PH27151A - Catalytic solid which can be used for the stereospecific polymerization of alpha-olefins process for the preparation thereof and process for the polymerization of alpha-olefins in the presence thereof - Google Patents

Description

: - : : . a . 27S) - : The present invention relates to a catalytic solid which can be used for the stereospecific poly- - merization of alpha-olefins, to a process for the preparation of this solid and to a process for the polymerization of alpha-olefins in the presence of this solid.

The stereospecific polymerization of alpha- : olefins such as propylene using a catalytic systems ; which comprises a titanium trichloride-based solid constituent and an activator which consists of an organometallic compound such as an alkylaluminium chloride is known. . Hyperactive solid catalytic complexes based on

TiCl, with a high internal porosity which enable

BN “15 propylene polymers with very good stereoregularity to be obtained have been described in patent BE-A- 78/0,758 (SOLVAY & Cie).

A preactivation treatment of these hyperactive solid catalytic complexes which enables them Lo be stored under hexane for long peripds of time without losing thedr qualities has been described in patent ”

oo. oC : . . EA . ~ . 235

BE-A-80/3,875 (SOLVAY & Cie). The preactivator employed may be chosen from amongst organoaluminium compounds and in particular, depending on formula (1) which specifies their nature, from amongst hydracarby | hydrncarbyl oxyhalides of aluminium.

However , diethylaluminium chloride, ethylaleminium sesquichloride, ethylaluminium dichloride and tri- : ethylaluminium are used in practice. . Unfortunately, the stereospecificity of these catalytic complexes is not adequate under all condi- : tions of polymerization under which they may be re- quired to be used and is inadequate especially at ’ the relatively high temperatures at which the poly- . merization of propylene in the gaseous phase is often carried out, In fact, when polymerization is " carried out at relatively low temperatures, a sig- nificant decrease in productivity of the catalyst is observed.

Attempts have been made to overcome this disad- vantage by carrying out the polymerization of pro- pylene in the presence of catalytic systems which com- prise the hyperactive solid catalytic complexes

CC -4-

. . j a . . , 29151 mentioned above, modified by the introduction of a third constituent, which is generally an electron ) donor compound (Lewis base), into the polymerization medium. A very largg number of electron donor compounds of various types have already been proposed as the third ronstituents capable of increasing the stereo- specificity of these catalytic systems (see for example patent BE-A-82/2,941 (ICI)). Among this very large number of electron donor compounds which can be employed for this purpose, some phenolic compounds (European Patent Application EP-A-0,036, 549 (BASF) and some hydroxyaromatic compounds (US

Patent Application US-A-4,478,989 (SHELL OIL) have, " in particular, been proposed. However, the improve- ment in stereospecificity obtained by the intro- duction of such electron donor compounds into the polymerization medium is significant only when the guantfty. of the electron donor compound is relatively high (the weight of electron donor compound is ge- nerally at least equal to the weight of the solid catalytic complex present in the medium and often ~ much higher). As a result, deleterious secondary eéfects such as av unacceptable drop in the produc- tivity of the catalyst and the appearance of inter-

) . , . _ 29s] fering colours in the polymer collected, not to mention the complications which may be caused by the requirement to removed the residues of the third constituent from the polymer, are observed.

The present invention aims to providing a catalytic solid with a very high stereospecificity, without theeneed for introducing a third constituent into the polymerization medium. ’ "To this end, the present invention relates to complexed titanium trichloride-based catalytic solids which can be used for the stereospecific polymeri- zation of alpha-olefins, preactivated by bringing them into contact with an organoaluminium preacti- vator comprising the product of reaction between an : organoaluminium compound (a) and a compound (b) chosen from amongst hydroxyaromatic compounds, the hydroxyl group of which is sterically hindered.

The complexed titanium trichloride-based solids employed as precursors for the preparation of the preactivated catalytic solids according to the present invention may be obtained by any known pro- cess. The use of solids obtained by processes which -G -

oo oo oo | SHS involve an iniéial reduction of titanium tetrachlo- : ride is generally preferred. This reduction may be ‘carried out using hydrogen or metals such as magnesium and preferably aluminium. Best results are obtained starting with solids produced by the reduction of titanium tetrachloride with an organometallic redu- cing agent. This may, for example, be an organomag- nesium reducing agent. Illowever, the best results are obtained with organoaluminium reducing agents (1).

The organoaluminium reducing agents (1) which may preferably be employed are compounds which con- tain at least ony hydrocarbon radical directly bound to the aluminium atom. Examples of compounds of this type are mono-, di- and trialkylaluminiums, the : . i5 alkyl radicals of which contain from | to 12, and preferably from | to 6, carbon atoms, such as tri- ethylaluminium, fsoprenylaluminiums, diisobutylalu- minium hydride and ethoxydiethylaluminium. With compounds of this type, best results are obtained . 20 with dialkylaluminium chlorides and, in particular, with diethylaluminium chloride. -F

Co 29151

In order to obtain the complexed titanium : trichloride-based solids (hereinafter called '"pre- cursors") which are employed for the preparation of the preactivated catalytic solids according to the present invention, the reduced solids men- tioned ahove are subjected to a treatment with } at least one complexing agent which is generally chosen from amongst organic compounds containing one or more atoms or groups having one or more free electron pairs capable of ensuring the coor- dination with the titanium or the aluminium atoms present in the titanium or aluminium halidds. }

The complexing agent is preferably chosen from the group consisting of aliphatic ethers, and more par- ticularly from amongst those of which she aliphatic radicals contain from 2 to 8 carbon atoms, and preferably 4 to 6 carbon atoms. A typical example . of an aliphatic ether which gives very good results is didsoamyl ether.

These treatments which complexing agents, which are appropriate for stabilizing or for improving the productivity and/or the stereospecificity of catalytic solids, are well known and have been .

. | 2715] comprepensively described in the literature.

Thus, for the preparation of the precursor, the treatment with the complexing agent may consist of a grinding of the reduced solids in the presence of the complexing agent. “It may consist of a thermal . treatment of the reduced solid in the presence of : the complexing agent. It may also consist of washing the reduced solid extractively, in the presence of mixed solvents containing a liquid hydrocarbon com- “10 pound and an. auxiliary polar golwent, for example an ethet. The reduction &f titanium tetrachloride may also be carried out with the organo-aluminium redu- ’ cing agent (1), in the presence of the complexihg agent, for example by adding, to the titanium tetrachloride, : 15 a hydrocarbon-containing solution of the reaction pro- duct of the complexing agent with this reducing agent, i | and the reduced solid thus obtained may then be sub- jected to a thermal treatment in the absence of the complexing agent or in the presence of a fresh quantity complexing agent, which may be identical to or different . from the previous. The treatment with the complexing agent. pay also be accried out with a quantity of the i : latter which is sufficient to form a homogenous solution of the titanium trichloride based solid, and the solid thus dissolved may be reprecipitated by heating. : 5 For the preparation of the precursor, the treatment with the complexing agent may be combined with or followed by an activation treatment. These activation treatments are also well known and have also been described in the literature. They are generally carried out using at least one agent . chosen from amongst inoeranic halogenated compounds, organic halogenated compounds, interhalogenated compounds and halogens. Among these agents, there may be mentioned: ;

As inorganic halogenated compounds, halides of metals and non-metals, such as, for example, titanium and silicon halides;

As organic halogenated compounds, halogenated hydrocarbons such as, for example, halogenated alkanes and carbon tetrahalides;

As interhalogenated compounds, for example

- | | oo 2 iodine chloride and iodine bromide; and

As halogen, chlorine, bromine and iodine.

