SI8711789A8 - Method of titanium three-chlorides containing catalyt's solid component production for application during alpha-olefines polymerisation. - Google Patents

Abstract

Catalytic solids based on complexed titanium trichloride, which can be employed for the stereospecific polymerisation of alpha-olefins preactivated by being brought into contact with an organoaluminium preactivator comprising the product of reaction of a compound (a) chosen from organoaluminium compounds and of a compound (b) chosen from hydroxyaromatic compounds in which the hydroxyl group is sterically blocked. These solids enable propylene to be polymerised with an improved stereospecificity.

Description

PROCEDURE FOR OBTAINING SOLID CATALYST BASED ON TITANIUM TRICHLORIDE COMPLEX FOR POLYMERIZATION OF ALFAOLEPHINE SPECIFIC CHARACTER

Obalst Techniques

The invention is in the field of chemistry, more precisely the chemistry of polymers.

Technical problem

The invention is solved. a technical problem of the process for the preparation of a solid catalyst based on a titanium trichloride complex for use in the polymerization of alpha-olefins.

The state of the art

Stereospecific polymerization of alpha-olefins such as propylene in the presence of a catalytic system comprising a titanium trichloride-based solids and activator comprising an organometallic compound such as alkylaluminum chloride is known.

Patent BE-A-780758 (Solvay & Cie) discloses superactive solid catalytic systems based on TiCl ^ that can be stored under hexane for extended periods of time without changing the properties. A suitable reactivator selected from the group may be used

2.

organoaluminum compounds, such as alumina hydrocarbylhydrocarbonyloxyhalides shown by the general formula I. However, diethylaluminum chloride, ethylaluminum sex chloride and ethylaluminum dichloride are used in practice, and tr and e tiluminium are not used.

Unfortunately, the stereospecificity of the catalytic complexes is not quite satisfactory under the conditions used for polymerization, especially at relatively high temperatures at which propylene gas phase polymerization is often carried out. However, when polymerization is carried out at relatively low temperatures, a significant decrease in catalyst productivity is observed.

Therefore, the polymerization of propylene is carried out in the presence of catalytic systems which are solid and superactive which are modified by introducing into the polymerization medium of a terconstituent which is mainly an electron donor compound (Lewis base).

For the constituents, in order to increase the stereospecificity of the catalytic systems, a number of compounds of various electrodonor nature are proposed (see, eg, patent BE-A-822941) (ICI). Among these, a particularly large number of phenolic compounds (patent EP-A-0036549) (BASF) ) and some h idr oxiarine parent compounds (US-A-4478989 (SHELL OIL). The improvement in stereospecificity resulting from the introduction of electrodonor compounds into the polymerization medium is not particularly significant since a relatively large amount of these compounds are used (electrodonor mass The compounds are at least equal to the mass of the solid catalytic complex applied and are often much larger.) In this case, other secondary effects are observed, such as the unacceptable decrease in catalyst productivity and the appearance of parasitic dyes in the resulting polymer, as well as complications resulting from polymer purification from the remnants of the terconstituents.

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Description of solution of technical problem with examples of realization

3.

The present invention is intended to provide a solid catalyst having a high stereospecificity without the need for introducing the tertiary constituent into the polymerization medium.

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the invention aims to obtain a solid catalyst based on titanium trichloride that can be used in stereospecific polymerization of alpha-olefins, which is reactivated by contact with an organoaluminum compound as a preactivator, comprising the reaction product of organoaluminum compounds (a) and hydrocarbons whose hydroxy group is blocked by esterification.

solids based on titanium chloride complexes used as precursors for the preparation of solid reactivated catalysts according to the invention can be prepared in a known manner. It is generally preferred that solids be obtained by processes involving the initial reduction of titanium tetrachloride. This reduction may be effected by hydrogen or metal such as magnesium or preferably aluminum. The most general results are obtained from the solid suspensions obtained by the reduction of titanium tetrachloride with organometallic reducing agents. This may be, for example, some organomagnesium, however, the best results are obtained with organoaluminum reducing agents (1).

Organoaluminum reducing agents (1) that can be used are preferably compounds containing at least one hydrocarbon radical that is bonded directly to the aluminum atom. Examples of compounds of this type are mono-, di-, and tri-alkylalumines. Their alkyl radicals contain 1-12 and preferably 1-6 carbon atoms, such as triethylaluminum, isoprenylaluminium yum, d-isobutyl la-luminium hydride, and ethoxydiethylaluminum. The best results are obtained with dialkylaluminum chlorides and in particular diethylaluminum chloride.

For the sake of obtaining solid suspensions based on titanium trichloride complexes (precursors) used to obtain Solid Preactivated

4.

The catalysts of this invention are subjected to the aforementioned solids as a complexing agent, which is generally selected from organic compounds comprising one or more atoms or groups having one or more free electron pairs that provide coordination with titanium or aluminum atoms in the by titanium or aluminum halides. Preferably, the complexing agent is selected from the family of aliphatic ethers, especially those whose aliphatic radicals comprise 2-8 carbon atoms, preferably 4-6 carbon atoms.

An example of an aliphatic ether that produces very good results is diisoamyl ether.

This treatment with the aid of complexing agents to stabilize or improve the productivity and / or stereospecificity of the solid catalyst is well known and extensively described in the literature.

