CA1184167A - Process for the polymerization of 1-olefins - Google Patents

Abstract

Abstract of the disclosure:
In the polymerization of l-olefins using a sup-ported catalyst, the titanium-containing component of which is produced by mixing a magnesium halide, an electron donating compound and a chlorine-containing titanium compound, polymers are obtained with an ade-quately high isotactic fraction, a high bulk density and low fines in very high yield, when, for the pre-paration of the titanium-containing component, the magnesium halide is initially milled together with the electron-donating compound, the chlorine-containing titanium compound is then added and the milling is car-ried out in the presence of a defined amount of an inert solvent.

Description

- 2 ~ HOE 81/F 193 K
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'~le present invention relates to a pr~cess for the polymerization of l-olefins ~hich provides pol-ymers in very high yield, and -thus in which it is possible to - dispense with removal of catalyst residues ~rom the polymerO
Processes for the pol~merization of l-olefins, principally to give crystalline polymers, using certain catalysts applied to supports have been described in a large number of publications.
Ca+alysts which are prepared by the dry milling of magnesium or manganese halides with titanium tetra-halide~electron donor complexes in the absence of dilucnts are kno;m and are employed9 together wi'~'n aluminum alkyls~ for the polymerization of propylene (cf. Germ~n Offenleg~ngsschrift 2~230~672). m e stereo-. specificity of these catalysts is, however, still unsatisfactory and the catalytic yields are no+ high enough for i-t to be ~ossible to leave catalyst residues in the pol~er.
Furthermore, a catalyst system is knc~n which makes possible the polymerization of propylene in a ver.y good yield and wi.-th a high isotactic fraction (cf.
German Offenleg~mgsschrift 2,643~143). Magnesium chlor-ide is milled with an electron-dona-ting compou~d, in parti.cular with an ester o~ an aromatic carboxylic acid, .~uch as ethyl ~en~oa-te. The milled ma+erial is reac-ted with a larger amou~t of titanium te-trachloride. The

3 --catalyst component thus obtained is thoroughly washed with a hydrocarbon. The activator employed is an alu-minum trialkyl in combination with an ester of an aromatic carboxylic acid, such as, for example, methyl 5 4-methylbenzoa-te. m e disadvantage of this ca-talys-t system is the necessity of working with large amounts - i o~ titanium tetrachloride, although only a small amount of titanium is ~ixed~ and the produc-tion of a still larger amount of hydrocarbon wash liquor containing 1~ titanium tetrachloride. Furthermore, the polypropylene obtained with this catalys-t system contains relatively large amounts of fines below 100 ~m.
A process for the preparation of a catalyst has also been described in which -the milling of MgC12 15 with an electron--donating compound can also be carried - out in the presence of inert hydrocarbons (cf. German O~fenlegungsschrift 2,55~,104j~ The subsequent treat ment with titanium tetrachloride and the following washes with hydrocarbon are again associated wi-th the 20 production of excess titanium tetrachloride and wash liquors containing ti-tanium tetrachloride.
Thus, the object of the invention was to flnd a process for the polymerization of l-olefins which, on the one hand9 provides a polymer9 having a sufficiently high isotactic fraction) a high bulk density and low fines, in a yield high enough for it to be possible to dispense with processing the polymer9 and which, on the other hand, is simpler to carry out even for the pre-paration of the catalyst to be used.