Examples of agents which are very well suited for the activation treatment are titanium tetrachlo- ride, silicon tetrachloride, iadobutane, monochloro- ethane, hexachloroethane, chloromethylibenzaae, carbon tetrachloride, iudine zhloride and iodine. Best results were obtained with titanium tetrachloride. . ’ The physical form of the complexing agents and the agents which are used for the optional activation treatment 3s not critical for the preparation of the precursor. These agents may be .employed in gaseous form or ian liquid form, the latter being the most- common form in which they are present under usual temperature and pressure conditions. The treatment with the complexing agent and the optional activation treatment may also be carried out in the presence of an iaert hydrocarbon diluent which is generally chosen . from amongst liquid aliphatic, alicyclic and aromatic hydrocarbons such as liquid alkanes and isoalkanes and benzene.

oo | est

Details on the most commonly used operating conditions for the complexation and actrvation treat- ‘meats may be found especially in patent BE-A-86/4,708 (SUMITOMO CHEMICAL COMPANY LTD), in patent US-A- 4,295,991 (EXXON RESBERACH AND ENGINEERING CO) and ia the documents mentioned in the latter. rE

At any time during its preparation, either afte. the reduction or the complexation stage, or after 3 : | the optional activation stage, but preferably after h " the reduction stage, the precursor nay be subjected to a treatment aimed at reducing the friability of the constituent particles thereof. This ‘treatment, which is referred to as "prepolymerization", consists . in bringing the solid into contact with a lower . alpha-monoolefin such as ethylene, or preféeably : propylene, under polymerizing conditions so as to obtain a solid which generally contains between appro- ximately 5 and 500% by weight of "prepolymerized" - alpha-monoolefin. This prepolymerization’ may

Co , 20 -~ddgant ageously be carried out in a suspension of the sedi? in the inert hydrocarbon dileent as defined : oo. above for a period sufficient to obtain the desired oo quantity of the prepolymerized alpha-monoolefin on the s@lid. The precursor obtained according to this

Co | | | - 2315] variaal is less fridble and enables polymers with good morphology to be obtained even when the polymeri- . zation is carried out at a relatively high temperature.

For its conversion into preactivated catalytic solid, as described later, the precursor may be employed as such, i.e. without separating it from the medium in which it was prepared, or, preferably, after separation and optional washing with an inert hydrocar- bon diluenlL as defined abowe.

A preferred method for the preparation of complexed titanium trichloride-based solids which can be used as precursors for the preparation of the preactivated . catalytic solids according to the present invention - has been described in patent BE-A-7B/0,758. This method consists in the reduction of titanium tetrachloride using an organoaluminium reducing agent (1) which, in this case, is preferably a dialkylaluminium chloride, the alkyl chains of which contain from 2 to 6 carbon atoms, under mild conditions. After an optional thermai : 20 treatment of the reduced solid thus obtained, the latter is subjected to a treatment with a complexing agent as defined above. Finally, a treatment with titanium tetrachloride is carried out and the complexed titanium

Co ols] trichloride~-based solid thus formed is separated and it is optionally washed with an inert hydro- carbon diluent as defined above, preferably chosen "from amongst liquid aliphatic hydrocarbons con- taining from 3 to |2 carbon atoms aad which is, moreover the diluent which may be employed through- out the preparatipn of the sald solid.

The preferred preparation methods defined in the preceding paragraph leads tothe complexed titanium trichloride~based solid particles which } are also described in patent BE-A-78/0,758. These aprticles are spherical and penerally have a diameter of between 5 and 100 micreas and most frequently between 10 and 50 microns. They consist of an micropasrticlea,which arc also spherical, which have a diameter of between 0.05 and | micron, most fre- quently between 0.1 and 0.3 micron and which are extremely porous. As a result, the particles have a specific surface area greater than 75 nl/g and most . frequently Jocated between 100 and 250 m?/g and a total porosity greater than 0.15 em3/g and most commonly between 0.20 aad 0.35 em’ /g. The internal porosity of the microparticles forms the most significant contribution to this total porosity of the particles, as evidenced by the high value for the pore volume corresponding to pores less than 200 A in diameter, which is greater than 0.11 cm fy and most commonly between 0.16 and 0.31 3 cn /g.

The complexed titanium trichloride-based solids (precursors) obtained according to the pre- paration method described in patent BE-A-78/0,758, choosing the preferred operating conditions, cor- respond to the formula: . 1 " + a TiCl,. (ALR Cy,) Cy in which R" is an alkyl radical containing from 2 ) 15 to 6 carbon atoms, C is a complexing agent as defined above, x is any number less than 0.20 and y is any number greater than 0.009 and generally less than 0.20.

As an alternative form of this preparation method, there may be mentioned that, mentioned .

above, which consists in "prepolymerizing' the reduced solid, aftar the optional thermal treatment and before \ treatment wilh the complexing agent, with a lower alpha-monoolefin (propylene) under polymerizing condi- tions. This “prepolymerization™ is carried out in a suspension of the reduced solid in the inert hydro- carbon diluent as defined above, belween approximately : 0 , . 20 and 80°C, for a period penerally between I minute and | hour. .

According to the invention, the precursor, which is prepared as described above, is brought into contact i with an organo aluminium preactivator comprising the product of reaction between an organcaluminium compound (a) and a compound (b) chosen from amongst hydroxy- aromatic compounds, the hydroxyl group of which is } i sterically hindered.

The organoaluminium compound (a) is generally . chosen from amongst compounds of formula: - : . X. .

Al ®n 3-n in which R represents hydrocarbon radicals, which may be identical or different, containing from to 18 carbon atoms, chosen in particular from amongst = 16 = . BAD r

BAD ORIGINAL ¢}

27 (51 alkyl, aryl, arylalkyl, alkylaryl, cycloalkyl, alkoxy and aryloxy radicals; X is a halogen and n is a number such that 0<n < 3.