Thus, to obtain a precursor, treatment with a complexing agent consists in heating the reduced solid product in the presence of a complexing agent. It may consist in the thermal treatment of a solid reducing product_ in the presence of a complexing agent. It may also consist in the extraction of that flush of the reduced solid product, in the presence of a solvent mixture comprising a liquid hydrocarbon compound and some auxiliary polar solvent, e.g. ether. Reduction of titanium tetrachloride may also be carried out by an organoaluminum reducing agent (1) in the presence of a complexing agent, e.g., by adding titanium tetrachloride to a hydrocarbon solution of the reaction product of the complexing agent with the reducing agent and then subjecting the thus obtained solid reduced product to thermal treatment in the presence or absence of for complexing which may be identical or different from the previous one. The complexing agent may also be treated in an amount sufficient to form a homogeneous titanium trichloride-based solid solution and to re-precipitate by heating the solute thus dissolved.

5.

To obtain a precursor, treatment with a complexing agent may be combined or may accompany activation treatment. These activation treatments are also well known and described in the literature. They are carried out mainly by means of at least one agent selected from organic and inorganic halogen compounds, interhalogens and halogens. These may include:

Inorganic halogen compounds: metal and non-metal halides such as titanium and silicon halides, organic halogen compounds: halogenated hydrocarbons such as halogenated alkanes and e.g. carbon tetrhalides, interhalogen compounds: e.g. chloride and bromide of iodine, halogens: chlorine, bromine and iodine.

Examples of good activating agents are titantetrachloride, silicon tetrachloride, iodobutane, monochloroethane, hexachloroethane, chloromethylbenzene, carbon tetrachloride, iodine chloride and iodine. The best results are obtained with titrant tetrachloride.

The physical form of the complexing and possibly activating agent is not critical for obtaining precursors. These agents may be in gaseous and liquid form, the latter being more common since they are in liquid form under conditions of ordinary temperature and pressure. Both of these treatments can be performed in the presence of an inert hydrocarbon diluent, which is generally selected from liquid aliphatic, cycloaliphatic and aromatic hydrocarbons such as liquid alkanes, isoalkanes and benzene.

Details of suitable operational conditions for complexation and activation treatment can be found in patent BE-A864708 (Sumitorno Chemical, Company, Ltd), in patent US-A-.4295991 (Εχχοη Research and Engineering Co.) and in the documentation cited in by the last.

6.

Upon preparation, after the reduction or complexing phase or 'after the eventual activation phase, but preferably after the reduction phase, the precursor may be treated to reduce the brittleness of the constituent particles. This treatment, called prepolymerization, consists in contacting a solid with some lower alpha-olefin, such as ethylene or better propylene, under polymerization vessels, in such a way as to obtain a solid having substantially between 5 and BOO. % by weight of prepolymerized alpha-monoolefin. This prepolymerization can be conveniently carried out in suspension of the solid in an inert hydrocarbon diluent, as defined above, for a period of time sufficient to obtain the expected amount of prepolymerized alpha-monoolefin on the solid. The precursor obtained according to this variant is less mole and allows to obtain polymers of good morphology when polymerization is carried out at a relatively elevated temperature.

For transformation into a solid reactivated catalyst, which is described later, the precursor can be used as such, that is, without separation from the medium in which it is obtained or preferably, after separation and eventual washing with an inert hydrocarbon diluent, as defined above.

a preferred process for the preparation of solids based on titanium trichloride complexes that can be used as precursors for the preparation of catalysts. of the reactivated .. solids according to the invention is in patent BE-A-780758. This process involves the reduction of titanium trichloride using an organoaluminum reducing agent (1) which is preferably a dialkylaluminum chloride having a range of 2-6 carbon atoms under moderate conditions. After the eventual thermal treatment of the reduced solids thus obtained, this is subjected to treatment with the aid of such a complexing agent as defined above. Finally, titanium trichloride treatment is carried out and a rewarded solid based on the titanium trichloride complex is then released, which is eventually washed off with an inert hydrocarbon diluent, as defined above, which is preferably selected from liquid aliphatic hydrocarbons containing 3-12 carbon atoms and which may be used throughout the preparation period of said solids.

The preferred process defined in the preceding paragraph provides solid particles based on the titanium trichloride complexes also described in patent BE A-780758. These fragments are spherical and have a coal diameter between 5 and 100 micrometers and: .common between 30 micrometers and more. They consist of agglomerates of microparticles which are also spherical in diameter between 0.05 and 1 micrometer, more often between 0.1 and 0.3 micrometer and which are extremely porous. Therefore, the resulting particles have a specific surface area above 75m / g 2 and more often between 100 and 250 m / g and have a total porosity above 0.15

3 cm / g and leaves between 0.20 and 0.35 cm / g. The internal porosity of the microparticles makes a significant contribution to the total porosity of the particles, as shown by the increased value of the corresponding porous volume 3 with pores with a diameter of at least 20nm above 0.11 cm / g and most often 3 between 0.16 and 0.31 cm / g.

Titanium trichloride complexed complexes (precursors) obtained according to the method described in patent BE-A-780758 obtained under desirable operating conditions have the formula

TiCK. (A1R'C1) .C «3 £ x y where R 'is an alkyl radical comprising 2-6 carbon atoms,

C is a complexing agent as defined above, x is some number less than 0.20 and y is some number greater than 0.009 and generally less than 0.20.

