STATE OF THE ART PRIOR TO THE INVENTION

[0001] It is well known that metallocene compounds such as bis(cyclopentadienyl)titanium dialkyl or bis(cyclopentadienyl)zirconium dialkyl in combination with alkyl aluminiums act as catalysts for olefin polymerization in homogeneous phase. Thus, German patent DE-2,608,863 describes the use of bis(cyclopentadienyl)titanium dialkyl in combination with trialkylaluminium and a controlled quantity of water in olefins polymerization.

[0002] The controlled hydrolysis of alkyl aluminiums gives rise to the formation of species containing an Al—O bond (aluminoxane) which are real co-catalysts in the polymerization of olefins with metallocenes. Kaminsky (Adv. Organomet. Chem. b 1980, 18, 99) shows that aluminoxanes in combination with dichlorometallocenes produce catalyst systems which are very active in ethylene polymerization.

[0003] It is also possible (Turner, EP 277004 and Ewen et al. EP 426637) to use co-catalysts formed by bulky boron compounds which, acting as non-coordinative anions, stabilize the cationic form of the metallocene without preventing the incorporation of the olefin in the polymerization process.

[0004] The polymerization processes that use homogeneous catalyst systems produce high polymerization activities. However, most industrial processes require heterogenous catalyst systems which on the one hand produce polymers with a controlled morphology, but on the other hand have an activity of the order of the homogeneous systems.

[0005] In European patent EP 206794 it is described heterogeneous catalysts obtained through simultaneous or subsequent (in any order) addition of aluminoxanie and metallocene onto an inorganic support.

[0006] This process, according to patent EP 260130, can also be applied to multicomponent systems. These catalysts are those which contain various metallocenes or one metallocene and one non-metallocene compound of a transition element. In this way, polyolefins with a multimodal molecular weight distribution are obtained.

[0007] In patents EP 361866, EP 323716, EP 367503, EP 368644 and US 5057475 it is described the preparation of a heterogeneous catalyst system composed by one aluminoxane and one metallocene characterized in that the aluminoxane is generated “in situ” through reaction of a trialkylaluminium with undehydrated silica. The use of this catalyst system in α-olefins polymerization gives rise to high activities.

[0008] Another well known technique used in the preparation of heterogeneous catalysts is the chemical modification of the inorganic support. In patents EP 474391 and EP 314797 it is described a process wherein the support, before the addition of the metallocene, is treated with an organoaluminium compound which reacts with the hydroxyl groups present on the silica surface.

[0009] The above described catalyst systems present the drawback that the catalyst is not tightly enough bonded to the support so that the separation of the metallocene from the support can occur, producing polymerization in solution, which prejudices the morphology of the obtained polymer.

[0010] As a consequence of that, methods for obtaining the formation of a chemical bond between the support and the metallocene are looked for. A possible solution is the formation of a chemical bond by reacting a functionalized metallocene and a partly dehydrated silica. In patents EP 293815 and DE 3718888 it is described a method for the preparation of a supported catalyst wherein the chemical bond between the support and the metallocene is obtained by reacting an alkoxysilane group united to the metallocene and an hydroxy group of the support. The synthesis of this catalyst is difficult and very low yields are obtained. Furthermore, the activity in the polymerization of the olefins of the resulting catalysts is rather low.

[0011] Patent DE 3840772 describes the use of metallocenes functionialized with vinyl groups united to the cyclopentadienyl ring. Heterogeneous systems are obtained by reacting the double bond with polysiloxanes in the presence of a fit catalyst. This method presents the drawback of needing an additional purification process for removing this catalyst.

[0012] According to patent EP 628566, it is possible to prepare heterogeneous catalysts by reacting ligands already chemically bonded to the support first with alkyllithium and then with metal halides MX₄ (wherein M is a transition metal and X is a halide). This process produces catalysts with the metallocene tightly bonded to the support. They are used in olefins polymerization in combination with alumoxanes. Also in this case it is necessary a purification of the catalyst system to eliminate the residues of the reagents used in its formation.