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It has been found that it is possible -to achieve this object b3r ini-tia].ly milling a magnesium halide with an electron donor and su~sequen-tly adding the halogen containing titanil~m compound to the milled material and carrying out the milling in the presence o~ a de~ined amoun-t o~ an inert solvent, it bei.ng pos~
sible to increase fllrther the catalytic yield of the catalyst, while keeping the stereospeci~icity constant, and, vice ~ersa, substantially improving the stereo-speci~icity with the same catalytic yield, by addingmodifying agents whi].e millingO
m us, the invention relates to a process lor the polymerization of l-olefins of the formula R~-CH=CH~, wherein R3 denotes hydrogen or an alkyl radi-cal having 1 to 8 carbon atoms, or to the copolymerlza-tion of -these 1 olefins with one ano-ther in the presence of a mixed catalyst, which has been prepared by modi-fication of a magnesium halide with an electron donor, bringing the modified support into contact wi-th a halogen--containing titanivm compound and mixing the ca-talyst component A thus obtained with a halogen-free organo-aluminum compound (component B) and a stereoregulator (component C),which process comprises carrying out the poly-merization in the presence o~ a mixed catalyst; the component A of which has been prepared in a manner such that the magnesium halide was initially milled wi-th the electron donor for 1 to 100 hours, then a chlorine~
containing titanium ~ompound was added and -the batch ~as milled ~or a further 5 tolO0 hours7 1 to 20% by weight, relative to the total amount of thematerial in the mill,of an inert hydrocarbon having been added -to the mat;erial in the mill~
The invention also relates to the mixed ca-ca-lyst to be used for this process and to its preparation.
The mixed catalyst to be used according to the invention is composed of A~ a titanium-containing catalys-t component which has been obtained as a free-flowing milled material from a magnesi~m halide, an electron donor and a chlorine-containing titanium compGund, B) an organoaluminum compound and C) a stereoregulator.
~or the preparation of the catalyst component A;
a magnesi~ hallde is initially milled with an electron-donating compound in the molar ratio of 40:1 to 5:1, preferably 20:1 to 10:1, in a mill for 1 to 100, pre-~erably 3 to 10, hours. For.the milling, all mills are suitable which can transfer suffi.cient mech-anical energy to -the material in the mill, for example vibratory ball mills~ Thenj an amount which is 2- to 0025-~old, preferably 1-- to 0.5-fold9 relative -to the amoun:t of the electron-donating compound, of a chlorine--containing titanium compound is added and milling iscon-tinued ~or 5 to 100, preferably 20 -to 60, hours.
1 to 207 pxeferably 5 to 15~ % by weigh-t, relative to .the total amount of the mat~rial in themill9 ofallinert hydrocarbon are added to the material in -the mill~

~ne addition of the hyd~ocarbon can be carried out at any t me during the millillg process,~r example,together ~ith-the magnesium halide, before, togetherwith or a~ter the elec-tron donor or before, together with orafterthe chlorine containing titanium compound9 preferably, how-ever, together with the electron donor or up to 10 hours thereafterr '~he magnesium halide to be milled is magnesium chloride, magnesium dibromide or magnesium diiodide, preferably magnesium dichloride, which is used in the com~ercia'ly a~ailable anhydrous form. This type of - magnesium chloride generally contains 0.05 to 1% by weight of wa-ter.
E-thers, amides9 amines, esters, ke-tones~ nitriles, 1~ phosphines, phosphinic acid esters, phosphoramides, thio~
ether.s or thioesters are employed as the electron-donating compound. Howe~er, the electlon dona'ing compounds used should contain no hydrogen which is bonded to oxygeny ni-trogen or sulfur.
- Examples of sui-table elec-tron-donating compounds are ~ie-thyl ether,dioxane, anisole9 dime-thylace-tamide7 tetramethylethylenediamine, ethyl aoetate, ace~tone, acetophenone, acetonitrile9 benzonitrile, triethylphos-phine, triphenylphosphine9 isobutyl me-thylethylphosphin~
a-te or hexamethylphosphoric triamide.
Esters of aromatic carboxylic acids, such as ethyl benzoate, methyl benzcate~ me-thyl p-toluateJ ethyl anisate or methyl anisate arç preferably used as the electroll-do~atlng compounds~

