WO2001004165A1

WO2001004165A1 - Pre-polymerized catalyst components for the polymerization of olefins

Info

Publication number: WO2001004165A1
Application number: PCT/EP2000/006613
Authority: WO
Inventors: Licio Zambon
Original assignee: Licio Zambon
Priority date: 1999-07-14
Filing date: 2000-07-10
Publication date: 2001-01-18
Also published as: ITMI991552A1; ITMI991552A0; AU6692400A

Abstract

Components of catalysts for the polymerization of olefins CH2=CHR wherein R is hydrogen or an alkyl radical with 1-12 carbon atoms or an aryl radical, comprising the product obtained by contacting a Ti V, Zr or Hf compound containing at least a metal halogen bond and optionally a metal-π bond, with a prepolymer having porosity (mercury porosimetry) higher than 0.3 cm3/g obtained with a catalyst comprising a Ti, V Zr or Hf compound of the type above indicated, supported on a porous support containing a Mg dihalide formed in situ by conversion of a Mg compound different from the Mg dihalides or on TiC1¿3? and/or VC13, having surface area higher than 100 m?3¿/g and porosity greater than 0.5 cm3/g (by nitrogen).

Description

PRE POLYMERIZED CATALYST COMPONENTS FOR THE

POLYMERIZATION OF OLEFINS.

The present invention relates to components of catalysts for the polymerization of olefins

CH₂=CHR, wherein R is hydrogen or a hydrocarbon radical with 1-12 carbon atoms, to the catalysts obtained from said components, and their use in the polymerization of the above olefins.

BACKGROUND OF THE INVENTION

In a previous, still pending patent application (Italian application MI-A-98001823), there are described components of catalysts for the polymerization of olefins, which are obtained by reaction of a Ti compound such as TiCl , with a prepolymer obtained by

(co)polymerization of an olefin CH₂=CHR or a diolefin using a catalyst comprising a catalyst component containing a compound of Ti, V, Zr or Hf supported on a halide of magnesium in active form, preferably Mg dichloride.

The catalysts obtained from said components are endowed with high polymer yield referred to the solid catalyst component present in the prepolymer (one or more times higher than the yield of catalysts obtained from the prepolymer not reacted with the Ti compound).

The polymer yield, however, is not remarkably high if referred to the total prepolymerized solid component comprising the prepolymer.

The high content of polymer present in the solid catalyst component may create problems particularly regarding the feeding of the component into the polymerization plant.

DESCRIPTION OF THE INVENTION

It has unexpectedly been found that it is possible to obtain prepolymer-containing solid components of highly active catalysts capable of providing sufficiently high polymer yields even when the yield is referred to the total prepolymerized catalyst component.

The catalyst components of the present invention comprise the product obtained by contacting a compound of Ti, V, Zr or Hf or mixture thereof, containing at least a transition metal-halogen bond and optionally one or more transition metal-π bonds, with a prepolymer having porosity greater than 0.3 cm³/g (by mercury porosimetry) used in amount from 0.5 to 50 g per g of the solid component of the catalyst used in the preparation of the prepolymer. and obtained by polymerization of olefins CH₂=CHR wherein R has the meaning as above specified and/o diolefins with a catalyst the solid component of which is prepared by contacting a Ti, V, Zr, or Hf compound or mixtures thereof of the type hereinafter specified with a support selected from: a) inorganic porous oxides or porous polymers, having porosity of at least 0.5 cm³/g (by nitrogen porosimetry) and surface area of at least 100 m²/g (BET), containing supported therein a Mg dihalide, preferably Mg dichloride, formed in situ by conversion of a Mg compound different from the Mg halide, fixed on the support; b) Ti and/or V trihalides having surface area higher than 100 m²/g (BET) and porosity greater than 0.3 cm³/g (by nitrogen porosimetry), said trihalides being preferably supported on a porous support having porosity greater than 0.5 cm³/g (by nitrogen) and surface area higher than 100 m²/g (BET) .

