Components and catalysts for the polymerization of olefins

Details Components and catalysts for the polymerization of olefins Components and catalysts for the polymerization of olefins

1997-06-27

2001-09-18

Wu, David W. (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S113000, C526S124300, C526S124900, C526S160000, C526S348000, C526S352000, C526S943000, C526S119000, C502S113000, C502S134000

Reexamination Certificate

active

06291607

ABSTRACT:

The present invention relates to components and catalysts for the polymerization of olefins, to a method for their preparation and to their use in the (co)polymerization of olefins CH
2
═CHR, in which R is hydrogen or an alkyl, cycloalkyl or aryl radical with 1-10 carbon atoms.
The patent literature describes bimetallic catalysts comprising a compound of titanium or vanadium supported on a magnesium halide which is reacted with a metallocene compound containing at least one cyclopentadienyl ring coordinated on a transition metal selected from V, Ti, Zr and Hf.
Examples of such catalysts are described in USP 5,120,696, EP-A-447070 and 447071.
Bimetallic catalysts obtained by impregnating silica with a magnesium compound of the type MgR
2
, where R is a hydrocarbon radical, and then treating the support with a compound of Ti, such as TiCl
41
optionally with SiCl
4
, and thereafter with a metallocene compound, are known from U.S. Pat. No. 5,183,867 and from EP-A-514594.
Bimetallic catalysts obtained by treating MgCl
2
with halogenated compounds of Ti and then with titanocenes such as Cp
2
TiCl
2
and bis(indenyl)TiCl
2
are known from EP-A-412750.
Catalysts obtained by treating carbonated compounds of Mg, such as alkylmagnesium carbonate, with TiCl
4
in the presence of a metallocene compound of Hf or Zr, are known from WO 94/03508.
Bimetallic catalysts comprising a titanium-based catalyst in which the Ti compound is supported on Mg halide, a metallocene compound and poly(methylaluminoxane) (MAO) are known from EP-A-436399.
The macroporosity of the solid components used in the preparation of the catalysts of the above cited prior art is not sufficiently high to allow their use in processes carried out in the gas phase. The above catalysts are characterized in that they give polymers, in particular polyethylene, with a narrow molecular weight distribution. As a consequence of the insufficient macroporosity, the metallocene compound is poorly fixed inside the particles of the support or of the component containing the titanium compound. Instead, it tends to be deposited on the surface. The catalyst obtained therefrom has poor activity in gas-phase polymerization processes. The presence of the metallocene compound and of the polymer layer that forms at the surface tends to prevent the access of the monomer to the active sites containing the titanium compound and to undermine its activity. The polymer particle that forms is inhomogeneous and frequently the outer layer comes off from it, giving rise to the formation of polymer in powder form with consequent difficulty in carrying out the process in the gas phase.
Components of bimetallic catalysts have now been found which are particularly suitable for gas-phase polymerization processes, the said components comprising non-metallocene compounds of Ti or V, metallocene compounds and/or their reaction products with the support uniformly dispersed in the particle.
The components of the catalysts of the invention comprise the product obtained by contacting:
(a) a compound of a transition metal M selected among Ti, V, Zr and Hf containing at least one M-&pgr; bond with a solid component comprising a compound of Ti or V not containing M-&pgr; bonds, and optionally an electron-donor compound supported on a Mg halide, or
(b) a compound of Ti or V not containing M-&pgr; bonds with a solid component comprising a compound of V, Ti, Zr or Hf containing at least one M-&pgr; bond supported on a Mg halide, or
(c) a compound of Ti or V not containing M-&pgr; bonds and a compound of V, Ti, Zr or Hf having at least one M-&pgr; bond with a support comprising a Mg halide,
the component as in (a) and (b) and the support as in (c) being characterized in that they have a porosity (due to pores with radius up to 10000 Å, measured with the mercury porosimeter), greater than 0.3 cm
3
/g, preferably between 0.4 and 1.5 cm
3
/g.
The total porosity (mercury method) is generally between 0.6 and 4 cm
3
/g. The porosity (due to pores with radius up to 10000 Å, measured with the mercury porosimeter) of component (a) is generally between 0.3 and 0.8 cm
3
/g, whereas the total porosity is greater than 0.8 cm
3
/g.
The surface area (mercury method) is generally between 10 and 100 m
2
/g.
The porosity determined by the BET method depends on the type of solid component. In the case of solid component (b) and of support (c) the BET porosity is generally greater than 0.2 cm
3
/g, and preferably between 0.3 and 1 cm
3
/g; in the case of component (a) the porosity (BET) can be the same as that of component (b) or even lower. Values of 0.1 cm
3
/g or lower are possible in some cases.
The surface area (BET) of component (b) and of the support (c) is generally greater than 40 m
2
/g, and is preferably between about 60 and 400 m
2
/g; that of the support (c) can be as high as 500 m
2
/g or even higher.
The surface area (BET) of component (a) is generally between 20 and 400 m
2
/g. When the porosity (BET) of component (a) is low (0.2 cm
3
/g or less) the surface area (BET) is also low (20-40 m
2
/g).
The components (a) and (b) and the support (c) are preferably used in the form of spherical particles with mean diameter between about 10 and 150 microns.
Component (a) and the support (c) are prepared according to known methods. Suitable methods are described, for example, in EP-A-395083, EP-A-553806, U.S. Pat. No. 4,399,054, whose description with respect to the preparation method and to the characteristics of the products is herein incorporated by reference. A method of preparation of component (b) is described in Italian Application MI-94-A-001065.
The Mg halide, preferably Mg chloride, that can be used as support (c) or for preparation of the components (a) and (b), as well as having the characteristics of surface area and porosity stated above, may have the following additional characteristics.
The Mg halide can include, in smaller proportions, other components that act as co-supports or are used for improving the properties of the catalytic component. Examples of these components are AlCl
3
, SnCl
4
, Al (OEt)
3
, MnCl
2
, ZnCl
2
, VCl
3
and Si (OEt)
4
.
The Mg halide can be complexed with electron-donor compounds not containing active hydrogen in a quantity of up to about 30 mol %, preferably 5-15 mol % based on the Mg halide. Non-limiting examples of electron donors are ethers, esters and ketones.
The Mg halide can, in its turn, be supported on an inert support having area and porosity such that the obtained supported product has the values stated previously. Suitable inert supports can be metal oxides such as silica, alumina and silica-alumina, which have values of porosity (BET) greater than 0.5 cm
3
/g and of surface area (BET) greater than 200 m
2
/g and between, for example, 300 and 600 m
2
/g. Other possible inert supports are porous polymers such as polyethylene, polypropylene and polystyrene.
Partially crosslinked polystyrene, which has high values of surface area and porosity, is particularly suitable. Polystyrenes of this type are described in U.S. Pat. No. 5,139,985 whose description of the method of preparation and supporting of the Mg halide is herein included for reference. These polystyrenes generally have values of surface area (BET) between 100 and 600 m
2
/g and of porosity (BET) greater than 0.15 cm
3
/g.
Generally, the amount of Mg halide that can be supported is between 1 and 20% by weight based on the total. The preferred Mg halide is Mg chloride. The Mg halide can be supported according to known methods, starting from its solutions in solvents such as tetrahydrofuran or by impregnation of the inert support with solutions of the halide in an alcohol; the alcohol is then removed by reaction with a compound such as a trialkyl-Al or dialkylaluminium halide or silicon halides. The alcohols used generally have 1-8 carbon atoms.
A very suitable method for the preparation of Mg halides having the characteristics of porosity and area stated above consists of reacting spherulized adducts of MgCl
2
with alcohols, the said adducts containing fr

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