CA1207499A - Process for the preparation of a polyolefin, and a catalyst for this process - Google Patents

Abstract

Abstract of the disclosure:

Polyolefins having a broad molecular weight dis-tribution are obtained in a very high yield, even using a catalyst based on a product from the reaction of a magnesium alcoholate with titanium tetrachloride, if the hydrocarbon-insoluble product from the reaction of the magnesium alco-holate with titanium tetrachloride is heated at a fairly high temperature with further titanium tetrachloride.

Description

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- 2 - HOE 81/F 148 Processes are known for the preparation of poly-olefins by means of cat~lysts which are formed by reacting magnesium alcoholates and/or complex magnesium alcoholates with transition metal halides. (German Auslegeschriften 1,795~197 and 1,957,679 and German Offenlegungsschrift 2,000,566).
In one case, a temperature range of O to 200C is recommended for the reaction of the magnesium compound and the chlorine-containing titanium compound, but the upper temperature limit should be so ehosen that no decomposition products are ~ormed. In addition to the high activity of ~he polymerization catalysts~ it Is mentioned as a special advantage that it is possible to prepare ethylene homo-polymers and ethylene/~-olefin copolymers which have a narrow molecular weight distribution (German Auslegeschriften 1,795,197 and 1,957,679).
In another case, the reaction of the metal alco-holate with the transition metal compound is carried out in the presence or absence of an inert diluent at tempera-tures of 40 to 210C; the duration of the reaction is, ln general, between 5 and 240 minutes (German Offenlegungs-schrift 2,500,566). An express warning is given against a longer reaction time, since it is alleged to cause an impairment in the properties of the catalyst. In this publication too, it is mentioned as an advantage of the catalysts that they have a high activity and that it is possible to prepare polyole~ins which have a narrow ~ 7~9 molecular weight distribution. A catalyst which is obtained by reacting magnesium ethylate with vanadium tetrachloride and which produces a polyethylene having a broad molecular weight distribution is described at the same time. However, vanadium co~pounds hav~ the great disadvantage that, in ' oor.trast with titanium compounds, they are extre~.ely toxic.
i Products containing vanadium compounds can, therefore, only ¦ be employed to a limited extent. In addition9 high costs are incurred in working up the catalyst mother liquors if vanadium compounds are employed in industrial polymerization processes.
The object was therefore presented of finding ~ polymeri~ation catalysts based on a magnesium alcoholate, by means of which polyole~ins having a broad molecular lS weight distribution can be prepared in a high yield.
It has now been found that it is also possible to o~tain polyolefins which have a broad molecular weight distribution, and in a very high yield, using the reaction Froducts of magnesium alcoholates with titanium tetra-ehloride, if the reaction ~etween the magnesium alcoholateand the titanium tetrachloride is carried out at a relà-tively low temperature and the reaction mixture is then subjected to a heat treatment in order to split off alkyl chlorides, at a fairly high temperature and with the addition of TiC14.
The invention relates 9 therefore, to a process for the polymerization of 1-olefins of the formula R4CH=CH2 in whiGh R4 denotes hydrogen or an alkyl radical having up to 10 carbon atoms 9 in the presence of a catalyst composed ~(37~3 - 4 - .
of a component containing magneslum and titanium (component A) and an organometallic compound of ~roup X to III of the ~eriodic system (component B), which comprises carrying : out polymerization in the presence of a catalyst in which the component A has been prepared by a procedure in which, in a first reaction stage7 a magnesium alcoholate is reacted with titanium tetrachloride in a hydrocarbon at a tempera-ture of 50 to 100C, the resulting reaction mixture is subjected, in a second reaction stage, to a heat treatment 10 at a temperature of 110 to 200C7 with the addition of TiCl49 for 8 to 100 hours, and the solid is then freed from ~oluble reaction products by washing several times with a hydrocarbon.
The invention also relates, however, to the cata-lyst used for this process and to its preparation.
A magnesium alcoholate is used for the praparation of the component A. This magnesium alcoholate can be a "simple" magnesium alcoholate of` the ~ormula Mg(OR)2 in which R denotes identical or different alkyl radicals 20 having 1 to 6 carbon atoms. Examples are Mg(OC2H5)2, Mg(OiC3H7)2, M~(OnC3H7)2, ~g(OnC4H9~2, Mg(OCH3~(0C2H5) and Mg(OC2H5)(0nC3H7). It is also possible to use a "simple"
magnesium alcoholate of the formula Mg(OR)nXm in which X
i halogen (S04)1/~, OH~ (C3)1/2' (P4)1/3 the meaning mentioned above and n + m is 2.
It is also possible, however3 to employ a "complex" magnesium ~ alcoholate. The tenm "complex~'nagnesium alcoholate describes a ¦ magnesium a.lcoholate which, as well as magnesium, contains ¦ at least one metal of the 1st to 4th main group of the . 1~
~. . .. . . ... ... ., . ., .. ..... . . _ ~z~
_ 5 _ periodic system. The following are examples of a complex magnesium alcoholate o~ this type: ~Mg(OiC3H7)4]Li2;
l 2( 3H7j8]Mg; ~Si(OC2H5)63Mg; [M8(C2H5)3JNa;