As a variant of this process, one can ". .Cite, which, as mentioned above, consists in the prepolymerisation of the reduced solid, after possible thermal treatment, by means of a copolymer, with lower alpha-monoolefin (propylene) under polymerization conditions. This prepolymerization is carried out in suspension of the solid reducing substance in inert hydrocarbon diluents, as defined above, between about 20 and 80 ° C, for a time between 1 minute and an hour.

According to the invention, the precursor obtained as described above is contacted with an organoaluminum preactivator comprising

8.

the reaction product of organoaluminum compound (a) and compound (b) selected from hydroxy aromatic compounds whose hydroxyl group is sterically blocked.

Oragnoaluminum compound (a) is generally selected from compounds of formula:

wherein R represents identical or different hydrocarbon radicals containing 1-18 carbon atoms, such as alkyl, aryl, arylalkyl, alkylaryl, cycloalkyl, alkoxy and aryloxy,

X is halogen, n is a number between 0 and 3.

In the above formula, R is preferably a linear or branched alkyl radical containing 2-8 carbon atoms, X is preferably chlorine and n is preferably a number between 1 and 3.

The following may be cited as examples of compound a): trialkylaluminum, such as trimethyl-, triethyl-, tri-n-propyl-, tri-n-butyl-, tri-i-butyl, tri-n-hexyl, tri-i -hexyl, tri-2-methylpentyl and tri-nactylaluminum; dialkylaluminum monohalides, such as diethyl; -, di-n-propyl- and di-butylaluminum monochlorides, ethyl aluminum monofluorides, monobromides and mono-iodides; alkylaluminum.dl- .alpha.-halides, such as methyl- and ethylaluminum-sequochlorides and ethyl- and isobutylaluminum-dichlorides; alkoxyaluminum halides such as methoxy and isobutoxyaluminum dichlorides; alkoxyalkylaluminum such as monoethoxydiethylaluminum, diethoxymonoethylaluminum and dihexanoxyimono-nhek with ilalumine or um.

Very good results were obtained with salalkyl lumines and dialkylaluminum chlorides, more specifically with triethylaluminum and diethylaluminum monochloride.

9.

Compound b) is selected from hydroxy aromatic compounds whose hydroxy group is sterically blocked. By hydroxy aromatic compounds whose hydroxy group Sterni is blocked, is meant all hydroxy aromatic compounds comprising a secondary or tertiary alkyl radical in two ortho positions relative to the hydroxyl group.

Compound Ib) is generally selected from mono- or polycyclic hydroxy arylene substituted as indicated above, and particularly from hydroxybenzene, hydroxynaphthalene, hydroxyanthracene and hydroxyphenanthrene so substituted and whose aromatic nuclei may carry other substituents.

The following may be cited as examples of compound b):

-monocyclic monophenols which are di-tert- or di-sec-alkylated in ortho positions relative to the hydroxyl group, such as

2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 3,5-tert-butyl-4-hydroxy-alpha-hydroxybenzene, 2,6-di-tert-decyl 1-4- methoxyphenol, 2,60di-tert-butyl-4-methoxyphenol and 2,6-di-t-butyl 4-sec-butyl-phenol;

3- (3 ', 5' '- di-tert-butyl-4-hydroxyphenyl) propionic acid monoesters, such as methyl, ethyl, n-propyl, n-butyl, n-octyl n-dodecyl and n- octadecyl 3- (3 5 '-di-tert-butyl-4-hydroxyphenyl) propionate /

-di-tert-alkylated polyphenols in ortho positions relative to hydroxyl groups such as 2, 2-bis (2,6-di-tert-butyl) hydroxyphenyl) propane, bis (3,5-di-tert-butyl) -4-hydroxybenzyl) methane,

4,4-methylenebis (2,6-di-tert-butyl) phenol, 2,2 '-methylene-bis (4-ethyl6-tert-butyl) phenol, 1,3,5-trimethyl-2, 4,6 -bis (3,5-di-tert-butyl) phenol, 1, 3,5-trimethyl-2, 4,6-bis (3,5-di-tert-butyl) phenol, 1,3,5 trimeth 1- 2. 4,6-bis (3,5-di-tert-butyl-4-hydroxybenzyl) benzene and tris (2,6-di-tert-hexylhydroxy-phenyl) benzene / ^!

10.

3- (3,5-Di-tert-butyl-4-hydroxyphenyl) propionic acid polyesters, such as tetrakis / methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate / methane;

- polycyclic monophenols which are di-tert- and di-sec-alkylated in ortho positions at the same time as the hydroxyl group, such as

1,3-di-tert-butyl-2-hydroxyanthracene, 1,2-di-tert-hexyl-2-hydroxyphenanthrene, 2,8-di-tert-butyl-hydroxynaphthalene and 1,3-diisoamyl-2-hydroxynaphthalene.

Very good results are obtained with di-tert-alkylated monocyclic phenols, in particular 2,6-di-tert-butyl-4-methylphenol and 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionic monoesters acids, especially with n-octadecyl-3- (3, 5-di-tert-butyl-4-hydroxyphenyl-1-propionate, wherein the use of the latter gives great sterospecificity to the solid catalytic substances.

The general conditions in which compound a) is contacted with compound b) are not critical, as long as they provide the chemical reaction of these compounds; It is mainly done in the liquid phase, e.g., by mixing compound b) and compound a) in the absence of a liquid-decomposer, wherein the compound is

a) most often liquid under normal temperature and pressure conditions. Also; may be operated in the presence of an inert hydrocarbon diluent, as defined above.