The Ti, V, Zr or Hf compound used in the reaction with the prepolymer, as well as that supported on the solid component of the catalyst used for the prepolymer preparation, is preferably choose among TiCl , VOCl₃, ZrCl and metalloce compounds of Ti, Zr and Hf containing two pentadienil rings coordinated with the transition metal, and optionally substituted with halogen, hydrocarbon radicals or other radicals and/or bridge-connected or condensed with other rings.

Examples of representatives metalloce compounds are described in WO 95/26369, the relevant part of which is herein incorporated by reference.

Other usable compounds, particularly when the catalyst is used in the (co)polymerization of ethylene, are Ti(OR)_n-_y X_y compounds, wherein n is the valence of Ti and y is a number from 1 to n; X is halogen; is a hydrocarbon radical with 1-12 C. Representatives compounds are Ti(OR) and the halogenated derivatives thereof, wherein R is an alkyl radical whit 1-8 C, such as Ti-tetrabutylate and Ti-mono and Ti-dichloroalcoholates. Ti amides and chloro-Ti-amides are also suitable compounds.

The inorganic porous oxides have a porosity of preferably 1 to 3.5 cm³/g and surface area from 100 to 500 m²/g.

Preferably, the oxide is selected from silica, silica-gel and alumina.

Examples of silica are Grace Devison 952 silica with surface area of 270 m²/g, porosity (by nitrogen) of 1.53 cm³/g and water content (Fischer method) of 4.3% by weight; Grace 332 silica-gel (surface area of 330 m /g, porosity of 2.0 cm /g - by nitrogen - and water content of 4% by weight) or a silica gel with diameter of the particles from 20 to 45 micron, porosity (by nitrogen) of 1.75 cm /g and surface area of 320 m /g. AKZO Ketijen B alumina (pseudo bohemite crystalline form with surface area of 266 m /g, porosity - by nitrogen - of 0.64 cm /g and water content of 17%> by weight (Fischer method), is an example of suitable aluminas.

In the above Katijen alumina, the water content is lowered to 3-4%> by weight prior preparation of the catalyst component.

The metal oxide support contains surface hydroxyls in quantity that can reach 3 m.mols and more per g of oxide.

Preferably, in addition to the hydroxyl groups, chemically uncombined water is also present in quantity up to 20 m.mols per g of oxide.

The amount of OH groups is regulated by heating the oxides at temperatures from 150 to

300°C (higher is the heating temperature lower is the content of hydroxyls).

The chemically uncombined water is added according to various procedures.

One of the preferred method consists in passing a stream of humidity - containing nitrogen over the oxide previously dried.

The quantity of hydroxyls is preferably comprised from 1 to 3 m.mols per g of oxide; water can be present in amount from 1 to 10 m.mol per g oxide.

The polymeric supports preferably are in form of microspheroidal particles with diameter of 20 to 200 micron.

A class of polymeric supports particularly suitable is represented by the styrene polymers partially cross-linked with monomers such as divinylbenzene.

A method of preparation of said polymers is described in USP 4,224,415, the content of which is herewith incorporated by reference.

As example, a microspheroidal polystyrene support has surface are of 370 m /g, porosity

1.70 cm /g (by nitrogen), average radius of pores of 94 A (BET) and particle size of more

50% of the particle from 150 to 180 micron.

The supportation of the Mg halide, on the inorganic porous support is made according to various methods. One of these (described in E-P-A-0437264) consists in reacting the metal oxide with a Mg alkyl compound such as CH₃ Mg Br, CH₃ Mg Cl, nC₄H₉ Mg Cl, nC₃H₇ Mg Cl and complexes thereof with ethers such as ethyl ether and tetrahydrofurane, in quantity of not causing reduction of the titanium compound in the subsequent reaction of the support with a compound of tetravalent Ti. The Mg halide is formed in situ by reaction of the metalorganic Mg compound fixed on the metal oxide support with a halogenated compound of tetravalent Ti.