r ~Al2~0iC4Hg)~]Mg; and [Al2(0-s~cC4Hg)6(0C2H5)2]Mg.
I 5 ~he complexr~esium alcoholates (alkoxo ~ts) are prepared by known methods (literature references: Meerwein; Ann.
455 (19273, page 234 and 476 (1929), page 113; Houben-Weyl, Methoden der organischen Chemie ~"Methods of organic chemistry~'], volume 6/2, page 30). The following examples of the preparation o~ the complex magnesium alcoholate may be mentioned:
1. Two metal alcoholates are allowed to act on one another in a suitable'solvent, for example 2Al(OR~3 ~ Mg(OR)2 ~ [A12(0R)8~Mg 2. Magnesium is dissolved in ~n alcoholic solution of a metal alcoholate 2LiOR + Mg ~ 2 ROH ~ _~ ~Mg(OR)4~Li2 + H2

3. Two metals are dissolved in alcohol simultaneously 8 ROH + Mg + 2 Al - -~ [Al2(OR)8]M~ + 4 ~2 The simple magnesium alcoholates, in particular Mg(oc2H5)2~ ~g(OnC3H7)2 and Mg(OiC3H7)2' are pre Y
used. The magnesium alcoholate is employed in a pure form or ~ixed on a support.
The preparation o~ the component A is effected in two reaction stages at di~ferent temperatures.
In a firs~ reaction stage, the magnesium alco-holate is reacted with titanium tetrachloride at a tempera-ture of 50 to 100C, preferably 60 to 90C, in the presence of an inert hydrocarbon and while stirring~ 0.9 to 5 moles r j ~

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~, 6 ~, of titanium tetrachloride are employed for l mole ~f mag-nesium alcoholate, preferably 1.4 to 3.5 moles of titanium ~etrachloride for l mole of magnesium alcoholate.
A suitable inert hydrocarbon is an al$phatic or cycloaliphatic hydrocarbon, such as butane, pentane, hexane, heptane, isooctane, cyclohexane or methylcyclohexane, and an aromatic hydrocarbon, such as toluene or xylene; it is also possible to use a hydrogenated diesel oil or gasoline ¦ fraction which has been carefully freed from oxygen, sulfur compounds and moisture.
The reaction time in the first stage is 0.5 to 8 hours, preferably 2 to 6 hours.
A substantial replacement of the alkoxy groups of the magnesium alcoholate by the chlorine groups of the titanium tetrachloride takes place in the first reaction ~ stage. The reaction product ob1ained in this stage is a ¦ solid which i~ insoluble in hydroGarbons and contains ~ magnesium and titanium, and titanium compounds which are } soluble in hydrocarbons and contain chlorine and alkoxy groups.
The product insoluble in the hydrocarbon, from the reaction of the magnesium alcoholate with the titanium ¦ tetrachloride, is then freed from unreacted, soluble titanium ! compounds by washing several times with an inert hydrocarbon.
The resu]ting solid is again suspended in a hydro-carbon and is subjected, in a second reaction stage, to a heat treat~ent at a temperature of llO to 200C, preferably llO to 160C, with the addition of titanium tetrachloride.
In the second reaction stage, O.l to 3 molar parts, , .