The molar ratio in which compound a) and compound b) are mixed can be varied widely, that var ir a. Usually 50 to 0.1 moles of compound a) per mole of compound b) are used, preferably between 15 and 0.5 moles of compound a) per mole of compound b) and very good results are reported for the molar relations of unity a) according to compound b) between 3 and 1.

Compounds a) and b) can be contacted typically at temperatures between about 0 and 90 ° C, preferably at about 25 ° C, for a satisfactory period of time for chemical reaction, which is generally between 5 minutes and 5 hours. This reaction is usually accompanied by the release of gases, which can be used to monitor the progress of the reaction.

The correct chemical struc v · · _ ^U * ture of the reaction product of the compound

11.

compounds are not known with certainty. However, it is practically certain that the product is at least partially consistent with the empirical formula:

R Al (OR ') X P q

3- (p + q) where R has the previously given meaning, represents the same hydrocarbon radicals present in the organoaluminum compound a);

OR 'represents the ar.i_loxy groups of the compounds b);

X is halogen;

p is a number between 0 and 3, preferably between 0.1 and 2.5;

q is a number between 0 and .2, preferably 0.5 and 1.5;

the sum (p + q) is a number between 0 and 3.

According to the invention, the organoaluminum preactivator obtained as described above is reacted with the precursor.

The operational conditions for contacting the precursor with the precursor are not critical as long as they provide at least partial binding of the reactivator with the precursor,

This contacting is carried out as in the known process. It can be e.g. be done by heating an impregnated precursor with a liquid phase containing the reactivator.

Most often the reactivator is contacted in the form of ...

solution, in an inert hydrocarbon diluent which is optionally used to prepare it:

1) the reaction product of compound a) and compound b) possibly followed by

2) excess of compound a) or non-reactant compound b).

12.

In this case, it is desirable to introduce a preactivator solution containing ingredient 1) and possibly ingredient 2) into the precursor suspension in the same carbon diluent. This suspension is then maintained mainly at a temperature between 0 ° C and a boiling point of an inert hydrocarbon diluent in which the reactivator is rewarded, preferably between 20 and 40 ° C, for a period of time generally between 5 and 200 minutes, preferably between 15 and 90 minutes. The corresponding amounts of precursors and reactivators used are such that the molar ratio between the total initial amount of compound a) and the amount of -3 present TiCl., In the reactivator generally between 10 and 10, is positive -2 ^J between 10 and 1. Very good the results are obtained when the molar ratio between 0.05 and 0.5 is predetermined.

At the end of the reactivation step, the solid reactivated catalyst is separated from the reactivation medium and washed to eliminate unbound preactivator residues, preferably with the aid of an inert hydrocarbon diluent of the same nature as optionally used in the preparation of the precursor and the peractivator solution.

The reactivated solid catalyst, separated and purged, may then be dried, e.g. to a liquid hydrocarbon diluent content below <RTI ID = 0.0> Wt. </RTI> preferably below 0.5 wt.% by weight of the tyrant trichloride containing, according to the operating conditions described in patent BE-A-846911 (Solvay & Cie).

The reactivated solid catalyst thus obtained always contains a certain amount of solid-substrate-bound preactivator which cannot be removed by purely physical separation processes. This amount of reactivator is generally between 5 and 500 g per kg of TiCl 2 present in the solid, preferably between 50 and 300 g / kg. Thus, a solid catalyst deactivated according to the invention contains less TiCl2 per unit mass than the solid used as a precursor for its production. The reactivated solid catalyst contains generally at least 50 wt% TiCl2 relative to the total mass and rarely contains more than about 80 %.

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External morphology of Solid Catalyst Particles Reactivated according to the invention is no different from that of precursor particles used to obtain them. Thus, when starting from spherical particles composed of agglomerates of spherical porous microparticles,. have the same .structure, same dimensions and same shapes as the starting particles. However, solid preactivated catalyst particles are less porous, no longer characterized by a large specific surface area that follows a large porous volume characteristic of precursor particles.

After being washed and eventually dried, solid preactivated catalysts according to the invention can be contacted immediately with an inert organic diluent as defined above and which can also be used as a diluent in the polymerization suspension. Solid catalysts reactivated according to the invention can also be subjected to prepolymerization as described above for the precursor. They can be stored in hexane in the dried form, preferably in the cold for extended periods without changing the quality.

For polymerization, a solid catalyst reactivated according to the invention is used together with an activator selected from organometallic metal compounds of Groups Ia, IIa, IIb and Illb Periodic Table of the Elements / Kirk-Othmer Encyclopedia of Chemical Technology, 2nd complete revised edition, vol. 8, 1965, p.94) and preferably between the compounds of formula:

where R is a hydrocarbon radical containing 1-16 carbon atoms and having - .. c preferably 1-12 carbon atoms selected from alkyl, aryl, arylalkyl, alkylaryl and cycloalkyl radicals / best results are obtained for alkyl radical containing 2-6 atoms carbon;

Y is a halogen selected from fluorine, chlorine, bromine and iodine; the best results are obtained when Y is chlorine.

m is an integer between 0 and 3 and preferably between 1.5 and 2.5;

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the best results are obtained for m = 2.

Diethylaluminum chloride (DEAC) provides the maximum activity and stereospecificity of the catalytic system.

