Organic compounds -- part of the class 532-570 series – Organic compounds – Aluminum containing
Reexamination Certificate
1999-12-16
2003-07-22
Bell, Mark L. (Department: 1755)
Organic compounds -- part of the class 532-570 series
Organic compounds
Aluminum containing
C556S001000, C556S186000, C502S103000, C502S117000, C502S122000, C502S125000, C502S128000, C526S125700, C526S144000, C526S160000, C526S943000
Reexamination Certificate
active
06596891
ABSTRACT:
The present invention relates to an activating composition of metallocene complexes in the catalysis of processes for the (co)polymerization of &agr;-olefins.
More specifically, the present invention relates to an organometallic composition without boron and with a low content of other metals, particularly aluminum, capable of forming a catalyst with a high activity for the polymerization of &agr;-olefins, combined with metallocene complexes of group 4 -of the periodic table of elements. The present invention also relates to said catalyst, as well as a polymerization process of &agr;-olefins which uses it.
It is generally known in the art that ethylene, or &agr;-olefins in general, can be polymerized or copolymerized by means of low, medium or high pressure processes with catalysts based on a transition metal. A particular group of catalysts active in the polymerization of olefins consists of the combination of an organic oxyderivative of aluminum (in particular, polymeric methylaluminoxane or MAO) with an &eegr;
5
-cyclopentadienyl derivative (metallocene) of a transition metal of group 4 of the periodic table of elements (in the form approved by IUPAC and published by “CRC Press Inc.” in 1989). For a known preparation technique of the above compounds, reference can be made to the description of H. Sinn, W. Kaminsky, in Adv. Organomet. Chem., vol.18 (1980), page 99 and to the U.S. Pat. No. 4,542,199.
In spite of the numerous advantages with respect to the prior known art, represented by traditional heterogeneous catalysts, of the so-called Ziegler-Natta type, having a multicentric nature, catalysts based on metallocenes have also proved to have various disadvantages which have limited their industrial development. Among these the production of polymers with an insufficient average molecular weight, especially with high temperature polymerization processes, an unsatisfactory activation rapidity of the catalytic system in processes characterized by reduced residence times in the reactor, the use of significant quantities of MAO activator and the difficulty of preparing and conserving the latter on an industrial scale, can be mentioned.
In an attempt to overcome problems in particular relating to the use of MAO, metallocene-type catalysts capable of polymerizing olefins also without aluminum compounds, or in the presence of a more limited quantity of this metal, have recently been developed. These systems however are based on the formation of a catalytic species of a cationic nature, obtained by contact of a suitable metallocene with an activator consisting of a strong Lewis acid or, more advantageously, of an organometallic salt whose anion has a delocalized charge and is weakly co-ordinating, normally a fluorinated tetra-arylborane. Various cationic systems of this type are described for example, in the publications of R. R. Jordan in “Advances in Organometallic Chemistry” vol. 32 (1990), pages 325-387, and X. Yang et al. in “Journal of the American Chemical Society”, vol. 116 (1994), page 10015, which provide, in addition to a wide description of the field, numerous patent references on the matter.
The activity of cationic metallocene catalytic systems is however generally lower than that, which is considerable, of systems using methylalumoxane. In addition, the known methods for the preparation of the above ionic activators based on fluoroarylboranes are complex with not completely satisfactory yields, thus further limiting the industrial use of cationic catalysts. Another disadvantage lies in the sensitivity of these ionic activators to air and humidity which makes their transfer and storage difficult.
Another aspect of the above catalysts, both ionic and those based on MAO, which is not entirely satisfactory, relates to their behaviour in the copolymerization of ethylene with &agr;-olefins and/or dienes, to produce linear low density polyethylene or olefinic elastomers, again owing to the difficulty of obtaining copolymers with sufficiently high molecular weights, suitable for their multiple industrial applications. The necessity is known, in fact, of operating with high quantities of comonomer to insert the desired quantity into the copolymer, with a consequent increase in the chain transfer reaction rate, which is competitive with the polymerization, and production of unsatisfactory molecular weights. This drawback becomes even more critical when operating with high temperature polymerization processes in which the chain transfer reaction is already significant without the comonomer.
Other cationic systems based on metallocenes and fluoroaryl aluminates are described in international patent application WO 98/0715, which claims a higher catalytic activity. These catalysts however are relatively complex to prepare and are particularly unstable to air and humidity, similarly to those containing boro-anions and are not easily adaptable to non-alkylated metallocene complexes.
The Applicant has now found a new group of activators of metallocene complexes, suitable for forming (co)po-lymerization catalysts of &agr;-olefins with a high activity and without the above disadvantages. These activators are based on certain extensively fluorinated di-unsaturated cyclic compounds, and allow the preparation of high activity catalysts with a low aluminum content. In particular, they can be prepared at the moment of use starting from precursors obtained with processes analogous to known and relatively simple processes, which are stable to air and humidity, thus solving the problem of handling, transfer and storage.
A first object of the present invention therefore relates to an organometallic composition which can be used as activator of a metallocene complex of a metal of group 4 to form a (co)polymerization catalyst of &agr;-olefins, characterized in that it comprises the reaction product between:
(A) a fluorinated organic compound, comprising at least one di-unsaturated cycle with 5 or 6 carbon atoms, having the following formula (I):
wherein: each R
i
group (i being an integer from 1 to 7) is a substituent of the di-unsaturated cycle independently selected from hydrogen, fluorine and a fluorinated or non-fluorinated, aliphatic or aromatic hydrocarbyl group, having from 1 to 20 carbon atoms, optionally joined to a different R
i
hydrocarbyl group to form a further cycle,
on the condition that at least two, preferably at least three, of the groups R
1
, R
2
, R
3
R
4
or R
5
are is independently selected from the group consisting of:
fluorine, or
a fluorinated alkyl group having the formula —CF(R
9
R
10
), wherein each R
9
or R
10
group can have any of the above meanings of the R
i
groups and at least one of them is fluorine, or fluorinated alkyl at least in position 1, or a fluorinated aryl Ar
F
as defined below, or a fluorinated vinyl group V
F
as defined below, or
a fluorinated aryl group Ar
F
substituted on the aromatic ring with at least two groups selected from fluorine, a —CF(R
9
R
10
) group as defined above or a different Ar
F
group, or
a fluorinated vinyl group V
F
substituted on at least two positions of the double bond with groups selected from fluorine, a —CF(R
9
R
10
) group or an Ar
F
group as defined above;
the R
8
group is hydrogen, —OH, —SH, or, together with said R
5
group, it forms a carbonyl oxygen; and “m” can have the values of 0 or 1;
(B) an organometallic compound having the following formula (II):
M′R
n
X
(p−n)
(II)
wherein: M′ is a metal of group 2 or 13 of the periodic table of elements, preferably Mg or Al, more preferably Al, each R is independently a hydrocarbyl, preferably alkyl, group having from 1 to 10 carbon atoms,
each X is a halogen atom, preferably chlorine or bromine,
“p” is the valence of M′ and is equal to 2 for group 2 and 3 for group 13,
“n” is a decimal number ranging from 1 to p, preferably p.
A second object of the present invention relates to a catalytic composition active in the (co)polymerization of &agr;-olefins comprising the following components in contact with each other:
the above
Borsotti Giampietro
Masi Francesco
Proto Antonio
Santi Roberto
Sommazzi Anna
Bell Mark L.
Enichem S.p.A.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Pasterczyk J.
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