In the ahove formula, R is preferably a straight- chain or branched alkyl radical containing from 2 to 8 carbon atoms, X is preferably chlorine and n is : . preferably such that I< n <3. .

As exanples of compounds (a), there may be men- . tioned: trialkylaluminiums such as trimethyl=-, tri- ethyl-, tri-n-propyl-, tri-n-butyl-, tri-isobutyl-, tri-n-haxyl-, tri-isohexyl-, tri-2-methylpentyl- and tri-n-octylaluminium; dialkylaluminium monohalides such as diethyl-, di-n-propyl- and di-iso-butylalumi- . nium monochlorides, ethylaluminium mono fluorides, monobromides and monoiodides; alkylaluminium di- and sesquihalides such as methyl- and ethylaluminium } sesquichlorides and ethyl- and isohutylaluminium di- chlorides; alkoxyaluminium halides such as methoxy- aluminium and iso-butoxyaluminium dichlorides; alkoxyalkylaluminiums such as monvetheikydiethylalumi- nium, diethorymonoethylaluminium and dihavanesoxymono- n-hexyl-aluminium. i oo oo Ces

Vers good results were ohtained with trialkyl- ~ aluminiums and dialkylaluminium chlorides, in particular with triethylatuminium and diethylaluminium monochloride.

The compound (b) is chosen from amongst hydroxy- aromatic compounds, the hydroxyl group of which is sterically hindered. "Hydroxyaromatic compound, the hydroxyl group of which is sterically hindered" refers to all hydroxyaromatic compounds which contain a secondary or tertiary alkyl radical in the two ortho positions relative to the hydroxyl group.

The compound (bh) is geherally chosen from amongst substituted mgno- or polycyclic hydroxyarylenes as mentioned above, in particular from amongst hydroxy- henzenes, hydroxynaphthalenes, hydroxyanthracenes and hydroxypenanthrenes thus substituted, ‘and the aromatic : rings of which may also carry other substituents. : As examples of compounds (b), there may be men- tioned: monocyclic monophenols which are di-tert- and . di-sec-alkylated in the ortho positions relative to the hydroxyl group, such as 2,6-di-tert-butylphenol,

A

- 18 - AD ORIGIN" F oo oo oo C97] . 2,6-di~tert-butyl-4-methylphenol, 3,5-tert-butyl- 4-hydroxy- d -hydroxybenzene, 2,6-di~tert-decyl-4- . methoxyphenol, 2,6-di-tert-butyl-4-isopropylphenol, 2,6-dicyclohexyl-4-methylphenol, 2,6-diisopropyl- 4-methoxyphenol and 2,6~-di-tert-butyl-4-sec-butyl- phenol } 3-(3',5 ~di~tert-hutyl-4-hydroxyphenyl)propio- nic acid monuesters such as methyl, ethyl, n-propyl, _ n-butyl, n-ocytl, n-dodecyl and n~octadecyl 3-(3', 5'-di-tert-butyl-b-hydroxypheny!)propisnaces; . polyphenols which are di-tert-alkylated au the ortho positions relative to the hydroxyl groups, such as 2,2-bis(2,6-di-tert-butylhydroxyphenyl)propane, : bis(3,5-di-tert-butyl-4-hydroxybenzyl)methane, 4,4'~

I5 methylene-bis(2,6-di-tert-butyl)phenol, 2,2'-methylene- his(4-ethyl-6-tert-butyl)phenol, 1,3,5~trimentyl-2,4, 6,bis(3,5-di-tert-butyl-4-hydroxybenzyl)benzene and tris(2,6-di-tert-hexylhydroxyphenyl)benzene; 3-(3',5'-di-tert-butyl-4-hydroxyphenyl)propionic acid polyesters such as tetrakis[{methylene-3-(3',5'~ di-tert-butyl-4"'-hydroxyphenyl)propionate Jmethane.

oo | Cogs polycyclic monophenols which are di-tert- and i di-sec-alkylated in the ortho positions relative to the hydroxyl group, such as 1,3-di-tert-hutyl-2- hydroxyanthracene, l,3-di-tert-hexyl-2-hydroxy- phenanthrene, 2. 8-di-tert-butylhydroxynaphthalene, ’ 1,3-di~tert-hexyl-2-hydroxynaphthalene and !,3-diiso- amyl-2-hydroxynaphthalene.

Very good results were obtained with di-tert- alkylated monocylic monophenols, in particular with 2,6-di-tert-butyl-4-methylphenol and with 3-(3',5'- di-tert-butyl-4-hydroxyphenyl)propionic acid mono- esters, in partticular with n-octadecyl 3-(3',5'- di-tert-butyl-4-hydroxyphenyl)propionate, the use of ) the latter giving an excellent stereospecificity to 5 the catalytic solids prepared using it.

The general conditions under which compound (a) is brought into contact with compound (b) are not : critical insofar as they induce a chemical reaction : between these compounds. The reaction is generally carried out in the liquid phase, for example by mixing compound (b) and compound (a) in the absence of a } liquid diluent, compound (a) often being liquid under normal temperature and pressure conditions. It is also possidle to work in the presence of an inert hydrocarbon diluent as defined above.

The molar ratio in which compound (a) and - 5 compound (b) are brought into contact with each other may vary Lo a large extent. In general, 50 to 0.1 moles of compound (a) are employed per mole of compound (b); the quantity of compound (a) employed . 1s preferably between 15 and 0.5 moles per mole of . compound (b); very good results have been recorded for molar ratios of compound (a) to compound (b) of between approximately 3 and I. : Compounds (a) and (b) may be brought into con- tact with each other at temperatures generally between approximately 0 and 90°¢c, preferably at a temperature in the vicinity of ambient temperature (25°C) and the mixture thereof is maintained for a period suffi- cient for them to chemically react with each other, which is generally between 5 minutes and 5 hours.

A 20 This reaction is moet often accompanied by a gas evo- lution which enables its progress to be monitored.

. The exact chemical structure of the product . of reaction between compounds (a) aad (b) is not known with certainty. However, it is almost certain that this product correspends at least partially to the empivical formula:

R Al(OR' X p MOR (peg) in which: . R, which has the meaning given above, represenls the same hydrocarbon radical(s) ad that (those) contained in the organoaluminium compound (a);

OR' represents the aryloxy group derived from compound f(b); . X is a halogen}

P is a number such that O0¢p ¢3, preferably ’ : v 16 such that 0.1 <p £ 2.5; q is a number such that 0<q { 2, preferably . such that 0.5 € q € 1.5; and the sum (p+q) being such that 0¢ (p+q) < 3.

According to the invention, the organocaluminium preactivator obtained as described above is brought into contact with Lhe precursor.

The operating conditions under which the pre- activator is brought into contact with the precursor are not critical insofar as they bring about at least "a partial binding of the preactivator to the said precursor.