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preferably 0.1 to 2 molar parts, o~ TiCl4 are employed per molar part of magnesium alcoholate employed in the first j reaction stage~
All the soluble reaction products are then removed by washin~ several times with a hydrocarbon, and a solid which is insoluble in the hydrocarbon and which contains magnesium and t~tanium, is obtained; this will be desig-nated component A.
The polymerization catalyst to be used in accordance with the invention is prepared by bringin8 into contact with one another the component A and an urganometallic com pound of Groups I to III of the periodic system (component B)-It is preferable to use organoaluminum compounds lS as the component B. Suitable organoaluminum compounds areorganoaluminum compounds containing chlorine, the dialkyl-aluminum monochlorides o~ the formula R22AlCl or the alkyl-aluminum sesquichlorides of the formula R3Al2Cl3 in whieh . R2 can be identical or different alkyl radicals having , 20 1 to 16 carbon atoms. The following may be mentioned as examples: (C2H5)2AlC19 ~iC4H9~2AlCl and (C2H5)3Al2Cl3.
It is particularly preferable to employ chlorine~
free compounds as the organoaluminum compounds. Compounds ¦ suitable for this purpose are, firstly, the products from the reaction of aluminum trialkyls or aluminum dialkyl-! hydrides with hydrocarbon radicals having 1 to 6 carbon atoms, preferably the reaction of Al(iC4Hg)3 or Al(iC4H9~2H
. with diolefins containing 4 to 20 carbon atoms, preferably isoprene. Aluminum isoprenyl may be mentioned as an .' .. . .. _ . . . , . -- , 7~

e~ample .
Secondly, chlorine-free organoaluminum compounds of this type are aluminum trialkyls AlR3 or aluminum di-alkylhydrides of the formula AlR3H in which R3 denotes identical or different alkyl radicals having 1 to 16 carbon atoms. Examples are Al(C2H5)3, Al(C2H5)2H, Al(C H )3, Al(C3H7)2H, Al(iC4Hg)3~ 4 9 2 Al(CBH17) 9 Al(C12H2 ) , Al(C2H 3(C 2H2 ) and . , 3 5 3 5 1 5 2 ~1 Al(iC4H9)(C12H25)2 It is also possible to employ mixtures of organo-metallio compounds of Group I to III of the periodic system, particularly mixtures of different organoaluminum compounds. The following mixtures may be mentioned as (C2~s)~ and Al(iC4Hg)3- Al(C2H5)2C1 and 15 Al(C H )3, Al(C2H5~3 and Al(C8H17)3, 4 9 2 Al(C8H17)3, Al(iC4Hg)3 and Al(C~H17)3, Al(C2H~)3 and Al(C H 5)3, Al(iC4Hg)3 and Al(C12H25)3, 2 5 3 C16H33)3- Al(c3H7~3 and Al(C18H37)2(iC4H9) or hl(C2H5~3 and aluminum isoprenyl (the reaction product of isoprene with Al(iC4Hg)3 or Al(iC4Hg)2H).
The component A and the compcnent B can be mixed in a stirred kettle at a temperature of -30C to 150~C, ! preferably -10 to 120C, before the polymerization. It is also possible to combine the two components directly in the polymerization kettle at a polymerization temperature . of 20 to 200C. The addition of the component B can, how-ever, also be effected in two stages by pre-activating the component A with part of the component B at a temperature of -30C to 150C before the polymerization reaction, and ~ ., .

_ 9 _ adding the remainde~ of the component B in the polymer-ization reactor at a temperature of 20 to 200~C.
The polymerization catalyst to be used in accord-ance with the invention is employed for the polymerization of l-olefins of the ~ormula R4CH=CH~ in which R4 denotes hydrogen or an alkyl radical having 1 to 10 carbon atoms, ~or example ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene or 1 octene. It is preferable to poly-merize ethylene on its own or in the form of a mixture containing at least 70% by weight of ethylene and not more than 30% by weight of another 1-olefin of the above formula.
In particular, ethylene is polymerized on its own, or a mixture containing at least 90% by weight of ethylene and not more than 10% by weight o~ another 1-olefin of the above formula is polymerized.
The polymerization is carried out in a known manner in solution, in suspension or in the gas phase, continuously or discontinuously, in a single ,stage or in several stages and at a temperature of 20 to 200C, preferably 50 to 150C. The pressure is 0.5 to 50 bar. Polymerization within the pressure range from 5 to 30 bar, which is of particular interest in industry, is pre~erred.
In ~ s polymerization,-the com~onent A is used in a concent-._ .
ration, calculated as titanium, o~ 0.0001 to 1, preferably 0.001 to 0.~, mmole of Ti per liter of dispersing agent or per liter of reactor volume. The organometallic compound is used in a concentra~ion of 0.1 to 5 mmoles, preferably 0.5 to 4 mmoles, per liter of dispersing agent or per liter of reactor volumeO In principle, however, higher concentrations are ~so possible.