[0013] EP-A-757053 discloses new metallocenes characterized by the following general formula X_mM(L-M²(R¹R²)-A-ZR³_oHal_p)_n, wherein M is a metal of group 4, 5 or 6 of the periodic table, each X is independently selected from hydrogen, halogen or a C₁-C₄₀ carbon-containing rest; m is equal to 1, 2 or 3; n is equal to 1 or 2; each L is independently a n ligand, which coordinates to the central atom M; each M² is independently selected from silicon, germanium or tin); R¹ is a C₁-C₂₀ carbon-containing group; R² is a C₁-C₂₀ carbon-containing group or a n ligand, whichl coordinates to the central atom M; each A is independently a divalent C₁-C₄₀ carbon-containing rest; each Z is independently selected from boron, silicon, germanium or tin; each R³ is independently selected from hydrogen or a C₁-C₂₀ carbon-containing rest; o is equal to 0, 1 or 2; each Hal is independently selected from a halogen atom; p is equal to 1, 2 or 3.

[0014] These compounds are characterized by the presence of a hydrocarbon bridge connecting two silicon, germanium or tin atoms to whom the halogen atom is connected. This characteristic makes them especially suitable in the preparation of supported catalysts.

[0015] An object of the present invention is to provide new catalyst component comprising a bridged metallocene having a Si—Cl functional group bonded to bridge. These compounds can be supported on silica.

DESCRIPTION OF THE INVENTION

[0016] In this invention it is described organo metallic compounds of transition metals of groups 3, 4, 5 or 6 of the periodic table of the metallocene-type. Besides, the compounds of the present invention are characterized in that they have at least one link or bridge between the cyclopentadienyl type unities. The bridge is characterized in that it shows at least one functionality, either included in the bridge or bonded to it, this being a Si—Y, Ge—Y or Sn—Y-type unity, preferably Si—Y, Y being halogen; preferably Y is chlorine or bromine.

[0017] In the present invention it is described the synthesis of these metallocenes as well as methods for supporting these compounds onto solids.

[0018] The invention refers in general to metallocenes represented by the following formula (Formula I) 2

[0019] wherein:

[0020] Y is halogen;

[0021] M is a transition metal of groups 3-6 of the periodic table;

[0022] each L is selected from a cyclopentadienyl-type unity, including indenyl or fluorenyl, substituted or not and the substituents being equal or different, united to M through a π bonlti; Z is a group that forms a union bridge between the two unities L, which can have between 0 and 20 carbon atoms and between 0 and 5 oxygen, sulfur, nitrogen, phosphorus, silicon, germanium, tin or boron atoms; E is a spacer group that unites Z and Y and can have between 0 and 20 carbon atoms and between 0 and 5 oxygen, sulfur, nitrogen, phosphorus, silicon, germanium, tin or boron atoms. It is characterized for having in its skeleton at least one silicon, germanium or tin atom, which the substituent Y is united to;

[0023] o is a number of value 0 or 1;

[0024] k is a number of value 1, 2 or 3;

[0025] m is a number equal to or highler than 2 and coinciding with the oxidation state of the transition metal;

[0026] j is a number of value 0 or 1 with the condition that its value is 1 at least once; when j is 1 and o is 0, Z is characterized by having at least one silicon, germanium or tin atom which Y is directly united to;

[0027] with the proviso that the conipounid does not have general fornula

X_mM¹(L′-M²(R¹R²)-A′Z′R³_oHal_p)_n,

[0028] wherein M′ is a metal of group 4, 5 or 6 of the periodic table, each X is independently selected from hydrogen, halogen or a C₁-C₄₀ carbon-containing rest; m′ is equal to 1, 2 or 3; n′ is equal to 1 or 2; each L′ is independently a n ligand, which coordinates to the central atom M¹; each M² is independently selected from silicon, germanium or tin; R¹ is a C₁-C₂₀ carbon-containing group; R² is a C₁-C₂₀ carbon-containing group or a n ligand, which coordinates to the central atom M¹; each A′ is independently a divalent C₁-C₄₀ carbon-containing rest; each Z′ is independently selected from boron, silicon, germanium or tin; each R³ is independently selected from hydrogen or a C₁-C₂₀ carbon-containing rest; o′ is equal to 0, 1 or 2; each Hal is independently selected from a halogen atom; p′ is equal to 1, 2 or 3.