When using TiCl₄ the reaction is conducted using an excess TiCl₄ on the porous support;

TiCl₄ containing an electron-donor compound when the catalyst components has to be used in the stereoregular polymerization of propylene or similar olefins.

The reaction is carried out at 40°C - 130°C, preferably 80-130°C with a duration of 0.25 to

1 or more hours.

After reaction, the TiCl excess is separated while hot and the solid repeatedly washed with a hydrocarbon (hexane) to complete removal of the chloride ions.

Conveniently, the treatment with TiCl is repeated one or more times and the solid washed as above indicated.

Any electron-donor capable of forming complexes with the Mg dichloride is usable.

Preferred compounds are the esters of aromatic acids, particularly dicarboxylic acids such as the phthalates e.g. dusobuthyl, dioctyl and diphenyl- phthalates and the esters of malonic, pivalic, succinic and carbonic acids.

Dieters such as 2.2-diisobutyl-1.3-dimethoxy-propane, 2-isopropyl-2-isopentyl-1.3- dimethoxy-propane, 1.1 bis (methoxy methyl) indene, and 9.9-bis-methoxy methyl - 2.3,

6,7 tetrame hyl fluorene and derivatives thereof substituted with hydrocarbon radicals or halogens are examples of preferred compounds.

The quantity of electron-donor compound is from 0.1 to 1.5 mols, preferably 0.2-0.4 mols per Mg-g-atom.

The Mg content in the oxides is comprised from 0.5 to 20% by weight.

The ratio Mg/Ti ranges from 1.5 to 10; the electron-donor compound is present from 5-

20% by mols referred to the Mg-g-atoms.

The surface area of the catalyst components is from 100 to 300 m²/g and the porosity is greater than 0.5 cm³/g (by nitrogen).

An other method for supporting the Mg halide on the inorganic porous support is described in USP 4.857.613, the relevant disclosure of which is herewith incorporated by reference.

According to this method, silica gel previously dehydrated is treated whit alkyl Mg compounds such as Mg (butyl-octyl) and Mg dibutyl and thereafter with a chlorinating agent (HC1) to decompose the metalorganic compound to form Mg Cl₂ in situ. An alkanol such as ethanol is thereafter reacted to form an adduct Mg Cl .3C₂H₅OH which is than dealcoholated by reaction with TiCl₄.

A further method consists in dissolving MgCl in absolute ethanol, in adding a part of the obtained solution to a suspension in ethanol of silica gel (GRACE 332), in treating the suspension whit TiCl₄ in excess and containing an electron-donor compound, at temperatures from 100° to 120°C.

The treatment with TiCl is repeated one or more times and the solid is repeatedly washed with hexane.

The supportation of the Mg halide on the polymeric supports is carried out with methods similar to those used for the supportation on the metal oxides.

For example, it is possible to treat the polymeric support with a quantity of solution of Mg halide, preferably Mg Cl₂, in an alcohol, such as ethanol and butanol, in quantity to fix from 1 to 20 g of Mg per 100 g of support and from 1 to 6 mols alcohol.

The adduct thus supported is thermally dealcoholated to form the Mg halide or is reacted with compounds such as SiCl and Al-trialkyls.

The treatment with transition metal compound is therefore made.

Preferably, the Mg halide is formed by reaction with TiCl₄ in excess: this allows to obtain the Mg halide and contemporaneously of fixing the Ti compound on the halide.

Similar methods are used when it is desired to support a trihalide of Ti or V.

In this latter case, the trihalide, preferably TiCl₃ obtained from TiCl by reduction with hydrogen, or VC1₃, is dissolved in alkanol (preferably ethanol or butanol), in quantity to fix

1-40 g of Ti or V per lOOg of support and from 1 to 6 mols, preferably 3 mols, of alcohol per g-atom of Ti or V.

The adduct is fhermically dealcoholated to form the Ti or V trihalide in active form or by reaction with compounds such as SiCl and Al-triethyl.

The treatment with the transition metal compound follows.

