Catalysts for the polymerization of olefins

Abstract: Catalysts for the polymerization of olefins, obtained from special zirconocenic compounds and from alkyl-Al compounds.

Description: The present invention relates to catalysts for the polymerisation of olefins, obtained from zirconocenic compounds and from alkyl-Al compounds. It is known how to polymerize ethylene by using catalysts obtained from zirconocenes and from trialkyl aluminum. The zirconocenes used in the known art can be represented by to the general formula: (A) (C₅R n H 5-n )₂ZrX₂ where R is an alkyl with 1 to 8 C-atoms, n may be 0 or 1 or 2 and X may be a halogen atom, an alkoxy group or the anion of an organic or inorganic acid. Examples of such catalysts have been reported in US Pat. 2,924,593. The activity of the aforementioned catalysts is extremely low in the polymerisation of ethylene and practically nil in the polymerisation of the higher alpha olefins. It has now been found unexpectedly that by using in place of the zirconocenes employed until now, compounds of the general formula: (A') (C₅R' n H 5-n )R'' p (C₅R' m H 5-m )ZrX q it is possible to obtain, in combination with trialkyl aluminum compounds or alkyl aluminum monohydrides, catalysts endowed with elevated activity in the (co)polymerization of ethylene and CH₂=CHR alpha olefins where R is an alkyl radical with 1-8 carbon atoms. The compounds of formula (A') used in the present invention can be prepared according to the methods described in L.A. Paquette - K.J. Moriarty - P. Meuner - B. Gautheron - C. Jornay - R.D. Roger - A.L. Rheingold - Organo-metallics - 8, (1989) 2159. In the formula A', (C₅R' n H 5-n ) and (C₅R' m H 5-m ) are cyclopentadienyl groups, which may also be alike, in which R' is an alkyl, alkenyl, aryl, alkylaryl or arylalkyl group containing from 1 to 20 C-atoms or else a -CR₂SiR₃ group or a -SiR₃ group with R defined the same as R', or else, two (or four) R' substituents of the same cyclopentadienyl group form a ring having from 4 to 6 carbon atoms; R'' is a bivalent radical chosen from a possibly substituted alkylenic group containing from 1 to 8 carbon atoms, a SiR₂, PR or NR group with R defined the same as R', said R'' forming a connecting bridge between two cyclopentadienyl groups; X stands for hydrogen, halogen, -OH, -OZr(C₅R' n H 5-n )(C₅R' m H 5-m ), -OR with R defined the same as R', or else a hydrocarbon radical having the meaning of R'. In the formula when q is equal to 2, the X substituents may also differ from each other; q is 1 if Zr is trivalent and it is 2 if Zr is tetravalent; p is 0 or 1 and n, m are numbers from 0 to 5; (n+m) is ≧5 in the case where R' is a hydrocarbon radical and p = 0; if p = 1, (n+m) is ≧3: finally, when R' is a -SiR₃ or -CR₂SiR₃ group, (n+m) is ≧1 if p = 0 or if p = 1 and R'' is an alkylenic group; (n+m) is ≧0 if p = 1 and R'' is SiR₂, PR or NR. Nonlimiting examples of the A' zirconocenes are: [C₅(CH₃)₃H₂]₂ZrCl₂, [C₅(CH₃)₄H]₂ZrCl₂, [C₅(CH₃)₅]₂ZrCl₂, [C₅(CH₃)₅]₂Zr(CH₃)₂, [C₅(CH₃)₅]ZrH₂, [C₅(CH₃)₅]₂Zr(OCH₃)₂ [C₅(CH₃)₅]₂Zr(OH)CL, [C₅(CH₃)₅]₂Zr(OH)₂, [C₅(CH₃)₅]₂Zr(C₆H₅)₂, (C₅(CH₃)₅]₂Zr(CH₃)Cl, [C₅(C₂H₅)(CH₃)₄]₂ZrCl₂, [C₅(C₆H₅)(CH₃)₄]₂ZrCl₂, [C₅(C₂H₅)₅]₂ZrCl₂, [C₅(CH₃)₅]₂Zr(C₅H₅)Cl, [C₅(CH₃)₅]₂ZrCl, bis(indenyl)ZrCl₂, bis(indenyl)Zr(CH₃)₂, ethylene bis(indenyl)ZrCl₂, ethylene