Providing this condition is met, this contacting may be carried out by any known process. - This con- tacting may be carried out, for example, by grinding the precursor which is impregnated with a liquid phase containing the preactivator. . 15 The preactivator is most often employed in the fore of a solution of the following in the inert hydfocarbon diluent optionally employed for the pre- paration thereof} ’ (1) the reaction product of compound (a) with compound (b) possibly accompanied by :

————————————— ee ————————————— er

SUS

(2) the unreacted excess of compound (a) or of compound (b) employed.

Ia this case, it is preferable to jntroduce the sreactivator solution containing ingredient (1) and possibly ingredient (2) into a suspension of the precursor jn this same hydtocarbon diluent.

This suspension is then generally maintained at a - temperature hetween 0% and the anormal boiling point of the inert hydrocarbon diluent in which the preactivator was dissolved, preferably between ‘approximately 20 and 40°¢, for a period generally between approximately 5 and approximately 120 minutes, preferably between 15 ani 90 minutes. The respec- tive quantities of precursor and preactivator employed are such that the molar ratio between the ‘ total initial quantity of compound (a) employed and the quantity of TiCl, preseat in the precursor is generally between TO and 10, preferably between 1072 and }. Very good results are obtained when the molar ratio defined above is between 0.05 and 0.5.

AL the end of this preactivation stage, the

I | 241%] . catalytic solid thus preactivated is separated from . thenpreactivation medium and washed in order to remove the residues of unbound preactivator, preferably " using an inert hydrocarbon diluent of the same type

I) as those optionally employed for the preparation ’ of the precursor ‘and Lhe preactivator solution.

The preactivated, separated and washed cataly- | ’ tic solid may then he dried, if required. For example, it may be dried until the residual liquid hydrocar- : 10 © bon diluent content thereof is less than 1% by weight, preferably less than 0.5% by weight relhetive to the welght of titanium trichloride it cc-tains, according to the operating conditions described in the patent

BE-A-86/6,911 (SOLVAY & Cie).

The preactivated catalytic solid thus obtaihed always contains a certain amount of preactivator which is bound to the solid and which cannot be i dissociated from the latter by purely physical sepa- ration methods. The quantity of preactivator in this form is generally between 5 and 500 g per kg of . : TiCl, present in the solid and preferebly between oo | ag] 50 and 300 g/kg. Consequently, the preactivated catalytic solid according to the javention contains less TiCl per unit weight than the solid used as precursor for its prepavation. Although the pre- activated catalytic solid generally contains at least 50% by weight of TiCl, relative to the total weight, it rarely contains more than approximately 80% of the latter.

The external morphology of the preactivated catalytic solid particles according to the invention is ao different from that of the particles of pre- cursor used in their preparation. Thus, when they : are prepared starting with spherical particles consisting of an agglomerate of porous spherical microparticles, they have substantially the same structure, the same dimensions, and the same shapes as the particles used at the start. However, the preactivated cataljtic solid particles are less B porous, i.e. they are no longer characterized by the high specific surface area associated with the high pore volume which characterizes the particles of the precursor. .

CL o- 26 -

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After being washed and optionally dried, the preactivated catalytic solids according to the invention may immediately be brought into contact again with an inert hydrocarbon diluent such as those : 5 defined above, which can also be used as diluents in suspension polymerization. The preactivated "catalytic solids according to Lhe invention may also be subjected to a "prepolymerization" treatment as ~ described above in connect ion with the precursor. :

They may be stored in hexane or in the dry form, pre- ferably in the cold state, for long perinds of time without losing their qualities.

For polymerization, the preactivated catalytic } solid according to the inventian is employed together with an activator chosen from amongst organometallic compounds of metals of groups Ia, Ila, IIb and IIIb of the Periodic Table (version published in Kirk-

Othmer Encyclopedia of Chemical Technolopy, 2nd completely revised édition, volume 8, 1965, page 94)and preferably from amongst the compounds of formula: . : Al R*''m Y3-m

} ie which R''' is a hydrocarbon radical containing from |! to 18 carbon atoms and preferably from to 12 carbon atoms, chosen from amongst atkyl, “aryl, arylalkyl, alkylaryt and cycloalkyl radicals; best results are obtained when R''' is chosen from amongst alkyl redicals containing from 2 to 6 carbon atoms;

Y is 2 halogen chosen from amongst fluorine, chlorine, bromine and iodine; best results are ob- tained when Y is chlorine; m is any number such that O0¢m ( 3 and preferably such that 1.5 < m & 2.5; best results are obtained when m is equal to 2. .

Diethylaluminium chloride (DEAC) ensures maxi- mum activity and maximum stereospecificity of the catalytic system.

The catalytic systems thus defined can be i applied to the polymerization of olefins with termi- nal unsaturation, containing from 2 te 18 and preferab- ly from 2 to 6 carbon atoms in the molecule, such } as ethylene,propylene. l-butene, I-pentene, methyl-

-butene, I-hexene, 3- and 4-methyl~1-pentenes and vinylcyclohexenes. They are particularly useful in the stereospecific polymerization of propylene, l-butene and 4-methyl-l-pentene into highly iso- tactic, crystalline polymers. They can also be applied to the copolymerization of these alpha- olefins between one another as well as with di- olefins containing from 4 to 18 carbon atoms. The diolefins are preferably unconjugated aliphatic "diolefins such as !,4-hexadiene, unconjugated mono- cyclic diolefins such as 4t-vinylcyclohexene, ali- cyclic diolefins having an endocyclic bridge, such as dicyclopentadiene, methylene- and ethylenenor- bornene and conjugated aliphatic diolefins such as butadiene or isoprene.

They also be applied to the manufacture of the so-called block copolymers which are formed starting with alpha-olefins and diolefins. These block copolymers consist of successions of chain segments of variable lengths; each segment consists of a homopolymer of an alpha-olefin or of a random copolymer containing an alpha-olefin and at least one comonomer chosen from amongst alpha-olefins and oo | oo oo oH] \ diolefins. The alpha-olefins and the diolefins are chosen from amongst those mentioned above.

The preactivated catalytic solids according to the invention are particularly well suited to the manufacture of homopolymers of propylene and copo- . ’ lymers containing in total at least 50% by weight © of propylene and preferably 752 by weight of propy- lene. C :

The polymerization may be carried out according to any known process: in solution or in suspension in a solvent or in an inert hydrocarbon diluent, such . as those defined in connection with the preparation of “he catalytic solid and which is preferably chosen from amongst butane, pentane, hexane, heptane, cyclo- 13 hexane, methylcyclohexane or mixtures thereof. The polymerization may also be carried out in the monomer ’ or with one of the monomers maintained in the liquid state or in the gaseous phase. The use of the pre- . ‘ activated catalytic solids according to the invention is very advantageous in polymerization in the gaseous phase. In fact, inso-far as the appearance of amor- phous and sticky by-products is particularly harmful ‘ in this type of polymerization, the technology of which

J3151 } . does not enable them to be removed, the use of highly stereospecific catalytic systems is parti- cularly advantageous.