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Sui-table c~orine-containing titaniwm compounds are titanjum -tetrachloride, -ti-tanium trichloride or chloroti-tanic esters of -the formulae TiC12(OR)2 and TiCl3(0R)9 wherein R denotes an alkyl radical having 1 to 8 carbon atoms. Titanium tetrachloride and~titanium trichloride are preferably employed.
I It is possible to employ as titanium trichlor-lde both the products which are ob~ained by reduction of titanlum tetrachloride ~ith metal~s, such as aluminum, or with organometallic compounds, for example, a pro-duct obtained by reduction of titanium tetrachloride with al~inur~ having the composition 3TiC13 AlCl~, which can still ~e activated by milling, ard also a titani~
trichloride which is obtained by reduction o~ titanium tetrachloride with an or~anoaluminum compound~ for example, of -the foI~ula AlR23 nXn, wherein R2 deno-tes an alkyl radical having 1 - 10 carbon atoms and X
deno-tes R2 or halogen and n is O to 2.
m e inert hydrocarbon is an aliphatic or aro-matic compound or also a mixture of various compounds.
Exarnples of such hydrocarbons are n- and i-C5-to C12-alkanes, diesel oil frac-tions, kerosine~paraffin oil, white oil, cycloaliphatic compounds, benzene, toluene and ethylbenzene.
The amount of hydrocarbon added should cer-tainly be as large as possible, but it is limlted by the necessity to maintain the free flowing of the material in ~he r~ill and to prçvent the forma-tion of lumps. A con-tent of h~drooarbon wi-thin the scope lndica-ted above has been fo~ld to be advantag:eousc For exa~ple, on wet-milling the cornponents in the abovementi.oned hydro-carbon (about 100,' by t.reight relative to the remaining ma-terial in the mill) 9 a marked decrease in the bulk density and the cacaly~tic yield is observed~ On the other hand, -the hydrocarbon onceadded should not bere--mo~ed again, since this t-ype of "dried" catalys-t component leads to polymerization product.s having a markedly reduced bulk densit.yc The acid halide to be used as a modification agent is derived from an element o~ the groups IIa, IVa~
Va, I~rb and Vb. Halides of Al, Si, Sn, P, Sb and Nb, particula.rly AlC13, Si~14, SnClL~, PC13, SbC 5 5 are preferably usedO These acid halides can be employed as s~ch or as co~plexe~ with elec-tron donors as des cribed previously. The amount of the acid halide is selected so that the molar ratio of halide to -titanium . is 0.1 to 100~ preferably 0.2 to 2. '~he point in tlme of addition of the acid halide during the milling of ~.he other components can be freely selected. The acid halide can be introduced into -the milling vessel both in ~ liquicl and also in a solid form~ I-t is also pos-sible to carry out the milling ln an a-tmosphere of the vapor of the acid halide.
The catalyst componen-t 'according`to -the inven-tiGn can be stored under a pro-tective gas both in the .solid state and a:Lso in sllspension for several months until llsed. Prefera~ly, 'che cata~.ys~ component is employed as a suspension in diesel oil~

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~ L~ 7 Straight-chain an~ bran&hed alumin~ alkyls of the formula AlR2~, in which R2 denotes an a]kyl radical having i to 10 carbon atoms, such as, for example, aluminum trimethyl9 al~.minum triethyl, alu-5 minum triisobutyl and aluminum tri.dli.sobutyl are sui-t-able as the halogen-free organoalumlnum compound (component B). The reaction products of alumi.num tri-isobutyl or aluminum diisobutyl hydride with isoprene, which are commercially available under the name alu-minum isoprenyl 7 are also suitable. Aluminum trie~thyland aluminum triisobutyl are particularly sui-table.
The molar ratio of catalys-t component ~ to catalyst component A is in the range from 5 to 600:1.
m e mixed catal.yst component C is a stereo-regulator which is selected from the group which isformed from cyclopolyenes and electron donors, such as es-ters o~ aromatic carboxylic acids~ esters of phos-phinic acid5 hexamethylphosphor.ic triamide and 1,2-di-methoxybenzene; Of the cyclopolyenes, 1,3,5-cyclo-heptatriene and cyclooc-tatetraene a.re preferred, of -the es-ters of aromatic carboxylic acids, methyl benzoate, e~lyl benzoate, ethyl p-~toluate, methyl p-toluate, ethyl anisate and methyl anisate are preferably used7 and of the esters of phosphinic acid, isobutyl methyl-ethylphosphinate. The compounds can be employed alone or in a mixture, for examples l,3,5--cyclohep~ta~triene and esters of aromatic carbo~Jlic acids or 1,3,5 cyclo-hepta-triene and esters of methylphosphinic acid. The componen-t C can be brough-t to reaction with the mixed -- 10 -- .
catalyst component ~ by mixing before polymerization, and it can also be introduced directly i.nto -the poly merization vQssel. The components A, B and C can also be metered iXl in -the sequence B-C-A, or also in such a manner that initially B and C are dissolved in a liquid - hydrocarbon, a part of this solution is introduced into the polymerization reactor and the remainder of the solution is added to component A and -then the mixture is put into the reactor. The amount of catalyst com-ponent C depends on the amount of catalyst component B.e molar ratio of component B to component C should be greater than 1:1, preferably 1~5:1 to 15:1.
The l-olefins are those of the formula CH2=CHR3, wherein R3 denotes hydrogen or an alkyl radical having 1 to B carbon a-tom~ ylene, propylene, l-butene3 l-pentene, 3-methyl-1-butene, 4-methyl-1-pentene and 3-methyl-1-pentene are pre~erably polymerized wi-th the aid of the catalyst according to the invention9 but especially prop~lene. Apart from homopolymerization~
the mixed catalyst according to the invention is also suitable for polymerization of mixtures of the higher l-ole~ins (C~ and above) with one another and/or with ethyleneS the content of one of the mentioned l-olefins in the mixture being 99.6 to 94% by weight and the con-tent of ethylene being 0.4 to 6% by weight; in eachcase relative to the total amount of monomers. Mix-tures of propylene with small amounts of ethylene are particularly preferred, the ethylene content being 0.5 -~o 5, preferably 1~5 to 39 % by weight. In addition~