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Suspension polymerization is carried out in an inert dispersing agen~ which is customary for the Ziegler low-pressure process, for example in an aliphatic or cyclo-aliphatic hydrocarbon; butane, pentane9 hexane, heptane, 5 isooctane, cyclohexane or methylcyclohexane may be mentioned as examples of such a hydrocarbon. It is also possible to use a gasoline or hydrogenated diesel oil fraction which has been carefully freed from oxygen, sulfur compounds and moisture. The molecu~ar ~eight of the polymer is regulated in a kno~ manner; it is preferable to use hydrogen for this purpose.
As a result of the high activity of the catalyst to be used9 the process according to the invention produces I polymers having a very low content of titanium and halogen ! and, therefore, extremely good values in the test for 15 color stability and corrosion. It also makes it possible to prepare polymers having a very broad molecular weight distribution; the Mw/Mn values of the polymers are over 10.
A further decisive advantage of the process accord-ing to the invention can be seen in the fact that it makes ~0 it possible to prepare polymers having molecular weights P which differ very greatly, merely by varying the concen-tration of hydrogen. For example, polymers having molecular weights above 2 million are formed in a polymerization in the absence of hydrogen9 and polymers having molecular weights in the region of 30,000 are formed at hydrogen contents of 70% by volume in the gas space.
The polymers can be f`abricated at high throughput rates by the extrusion and blow-extrusion process to give hollow articles, tubes, cables and films which have smooth ~'' .

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surfaces.
By virtue of a special structural compositlon, the hollow articles and bottles produced from the polyolefins obtained in accordance with the invention are distinguished by a considerable lack of sensitivity to stress cracking.
Furthermore, the process according to the invention makes it possible to prepare, by suspension and gas phase polymerization, free-flowing polymer powders having high bulk densities, so that they can be processed further directly to give shaped articles without a granulation stage.
EXAMP~ES
In the examples which follow, a hydrogenated diesel oil fraction having a boiling range of 130 to 170JC is used for the preparation of the contact catalyst and for the polymerization.
The tit~nium content of the catalysts îs determined colorimetrically (literature reference: GØ Muller, Praktikum der quantitativen chemischen Analyse ["Practical manual of quantitative chemical analysis"], 4th edition (1957), page 243).
The melt index MFI is determined as specified in DIN 53,~735 (E).
The ~w/Mn values are determined from the ~raction-ation data of a gel permeation chromatograph at 130~C,using 1,2,4-trichlorobenzene as the solvent and eluent.
The intrinsic viscosity is determined as specified in DIN 53,728, sheet 4, using an Ubbelohde viscometer, w~th decahydronaphthalene as the sol-~ent.
The density is determined as specified in DIN
53,479 and the bulk,density as specified in DIN 53,468.
Example 1 a) Preparation of Component A
114.3 g of magnesium ethylate were dispersed, under a blanket of N29 in 1.5 1 of a diesel oil fraction in a 3 l ~-necked flask equipped with a dropping funnel, a KPG
! stirrer, a re~lux condenser and a thermometer. 332 g of titanium tetrachloride were added dropwise to this dis-persion at 90C in the course of 2 hours. The product was then w~shed at 100C with diesel oil until the supernatant solution no lor.ger contained any titanium., 57 g of titanium , tetrachloride were then added dropwise at 13~C in the course oE one hour, and the mixture was stirred for a further 40 hours while passing a gentle stream of N2 over ' it.
The reaction product was then washed with the diesel oil fraction mentioned above, ul-til the supernatant 501-ution no longer contained any titanium.
~ After drying9 the solîd (component A) had the c following analytical composition:
Ti 15.7% by weight Mg i3.5~ by weight Cl 54.1% by weight.
b) re-activation of the component A
; 30.5 g of the component A were made up to 150 ml with die~el oil and 100 ml of a solution of aluminum tri-isobutyl, containing 0.5 mole of Al(iC4Hg)3 per 1 l, were I