The catalytic systems thus defined are applicable in the polymerization of olefins with terminal unsaturation of a molecule containing 2-18 and preferably 2-6 carbon atoms, such as if they are. . ethylene, propylene, butene-l, pentene-l, methylbutene-l. .hexen-1, 3- and 4-methylpentenyl-1 and vinylcyclohexene. Particularly interesting are the intrinsic stereoscopic polymerization of propylene, butene-1 and 4-methylpentene-1 into a crystalline polymer of the isotactic form. They are equally applicable in the copolymerization of alpha-olefins among themselves as with diolefins spanning 4-18 carbon atoms. preferably, diolefins are but.phatic unconjugated diolefins such as hexadiene-1, 4, -. monocyclic diolefins, unconjugated such as 4-vinylcyclohexene, alicyclic diolefins with an endocyclic bridge, such as dicyclopentadiene, methylene and ethylenorbornene, and conjugated aliphatic diolefins such as butadiene or isoprene.

They are also applicable in the manufacture of copolymers called blocks which are graced by alpha-olefins and diolefins. These block copolymers consist of successive variable length chains; each segment consists of a homopolymer of alpha-olefin or a statistical copolymer comprising alpha-olefin and at least one comonomer selected from alpha-olefin and diolefin. The alphaolefins and diolefins are selected from those listed above.

Solid catalysts inactivated according to the invention are particularly suitable for the production of homopolymers of propylene and copolymers containing at least 50% by weight. propylene and preferably 75% by weight of propylene.

The polymerization may be carried out by a known process: in solution or in suspension in a diluent, or inert hydrocarbon diluent, as defined above, and preferably selected from butane, pentane, hexane, heptane, cyclohexane, methylcyclohexane. Polymerization is

15.

can also be carried out in monomer or in monomers maintained in liquid or gas phase. The use of solid reactivated catalysts according to the invention is very suitable for gas phase polymerization. In fact, the application of sterospecific catalytic systems is particularly interesting when amorphous and cast by-products occur, which are particularly harmful 'in this type of polymerization, because the technology does not allow them to be eliminated.

The polymerization temperature is selected from 20 to 200 ° C and preferably between 50 and 90 ° C, the best results being obtained between 65 and 85 ° C. The pressure is selected from atmospheric to 0.5MPa and preferably between 113 MPa. This printing naturally depends on the temperature used.

The polymerization can be carried out continuously or intermittently.

The preparation of copolymers called blocks may also be carried out by known methods. Preferably, a 2-phase process consisting of the polymerization of alpha-olefin, mainly propylene, according to the method described earlier for homopolymerization, is used. The second alpha-olefin and / or diolefin, mainly ethylene, is then polymerized in the presence of an even more active homopolymer chain. The latter polymerization may be carried out after the reaction is complete or since the monomer has partially reacted during the first phase.

The organimetallic compound and the solid reactivated catalyst can be added individually to the polymerization medium. They can also be contacted at a temperature of between -40 and 80 ° C for a period depending on the temperature applied and may be from 1 hour to several days before being introduced into the polymerization reactor

The total amount of organometallic compound contacted is not critical, generally above 0, 1 mol per liter of diluent, liquid monomer or reactor volume, preferably 0.5 mmol / liter.

The amount of reactivated solid catalyst to be used is determined depending on its content of TlCl ^ - It is usually chosen to have a concentration in the polymerization medium for TiCl ₃ above 0.01 mmol / liter diluent, liquid monomer or reactor volume and preferably above 0 , 05mol / lit.

The ratio of the amount of organometallic compound to the solid reactivated catalyst is no longer so critical. It is chosen in such a way that the molar ratio of the organometallic compound / TiCl ^ Azmedju is 0.5 i

20, and preferably between 1 and 15 (TiCl ₃ contained in a solid). The best results are obtained for the said molar ratio between 2 1 12.

The molecular weight of the polymers produced according to the process of the invention can be controlled by the addition to the polymerization medium of one or more agents, such as hydrogen, diethyl zinc, alcohols, ethers and alkyl halides.

The stereospecificity of the solid reactivated-catalysts according to the invention is significantly higher than the catalytic complexes described in patent BE-A-780758. Furthermore, this stereospecificity remains unchanged for longer periods of storage at a relatively high temperature. In their application, it is no longer necessary to add to the polymerization medium a terconstituent, which is commonly used to enhance stereospecificity, such as an ether or ester. It is evident that the addition of the terconstituent to the polymerization medium when using the preactivated solid catalytic system according to the present invention leads only to a marginal resp. a slight improvement in stereospecificity.

During the homopolymerization of propylene in the presence of solid reactivated catalysts according to the invention, the amount of amorphous polypropylene, determined as the mass of dissolved polypropylene in boiling heptane, relative to solid propylene produced during polymerization is almost always below 3%. The same result is achieved. _v io with a solid catalyst catalyst stocked at 45 C for several weeks.

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The following examples illustrate the invention.

In these examples, the symbols used have the following meaning:

t

1.1 = isotacticity index of the polymer, given as the fraction of the latter, expressed in% relative to the total amount of solid polymer insoluble in boiling heptane.

G = modulus of elasticity of polymer shear, measured at 100 ° C and a shear angle of 60 °, casting temperature 70 ° C, conditioning time 5 minutes (BS 2782-partI-method 150A; ISO 458/1, o method B; DIN 53447 and ASTM D 1043) Moduo is expressed in N / cm.

MFI = melt fluidity index measured at a load of 2.16kg at 230 ° C and expressed in g / 10 min (ASTM D 1238 standard).