bis(indenyl)Zr(CH₃)₂, {C₅[Si(CH₃)₃]H₄} ₂ZrCl₂, {C₅[Si(CH₃)₃]₂H₃}₂ZrCl₂, [C₅(CH₃)₅](C₅H₅)ZrCl₂, [C₅(CH₃)₅][C₅(CH₃)H₄]ZrCl₂, (CH₃)₂Si(C₅H₄)₂ZrCl₂, (CH₃)₂Si[C₅(CH₃)₄]₂ZrCl₂, (CH₃)₂C[C₅(CH₃)₄]₂ZrCl₂, (CH₃)₂C[C₅(CH₃)₄](indenyl)ZrCl₂, (CH₃)₂C(C₅H₄) (fluorenyl)ZrCl₂. Particularly suitable compounds are those in which the (C₅R' n H 5-n ) and (C₅R' m H 5-m ) groups are pentamethyl-cyclopentadienyl rings or else indenyl groups and the X substituents are chlorine atoms, or else alkyl groups, particularly those with 1 to 5 C-atoms, or else -OH groups. The trialkyl aluminum compounds or the alkyl aluminum monohydrides can be described by the formula AlR 3-z H z in which R is an alkyl, alkenyl or alkylaryl radical with 1-10 C-atoms and z = 0 or 1. Nonlimiting examples of the alkyl aluminum compounds which may be used are those in which R₃ is an alkyl radical with 1-10 carbon atoms. Specific examples are: Al(CH₃)₃, Al(C₂H₅)₃, AlH(C₂H₅)₂, Al(isoC₄H₉)₃, AlH(isoC₄H₉)₂, Al(C₆H₅)₃, Al(CH₂C₆H₅)₃, Al[CH₂C(CH₃)₃]₃, Al[CH₂Si(CH₃)₃]₃, Al(CH₃)₂(C₂H₅), Al(CH₃)(C₂H₅)₂, Al(CH₃)₂(isoC₄H₉). As indicated above, the catalysts according to the invention are suitable for the polymerization of ethylene and CH₂=CHR alpha olefins or their mixtures. The polymerization is carried out in the liquid phase in the presence of or without an inert hydrocarbon solvent or in the gaseous phase. The polymerization temperature generally ranges from 0 to 150°C, more particularly from 40 to 80°C. The hydrocarbon solvents may be aromatic or aliphatic such as, for example, toluene, hexane, heptane, or chlorinated hydrocarbons such as, for example, CH₂Cl₂ or C₂H₄Cl₂. The molecular weight of the polymers can be varied simply by varying the polymerization temperature, the type or concentration of the catalyst components or by using molecular weight regulators such as, for example, hydrogen. The catalysts according to the invention may also be used on inert supports. This is done by depositing the zirconocene compound or the product of the reaction of the latter with the alkyl aluminum compound or the alkyl aluminum itself on inert supports such as, for example, silica, alumina, styrene-divinyl benzene copolymers or polyethylene. The solid component thus obtained, if need be, in combination with a further addition of the alkyl aluminum compound, is used advantageously particularly in the polymerization in the gaseous phase. Particularly attractive results are obtained when the catalyst components are brought into contact with each other prior to the polymerization; the time of contact generally ranges from 1 minute to 1 hour and preferably from 5 to 10 minutes, at concentrations ranging for the zirconocenic compound from 10⁻³ to 10⁻⁸ mole/l and for the alkyl aluminum from 10 to 10⁻³ mole/l. The following examples are given as illustrative and nonlimiting versions of the invention. Example 1 A 1-liter autoclave equipped with a jacket for thermal control, a thermocouple, valves for feeding nitrogen and ethylene, a manometer and a magnetic stirrer made of steel, thermostated at 50°C, is put under a vacuum after prior evacuation and filling with nitrogen. Then, 1 atm of ethylene and 350 ml of toluene are introduced while maintaining an internal temperature of 50°C. In 50 ml of toluene and under a nitrogen atmosphere are reacted 2 mmoles of trimethyl aluminum and 1 mg of [C₅(CH₃)₅]₂ZrCl₂. After 5 minutes at ambient temperature, the solution is injected into the autoclave which is then pressurized with ethylene at 4 atm and the polymerization is