[0029] The invention preferably refers to metallocenes represented by the following formula (formula II): 3

[0030] wherein:

[0031] Y is halogen;

[0032] M is a transition metal of groups 3, 4, 5 or 6 of the periodic table;

[0033] each L is selected from a cyclopentadieniyl-type unity, including indenyl or fluorenyl, substituted or not and the substituents being equal or different, united to M through a π bond;

[0034] Q is an element of group 13, 14 or 15;

[0035] E is a spacer group that unites Q and Y and can have between 0 and 20 carbon atoms and between 0 and 5 oxygen, sulfur, nitrogen, phosphorus, silicon, germanium, tin or boron atoms and it is characterized by having in its skeleton at least one silicon, germanium or tin atom, which the substituent Y is united to;

[0036] R is selected from the group comprising: hydrogen, halogen, halocarbon, substituted halocarbon, C₁-C₂₀ alkyl, C₁-C₂₀ alkenyl, C₆-C₂₀ aryl, C₇-C₄₀ alkylaryl, C₇-C₄, arylalkyl, C₈-C₂₀ arylalkenyl, alkoxy, siloxy and combinations thereof; A, equal to or different from each other, is a bridge group between unities L aud Q constituted either by only one divalent atom of group 16, preferably —O—, or by a trivalent monosubstituted element of group 15, preferably >N—R, R being defined above, or a tetravalent disubstituted element of group 14, preferably >C(R)₂ or >Si(R)₂, R being defined above, or by a chain of 2 or more atoms substituted or not, this chain being preferably of type —C—C—, —C—Si—, —Si—Si—, —Si—O—, —C—O, —C—N—, —C—C—C, —C—Si—C—, —Si—O—Si—;

[0037] o is a number of value 0 or

[0038] k is a number of value 1, 2 or 3;

[0039] m is a number equal to or higher than 2 and coinciding with the oxidation state of the transition metal;

[0040] p, n, 1 are numbers of value 0 or 1.

[0041] j is a number of value 0 or 1 with the condition that its value is 1 at least once; when j is 1 and o is 0, Q is a silicon, germaniun or tin atom;

[0042] with the proviso that the compound does not have general formula

X_m—M¹(L′—M²(R¹R²)—A′—Z′R³_o—Hal_-—)_n—,

[0043] wherein M¹ is a metal of group 4, 5 or 6 of the periodic table, each X is independently selected from hydrogen, halogen or a C₁-C₄₀ carbon-containing rest; m′ is equal to 1, 2 or 3; n′ is equal to 0 or 2; each L′ is independently a n ligand, which coordinates to the central atom M¹; each M² is independently selected from silicon, germanium or tin; R¹ is a C₁-C₂₀ carbon-containing group; R² is a C₁-C₂, carbon-containing group or a π ligand, which coordinates to the central atom M¹; each A′ is independently a divalent C₁-C₄₀ carbon-containing rest; each Z′ is independently selected from boron, silicon, germanium or tin; each R³ is independently selected fromi hydrogen or a C₁-C₂₀ carbon-containing rest; o′ is equal to 0, 1 or 2; each Hal is independently selected from a halogen atom; p′ is equal to 1, 2 or 3.

[0044] In the most preferred embodiment the invention refers to metallocenes having the following general formulas (III) and (IV) 4

[0045] herein:

[0046] L, M, m, Y, E, R, I, n have already been defined; C is a carbon atom; T is selected from: silicon, germanium or tin.

[0047] What follows are descriptive and non-limiting examples of the structural formulas of some metallocene compounds according to the present invention: 5

[0048] In these formulas the following symbols have been used:

[0049] Y, R and M: above defined

[0050] Cp: cyclopentadienyl or substituted cyclopentadienyl ring, also including in this definition substituted or not indenyl rings and substituted or not fluorenyl rings, Cp being able to represent in the same formula equal or different rings.

[0051] The synthesis of the functionalized metallocenes object of the present invention can be obtained according to the general method represented in the following scheme. 6

[0052] being:

[0053] Y, Z, L, E, M, j, m and o defined above;

[0054] S: leaving group united to the cyclopentadienyl ring, preferably constituted by a unity T(R⁴)₃, T being silicon, germanium or tin and R is C₁-C₂₀ alkyl.