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added at 20C, while stirring. 40% by weight of the tetra-valent titanium were re~uced to titanium-~III) by this means.
c~ Polymerization of_ethylene in su~ension 100 l of diesel oil, 100 mmoles of aluminum iso-5 prenyl and 5~0 ml of the dispersion described under b) were charged to a 150 l kettle. 5 kg/hour o~ ethylene and sufficient H2 to give an H2 content of 50% by volume in the gas space were then introduced at a polymerization temperature of 35C. After 6 hours, the polymerization 10 was terminated at a pressure of 24.8 bar, by releasing the pressure. The suspension was filtered and the polyethylene powder was dried by passing hot nitrogen over it.
29.4 ~g of polyethylene were obt~ined. This cor-responds to a catalyst activity of 48.2 kg of poly-15 ethylene/g of catalyst solid (cornponent A) or 14.7 kg of polyethylene/mmole of Ti. The polyethylene powder had an MFX 190/5 of 2O0 g/10 minutes. The breadth of molecular weight distribu~ion ~w/Mn was 19,; the MFI 190/15/MFI l90fS
was 8.8. The density of the powder was 0.959 g/cm3 and ~0 its bulk density was 0.44 g/cm3.
Example 2 Polymerization of ethylene in suspension 100 mmoles of aluminum triisobutyl and 1.3 ml of r the dispersion described in Example lb~ were charged to 25 the kettle under the same conditions as those deseribed -in Example lc).

4 kg/hour of ethylene were then introduced at a polymerization temperature of 70C. After 6 hours, the polymerization was terminated at a pressure of 22.4 bar, .~

~2~ 3~3 by releasing the pressure. The suspension was filtered and the polyethylene powder was dried by passing hot nitro-gen over it. 23.2 kg of polyethylene were obtained. This corresponds to a catalyst activity of 146. 2 kg of polyethylene/g of catalyst solid or 44~6 kg of polyethylene/
mmole o~ Ti. The polyethylene powder had an intrinsic vis-cosity of 2,000 ml/g; this corresponds to a molecular weight of 1.6 million. The bulk density was 0.45 g/cm3.
Example 3 I 10 Polymerization of ethylene_in suspension 50 mmoles of diethylaluminum hydride and 12. 5 ml of the dispersion described in Exa~.ple lb) were charged to ¦ the kettle under the same conditions as those described in Example lc)~ 4 kg/hour of ethylene and sufficient H2 to give an H2 content of 70% by volume in the gas space were then introduced at a polymerization temperature of 85C.
¦ . After 6 hours, the polymerization was terminated at a pressure of 24.5 bar, by releasing the pressure. The sus-I pension was filtered and the polyethylene powder was dried by passing hot nitrogen over it. 23.0 kg of polyethylene were isolated. This corresponds to a catalyst yield o* 15.1 kg of polyethylene/g of catalyst solid or 4.6 kg of polyethylene/mmole of Ti. The polyethylene had an MFI 190/5 of 87 g/10 minutes, an intrinsic viscosity of ; 25 120 ml/g, a density of O.g64 g/cm3 and a bulk density of 0.45 g/cm3. The breadth of molecular weight distribution Mw/Mn was 21.

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s Copolymerization of ethylene and 1-hexene in suspension 750 ml of hexane, 5 mmoles of aluminum isoprenyl and 3.1 mg of the component A (Exanple la) were charged to a 1.5 1 steel autoclave. H2, at 6 bar, and ethylene, at 16 bar, were then injected at a polymerization temperature of 85C. Ethylene was subsequently metered in at a rate sufficier.t to maintain a total pressure of 22 bar. 25 ml/
hour o~ 1-hexene were metered in at the same time. The experiment was discontinued after 8 hours. The copolymer ¦ was removed by filtration and was dried in a vacuum drying cabinet. 184 g of copolymer were obtained. Th~s corresponds to a catalyst yield of 59.4 kg of polymer/g of catalyst solid or 18.1 kg of polymer/mmole of Ti. The 15 ethylene/1-hexene copolymer had a melt index MFI 190/5 of 0.52 g/10 minutes and a density of 0.950 g/cm3.
Example 5 _ ~
Copolymerization of ethylene and propylene in suspension 360 1 o~ hexane, 180 mmoles of tetraisobutylalumin-~xan and 31.3 ml of the dispersion described in Example lb) were initially charged to a S00 ml kettle. 17 kg/hour of ethylene, 1 l/hour of propylene and sufficient H2 to set up an H2 content of 4G% by volume in the gas space were then introduced at a polymerization temperature of 85C.
After 6 hours, the polymerization pressure had increased to 7.4 bar and the polymerization was discontinued by re-leasing the pressure. The polymer powder was removed by filtration and dried with hot nitrogen. 101.5 kg of poly-mer were obtained. This corresponds to a catalyst .