The adduct is dealcholated preferably by reaction with TiCl₄ in excess: this allows to directly fix the Ti compound on the Ti or V trihalide.

In the case in which the Ti or V trihalide is used as such without being supported on a porous support, the trihalide is converted into the form having the required characteristics by thermally dealcoholating adducts with 1 -6 mols of alcanol, preferably 3 mols of ethanol or butanol per mol of trihalide, or by reaction with compounds such as SiCl₄, TiCl₄ and Al- trialkyls.

The supportation of TiCl₄ or VOCl₃ and similar compounds on the porous support containing the Mg halide or on the Ti or V trihalide is carried out by reacting the Ti or V compound in excess, preferably operating in presence of an electron-donor compound such as an ether of the types above specified or an alkylphthalate, in quantity of 10-30%) by mols per g-atom of Ti or V of the trihalides.

The prepolymer preparation is carried out according to known methods operating at temperatures preferably from 0° to 25°C, in presence of an Al-alkyl compound, particularly Al-triethyl or triisobutyl, in molar ratio Al/transition metal compound present in the supported catalyst component preferably comprised form 10 to 50. The olefin may be any of the olefins CH =CHR wherein R is hydrogen or a hydrocarbon radical with 1-12 carbon atoms and/or a diolefin can be used.

When the catalysts are used for the production of ethylene or propylene polymers, ethylene or propylene are the olefins preferably used.

The catalyst used in the prepolymerization of olefins different from ethylene, is of preference stereospecific capable of providing polymers with isotacticity index higher than 80-90%.

As it is well know, the use of an electron-donor compound fixed either on the solid catalyst component (inside donor) and partially complexed with the Al-alkyl compound (outside donor) or fixed only on the solid component allows to render sterospecific a catalyst comprising a Ti compound supported on a Mg halide.

When the support is Ti or V trihalide, particularly TiCl₃ or VC1₃, the catalyst is per se sufficiently stereospecific: also in this case, however it is convenient to use an inside donor.

The preferred inside donors are the alkyl or isoalkylphthalates and the diethers as hereinbefore specified.

The catalyst components of the instant invention form with an Al-alkyl compound, preferably Al trialkyls such as Al triethyl and Al-triisobutyl, highly active catalysts for the polymerization of olefins CH₂=CHR, wherein R is hydrogen or an alkyl radical with 1-12 carbon atoms, or an aryl radical. When the catalyst has to be used for the stereoregular polymerization of olefins such as propylene, an inside donor and preferably also an outside donor is used.

The preferred inside donors are the ethers and the alkylphthalates as hereinbefore specified.

The phthalates are preferably used in combination with an outside donor such as a silane.

The molar ratio Al alkyl compound/transition metal compound present in the prepolymer is comprised in a wide range; preferably is greater than 10.

When the catalyst component comprises a metalloce compound of Ti Zr or Hf containing at least a metal-π bond supported on the prepolymer, the Al-alkyl compound is an alumoxane, preferably methylpolyalumoxane.

Compounds containing anions such as tetrakis pentafluorophenyl borate are also usable.

The use of compounds of the above type is described for instance in WO 92/00333.

The (co)polymerization of olefins with the new catalysts is carried out according to known methods operating in liquid phase or in suspension in an inert hydrocarbon solvent or in gas phase.

The new catalysts allow, besides other advantages, to eliminate the prepolymerization step which normally is used in the processes for the production of polyolefins and to obtain polymers with extremely low catalyst residues.

The following examples are provided to illustrate but not to limit the invention.

Comparison Example 1.

Example 1 of EP-A- 437264 is repeated obtaining polymerization results substantially corresponding to those reported in said example (TEST A).

The catalyst component prepared according to the Example of the European application is used in a prepolymerization test with propylene to obtain a weight ratio prepolymer/solid catalyst component of 3 : 1.

The prepolymerization was carried out in hexane using Al-triethyl (TEAL) in weight ratio with the solid catalyst component of 0.5, and 2-isopropyl-2-isopentyl-l,3- dimethoxypropane (DMP) as outside donor (molar ratio TEAL/DMP of 20).