The polymerization temperature is chosen generally between 20 and 200°C and preferably between 50 and 90%, the best results being obtained between 65 and 85°C. The pressuie is chosen generally bet- } weenatmospharic pressure and 50 atmospheres and prefer- ably between |0 and 30 atmospheres. This pressure depends, of course, on the temperature employed. . The pdlymerization may be carried out in contin- uous or discontinuous fashion.

The preparation of the so-called block copoly- ’ mers may also be carried out according to known pro- cesses, The use of a two-stage process which consists in polymerizing an alpha-olefin, generally propylene, according to the method described above for homopoly- merization, is preferred. The other alpha-olefin and/or diolefin, generally ethylene, is then polymerized in the presence of the homopolymer chain which is still active. This second polymerization may be carried

2A

N out after the complete or the partial removal of the monomer which has not reacted during the first . stage.

The organometallic compound and the preacti- “5 vated catalytic solid may he added separately to . the polymerizatiom medium. They may also be brought into contact with each other, at a temperature of between -40 and 80°c, for a period which depends } on this temperature and which may range from an hour to several days, before introducing them into the : polymerization reactor. .

The total quantity of organometallic compound employed is not criticaly it is generally greater than 0.1! mmol per litre of diluent, of liquid monomer, or of reactor volume, preferably greater than 0.5 - | nmol per litre. . The quantity of preactivated catalytic solid employed is determined according to the TiCl, content thereof. 1t is generally chosen so that the concen- tration of the polymerization medium is greater than 0.01 mmol of TiCl, per litre of diluent, of liquid oo oo 9451 monomer or of reactor volume and preferably greater than 0.05 mmol per litre.

The ratio hetween the quantity of organome- . tallie compound and that of the preactivated cata-

Iytic solid is not critical either. It is pgene- rally chosen so that the molar ratio organometallic compound: TiCl, present in the solid is between 0.5:1 and 20:1 and preferably between 1:1 and 15:1}.

Best results are obtained when the molar ratio is : 10 between 2:1 and 12:1.

The molecular weight of the polymers manufac- tured according to the process of the invention may be adjusted by adding to the polymerization medium one or more molecular weight-adjusting agents such as hydrogen, diethyl! zinc, alcohols, ethers and alkyl halides.

Ths stereospecificity of the preactivated cata- . lytic solids according to the invention is higher than that of the catalytic complexes described in : 20 patent BE-A-78/0,758, when they are prepared from the latter. Additionally, this stereospecificity oo As remains unchanged over very long periods of time, even when the preactivated catalytic solids are ’ stored at a relatively high temperature. Therefore, when they are employed, there is no longer any need to add to the polymerization medium a third : constituent which is conventionally known as im- proving this stereospecificity, such as, for example, an ether or an ester. It is self-evident that such addition of a third constituent to the polymerization medium containing a preactivated catalytic solid . according to the invention does not constitute a departure from the stope of the latter; however, such an addition leads, at the very most, to only a margi- nel improvement in steveospecificity.

During the homopolymer ization of propylene in the presence of the preactivated catalytic solids according to the invention, the proportion of amorphous polypropylene, determined by measuring the weight of polypropylene soluble in boiling heptane relative to the salid polypropylene manufactured during the polymerization, is almost always less than 3%. ~~ This property is conferred to the solid polypropylene manufactured, even when the preactivated catalytic solid has been stored at high temperature (45°C) ~ for several weeks. } The following examples serve to illustrate the invention.

Tue symbols used in these examples have the following meanings:

I.I = isotacticity index of the polymer, determined

Co by the fraction of the latter, expiessed as a percentage relative to the total quantity of solid polymer collected, whiéh is insoluble in boiling heptane. ’

G = torsional modulus of rigidity of the polymer, ' determined at 100°C and at a torsion angle of 60° of arc, the temperature of the mould being fixed at 70°C and the period of conditioning at 5 minutes (standards BS 2782 - part I - method 150A; ISO 458/11, method B; DIN 53,447 and ASTM D 1043). This modulus is expressed ) in daN/cm"™.

MFI = melt flow index determined under a load of

2.16 kg at 230°C and expressed in g/10 min (AST! standard D 1238).

AD = apparent density of the insoluble polymer fraction, determined by packing and expressed in g/l. d = catalytic activity, usually expressed in grams of insoluble polymer in the polymeriza- tion medium, obtained per hour and per gram of TiCl, contained in the preactivated cata- 1a lytic solid.

Example

A - Preparation of the precursor (complexed “titanium trichloride-based solid) 90 ml of dry hexane and 60 ml of ipure rict, }5 are introduced, under a nitrogen atmosphere, into an : 800-ml reactor equipped with a twin-blade stirrer, rotating at 400 rpm. This hexane-TiCl sclution is . cooled to 0 (+ 1%. Within 4 h, a solution congzs- ~ ting of 190 ml of hexane and 70 ml of diethylaluminium chloride (DEAC) is added thereto, while maintaining

} i . IHS] \ \ a temperature of 0 (+ 1)°C in the reactor.

After the addition of the DEAC-hexane solution, the reaction medium consisting of a suspension of fine particles is maintained stirred at | ( + 1% for 15 min and then heated, in the course of | h, to 257°C and maintained at this temperatuve for h and then heated, in the course of | h, to appro- ximately 65°C. The medium is maintained stirred for 2 h at 65°C.

The liquid phase is then separated from the solid and the solid product washed with 7 x 200 m! of dry hexane, the solid being resuspended during each washing.

The reduced solid thus pbtained is suspended in 456 ml of diluent (hexane) and 86 ml of diisoamyl ether (DIAE) are added thereto. The suspension is stirred for | h at 50°C. The solid thus treated is then separated from the liquid phase.

The latter solid is resuspended in 210 ml of . = hexane and 52 ml of TiCl, are added thereto; the sus-: : pension is maintained stirred (150 rpm) at 70°C for

2 h., The liquid phase is then removed by filtration and the complexed titanium trichloride-based solid is washed with 14 x 270 ml of hexane. :

B - Preactivation © 70 g of the complexed titanium trichloride-based solid (containing approximately 820 g of TiCl,/kg) suspended in 280 ml of hexane are introduced into an 800-ml reactor equipped with a blade-stirrer rotating at 150 rpm. 120 ml of a solution, in hexane, of a preactivator (hereinafter called preactivatér-A), prepared beforehand by mixing 80 g of DEAC (compound (a)) and 176.2 g of n-octadecyl 3-(3',5'~-di-tert-butyl- 4~hydroxyphenyl)propionate, marketed under the name

Irganox 1076 by CIBA-GEIGY (compound (b)) per litre of hexane, are introduced slowly (30 minutes) into this reactor. Thus, the molar ratio between compounds (a) and (b) eaployed in preparing the preactivato? is 2 and the molar ratio between the preactivator A and the complexed titanium trichloride~-based solid (expressed as moles of compound (a) initially employed per mole of Tic), present in the solid) is 0.2.

r

The preactivator solution is introduced into the reactor only after 15 minutes from Lhe time when the jas evolution observed during mixing compound (a) and compound (bh) ceases.

