55 17,320 20.0 360 335 12 4 TEA 45 20,425 5.5 430 345 13 5 TIBA 45 41,435 7.0 390 340 14 6 TEA 55 23,890 26.1 435 355

Claims

1. PATENT CLAIMS

1. A process for the preparation of a polyolefin by polymerization of alpha-olefins at a temperature of 50 to 150°C and a pressure of 1 to 40 bar in the 5 presence of a catalyst composed of a transition metal component (component A) and an organometallic compound (component B), the component A of which has been formed by reaction of an organomagnesium compound with an electron donor, an organic chlorine 10 compound and a transition metal compound, wherein the polymerization is carried out in the presence of a catalyst, the component A of which has been prepared, without separating off intermediates, by a) reaction of an organomagnesium compound of the 15 formula [ (n-C^H 0 ) 12 _ 17 (n-C 8 H 17 ) 0 3 . 0 8 Mg] with an aliphatic chlorinated hydrocarbon in an amount of 0.5 to 2.5 mol of the chlorinated hydrocarbon, based on 1 mol of the organomagnesium compound, at a temperature of 30 to 110 °C, 20 b) treatment of the resulting suspension with an electron donor in an amount of 0.1 to 1 mol per gram atom of magnesium contained in the solid at a temperature of 0 to 100 °C, and c) reaction of the support material thus obtained 25 with a compound of the formula TiX^OR 1 )^, in which R 1 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 0.5 to 2 mol per gram atom of magnesium contained in the support 30 material, at a temperature of 30 to 120’C.

2. The process as claimed in claim 1, wherein the electron donor used is diethyl sulfite or diethoxydimethylsilane.

3. The process as claimed in claim 1, wherein TiCl 4 was employed. IE 912163 - 12

4. A process as claimed in claim 1, substantially as hereinbefore described and exemplified.

5. A polyolefin whenever prepared by a process claimed in a preceding claim.