[0055] S represents preferably groups Si(CII₃)₃ and Sn(CII₃)₃. In case represented by this scheme, S can represent unities equal or different; in general, the union L—S can represent an ionic, s or π bond or a combination thereof.

[0056] The union L—M always represents a bond with a high π character.

[0057] Preferred compounds of general formula III can be obtained according to the following scheme: 7

[0058] The synthesis of functionalized metallocenes having a carbon bridge as depicted in formula IV could be achieved following the general procedure described in this document starting from a suitable ligand: 8

[0059] In order to achieve a suitable functionialized ligand, an olefinically unsaturatcd precursor having the unsaturation within unit E in the formula could be used. Reacting this precursor under hydrosilylation, hydrogermanilation or hydrostannilation conditions the suitable functional group (Si—Y, Ge—Y or Sn—Y) could be obtained.

[0060] Alternatively, a functionalized metallocene according to formula IV could be obtained from a metallocene already having an olefinic unsaturation as part of unit E.

[0061] Metallocenes of this type are known in the current literature, for example EP 685495 (Phillips). The functionalization of the metallocene could be achieved again by reacting it under hydrosilylation, hydrogermanilation or hydrostannilation conditions to attach the suitable functional group (Si—Y, Ge—Y or Sn—Y).

[0062] In order to illustrate the different approaches towards the synthesis, the followilng scheme of a compound having the structure Cl₃SiCH₂CH₂CH₂CH₂C(CH₃)Cp₂ZrCl₂ is shown. All the reactive steps shown in this scheme (represented by an arrow) can be of common knowledge for a person skilled in the art of metallocene synthesis and can be obtained by employing reagents different from those shown in the scheme.

[0063] The procedure employed for step (a) can be learned, for example, from Stone et al. In J. Org. Chem. 1984, 49, 1849. The procedure of step (b) call be learned, for example, from J. Organomet. Chem., 1992, 435, 299, or J. Chem. Soc., Dalton Trans. 1994, 657 or EP 685495. The procedure for step (c) can be learned from U.S. Pat. No. 5,191,132. Step (d) is the obtaining of the dianion and could be achieved with many different reagents (e.g. Li, Na, K, BuLi, BuMgBr, etc.), here BuLi is shown in order to illustrate one of the most popular reactants employed. Step (e) is also of very common use in the synthesis of metallocenes, see again, for example, J. Organomet. Chem., 1992, 435, 299, or J. Chem. Soc., Dalton Trans. 1994, 657 or EP 685695. Procedures for steps (I), (g) or (j) can be learned from the present document but also from Organometallics 1995, 14, 177 or Angew. Chem. Int. Ed. Engl., 1994, 33, 1479. Hydrosilylation [steps (h) and (i)] can also be achieved with different reagents, being H₂PtCl₆·6H₂O one of the most commonly employed (see for example Adv. Organomet. Chem. 1979, 17, 407 or J. Fluorine Chem. 1994, 68, 71 or EP 628566). 9

[0064] These processes for the synthesis of metallocenes with functionalized bridge can be done in the presence of solvent or not. In case a solvent is used, this can be preferably an aliphatic hydrocarbon, an aromatic hydrocarbon, or mono or polyhalogen containing derivatives therefrom. A mixture of two or more solvents can be used too.

[0065] These processes for the synthesis of metallocenes with functionalized bridge can be done in a temperature range between −20 and 300° C., preferably between 0 and 200° C., or at the reflux temperature of the used solvent system.

[0066] These processes for the synthesis of metallocenes with functionalized bridge can be done with or without protection from light. Another object of the present invention is to provide new supported catalyst components showing a good productivity and producing polyolefins characterized by a good morphology.

[0067] The supported catalyst component comprising an inorganic support and a metallocene described in the present invention can be prepared by adding the reagents to a fit inert solvent. Examples of useful solvents are ethers such as tetrahydrofurane (THF), aromatic hydrocarbons, such as toluene and aliphatic hydrocarbons such as heptane or hexane.