PSA = specific mass occurring as a fraction of insoluble polymer, measured in yield and expressed in g / l.

alpha = catalytic activity usually expressed by grams of insoluble polymer in the polymerization medium obtained in hours and grams of T1Cl3 contained in a solid reactivated catalyst.

EXAMPLE 1

A Preparation of precursors (solid based on titanium trichloride complexes)

Into an 800ml reactor equipped with a 2-blade mixer rotating at a speed of 400 rpm, it is introduced under a nitrogen atmosphere of 90ml of dry heskane and 60ml of pure TiCl ^. This solution was cooled to 0 (+1) ° C. A solution containing 190 ml of hexane and 70 ml of diethylaluminum chloride (DEAC) was added over 4 hours maintaining the temperature in the reactor at 0 (+ 1 ° C).

After the addition of the DEAC-hexane solution, the reaction medium consisting of the fine particle suspension was stirred at 1 (+1) ° C.

minutes and then 1 hour at 25 ° C ..and 1h-as.-na-. 65 ° C. The reaction medium is then stirred at 65 ° C for 2 hours with stirring.

The liquid phase is separated from the solid and the solid is washed 7 times with 200 ml of dry hexane while reflecting the solid in suspension during each rinse.

The reduced solid residue thus obtained was suspended with 456ml of diluent (hexane) and 86ml of di-isoamyl ether (EDIA) added. The suspension was stirred for 1 hour at 50 ° C and the solid phase thus treated was separated.

The solid was suspended in 210 ml of hexane and 52 ml of TiCl 2 was added, the suspension was maintained under stirring (150 rpm) at 70 ° C for 2 hours. The liquid phase is then eliminated by filtration and the titanium trichloride-based solid is washed 14 times with 270 ml of hexane.

B Reactivation

Into an 800ml reactor provided with a blade mixer. Turning at a speed of 150 rpm, 70g of a solid based on a titanium trichloride complex is introduced ./( containing about 820g of TiCl ^ / kg) suspended in 280ml of hexane. The plaque was introduced (about 30 minutes) into a reactor of 120 ml of a reactivator solution in hexane (hereafter called pceactivator .A) previously prepared by mixing 80g of DEAC (compound 1) and 172, 6g of 3- (3 ', 5'-di-tert- butyl-4-hydroxy-phenyl) propionate of n-octadecyl, which is commercially known as Irganox 107 6 (CIBA-GEIGY) (compound b) per liter of hexane. The molar ratio between compounds a) and b) applied in the preparation of preactivate is 2, and the molar ratio between preactivator A and the solid substrate based on the titanium trichloride complex (expressed in moles of the compounds

a) initially, by the number of moles of TiCl ^ in the solid suspension) is 0.2.

The reactivator solution is not introduced into the reactor for 15 minutes after the cessation of gas release that occurs during the mixing of compound a) and compound b).

.

The suspension of the reactivator A thus added is maintained for 1 hour at 30 ° C with stirring.

After decanting, the resulting pre-acidified catalytic solids were washed 5 times with 100 ml of dry hexane, while maintaining the solids in suspension during each wash. Then they were dried by blowing nitrogen through the fluid bed for 2 hours at 70 ° C.

The reactivated solid catalyst thus obtained contains per kilogram 64lg of TiCl-j, 12g of aluminum, 31g of EDIA and an amount estimated at about 250g of reactivator A.

C Propylene polymerization in suspension in liquid monomer in the presence of a solid overactivated catalyst

A 5 liter autoclave, previously dried and maintained under a nitrogen atom, is introduced with a nitrogen stream:

-400mg DEAC (as a solution in hexane at 200g / liter) commercialized by SCHERING (Cl / Al atomic ratio was adjusted to l, o2 by the addition of ethylaluminum),

- lOOmg of solid reactivated catalyst (the molar ratio between DEAC and TiClg present in the solid substrate about 8),

- hydrogen at partial pressure 1 bar, liter of liquid propylene.

The reactor was maintained under stirring at 65 ° C for 3 hours. The excess propylene was separated and the rewarded polypropylene (PP) was collected, yielding 643g of dry polypropylene.

The alpha activity of the reactivated solid catalyst is 3340, the productivity is raised to 6430 g of polypropylene / g of solid reactivated catalyst.

20.

This polypropylene has the following characteristics:

I.I = 98.1%

G = 678 N4cm

MFI = 3.16g / 10min

PSA = 510 g / l.

Examples of IR - 5R

These examples are given for comparison.

For example, IR

A solid was obtained on the basis of the titanium trichloride complex as described in Example 1, Part A, without the reactivator as indicated in Part B of this example.

This solid, dried as indicated in Example 1, contained 811g of TiCl2, 2.8g of aluminum and 61g of EDIA.

The polymerization test is carried out in the presence of a solid thus obtained unreacted, under conditions strictly comparable to those defined in example 1, part C. It is separated during the dry PP test 785g.

Alpha activity is 3230 and productivity is raised to 7850g PP / g solids.

This polypropylene has the following characteristics:

I.I = 94.9%

G = 572 N / cm ² MFI = 7.3 g / 10 min PSA = 490 g / 1.

The significant differences of the insoluble fractions in boiling heptane and the corresponding modules G of the obtained polymers under the comparison conditions of Examples 1 and IR demonstrate the better stereospecificity of the catalytic system containing the solid reactivated catalyst of Example 1.