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the catalys~ acc.oi~ding to the invention is suitable ior block copoiymerization o~ these l-olefins with one another and/or with ethylene, the content of ethylene being ~ to ~5~o by ~eight9 and preferably for the pre~
paration of block pol~ners of propylene and ethylene.
- 'm ese block polymers are distinguished by a high degree of hardness and an excellent impact streng-th at temper-atures below 0C.
ne polymeri~.ation is carried out continuously or.discontinuously in suspension or in the gas phase ; under a pressure of 1 to 50 b~r, preferably 1 to 40 bar and at a tempera-ture o~ 40 to 160C, preferably 60 to ~OCC
The suspension polymerization is carried ou.-t in an ine-~-t solven+. The ~o]lowing can be used: a pet~
role~n frac-tion of low olefin content having a boiling range from 60 to 250C, from which oxygen~ sulfur com-pounds and moisture must be carefully removed, or saturated aliphatic and cycloaliphatic hydrccarbons, such as butane9 pentane, hexaneS heptane, cyclohexane~
methyl cyclohexane or, for TiCl~-containing ca-talysts, also aromatic compounds, such as ben7.ene5 toluene and . x~lene. The suspension pol~nerization can also be car-ried out advantageously using the l-olefin to be polymerized as a dispersing agent9 ~or example in li.quid propylene.
A fur-ther procedure comprises carrying out the polymerization in the absence of a ~olvent ir. the gas phase ~ th lnitial in.-troducti.on of a previously formed pol.ymer, for example in a fluidized bed.
The molecular weight is adJusted9 where neces-sary, by the addition of hydrogen.
. . ~le advantage of -the process according to the invention is that a ca'talyst is prepared in one pro-cess step, without any produc-tion o.f excess ~itanlum halide or ~Jash liquors J the activity of which is suf-~i.c:iently high to permit catalyst residues to remain in the polymerO The stereospecificity of the catalyst, the bulk density and the ~ines of the polymer formed also ~`ulfil the requiremen-ts of a modern catalys-t system Example 1 lol F~ 7r~ the ca~ t component A
7~o2 g (0.83 mole) o:~ MgC12 (water content 0 05 15 - 1% by weigh-t~ 6.5 g (0.043 mole! of ethyl benzoate and 12.6 ml of n-heptane were milled in a vibratory ball mill having a volume of 0~7 1 alld containing 2~1 kg of V4A steel balls having a diameter of 15 mm. The filling..coeficient was 135 g/l of the total volume.
~he milling temperature set up was be-~een 40 and 70C.
The ini-tial milling time was 6 hours. Therea~ter, 7 89 g (0~042 mole) of TiCll~ were added and mil].ing continued for 40 hours. The filling of the mill wi-th -the produc-ts-to be milled, the milling and the removal of -the catalys~t c'ompo~en-t ~rom the milling vessel were carried out under an a-tmosphere of argon.
1~ 2 Polyrneriz.atlon in ~the liauid monomer 0,2 bar of H2 ~.~as ini-tially introduced in-to a 16 1 s-tirred au-toclave, with'.eY~clusion of air and - 13 ~
moistule and. at room temperature, and the ~ollowing componen-ts were metered in by means of a pressure lock:
40 mmoles of Al(C2H~)3 in ~.2 1 of liquid propylene, 1~.6 mrnoles ofmethyl 4~methylbenzoate in 3.2 1 of liqui.d 5 propylene and then 5.,2 ml of a Sl1Spension of the cata~
lyst componen~t A (= 0.1 mmole of T.i) in 6.2 1 of liquid propyleneO The polymeriza~tion started after a few sec-onds and the con~tents of the vessel were slowly brought to 70C by means of an automatic regulator and then held at this temperat.ure. m e pressure in the vessel ~s 29 bar. After a polymerization time of 1 hour, the ves-sel was cool~d down to room temperature and -the remain-ing propylene was evaporated. The polymer was dried in a vacuum oven at 70Go 1~770 g of polypropylene were o~tained which corresponds to a caialytic yield of 370 kg of PP/g of '~i. The polymer had a bulk densi-ty of 450 g/l and an indentation hardness of 68 N/mrn2.
e 2-_ Poly__r ation in suspension in a diesel oil fraction A 1.5 1 stirred autoclave was filled with 750 ml of a diesel oil fraction (boiling range 1~5 - 170C) under propylene gas. The following were then added con-secutlvely under protective gas: 6.5 rnmoles of tri ethylaluminurn in 6 ml of diesel oil fraction and 2.0 mmoles of rnethyl 4~methylbenzoate in 2 ml of diesel oil and 95.8 ~ng (= 0~04 mmole of Ti) of catalyst componen-t 1.1 suspended in 10 ml of diesel oil fractlonq The propylen~ pressure was arljus-ted to '7 ~ar and -the ~tempera~
-ture -to 70C. The rate of stirring was 1~000 rpm and the polymerizat.ion time was 2 hours.
After completion of polymerizatlon9 the ~res-sure in the autoclave was released and -the polymer was filtered off hot~ The polymer was dried in a vacuum oven at 70C. me yield was 410 g (= 214 kg of PP/g of Ti). The filtra-te was evapora-ted -to dryness in a rot-ary evaporator and 10.1 g of soluble fractions (= 2.4%) were found by weighing the residue~ The polymer had a bulk densi-ty of 420 g/l and an indentation hardness of 75 N/mm2 r Exarnple_~:
Po~_erlza- e,~