The prepolymerized catalyst component is used in a polymerization test of propylene under the conditions of Example 1 of the European application (TEST B).

The polymer yield referred to the prepolymer was of about 3 times less than that obtained with the catalyst of TEST A. Example 1

The prepolymer obtained according to Comparison Example 1 is suspended in TiCl containing DMP, in amount such as to have a ratio of 50 g prepolymer per 1000 ml of

TiCLt and of 10% by weight of DMP on the prepolymer.

The temperature is raised to 80°C and the mixture is maintained under stirring for 1 hour.

After this time, the liquid is siphoned of and the solid washed with hexane.

The treatment with TiCl₄ is repeated in the absence of DMP, and the obtained solid is washed with hexane.

The propylene polymerization test using the catalyst component as above prepared is carried out under the condition of Comparison Example 1.

A polymer yield referred to the prepolymerized catalyst component is obtained higher than the yield of TEST B of Comparison Example 1.

Comparison Example 2.

The test of Example 2 of USP 4.857.613 is repeated obtaining polymerization results substantially corresponding to those therein reported (TEST A).

The catalyst component prepared according to the above example is prepolymerized with propylene under the condition reported in Comparison Example 1 to obtain a weight ratio prepolymer/solid catalyst component of 3 : 1.

The prepolymer is then used in the polymerization of propylene under the conditions reported in Example 2 of USP 4.857.613.

The polymer yield referred to the prepolymer of the catalyst component (TEST B) was of about 3 times less than that of TEST A.

Example 2.

The prepolymer obtained as indicated in Comparison Example 2 is treated with TiCl₄ and

DMP under the conditions reported in Example 1.

The polymeric solid component was thereafter used in a polymerization test of propylene under the conditions of Example 2 of USP 4.857.613.

The polymer yield referred to the prepolymerized catalyst component was higher than that obtained according to TEST B of Comparison Example 2.

Comparison Example 3.

A solution of MgCl in ethanol containing 10 g MgCl₂ is added to a suspension of silica gel (Grace 332) in ethanol, and maintained under stirring for 0.5 hour. The suspension is dried at 50°Cunder vacuum to obtain a solid containing 4 mols of ethanol per mol of MgCl .

The solid is added to TiCl (weight ratio 1 :30 with respect to TiC14) and the mixture heated to 100°C.

At 70°C, di-n-butylphthalate(DNBF) is added in molar ratio Mg/DNBF of 4.

The mixture is maintained at 100°C for 2 hours and, after decantation, the treatment is repeated at 1 10°C for 1 hour.

Part of the solid product washed with hexane is used in a polymerization test of propylene under the conditions of Comparison Example 1 with the only difference that no outside donor is used.

A polymer yield of 25 Kg/g of solid catalyst component having isotacticity index of 96%) in xylene at 25°C is obtained (TEST A).

Part of the solid catalyst component is used in a prepolymerization test with propylene at room temperature using Al-triethyl in weight ratio with the solid component of 0.05 and using DMP as outside donor in molar ratio TEAL/DMP of 20.

The polymerization is continued until 2 g polymer for 1 g of solid catalyst component are obtained.

The polymeric catalyst component is used in a test of propylene polymerization under the condition of TEST A.

A yield is obtained of 12 Kg polymer per g of polymeric catalyst component, having isotacticity index of 96% (TEST B).

Example 3.

The prepolymer obtained according to Comparison Example 3 is treated with TiCl and

DPM under the conditions of Example 1.

A portion of the obtained solid is used in a propylene polymerization test under the conditions of TEST A of Comparison Example 3.

The polymer yield referred to the prepolymer of the catalyst component is higher than that of TEST B of Comparison Example 3.

Comparison Example 4.

The preparation of Comparison Example 3 is repeated with the only difference that TiCl₃

(from TiCLt reduced with hydrogen) is used in place of the component supported on MgCl and that the solid product is dried to obtain a molar ratio ethanol/TiCl₃ of 3 : 1. A portion of the solid is used in a test of propylene polymerization carried out under the conditions of Comparison Example 3 (TEST A).