Example 2R

A solid substance based on the titanium trichloride complex obtained as described in Example l, part A is reactivated by a solution which does not t

contains compound b). Partial dissolution of the solid substrate is observed, which, among other things, occurs in the form of very fine grains. The polymerization assay performed as indicated in Example 1, part C was repeated with the amount of catalyst containing about 70mg of TiCl ₃ .

535g PP is obtained, equivalent to an activity of only 2550. This PP is present in the form of fine grains and PSA is only 100g / l, which eliminates the possibility of its application.

Example 3R

Repeat Example 1, Parts A and B with the exception of the addition of a solid substance based on the titanium trichloride complex in succession, first with a solution of compound a) in hexane and 15 minutes later with a solution of compound b) in hexane. The values of the molar ratios between compound a) and compound b) added separately and between compound a) and the amount of TiClg present in the solid are 2 and 0.2, respectively. Isolated solid catalyst contains 757 g / kg TiCl ₃ *

The polymerization test, performed as described in example l, part C, does not allow separation, with an alpha of 3090 polypropylene present in the form of unmanageable blocks.

Example 4R

Repeat Example 3R, but in the reverse order of introducing a solution of compounds a) and b). The same phenomenon is observed as in Example 2R, which is to say partial dissolution of a solid.

The polymerization test is performed as described in Example 1, part C, does not allow collection, with an activity of -alpha-3450, polypropene which is present in the form of very fine grains, whose PSA is only

22.

200 g / l, which eliminates the possibility of application.

Example 5R

A solid substance based on the titanium trichloride complex obtained as described in Example IR (which is to say, not inactivated) is used in the polymerization assay implemented as described in Example 1, part C, with the exception of being introduced into the polymerization medium, inter alia DEAG, a solid, hydrogen and propylene, is a product of Irganox 1076 in an amount that provides a molar ratio between this product and TiCl ^ present in a solid of about 0.2.

Obtained, with an alpha activity of 3 286, PP characterized by the following binary:

I.I = 95.2%

G = 575N4cm ²

MFI = 5.2g / 10min

PSA = 505g / l.

Example 2

A solid reactivated catalyst is obtained as indicated in Example 1, Parts A and B, except that the product Irganox 1076 is replaced by

2,6-di-tert-butyl "4 ~ mefeyl" phenol commercially available under the name Inol CP from SHELL.

The solid reactivated catalyst thus obtained contains per kilogram 632g of TiCl ₃ , 14g of aluminum, 30g of ADIA and the amount of preactivator estimated at about 17Og. Used to test polymerization under the conditions of Example l, Part C.

This test permits the separation, with an alpha activity of 3230, of polypropylene having the following characteristics:

.

Ι.Ι = 95,9%

G = 653 N / cm MFI = 9g / 10min PSA = 500g / l.

Example 3

A solid reactivated catalyst obtained as described in Example 1, Parts A and B, was used in the propylene polymerization suspension in hexane suspension under the operating conditions described below.

In an autoclave of 5 lit. of stainless steel repeatedly purged with nitrogen, 1 liter of hexane is introduced, dry and purified.

Then 400mg of DEAC (as a solution in hexane,

200 g / l) and an amount of solid catalyst equivalent to an amount of TiCl ^ of about 51 mg. The molar ratio of DEAC / TiCl ^ is then about 10.

The autoclave is heated to 65 ° C and kept at atmospheric pressure by gentle degassing. It then provides an absolute hydrogen pressure of 0.3 bar, after which propylene is introduced into the autoclave until a total pressure of 11.9 bar is reached.

This pressure is kept constant during polymerization by the introduction of gaseous propylene.

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

The contents of the autoclave are poured onto a Buchner filter, washed 3 times with 0.5 liters. hexane and dried under reduced pressure at 60 ° C. 251g pP insoluble in hexane was collected. After polymerization in hexane and rinsing, 0.75g of polymer was dissolved, corresponding to a value of 0.3%. The alpha activity is 1643. Productivity is raised to 3175 g PP / g solid solid reactivated catalyst.

PP insoluble in hexane has the following characteristics:

I.I = 98.2%

G = 654N4cm MFI = 2.9 g / lOmin PSA = 503g / l.

Example 6R

This example is given by a comparative goal.

The polymerization test was carried out in the presence of the Solid Catalyst obtained as indicated in Example 3 but excluding the preactivation phase and containing 735 g / kG 'TiCl ^ under the same conditions as in Example 3. Obtained with an alpha activity of 1719 , PP of which 1% by mass is soluble in hexane for polymerization and leaching and whose insoluble part has the following characteristics:

I.I = 95.7% Mr = 591 N / cm ² MFI = 9.5 g / lOmin PSA = 479 g / l

Example 4

Under the conditions generally given in Example 1, Parts A and B, a reactivated solid catalyst is obtained. However, after treatment of the reduced solids suspension for 2 hours at 65 ° C, this suspension is again cooled to about 55 ° C, then introduced into the gases in a 2 bar propylene reactor, this introduction is carried out for a sufficient period (about 45 minutes) to obtain per kg of solid, lOOg of polymerized propylene. The suspension of the solid substrate thus prepolymerized-rse-.timesim is then cooled to 40 ° C and the preparation is continued as indicated in Example l, Part A.

The solid catalyst catalyst finally obtained contains per kg,

611g of TiCl ^, 9g of aluminum, 14g of EDIA and the amount estimated at about 143g of reactivator A.

25.