The suspension to which the preactivator A has thus been added is maintained for | hour at 30°¢C, with stirring.

After decantation, the resulting preactivated ‘ catalytic solid is washed with 5 x [00 ml of dry hexane, the solid being resuspended during each washing, and then dried by sweepiag with nitrogen ia a fluidized bed for 2 hours at 70°C. ‘The preactivated catalytic solid thus obtained contains 641 of TiCl,, 12 g¢ of aluminium, 31 g of

DIAY and a quantity, which js estimated to be appro- ximately 250 g, of the preactivator A, per kg. c - Polymerization of propylene in suspension . in the liquid monomer, in the pressence of ’ the preactivated catalytic solid

The following are introduced, while being swept with nitrogen, into a 5-litre autoclave which has previonsly been dried and maintained under a dry nitrogen atmosphere:

A00 me of DREAC (in the form of a 200 g/l solu- tion in hexane) marketed by SCHERING (the Cl:Al atom ratio is adjusted to 1.02 by adding ethylaluminium dichloride); 100 ma of preactivated catalytic solid (the : molar ratio between Lhe DEAC and the TiCl, present in the solid is thus approximately 8); . hydrogen at a partial pressure of | bar; and 31 of liquid propylene. | .

The reactor is maintained at 65°C with stirring for 3 hours. The excess propylene is then degassed : and the polypropylene (PP) formed, which amounts to 643 g of dry polypropylene, is collected.

The activity (of the preactivated catalytic . solid is 3340; the productivity amounts to 5430 g of polypropylene/s of preactivated catalytic solid.

This polypropylene has the following charac~ teristics!

1.1 = 98.17% 2

G = 678 dali/cm ‘MFI = 3.16 g/10 min -

AD = 510 ofl.

Examples IR to SR ) These examples are given by way of comparison.

Example IR

A complexed titanium trichloride-based solid : is prepared as described in Example 1, part A, without preactivating it as mentioned in part B of this example.

This solid, dried as mentioned in Example |, contains B11 g of TiClg, 2.8 p of aluminium and 61 g of DIAE. .

A polymerization trial is carrjed out in the presence of the solid thus obtained, which is not preactivated, under conditions strietly comparable to those defined in Example !, part C. 785g of dry PP are collected at the ead of this trial.

The activity ([ is therefore 3230 and the productivity amounts to 7850 g of PP/g of solid.

This polypropylene has the following chavacteris- tics:

I.I = 94.97

GC = = 577 daN/cm2

MFI = 7.3 g/10 min

AD = 490 g/l.

The significant differences in the fractions ’ insoluble in boiling heptane and in the modules G respectively of the polymers obtained under compavable coaditions accordiag to Examples | and IR are proof . of the higher stereospecificity of the catalytic ' systems which contains the preactivated catalytic : solid of Example |. . 13 Example 2R

A complexed titanium trichloride-based solid . prepared as described in Example |, part A, is : preactivated with a solution which coatains only compound (b). A partial dissolution of the solid is observed, which solid is, moreover, in the form of very [ine particles. The polymerization trial,

ssl : carried out as mentioned ian Example 1, part C, is repeated with a quantity of catalyst such that it contains approximately 70 mg of TiCl,. : : 535 g nf PP are obtained, which corresponds to ap activity fof only 2550. This PP js in the form of fine particles and its AD is only 100 g/}, : which excludes the possibility of using it.

Example 3R

Example |, parts A and B, are repeated, the only exception being that the suspension of the oo complexed titanium trichloride-based solid is treated in sequence, first with a solutjon of compound (a) in hexane and then, 15 minutes after the addition

Co of the solution of compound (a) is complete, with a solution of compound (b) in hexane. The values for the molar ratios between compounds (a) and (b), which are added separately, and between compound (a) and the quantity of TiCl, present ia the solid, are 2:1 aad 0.2:1 respectively. the catalytic solid collected contajns 757 g/kg of TiCl,. - 43 - : . | } oo aro ORIGINAL > : \

HS

The polymerization trial, carried out as mentioned in Example 1, part C, only enables a polypropylene in the form of blocks, which cannot be used, to be collected with an activity (of 3000. ’

Example 4R

Example 3R is repeated, but veversing the se- . ’ quence of introduction of the solutions of compounds (a) and (b). the same phenomenon as in Example 2R is observed, i.e. a partial dissolution of the solid.

The polymerjzation trial, carried out as des- cribed in Example 1, part C, only eaables a polypropy- : lene in the form of very fine particles, with an AD of only 200 g/l to be collected with an activity of of 3450, which excludes the possibility of using it.

Example 5R

The complexed titanium trichloride-based solid prepared as described in Example IR (i.e. not pre- activated) is employed in a polymerization trial carried out as described in Example |, part C, with the exception that in addition to DEAC, the solid, hydrogen and propylene, the product Irganox 1076 oo oo a » is introduced into the polymerization medium in a quantity such that the molar ratio between this product and the TiCl, present in the solid is appro- ximately 0.2.

A PP caharacterized by the following properties . is obtained, with an activity << of 3286. 1.1 = 95.27% : :

G - 575 daN/cm’

MFI = 5.2 g/10 min ’ 10 AD = 505 g/1.

Example 2

A preactivated catalytic solid is prepared as ) . mentioned in Example |, parts A and B, except that the product Irganox 1076 is replaced with 2,6-di- tert-butyl-4-methylphenol, marketed under the name

Ionol CP by SHELL.

The preactivated catalytic solid thus obtained contains 632 g of TiCl,, 14 g of aluminium, 30 g of

DIAE and a quantity of preactivator, which is esti- 28 mated to be approximately 170 g per kg. It is employed in carrying out a polymerization trial under oo oo a7] . the conditions of Example 1, part C.

This trial enables a polypropylene with the ‘following characteristics to be collected, with an ‘ activity j of 3230: 1.I = 95.9%

G = 653 daN/cm?

MFI = 9 pg/10 min

AD = 500 g/l.