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¦ yield of 26.~ kg of polymer/g of catalyst solid or 8.1 kg of polymer/mmole of Ti.
The ethylene/propylene copolymer had a melt index MFI 190/5 of 0.65 g/10 minutes, an MFI 190/lS/MFI 190/5 ratio of 7.89 a density of 0.944 g/cm3 and a bulk density of 0.40 g/cm3 .
Bottles were produced from the powder on a blow-molding machine for hollow articles (extruder screw: D =
.
60 m~). A very high output, 57 kg/hour, was obtained at a screw speed of 40 r.p.m. The bottles had a smooth sur-~ace and exhibited a high resistance to stress cracking of more than 450 hours in the Bell stress cracking test.-Comparison Example_A
a) reparation o~ the component A
j 15 114.3 g of magnesium ethylate were dispersed, under a blanket o~ N2, in 1.5 l of a diesel oil fraction in a 3 l four-necked flask equipped with a dropping funnel, a ¦ ` KPG stirrer, a reflux condenser and a thermometer. 332 g of titanium tetrachloride were added dropwise to this dis-persion at 90~C in the course o~ 2 hours, while passing a gentle stream of nitrogen throu~h the flask. The reaction product was then washed with the diesel oil fraction until the supernatant solution no longer contained any titanium.
After drying, the solid (component A) had the following analyt1cal oomposition:
Ti 4.9% by weight Mg 19.8% by weight Cl 61.3% by weight .. . .. ..... .

b) Pre-activation of the component A
97~8 g of the component A were made up to 150 ml with diesel oil and 100 ml of an aluminum triisobutyl solution containing 0.5 mole of Al(iC4Hg)3 per 1 l were added at 20C, while stirring. 46% by weight of the tetra-valent titanium were reduced to titanium-(III) by this means.
c) Polymerization of ethylene in sus~ension 1 100 l of hexane 9 100 mmoles of aluminum triethyl and 12.5 ml of the dispersion described under b) were 10 charged to a 150 1 kettle. 5 kg/hour of ethylene and sufficient H2 to set up a hydrogen content of 30% by volume in the gas space were then introduced at 85C. After 6 hours, the polymerization was dlscontinued at a pressure of 5.2 bar, by releasing the pre,ssure. 28.6 kg of poly-ethylene were obtained. This corresponds to a catalyst yield of 5.8 kg/g o~ catalyst solid or 5.7 kg of polyethylene/mmole of Ti.
The product had an MFI 190/5 of 1.5 g/10 minutes, an MFI 190/15/MFI 190/5 o~ 5.0, a density of 0.956 g/cm3 and a bulk density of 0.42 g~cm3. The product had a narrow molecular weight distribution: Mw/Mn = 4.5.
When the powder was processed on a blow-molding machine for hollow articles (extruder screw: D = 60 mm), an output of 39 kg/hour was obtained at a screw speed of 40 r.p.m. The bottles had a rou~h surface9 since melt fracture occurred on processing. The resistance to stress cracking of the bottles in the Bell test was 53 hours.
d) Polymerization of ethylene in suspension 100 l of diesel oil, 100 mmcles of aluminum isoprenyl ~,~

. ~ . . ...

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1~ .
. . and 5 ml of the dispersion described under b) were charged to a 150 l kettle. 5 kg per hour of ethylene and sufficient H2 to give an H2 content of 50% by volume in the gas space were then introduced at a polymerization temperature of

- 5 85C. After 6 hours, the polymerization was terminated at a pressure of 25.2 bar, by releasing the pressure. The suspension was filtered and the polyethylene powder was dried by passing hot nitrogen over it.
26.3 kg of polyethylene were obtained. This cor-responds to a catalyst activity of 13.4 kg of poly-ethylene¦g of catalyst solid or 13.2 kg of polyethylene/
mmole of Ti. The polymer powder had an MFI 190/5 of 21 g/
10 minutes. The breadth of moleGular weight distribution Mw/Mn was 5.0 and the MFI 190/15/MFI 190/5 was 5.6. The density of the powder was 0.962 g/cm3 and the ~ulk density 0-39 gtcm3.
~ ~ . .
a) Preparation of the component A
114.3 g of magnesium ethylate were dispersed, under a blanket of N2, in 1 l of the diesel oil fraction in a 3 l four-necked flask equipped with a dropping funnel, a KPG ~tirrer, a reflux condenser and a thermometer.
g O~ titanium tetrachloride were added dropwise at 100C to this dispersion in the course of 2 hours, while passing a gentle stream of N2 through the ~lask. The pro-duct was then washed at 100C with diesel oil until the supernatant solution no longer contained any titanium.
38 g of titanium tetrachloride were then added dropwise at 140C in the course of one hour, and stirring was `

.