O.3 lcg of a previously prepared polypropylene po~der was initially introducedS under exclusion of air and moistv.re, into a hor.izontal 20 1 reac-tor havlng a stirrer sweeping the walls. Then 0.08 bar of H2 were injected and the -temperature was raised to 50C. 40 mmoles of AlE-t3, 12.6 mmoles of methyl 4~methylbenzo-ate and 4.5 ml of a suspensi.on o~ the catalyst componen-t 1.1 (= 0.1 mmole of Ti), each in 0.5 1 of liquid pro-pylene, were -then metered in usin~ a pressure lock.
After -the star-t of polymerization~ th~ temperature ~as allowed to rise to 70C and the internal pressure was maintained a-t 23 bar by continuous subsequent injec-tion of propylene. Af-ter a polymeriza-tion ~time of 1 hour, the reactor was cooled down and the pressure was released~ The polymer was-removed via a bottom valve and dried a-t 70C in vacuo. The yield. was 1,410 g of pol~p~opylene (not including the polypropylene troduced3, corresponding to a catalytic yield o~
295 ~g of PP/g of Ti, bulk density 410 g/l and indenta tion hardness 67 N/mm2.
Comparison experiment A
84 g (0~89 mole) of MgC12, 6.9 g (0.046 mole) - of ethyl benzoateand, a~ter 6 hours add.i-tionally 8.55 g ~Q.045 mole~ of TiC14, were milled without n-heptane in analogy to Example 1.13 ~he polymeriza-tion was carried out in analogy io to Example 1.2~ ~he results are compiled in Table 1, Comparison ex~eriment B
-~ 4 g o~ the catalyst componen-t accordingr to Example 1.1 ~rere dried at a temperature of the hea-ting bath of 60 - 70C and under a pressure of 0.1 mm Hg (about 0.1 mbar) for 5 hours~ The n-hep-tane corlten'~ OI
the catalyst component decreased from 6% by weight to less than 0. 6~o by weight.
The polymerization ~ras carried ou-t in analogy to ~xample 1.2. Ihe results are compiled in Tabl~ 1, xample 4:
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83.2 g ~0.87 mole) of MgC12, 6.75 g (0.045 mole) of.ethyl benzoa-teand 10 ml of diesel oil fraction were milled in a vibratory ball mill for 6 hours (mil-ling conditions as in Example 1.1)~ Then 8.36 g (0.044 Z5 mole) of TiClL~ were added and milling was continued for 40 hours.
~ le polymerization was carried out in analogy to ~xample 1.2. ~ne results are compiled in Table 2.
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~parison experiment C
3.29.5 g (1.36 moles) o~ M~C12, 10~65 g (0.71 mole) of e-thyl benzoate and 5 ml of diesel oll fracti.on, and after 6 hours additionally 12.9 g (0.068 mole) of TiCl49 were milled in analogy to Example 1.1.
- The polymerization was carried out in analogy to Example lo 20 The results are compiled in ~able 2.
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93..6 g (0.98 mole) of MgC12 ~ld 7.95 g (0.053 mole) of ethyl benzoa-te~rere milled in a vi.bratory ball mil~ for 3 hours (for milling condjtions see Example 1~1). ~nen 15 ml of diesel oil fraction were added and milled for ~ hours~ After addition of 9.3 g of TiC14, milling was continued for a fur-ther 40 hours~
The polymerizallon was carried out in analogy to Example 1.2. 2,110 g of polypropylene were obtained which corresponds to a catalytic yleld of 440 kg of PP/g o~ Ti~ m e polymer had a bulk density of ~60 g/l and an indenta-tion hardness of 68 N!mm2.
~0 Ex~ple 6:
-le -ethylene cop~ ization 50 1 of liquid propylene and 0.5 bar o~ 11ydro-gen were ini.-ti.ally introduced at room tempera-ture into a 70 1 stirred autoclave, with exclusion of ai.r and moi.sture, a~d the catalyst components (dilu-ted with a to~tal of 100 ml o~ diesel oil fraction) were added from a lock in the following sequence and -the following amou~-ts: 40 ~oles of aluminum triethyl~ 12.6 mmoles of methyl p~tolua-te and 0.15 mmole (relati.ve to Ti) o f the catalys-t cor.~ponent ~ r~ro~n F~ample 5.
The con.'~en-ts o:f the vessel were~ brou~ht to a tempera~ure o:~ 7CC!C withi.n 15 minutes by applica-tion of hf~at and. were then maintaired a-t this ~'emperature. The pre~ ure insi~ che vessel was 30 bar. A.f:-ter a poly-meri~a-tio~ t.ime c,f 50 minutesS the temperature was educed to 60C within 5 mimltes and suffici.ent et:hyl~
ene was continuously introduced ~or 20 minutes so th~t the -to~al pressure was 35 ~)ar~ The total ~mount ~f 10 eth~lene pa~sed in ~as 2,250 1 (STP). ~he temperature ~ra~ then Ieduced by evaporating t..he ethylene and pro-~ylene ancl '~he pressure in the vessel was thereby adjusted to l.~.i har. '~he liquid propylene was separated of~ ~rom the polymer at I`OOm r,er,lperature using a candle ilter~ e Polymer was th~en again sti.rrcfl wlt.h 30 1 o~ fr~sh li.quld propylene at room ~temperature f.or 30 minute~ and onc;e more separa*ecl of:f using a filter.
29 525 g o~ polymer -IYere ob-taine~ a~ter drying in a vacuwm dr-~ing oven, which corresponds to a catal~ytic 2V ~ of ~51 kg/g o~` Ti~ The polymel7 had a bull~ dens ity of 354 g~l ancl a melt flo~ dex (~FI 230/5) of 7,6 g/minu tv ~ The i.ndentation h.ardness ~ias 5C N/~m2.
The polymer tr.us obtai.ned contained 2206% by weight o~
polymerized e~thylene. The ~ro liqli.d propylene mother liquors s-tlll contained 81 ~ of soluble polymer ~ctio~is.
. . E~.ample 7:
92.1 g (0.9~ .~ole) c.f MgG12 and 10.05 g (0.0~7 mo]e) o.i ethyl benzo~te~ere ~ Lled in a v:3bratory bal.l.