Example 3 : A preactivated catalytic solid prepared as mentioned in Example |, parts A and B, is used in a trial for the bolymerizat lon of propylene in sus- pension in hexane under the operation conditions described below. | litre of dry and purified hexane is introduced into a 5-litre stainless steel autoclave which has been purged several times with nitrogen. 400 mg of DEAC (in the form of a 200 g/1 solution in hexane) and a quantity of catalytic solid equivalent to appro- ximately 51 mg of TiCl, are then introduced in sequence.

The molar ratio DEAC:TiCl, is there approximately 10.

oo SE os

The autoclave is heated to 65°C and the pressure is returned to atmospheric pressure by a slow degassing. An absolute hydrogen pressure of 0.3 bar is then set up therein and propylene is then ini.oduced into the auraoclave until a ' total pressure, at the temperature concerned, of } } 11.9 bars is obtained. This pressure is main- tained constant during the polymerization by introducing gaseous propylene.

After 3 hi, the polymerization is stopped by degassing the propylene.

The contents of the autoclave are poured onto a Buchner filter, rinsed with 3 x 0.5 1 of hexane . and dried under reduced pressure at 60°C. 251 2 of hexane~insoluble PP are collected. 0.75 g of . 0 soluble polymer, which corresponds to 0.3%, is found in the hexane used in the polymerization and in the washing. The activity «4ig 1643. The productivity amounts to 3157 g of PP/g of preactivated catalytic solid. - 47 - py a0 CRIGINAL p )

The hexane-insaluble PP has the following properties: 1.1 = 98.27%

G - 654 dati/cm’ * MFI = 2.9 2/10 min

AD - 503 g/1.

Example 6R

This example is given by way of comparison.

A polymerization trial is carried out under the same conditions as in Example 3, in the presence of catalytic solid prepared as mentioned in Example 3, but leaving out the preactivation stage, and containing 735 g/kg of TicCl,. A PP, 1Z of which is soluble in the hexane used in the polymerization and in the washing, and the insoluble part of which has : the following characteristics, is obtained, with an sctivity qof 1719: 1.1 = 95.7%

G = 591 daN/cm? .

MFI = .9.5 g/10 min "AD = 479 g/l.

oo Co 3719

Example & } :

A preactivated catalytic solid is prepared : according to the general conditions described in

Example 1, parts A and B. However, after treatment of the suspension of the reduced solid with stirring for 2 hours at 65°C, this suspension is cooled to approximately 55°C; propylene is then introduced into the gaseous atmosphere in the reactor, at a pres- sure of 2 bars. This introduction is continued for a period sufficient (approximately 45 minutes) to obtain 100 g of polymerized propylene per kg of solid.

The suspension of the solid thus "prepolymerized” is then cooled 40°C and the preparation is then continued ‘as mentioned in Example 1, part A.

The preactivated catalytic salid finally obtained contains 611 g of TiCl,, 9 8 of aluminium, 14 g of

DIAE and a quantity, which is estimated to be appro- ximately 143 g, of preactivator A per kg.

This preactivated catalytic solid is employed in a propylene polymerization trial comprising a first stage which is carried out in the liquid monomer and a second stage which is carried out in the gaseous phase under the operating conditions detailed below.

SE oo | 2301

The following are introduced, under a stream of nitrogen, into the 5-1litre autoclave used according } to Examnles 1 dnd 3. 800 mg of DEAC a quantity of catalytic solid equivalent to . 100 mg of TiCi,. : The molar ratio DEAC:TiCl4 is therefore appro- °° ximately 10:1.

An absolute hydrogen pressure of 0.2 bar is set . 10 up in the autoclave. 2 L of liquid propylene are } . then introduced, with stirring, and the autoclave is heated to 60°C. Polymerization is carried aut for - 30 min at this temperature. The autoclave is then degassed to a pressure of 15 bars, shile heating it to 70°C at the same time. An absolute hydrogen pressure of | bar is then set up therein and propylene is then introduced into the autoclave until a total pressure, at the temperature concerned, of 28 bars is obtained. After 3 hours, the polymerization is : 20 | stopped by degassing the propylene, and the PP formed, which amounts to 1150 g of dry PP, is collected. '

- oo oo 715] ’ The activity (| of the preactivated catalytic solid is therefore 3286 and the productivity amounts to 1027 g of PP/g of preactivated catalytic solid. This PP has the following characteristics: 1.1 = 97.9%

G = 698 daN/cm? }

MF 1 = 3 g/10 win .

AD - 520 g/l. :

Example 7R

This example is given by way of comparison.

A preactivated catalytic solid is prepared according to the procedure in Example 4, but leaving out the preactivation stage. This solid contains 718 3 of TiCl,4, 3.8 g of aluminium and B4 g of DIAE per kg. When used in a polymerization trial carried ) out according to the conditions described in-Example 4, it enables a PP, characterized by the following properties, to be obtained, with an activity q of ’ 3168: [.1 = 96.4%

G = 620 dal/cm?

MFI a 3 g/10 min ’

AD - 516 g/l. ~ 51

Ar ATIGINAL 2D ee ———————— A —————————————————— eset eee eee , Examples 5 to 7 - Preactivated catalytic solids are prepared according to the conditions mentioned in Example 4, except that the molar ratio between compounds 3 (a) and (b) employed in the preparation of the preactivator A (see Example |, part B) (Examples and 6) and the molar ratio between the preacti- vator A and the complexed titanium trichloride- based solid (expressed as mole -of compound (a) initially employed per mole of Ticl, present in the solid) (see Example |, idem) (Example 7) are modi- fied.

These preactivated catalytic solids are employed in trials for the polymerization of pro- pylene in suspension in hexane "according to the general conditions mentioned in Example 3.

The operating conditions specific to the : preparations of the catalytic solids and the results of the polymerization trials are collated in Table ) which follows:

RR EE Ge Se in pa RS ei Se TV a Tre me i LS SR a heals al Sate

Bre nici vine ode beni eins See bls Calle ptandiiit bat df tne Cl EE Co Toe NR mY

ES CL Co CE a CL SE oz

Table I ] Example | S | 6 | 7 | ~ . . Preparation of the preactivated catalytic solids | . _

Compound (a) . ————=meemew- (mole/mole) 50 10 10

Compound (b) ‘ !

TT

Compound (a) —-----=----=--- (mole/mole) 1 1 | 0.2 . TiClz contained in the solid

Ticly content of the preacti- 724 672 | 709 } vated catalytic solid (g/kg) . 1 1 !

Results of polymerization

Activity a 2160 2160 12130 i

N PP/g TiClz x h) i [ i

IPP soluble in the hexane 1.1 0.8 t.1 used in the polymerization [Cas Z of total PP) | \ ; ’ 1.1 (2) | 7" 98.2] 97. 6 (daN/cm®) | 678 | 688 | 689

MFI (g/10 min) | | 2) 7.