1~7~ 3 ~9 . . .
continued for a further 60 hours while passing a gentle stream of ~2 over the mix~ure. The reaction produ~t was then washed with the diesel fraction mentioned above until I the supernatant solution no longer containe~ any titanium.
¦ 5 After drying, the solid (component A) had the ~ollowing analytical composition:
I Ti 5.1% by weight Mg 20.8% by weight Cl 71.7% by weight 10 b) Pre-activation of_the component A
39.9 g of the component A were suspended in 150 ml o~ diesel oil, and 100 ml of an aluminum isoprenyl sol-ution containing O.S mole of aluminum isoprenyl per i 1 were added at 20C, while stirring. 35% by weight of the tetravalent tit~nium were reduced to titanium~(III) by this means.
I c) Polymerization o~ ethylene in suspension 100 1 of diesel oil, 25 mmoles of aluminum tri-isobutyl and 1 ml of the dispersion described under b) were charged to a 150 1 kettle. 5 kg per hour of ethylene and sufficient H~ to give an H2 content o~ 45% by volume in-the gas ~pace were then passed in at a polymerization temperature of 85Co After 6 hours the polymerization was terminated at a pressure of 25.5 bar, by releasing the pressure. The suspension was filtered and the poly-ethylene powder was dried by passing hot nitrogen over it.
~ 8.9 kg of polyethylene were obtained. This corresponds to a catalyst activity of 76.9 kg of polyethylene/g of catalyst solid or 72.3 kg of polyethylene/

.. . . ..

; . ~Lz~7~9e~3 c - 20 m~ole of Ti. The polyethylene powder had an MFI 190/5 of 0.79 g/10 minutesO The breadth of molecular weight dis-¦ tribution Mw/Mn was 18 and the MFI 190/lS/MFI 190/5 was 7~8. The density of the pow~er was 0.957 g/cm3 and its bulk density was 0.40 g/cm3 .
Example 7 a~ Preparation of the component A
142.3 g of magnesium isopropylate were dispersed, under a blanket of N2, in 0.8 i of the diesel oil fraction in a 3 1 four-necked flask equipped with a dropping funnel, a KPG stirrer, a reflux condenser and a thermometer.
949 g of titanium tetrachloride were added dropwise at 75C to this dispersion in the course of 4 hours. The product was then washed at 75~C with diesel oil until the supernatant solutlon no longer contained any titanium.
19 g of titanium tetrachloride were then added dropwis2 at 120C ln the course of hal~ an hour and stirring was continued for a further 60 hours while passing a gentle F stream of N2 over the mixture. The reaction product was then washed with the diesel oil fraction until the super-natant solution no longer contained any titanium.
After drying, the solid (component A) had the following analytical composition:
Ti 4~6% by weight Mg 22.1% by weight Cl 68.5% by weight b) Polymerization of ethylene in suspension 100 l of diesel oil, 50 mmoles of aluminum tri-isobutyl and 521 mg of the catalyst solid described under .
: ,....... .. . .

120t74~3 . - 21 -a) were charged to a, 150 l kettle. 5 kg per hour of ethylene and sufficient H2 to give an H2 content of 50%
by volume in the gas space wer~ then passed in at a poly-merization temperature of 85C. After 6 hours the poly-merization was terminated at a pressure of 25.2 bar, byreleasing the pressure. The suspension was filtered and the polyethylene powder was dried by passing hot nitrogen over it.
28.2 kg of polyethylene were obtained. This cor-responds to a cat~yst activity of S4.1 kg of polyethylene/g of catalyst solid (component A) or 56.4 kP~ of polyethylene/
mmole of Ti. The polyethylene powder had an MFI 190/5 of 3.2 g/10 minutes. The breadth of molecular weight distri-bution Mw/Mn was 16 and the MFI 190~15tMFI 190/5 was 7.5.
15 The density of the powder was 0.957 g/cm3 and its bulk density was 0.39 g/cm3.
Exam~le 8 Pol~merization of ethvlene in the ~as ~hase 500 g of polyethylene powder (MFI 190/5 = 3.5 g/
20 10 minutes and bulk density = 0~40 g~cm3) were initially introduced ~lto'a horizont~ 20 1 reactorequipped with a stirrer operating close to the wall. The reactor was freed from air by being evacuated several times and by flushing with ethylene for several hours and was then warmed to 80C.
50 mmoles of aluminum triethyl and 52 mg of the catalyst component prepared,in accordance with Example 7a) were added to the reactor.
500 g/hour of ethylene and sufficient hydrogen to keep the proportion of hydrogen in the gas space at 30%