mill for 6 ho-lrs (~or milling concllti.olls see Exc~ple l-1). Then 12.2 g (0. o64 rnole) of TiC14 dissolved .in l~ ml of ~iesel o.il fraction ~Yer~ added and mi].linr, ~tas continued for 40 hours.
750 ml of diesel o.il fraction~ 5 mmo].eso~ tri--- ethylaluminum and 0.01 mmole (rela~ti.ve to Ti) oi the ~atalyst; component A were placed in a 1.5 l steel au-to-clave. ~len, at a poiy~erization tempera-ture of 85C, 3 bar of H2 and 4 ~a~ of ethylene were injected. An amolmt of ethylene was subsequently metered in which main-tained -the total pressure at 7 bar. Af-ter 5 hours, the experiment was terminated~ The polyethylene was separated off by filtration and dried in a vacuum dry-ing oven. lO0 g of polymer were obtained. This 1~ corresponds to-a oata'ytic yield of 4.9 kg Gf polymei^/
g of solid catalyst or lO kg of polymer/~mole of Ti.
The polymer had a bulk densi-ty of 320 g/l, a melt-flow index ~MFI 230/5) ol 6.46 ~ minutes and a S value - ~MMF~ ) f 6Ø
8.1 Pr~paration of the cata~ c~ A
94.5 g (0.99 mole) of MgCl2 ~water con-tent 0.05 - 1% by ~reight) and 15.0 g (0 1 mole) of ethyl benzoate were mi~led in a vibratory ball mill having a volume of 0.7 l and containing 2.1 ~g of V4A steel balls having a diameter o~ 15 mm. The ~illing tempera~
t~lre set up was between 40 and 70C. The ini-Lial milling ti.me was 3 hours~ ~lereafter~ 6 ml of diesel oil ~raction were aclded and milling was carriecl out for _ ~ hours. After t,he addition of G.6 g (0.05 ~ole) o~
a~hydrous AlC13, milling was .conti.nue~ ~or a Lur-ther 20 hours, and a.~-',er the addition of' 9.4 g (0.05 mole) o~
T~ 1L~, milling was continueà for a f1lrther 20 hours.
'~e introductior of.t~e products to be milled into the . ~illS t~e mi.lling and,the removal of ~he catalys'c com-ponent from the milling vessel were carried out under an atmosphe.re of argon.
8.2 ~ rization in_ _ omer lQ . 0.2 bar of H~ was initially introducecl at room temperature into a lG 1 stirred au-tocla~re, with exclu-sion of air and mo.isture; and the following components were metered in by means of a ,pressure lock: 40 ~no'les of Al(C2H5~3 in 3.2 1 of liquid propylene, 12.~ ~oles of methyl 4-me-thylbenzoate in 3~2 1 o., liquid pro~yl.ene and -then 5.2 ml of a suspension of the catalys-t CO~I-ponent A (= O.1 mmole o~ Ti) in 6.2 1 of liqui.d propyl-ene. Polymeri.zat.ion star~ed after a few seconds alld the con-tents of the vessel were slowly brought -to 70~
20 by means of an automatic regulator and then main-taine~.
at this temperature. r~he pres~sure in the vessei was 29 bar~ Af~er a polymerization time of 1 hour~ the ves-sel was cooled down to room temperature and -the remai.n~
ing propylene was evaporated. The poly~ner was dr.ied in a ~acuum oven at 70C', The results of polymerization are listed in Table 3~ ' Exam~].e 9:
94 g (0~99 mole) of ~gC12 and 1l~.9 g (n~10 mole) o~'el,~Jl.ber~zoate ~lere m]lled in a vibra-tory ball. mil3 for 3 hour~ ~f`or milling con~itions see Example ~.1.). Then 6 ml of diesel oil fraction were added and mlll7r3g was carried out for 3 hours. After the additi.on of 6~6 g (0.05 mole) of PC13, milling was continued Yor a fur-ther 20 hours, and after the addition of 9.1 g ~0.05 .- luole) of TiC14, milling was continued :~or a fur-ther 20 hours.
The pol~erization was &arried out in analogy to ~xample 8.2. The resu].ts of p~olymerization are lis~
ted in Table 3.
E~ 0:
51.3 g (0.54 mole) of MgC12 and ~.4 g (o.06 mole) of ethyl ben~atewere milled in a v:ibratory ball mill for 3 hours (for mi.lling condit.ions see Example 15 ~ The~ 4 ml 07~ dlesel oll fraction were add~d and --milling was continued ~or 3 hours. Af-ter the addit:ion of 7.G g (0.03 mole) of tin tetrachloride, milling was continued ~or 20 hours? and after -~he ad.dition o:~ 5.1 g ~0O03 ~ole) of TiC14, milling was con-timled for a ~ur-ther 20 hours.
Polymeriza-tion was carried out in analogy to ple ~.2. ~e resul-ts of ~olymeriza-tion are lis~ted in Table 3.
Exam;e~
56.8 g (0c60 mole) of MgCl and 9.3 g~ (0.06 mole) o~ ethyl benzQa-te were millecl in a vibrato-ry hall mill.for ~ hours (for milllng conditi.ons see Example 801~- Then 4 ml o.i diesel oil f~ ction were added and m..l,.i.ng was continued for 3 hours~ After the adclit;lon , ~ 7.1 -o~ ~0 g 50.G3 I~.ole? o:~ silicon .etrachloride9 milling was continued for 20 hours9 and after -the addition of ~.7 ~ (0003 mcle) of TiCl49 mi.l:l.ing was contin~ed for a :Eux~ther 20 hOUI'S.
Polyme.rization was carr.ied Ollt in analogy to Example Ç~.2. The resu].ts of polymerizaticin are llsted in Ta~le 3.
~a~e ~
~8.2 g (0.61. mole) of ~gC12 and 4.9 g (0.03 mole3 o:E e'~yl ben~oate were milled in a ~ibratory ball . mil'l for 3 hours (for milling conditions see Example - ~.1). Tben i~ ml of diesel oil fraction were added and milling ~!as coniinued for 3 hoursa Af-ter t,he addition of 13.7 g (0.03 mole~ of the complex of antimony penta cl~ioride and e,,~ yl ~enzoate~ milling was continued Ior 20 hour.s, and af-ter the addition of 5,8 g (0,0~ mole) o.~ TiC14, milli.ng was continued for a furt,her 20 hours.
Polymerization ~as carri.ed out in analogy to ~xample 8.2. lrhe re,sults o~ polymeriza-tion are listed 2Q i-r, Table ~. -,Example 1 ;
98~7 g (l.GLL mole) of MgC12 and 1~.2 g (0,11 ~.ole) o~ etllyl.~enzoa-~e were m111ed in a vibratory ball mi].l for 3 hours (for milling conditi.ons see F.~ample ~1). Then 6 ml o~' diesel oil frac ti.on ~/ere added and ~il:Ling ~as contirLued for 3 hours. A.fter the a.ddi-tion 0.~ .o g 50~05 J~ole) of niobi.um pentachloride, rrlllling ~as contimled :Eor 20 hours, and a~ter the addition of 9.8 g ~0.0~ mole) of T:iCl~, rllilling was continued ~or a - 22 ~ t7 .urther ~0 ~n~rs~
Po~ymeri.Zat:iOrl wa5 carriecl QUt in analogy to F,xample ~2. ~.results Gf -polymeri.zation are listed in Ta~].e ~0 , .