AD (g/L) | 502 | s02 | 504 i | oo

\

Example 8 « ] A preactivated catalytic solid is prepared according to the procedure in Example 4 and it is used in a polymerization trial carried out accor- ding to the conditions described in part C of

Example 1, except that the reactor is maintained at 75°C with stirring for 2 hours.

Under these conditions, this preactivated catalytic solid enables a PP characterized by the , following properties ta be obtained, with an acti- vity oof 5010:

I.1 - 98.1%

G = (88 daN/cm? . MFI = 5.9 g/ 10 min

AD » 510 g/l. ’ : Examples 9 and 10

Preactivated catalytic solids are prepared - according to the conditions mentioned in Example |, parts A and B, exccpt that triethylaluminiup (TEAL) (Example 9) and ethylaluminium dichloride (EADC) (Example 10) are employed as compounds (a) respec~— tively.

A15]

These preactivated catalytic solids are used in trials for the polymerization of propylene in suspension in the liquid monomer, under the general conditions mentioned in Example 1, part C.

The characteristics of the preactivated cata- lytic solids employed and the results of these poly- merization trials are collated in Table II which follows.

—————————————————————————————————e eet oe rE A SES ed a Se a a Sey - RE

TER EAE EEA Ta ER Cah SR BT SE DE i 5 RL IS a ang . . ar a Ia [ a oC RARER ed se. gmree et LL < oo ik

Table 11 1

Example | 9 | 10 _ : Nature of compound (a) employed in TEAL EADC . the preparation of the preactivated J i catalytic solid

TiCly content of the preactivated 648 713 : catalytic solid (g/kg) : -_ © 1 ctivity a (g PP/g TiCL3 x h) By [7

Bh . | Properties of the PP 1.1%) | 98.0 | 97.7 6 (daN/cm®) 645 667 i - (g/10 min) | 3.4 | 3.7 | To lap (g/L) | 504 | 490 . - 5 6 —

Claims (14)

1. mt Tem oo 2415] ’ \ 1 all CLAIMS: 29 1 =!

   I. Titanium trichloride-based catalytic solid complexed by an aliphatic ether containing 2 to 8 carbon atoms which has been preactivated by : 5 bringing it into contact with an organcaluminum: preactivator in preactivation medium and removing it from said preactivation medium, characterized in that the said preactivator comprises the product of reaction between an organoaluminium compound (a) of formula: AIR Xo - in which oo R represents hydrocarbon radicals, which may be identical or different, containing from | to 18 carbon atoms, X is a halogen, and ' n is a number such that 0 n ( 3; and a hydroxyaromatic compound (b) the hydroxy group of which is sterically hindered selected from the group consisting of di-tert-alkylated monocyclic monophenols and 3-(3',5'-di-tert-butyl-4-hydroxy- phenyl)propionic acid monoesters. oo | - 57 -

   Lo ] . . os , - - os
2. 2. Solid according to claim |! wherein compound . (a) is selected from the proup consisting of tri- a alkylaluwinium and dialkylaluminium halide in which the alkyl groups maybe identical or different containing from | to 18 carbon atoms.
3. 3. Solid according to Claims I, characterized in that the preactivator is prepared by bringing compound (a) and compound (b) into contact with each other in a molar ratio of between 50 and 0.1 moles of compound (a) per mole of compound (b). 4, Solid according to claim | wherein the product } of reaction between compound (a) and compound (b) corresponds to the empirical formula: RpA1(0R')qx3- (pq) in which: : R represents hydrocarbon radicals, which may be identical or different, containing from | to 18 carbon atoms, - or! represents the aryloxy group derived from a hydroxyaromatic compound (b) the hydroxyl group of which is sterically hindered selected from the
4. Co | 271] group consisting of di~tert-alkylated monocyclic monophenols and 3-(3',5'~di~tert-butyl-4-hydroxy- phenyl) propionic acid monopsters X is a2 halogen, p is a number such that op (3: q is a number such that ¢< q¢ 2; and the sum (p+q) is such that 0¢ (p+q)=3.
5. 5. Solid according to claim-}, characterized in that the contacting with the preactivator is carried out by introducing the preactivator into . . - a suspension of the solid to be preactivated in an inert hydrocarbon diluent.
6. 6. Solid according to Claim 1, characterized in that the preactivator is brought into contact 13 with the solid to be preactivated, in a molar ratio } between the total initial quantity of compound (a) ! } employed and the quantity of TicCl, contained in the solid of between 10” 2 and | mole/nmole.
7. 7. Solid according to Claim |, characterized in that it is separated from the preactivation medium and washed with inert hydrocarbon diluent before eee eee — eee meme * 4 - - . - * hoe 27%] : being used in the polymerization.
8. 8. Solid according to Claim !, characterized in that it has been predctivated by bringing the pre- activator into contact with a solid precursor cor- responding to the formula: J " Ticl, (AIR c1,) Cy in which R" is an alkyl radical containing from 2 , to 6 carbon atoms, C is =a complexing agent selected from the group consisting of aliphatic ethers, the aliphatic radicals of which contain from 2 to 8 carbon atoms, x is any number less Lhan 0.20 and y is any number greater than 0.009.
9. 9. Solid according to Claim II, characterized : in that the solid precursor is in the form of sphetical particles of diameter between 5 and 100 microns, which consist of an agglomerate of micro- particles which are also spherical and which habe a diameter of between 0.05 and | micron and the porosity of which is Lhe specific surface area of the solid precursor is between 100 mand 250 ml/g and that the total internal porosity is between

   6.15 and 0.35 cm /g-

   em oo - - - - ot . 2H v oid!
10. 10. Process for the polymerization of alpha- olefins in the presence of a catalytic system coiaining an organometallic compound of metals of groups la, * _ 1Ia, I1b and IIIb of the Periodic Table and a titanium chloride-based patalytic solid complexed by an aliphatic ether containing 2 to 8 carbon atoms which has been preactivated by bringing it into con- tact with an organoaluminium preactivator, characte- rized in that the said preactivator contains the pro- duct of reaction between a compound (a) selected from tht group consisting of organocaluminium compounds according to claim 1 compound (b) selected from the group consisting of hydroxyaromatic compounds, accor- ding to claim | the hydroxyl group of which is steri- cally hindered.
11. 11. Process according to Claim 10, applied to the : stereospecific polymerization of propylene.
12. 12. Process according to Claim 10, applied to the stereospecific polymerization of propylene in suspen- sion in an inert hydrocarbon diluent.
13. 13. Process according to Claim 10, applied to the - 61 - SAY

    ~ Toe do

    : . stereospecific polymerization of propylene in the i monomer in the liquid state. So
14. 14. Process according to Claim 10, applied to the : stereospecific Polymerization of propylene in the oo gaseous phase. : . : ! * : gf : B® ¥ oo a. i i . } } - J - 62 - . -S r