~1 by volume during the polymerization were passed ln.
During the reaction time, the pressure rose to 19.8 bar. ) The polymerization was discontinued after 10 hours. 5.3 kg of polyethylene having an MFI 190/5 value of 3.6 g/10 .
minutes were obtained. This corresponds to a catalyst yield of 92 ~g of polyethylene/g of catalyst ~olid or 96 kg of polyethylene/mmole of Tio

Claims (8)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for the polymerization of a 1-olefin of the formula R4CH=CH2 wherein R4 denotes hydrogen or an alkyl radical having 1 to 10 carbon atoms, in the presence of a catalyst composed of the reaction product from the reaction of (A) a magnesium alcoholate with titanium tetrachloride and (B) an organometallic compound of Group I to III of the periodic system wherein component A has been prepared by reacting, in a first reaction stage, a magnesium alcoholate with titanium tetrachloride in a hydrocarbon at a temperature of 50 to 100°C, removing the soluble constituents by washing with a hydrocarbon, suspending the resulting solid in a hydrocarbon and subjecting the solid, in a second reaction stage, to a heat treatment at a temperature of 110 to 200°C, with the addition of titanium tetrachloride for 8 to 100 hours, and freeing the solid from soluble reaction products by washing several times with a hydrocarbon.

2. A process as claimed in claim 1 in which component A is prepared by reacting, in the first reaction stage, a magnesium alcoholate of the formula Mg(OR)2 wherein R denotes identical or different alkyl radicals having 1 - 6 carbon atoms, with titanium tetrachloride in a hydrocarbon at a temperature of 50 - 100°C, then removing the soluble constituents by washing with a hydrocarbon, suspending the resulting solid in a hydro-carbon and subjecting the solid, in a second reaction stage, to a heat treatment at a temperature of 110-200°C, with the addition of titanium tetrachloride for 8 to 100 hours and then freeing the solid from soluble reaction products by washing it several times with a hydrocarbon.

3. A process as claimed in claim 1, in which component A is prepared by reacting, in the first reaction stage, a complex magnesium alcoholate which, as well as magnesium, contains at least one metal of the 1st to 4th main group of the periodic system, with titanium tetrachloride in a hydrocarbon at a temperature of 50 - 100°C, then removing the soluble constituents by washing with a hydrocarbon, suspending the resulting solid in a hydrocarbon, subjecting the solid, in a second reaction stage, to a heat treatment at a temperature of 110 - 200°C
with the addition of titanium tetrachloride for 8 to 100 hours, and then freeing the solid from soluble reaction products by washing it several times with a hydrocarbon.

4. A process as claimed in claim 1, claim 2 or claim 3 in which the 1-olefin is selected from the group of ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene and 1-octene.

5. A process as claimed in claim 1, claim 2 or claim 3 in which the 1-olefin is ethylene.

6. A process as claimed in claim 1, claim 2 or claim 3 in which the 1-olefin is a mixture of at least 70% by weight of ethylene and not more than 30% by weight of another 1-olefin of the above formula.

7. A process as claimed in claim 1, claim 2 or claim 3 in which the polymerization is carried out at a temperature of from 20 to 200°C and at a pressure of 0.5 to 50 bar.

8. A process for the preparation of a polymerization catalyst composed of (A) the reaction product from the reaction of a magnesium alcoholate with titanium tetrachloride and (B) an organometallic compound of Group I - III of the periodic system in which component A is prepared by reacting, in a first reaction stage, a magnesium alcoholate with titanium tetrachloride in an inert hydrocarbon at a temperature of 50 - 100°C, then removing the soluble constituents by washing with a hydrocarbon, suspending the resulting solid in a hydrocarbon, and subjecting the solid, in a second reaction stage, to a heat treatment at a temperature of 110-200°C, with the addition of titanium tetrachloride, for 8 to 100 hours, and then freeing the solid from soluble reaction products by washing it several times with a hydrocarbon.