Another portion of the solid is prepolymerized under the conditions of Comparison

Example 3 to obtained 10 g polymer per g of solid component.

Part of the polymeric catalyst component is used in a propylene polymerization test carried out under the conditions of Comparison Example 3 obtaining a polymer yield of about 1 1 time lower that that of TEST A.

Example 4.

The prepolymer obtained under the conditions of Comparison Example 3 is treated with

TiCl₄ and DNBF under the conditions of Comparison Example 3.

A portion of the solid is used in a propylene polymerization test carried out under the condition of TEST A of Comparison Example 4 obtaining a polymer yield referred to the prepolymer of the catalyst component higher than that of TEST B of Comparison Example

4.

Claims

CLAIMS.

1. Components of catalysts for the polymerization of olefins CH =CHR, wherein R is hydrogen or a hydrocarbon radical with 1-12 carbon atoms, comprising a product obtained by contacting a compound of Ti, V, Zr or Hf containing at least a metal- halogen bond, and optionally at least a metal-π bond with a prepolymer having porosity higher than 0.3 cm g (Hg porosimetry) and containing from 0.5 to 50 g polymer per g of solid catalyst component characterized in that the catalyst used for the preparation of the prepolymer comprises a solid component obtained by contacting a Ti, V, Zr and Hf compound as above specified, with a support selected from: a) porous inorganic oxides or porous polymers having porosity higher than 0.5 cm³/g (by nitrogen) containing a Mg dihalide in quantity from 1 to 20 g Mg per 100 g of porous support, wherein said Mg dihalide is formed in situ by conversion of a Mg compound different from the Mg dihalide; b) TiCl₃ (from TiCl₄ by reduction with hydrogen) and/or VC1₃. having surface area higher than 100 m /g and porosity more than 0.3 cm /g (by nitrogen), or said trihalides supported on a porous support having porosity greater than 0.5 cm /g.

2. Catalyst components according to claim 1, wherein the solid component of the catalyst used for the preparation of the prepolymer is obtained by reacting TiCl with a silica or silica gel support having porosity higher than 0.5 cm /g and surface area of more than 100 m²/g.

3. Catalyst components according to claims 1 and 2, wherein the Mg halide supported on the porous support is Mg dichloride.

4. Catalyst components according to claim 3, wherein the Mg dichloride formed in situ is obtained by reaction of a chlorinating agent with Mg-alkyl compounds or Mg-alcoholates, or by thermal dealcoholation of MgCl₂.alkanols adducts containing from 1 to 6 mols alcohol per mol of MgCl₂, or by reaction of the adducts with SiCl₄, Al.trialkyl or TiCl₄.

5. Catalyst components according to previous claims 1-4, wherein the weight ratio polymer/solid catalyst component present in the prepolymerized catalyst component is less than 10.

6. Catalyst components according to previous claims 1-5, wherein the porosity of the prepolymer used in the reaction with the Ti, V, Zr or Hf compound is greater than 0.5 cm /g.

7. Catalyst components according to claim 1 part b), wherein the TiCl₃ and/or VC1₃ are supported on silica or silica gel having porosity greater than 0.5 cm³/g.

8. Catalyst components according to previous claims 1-7, containing an electron-donor compound in amount from 1 to 20%) molar with respect to the transition metal compound present in the prepolymer.

9. Catalysts obtained from a solid catalyst component according to anyone of previous claims 1 to 8 and from an Al-alkyl compound.

10. Catalysts according to claim 9, wherein the Al-alkyl compound is Al-triethyl and Al- triisobutyl.

11. Process for the polymerization of olefins CH =CHR wherein R is hydrogen or an alkyl with 1-12 carbon atoms or an aryl radical carried out in the presence of a catalyst according to claims 9 and 10.

12. Polyolefins obtainable with the process of claims 10 and 1 1.