allowed to proceed for 1 hour at 50°C while keeping the ethylene pressure constant. Stirring rate: 1100 rpm. The results are shown in Table 1. Example 2-9 The same operating procedure is followed as in Example 1, while using different alkyl aluminum compounds and different zirconocenes. The compounds employed and the results obtained are shown in Table 1. Example 10 The same operating procedure is followed as in Example 1, except for the fact that propylene is polymerized. The polymerization temperature is maintained at 23°C and the amount of dissolved propylene is such as to maintain a pressure of 4 atm. 18 mmoles of AlMe₃ and 4.4 mg of racemic ethylene bis(indenyl)ZrCl₂, dissolved in toluene, are injected into the autoclave in rapid succession. The polymerization is allowed to proceed at 23°C for 17 hours. Stirring rate: 1100 rpm. 4.74 g of isotactic polypropylene is obtained: (η)inh (THN, 135°C) = 0.37 M w = 29,149 M w/ M n = 4.47 Tm = 134.2°C Productivity: 4942 g polymer/g Zr Example 11 The same operating procedure is followed as in Example 10, except for the fact that 200 ml of CH₂Cl₂ is used as the solvent in place of toluene. 18 mmoles of AlMe₃ and 2 mg of racemic ethylene bis(indenyl)ZrCl₂, dissolved in 2 ml of toluene, are injected into the autoclave in rapid succession. The polymerization is allowed to proceed at 23°C for 17 hours. Stirring rate: 1100 rpm. 2.74 g of isotactic polypropylene is obtained. ηinh(THN, 135°C) = 0.33 Productivity: 6284 g polymer/g Zr. Comparative Examples 1-4 The same operating procedure is followed as in Example 1, except for the fact that the compounds of zirconium and of alkyl aluminum shown in Table 2 are employed. Table 2 also lists the results obtained.

Claims: Claims for the following Contracting States : AT, BE, DE, FR, GB, IT, NL, SE A catalyst for the polymerization of olefins comprising the product of the reaction between: A') a zirconocenic compound of the formula (C₅R' n H 5-n )R''p(C₅R' m H 5-m )ZrX q in which (C₅R' n H 5-n) and (C₅R' m H 5-m ) are cyclopentadienyl groups, which may also be identical, and in which R' is an alkyl, alkenyl, aryl, alkylaryl or arylalkyl radical containing from 1 to 20 C-atoms or else a CR₂SiR₃ group or SiR₃ group with R defined the same as R', or else, two or four R' substituents of the same cyclopentadienyl group form rings having from 4 to 6 C-atoms; R'' is a bivalent radical chosen from an optionally substituted alkenyl group containing from 1 to 8 C-atoms, a SiR₂, PR or NR group with R defined the same as R', said R'' forming a connecting bridge between two cyclopentadienyl groups; X stands for hydrogen, halogen, -OH, -OZr(C₅R' n H 5-n) (C₅R' m H 5-m ), -OR with R defined the same as R', or a hydrocarbon radical having the meaning of R'; when q is equal to 2, the X substituents may also differ from each other; q is 1 if Zr is trivalent and it is 2 if Zr is tetravalent; p is 0 or 1 and n, m are integers from 0 to 5; (n+m) is≧5 in the case where R' is a hydrocarbon radical and p = 0; if p = 1, (n+m) is≧3; when R' is a -SiR₃ or -CR₂SiR₃ group (n+m) is≧1 if p = 0 or if p = 1 and R'' is an alkylenic group; (n+m) is≧0 if p = 1 and R'' is SiR₂, PR or NR, B') a trialkyl-Al compound or an alkyl-Al monohydride of the formula: AlR 3-z H z in which R is an alkyl, alkenyl or alkylaryl radical with 1-10 C-atoms and z = 0 or 1. A catalyst according to Claim 1, in which the (C₅R' n H 5-n ) and (C₅R' m H 5-m ) groups are pentamethyl-cyclopentadienyl rings or indenyl rings and the X substituents are chlorine atoms, -OH groups or alkyl radicals with 1-5 C-atoms. A catalyst according to Claim 2, in which the alkyl-Al compounds are trialkyl-Al compounds and alkyl-Al monohydrides. A catalyst according to claim 1, in which the catalyst component A' and B' are brought into contact with each other in the absence of the monomer before being employed in the polymerization phase. A catalyst according to the claim 2, in which the catalyst components A' and B' or their reaction product are supported on porous inert, inorganic or organic supports. Claims for the following Contracting State : ES A polymerization process of ethylene and α-olefins CH₂=CHR, in which R is an alkyl radical with 1-8 carbon atoms or mixtures of ethylene with said α-olefins in the presence of a catalyst comprising the product of the reaction between: A') a zirconocenic compound of the formula (C₅R' n H 5-n )R'' p (C₅R' m H 5-m )ZrX q in which (C₅R' n H 5-n ) and (C₅R' m H 5-m ) are cyclopentadienyl groups, which may also be identical, and in which R' is an alkyl, alkenyl, aryl, alkylaryl or arylalkyl radical containing from 1 to 20 C-atoms or else a CR₂SiR₃ group or SiR₃ group with R defined the same as R', or else, two or four R' substituents of the same cyclopentadienyl group form rings having from 4 to 6 C-atoms; R'' is a bivalent radical chosen from an optionally substituted alkenyl group containing from 1 to 8 C-atoms, a SiR₂, PR or NR group with R defined the same as R', said R'' forming a connecting bridge between two cyclopentadienyl groups; X stands for hydrogen, halogen, -OH, -OZr(C₅R' n H 5-n )(C₅R' m H 5-m ), -OR with R defined the same as R', or a hydrocarbon radical having the meaning of R'; when q is equal to 2, the X substituents may also differ from each other; q is 1 if Zr is trivalent and it is 2 if Zr is tetravalent; p is 0 or 1 and n, m are integers from 0 to 5; (n+m) is ≧5 in the case where R' is a hydrocarbon radical and p = 0; if p = 1, (n+m) is≧3; when R' is a -SiR₃ or -CR₂SiR₃ group (n+m) is≧1 if p = 0 or if p = 1 and R'' is an alkylenic group; (n+m) is≧0 if p = 1 and R'' is SiR₂, PR or NR; B') a trialkyl-Al compound or an alkyl-Al monohydride of the formula: AlR 3-z H z in which R is an alkyl, alkenyl or alkylaryl radical with 1-10 C-atoms and z = 0 or 1. The polymerization process of claim 1, in which the (C₅R' n H 5-n ) and (C₅R' m H 5-m ) groups are pentamethyl-cyclopentadienyl rings or indenyl rings and the X substituents are chlorine atoms, -OH groups or alkyl radicals with 1-5 C-atoms. The polymerization process of claim 2, in which the alkyl-Al compounds are trialkyl-Al compounds and alkyl-Al monohydrides. The polymerization process of claim 1, in which the catalyst components A' and B' are brought into contact with each other in the absence of the monomer before being employed in the polymerization phase. The polymerization process of claim 2, in which the catalyst components A' and B' or their reaction product are supported on porous inert, inorganic or organic supports.

Inventors: ALBIZZATI ENRICO, GIANNINI UMBERTO DR, RESCONI LUIGI DR, ALBIZZATI, ENRICO, GIANNINI, UMBERTO, DR., RESCONI, LUIGI, DR.
Applicants: AUSIMONT SRL, HIMONT INC, MONTEDISON SPA, AUSIMONT S.R.L., HIMONT INCORPORATED, MONTEDISON S.P.A.
Application year: 1990
Main classification: C08F4
IPC codes: C08F4, C08F10