[0068] The inorganic support according to the present invention contains hydroxyl groups. Illustrative, but not limiting, examples of supports useful in the field of the present invention are the following: silicates, carbonates, phosphates, clays, metaloxides and mixtures thereof. More preferably: silica, alumina, silica-alumina, silica titanates, silica vanadates, silica chromates, aluminium phosphates, phosphated silica and possible mixtures thereof.

[0069] The surface area of the inorganic support is preferably 10-1000 m²/g, more preferably 150-650 m²/g. The pore volume is preferably 0.2-4.0 cm³/g, more preferably 0.6-2.7 cm³/g. The average particle size is preferably 1-1000 microns, more preferably 5-100 microns.

[0070] The water contained in the support can be optionally removed before reacting the support with the metallocene. The dehydration process can be performed by heating the support in an oven in inert atmosphere at a temperature between 120° C. and 1000° C. (preferably between 200 and 800° C.). The amount of hydroxyl groups on the support can be measured in several ways, for example by titration with n-butylmagnesium chloride or triethylaluminium.

[0071] The concentration of hydroxy-groups depends on the dehydration temperature and on the support used. In case silica is used, it can vary from 0,1 to 5 mmol OH/g of silica, preferably 0.3 to 3 mmol OH/g of silica or from 0,1 to 7 groups OH/nm², preferably 0.5 to 5 groups OH/nm². Once dehydrated, the support has to be protected from environmental humidity, for example by storing it under inert atmosphere (nitrogen or argon).

[0072] The inorganic support is used as such or it can be previously modified through reaction of the hydroxy-groups with compounds of formula V: 10

[0073] being:

[0074] R: atom of hydrogen, halogen, halocarbon, substituted halocarbon, C_1-20 alkyl, C_2-20 alkenyl, C_6-20 aryl, C_7-40 alkylaryl, C_7-40 arylalkyl, C_8-20 arylalkenyl, alkoxy, siloxy and combinations thereof

[0075] X: halogen or group OR⁴ wherein R⁴ has the same meaning given above

[0076] P: NH₂, NHR, SH, OH or PHR

[0077] v+z+w=3, v being different from 0

[0078] t and u are comprised between 0 and 10.

[0079] Some examples of compounds of formula III are:

[0080] 3-Mercaptopropyltrimethoxysilane, 3-aminopropyltrimethxysilane, N-Phenylptopyltrimethoxysilane, N-Methylpropyltrimethoxysilane, N-Aminopropyldimethoxymethylsilane, 3-mercaptopropyltrimethoxy-silane.

[0081] Both the functionalized metallocenes object of the present invention and their derivatives supported onto inorganic solids can be used in polymerization reactions in conjunction with one or various co-catalysts. Said co-catalysts are anionic non-coordinative compounds of alumoxane, modified alumoxane or boron compounds type. In case boron derivatives are used, the supported systems have to be previously treated for alkylating the metallocene unities. This alkylation can be done by using alkylating agents described in literature. Illustrative but non-limiting examples of co-catalysts are: methylalumoxane (MAO), dimethylaniline tetrakis(pentafluorophenyl)boro or trispentafluoro-phenylborane.

[0082] The catalyst systems described in the present invention are useful for the homo and copolymerization of α-olefins, in suspension or in gas phase, as well as in mass polymerization at high temperatures and pressures. The temperature can vary between −60° C. and 300° C., preferably between 40° C. and 250° C. The pressure can vary between 1 and 2000 atmospheres. The polymerization time can vary between 1 second and 6 hours, according to the process type.

[0083] The process is applicable to all olefins which can be polymerized by Ziegler-Natta catalysts, it is particularly fit for the homopolymerization of alpla-olefins from 2 to 20 carbon atoms such as ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene and similar, as well as cyclic monomers and/or dienes. It is also fit for the copolymerization of ethylene with alpha-olefins different from ethylene, having from 3 to 20 carbon atoms, preferably from 3 to 6 carbon atoms, such as propylene, 1-butene 1-hexene, 4-methyl-1-pentene and similar, as well as cyclic monomers and/or dienes. The copolymerization of more than two alpla-olefins is possible too.