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~1 !~ ~ r~-~
G3 ~-4 h ~I ~) Pl h ~1 ¦ Ei ~) r~ r-l Fj E-d¦ rX~ rJ~.l ~ ~1 rI~l ~abl ExampleYield ~atalytic Bwlk Indenta-tiol-. ~ie:ld density 11ardness (P5g of Ti) (s/13 (~/mm~) 2, 270 474 425 'I'l 2 1, ~ 0 385 ~30 83 , 470 511; 430 73

4 2, 060 431 4?~o 80 1, 200 25~ 360 ~3 6 1, 400 293 390

Claims (10)

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

1. A process for the preparation of a polymerization catalyst comprising (A) a magnesium halide which has been modified with an electron donor and contacted with a halogen-containing titanium compound, (B) a halogen-free organoaluminum compound, and (C) a stereoregulator, in which component (A) is prepared by initially milling the magnesium halide with the electron donor for 1 to 100 hours, and adding the chlorine-containing titanium compound and milling the batch for a further 5 to 100 hours, 1 to 20% by weight, relative to the total amount of the material in the mill, of an inert hydrocarbon being added to the material in the mill.

2. A process as claimed in claim 1 in which an acid halide of an element of groups III, IV and V of the periodic table is added to the material in the mill in a molar ratio of acid halide to titanium of 0.1 to 100.

3. A process as claimed in claim 1 in which the mag-nesium halide is magnesium chloride, magnesium dibromide or magnesium diiodide.

4. A process as claimed in claim 1, claim 2 or claim 3 in which the electron-donating compound has no hydrogen which is bound to oxygen, nitrogen or sulfur and is selected from the group of ethers, amides, amines, esters, ketones, nitriles, phosphines, phosphinic acid esters, phosphoramides, thioethers and thioesters.

5. A process as claimed in claim 1, claim 2 or claim 3 in which the halogen-containing titanium compound is selec-ted from the group of TiCl4, TiCl3 and chlorotitanic esters of the formulae TiCl2(OR)2 and TiCl3(OR) wherein R denotes alkyl having 1 to 8 carbon atoms.

6. A process as claimed in claim 1, claim 2 or claim 3 in which the halogen-free organoaluminium compound is selected from the group of straight-chain and branched alu-minum alkyls of the formula AlR2 wherein R2 denotes an alkyl radical of 1 to 10 carbon atoms, and reaction products of aluminum triisobutyl or aluminum diisobutyl hydride with isoprene.

7. A process as claimed in claim 1 in which the stereo-regulator is selected from the group of cyclopolyenes and the group of electron donors.

8. A process as claimed in claim 7 in which the electron donors are esters of aromatic carboxylic acids, esters of phosphinic acid, hexamethylphosphoric triamide and 1,2-dimethoxy-benzene.

9. A catalyst comprising (A) a magnesium halide which has been modified with an electron donor and contacted with a halogen-containing titanium compound, (B) a halogen-free organoaluminum compound, and (C) a stereoregulator, whenever obtained according to a process as claimed in claim 1.

10. A process for the polymerization of at least one l-olefin of the formula R3-CH=CH2 wherein R3 denotes hydrogen or an alkyl radical having from 1 to 8 carbon atoms in the presence of a catalyst as claimed in claim 9.