This fourth reactivated catalyst is introduced into a polymerization test comprising the first phase performed in the liquid monomer and the second phase performed in the gas phase under the operating conditions given below.

<

In an autoclave of 5 lit. used according to Examples 1 and 3, it is introduced under a stream of nitrogen:

-8Π0 mg DEAC

-the amount of solid catalyst equivalent to the amount of TiCl ^ from lOOmg.

the molar ratio of DEAC / TiC ^ is then about 10.

Ensure an absolute hydrogen pressure of 0.2 bar in the autoclave.

It is then introduced, under stirring 21it. of liquid propylene and the autoclave is heated to 60 ° C. At this temperature it is polymerized for 30 minutes. The autoclave was then degassed at a pressure of 15 bar and heated at 70 ° C at the same time. The absolute hydrogen pressure from Ibar is then provided, then propylene is introduced until the total pressure is reached, at a given temperature of 28 bar. After 3 hours, the degassing of the propylene halts the polymerization and collects the rewarded PP, 1150g of dry PP.

The alpha activity of the solid overactivated catalyst is 3268 and the productivity is increased to 7027 gPP / g of the solid overactivated catalyst. This PP has the following characteristics:

I.I = 97.9%

G = 698 N / cm ²

MFI = 3g / lomin

PSA = 520g / l.

Example 7R

This example is given for comparison.

A solid reactivated catalyst is prepared according to the indications of the examples

26.

This solid contains per kg, 718g TiCl2, 3.8g aluminum and 84g EDIA. Used in the polymerization test performed under the conditions set forth in Example 4, it is possible to obtain with the alpha activity of 3168, PP the following selections:

I.I = S €, 4%

Mr. = 6 20 ^T / cm ^

MFI = .. 3g / 10min.

PSA = 516g / l

Examples 5-7

According to the conditions given in Example 4, except that the molar ratio between compound a) and b) is modified to give reactivator A (see example l, part B) (examples 6 and 5) as well as the molar ratio between reactivator A and complex-based solids titanium trichloride (expressed as the number of moles of compound a) initially according to the number of moles of TiCl ₃ in the solid (see Example 1) (Example 7) solid reactivated catalysts are obtained.

These reactivated solid catalysts are used in the propylene polymerization assays in suspension in hexane under the conditions generally given in Example 3.

The specific operating conditions for the production of solid catalysts and the results of the polymerization tests are given in Table l, below.

27.

Table 1 '· ..

Example 56 7

Obtaining Preactivated Solid Catalysts

compound a ' - (mol / mol) compound b 50 10 10 compound a 1 1 -. 'C 0.2 \ ino ± / stainless steel / TiCK contained in solid substances the content of TiCl ^. rt. preactivated solid catalyst (g / kg) 724 672 • .- 'i 709

Results of polymerization

alpha activity (g PP / g TiCl ^ xh) 2160 2160 • 2160 PP dissolved in polymerization hexane (% of total PP) 1.1 0.8 1.1 I.I (%) 97, 3 98,2 . 97,4 G (N / cm ^) 678 688 689 MFI (g / 10 min) 7.1 5.0 7.7 PSA (g / l) 502 502 504

Example 8

The solid reactivated catalyst was prepared according to the indications of Example 4 and used in the polymerization test under the conditions set out in part C of Example l, except that the reactor was maintained at 75 ° C with stirring for 2 hours.

28.

In these suls, this solid reactivated catalyst provides a yield of 5010, PP characterized by the following properties:

I.I = 98.1%

G = 688 N / cm ²

MFI = 5.9 g / lOmin

PSA = 519 g / l.

No. Ρ-1789/87

Claims (8)

Patent claims A process for the preparation of a solid catalyst based on a titanium trichloride complex for the polymerization of a specific alpha-olefin, wherein the solid precursor based on the titanium trichloride complex is reactivated by contact with the reaction product of organoaluminum compound (a) of the formula: Al R X, n 3-n where R represents identical or different hydrocarbon radicals containing 1-18 carbon atoms; X is halogen; and n is a number defined to be 0 <n ^ 3, with a hydroxyaromatic compound (b) such as monoyl polycyclic hydroxyarylenes, the hydroxyl group of which is sterically blocked. A process according to claim 1, wherein compound (a) is selected from trialkylaluminum, dialkylaluminum chloride and alkylaluminum dichloride. A process according to claim 1, wherein compound (b) is selected from di-tert-alkylated monocyclic phenols such as: 2,6-di-tert-butyl-4-methylphenol and the 3- (3, monoesters). 5'di-tert-butyl-4-hydroxyphenyl) propionic acid TAKVA such as a n-octadecyl-3- (3 ^x 5-di-tert-butyl-4-hydroxyphenyl) propionate. The process of claim 1, wherein the reactivator is obtained by reacting compound (a) and compound (b) in a molar ratio between 50 and 0.1 moles of compound (a) per mole of compound (b). 5. The method of claim 1, wherein the preactivator contacts the solid precursor at a molar ratio between the total initial amount of compound (a) and the amount of TiCl ₇ in the precursor of 10-1: The method of claim 1, wherein contacting the precursor with the activator is carried out in an inert hydrocarbon diluent. The method of claim 1, wherein the solid precursor and the preactivator are contacted at a temperature between 2040 ° C for a period of 15 to 90 minutes. 8. The process of claim 1, wherein the solid reactivated catalyst is separated from the reactivation medium and evaporated with an inert organic diluent prior to use in polymerization.