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

1998-06-09

2001-08-28

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...

C526S125100, C526S124100, C526S348000, C526S351000, C526S352000, C526S348600, C502S126000, C502S127000, C502S102000

Reexamination Certificate

active

06281301

ABSTRACT:

The present invention relates to catalyst components for the polymerization of olefins, to the catalyst obtained therefrom and to the use of said catalysts in the polymerization of olefins CH
2
═CHR in which R is hydrogen or a hydrocarbyl radical with 1-12 carbon atoms. In particular the present invention relates to catalyst components, suitable for the stereospecific polymerization of olefins, comprising a titanium compound having at least a Ti-halogen bond and an electron donor compound selected from esters of malonic acid having a particular formula supported on a Mg halide. Said catalyst components used in the polymerization of olefins, and in particular of propylene, are capable to give polymers in high yields and with high isotactic index expressed in terms of high xylene insolubility.
The use of some esters of malonic acid as internal electron donors in catalysts for the polymerization of propylene is already known in the art.
In EP-A45977 is disclosed the use of an ester of the malonic acid (diethyl diisobutylmalonate) as internal donor of a catalyst for the polymerization of olefins. EP-A-86473 discloses a catalyst for the polymerization of olefins comprising (a) an alkyl compound, (b) an electron donor compound having certain reactivity features towards MgCl
2
and (c) a solid catalyst component comprising, supported on MgCl
2
, a Ti halide and an electron donor selected from many classes of ester compounds including malonates. In particular, the use of diethyl allylmalonate and di-n-butyl malonate as internal donors in a catalyst for the polymerization of propylene is exemplified. From EP-A-86644 is known the use of diethyl n-butyl malonate and diethyl isopropylmalonate as internal donors in Mg-supported catalysts for the polymerization of propylene in which the external donor is a heterocyclic compound or a ketone. The European patent EP-B-125911 discloses a process for producing (co)polymers which comprises (co)polymerizing at least one olefin, optionally with a diolefin, in the presence of a catalyst composed of (a) a solid catalyst component containing Mg, Ti and an electron donor compound selected from esters of polycarboxylic acids, (b) an organometallic compound of a metal selected from group I to III of the periodic table, and (c) an organosilicon compound having a Si—O—C or a Si—N—C bond. Examples of preferred esters compounds include diethyl methylmalonate, diethyl butylmalonate, diethyl phenylmalonate, diethyl diethylmalonate, and diethyl dibutylmalonate. Only the use of a catalyst containing diethyl phenylmalonate has been exemplified in the preparation of polypropylene.
However, a common drawback experienced in the use of the above mentioned malonates was represented by a poor polymerization yield and/or a not suitable isotactic index of the final polymer.
JP-08157521 relates to a process for preparing a solid catalyst component for polymerization of olefins which is characterized by contacting a solid catalyst component produced by the reaction among a magnesium compound, a titanium compound and an halogen compound, with one or mere of electron donating compounds represented by the general formula:
wherein R
c
and R
d
are, independently selected from the group consisting of: a straight-chain or branched hydrocarbon group having 1-10 carbon atoms, and R
a
and R
b
are independently selected from an aliphatic or cyclic saturated hydrocarbon group containing one or more secondary or tertiary carbons and having 3-20 carbon atoms. According to this patent the fact that the substituents R
a
and R
b
are branched is very important.
It has now surprisingly been found that another class of malonate esters wherein one substituent in 2 position is selected from a linear alkyl, alkenyl, aryl, arylalkyl or alkylaryl group, when used as an internal electron donor, leads to higher polymerization yields compared to those obtainable by using the electron donors of the prior art still maintaining very high stereoselectivity. This is particularly surprising in view of the direct teaching of JP-A-08157521, which excluded this class of compounds.
It is therefore an object of the present invention a solid catalyst component for the polymerization of olefins CH
2
═CHR in which R is hydrogen or a hydrogen radical with 1-12 carbon atoms, comprising a titanium compound, having at least a Ti-halogen bond and an electron donor compound supported on a Mg halide, in which said electron donor compound is selected from esters of malonic acids of formula (I):
wherein R
1
is a C
1
-C
20
linear or branched alkyl, C
3
-C
20
alkenyl, C
3
-C
20
cycloalkyl, C
6
-C
20
aryl, arylalkyl or alkylaryl group; R
2
is C
1
-C
20
linear alkyl, C
3
-C
20
linear alkenyl, C
6
-C
20
aryl, arylalkyl or akylaryl group; R
3
and R
4
are independently selected from the group consisting of C
1
-C
3
alkyl, cyclopropyl, with the proviso that when R
1
is C
1
-C
4
linear or branched alkyl or alkenyl, R
2
is different from R
1
; preferably R
2
is primary linear C
1
-C
20
linear alkyl or a primary C
6
-C
20
arylalkyl group.
These new electron donors permit to obtain higher yields in the polymerization process with respect to the catalyst containing the malonates known in the art.
Specific examples of preferred disubstituted malonates compounds are: diethyl-2,2-dibenzylmalonate, dimethyl-2-n-butyl-2-isobutylmalonate, diethyl-2-n-butyl-2-isobutylmalonate, diethyl-2-isopropyl-2-n-butylmalonate, diethyl-2-methyl-2-isopropylmalonate, diethyl-2-methyl-2-isobutylmalonate, diethyl-2-isobutyl-2-benzylmalonate.
The magnesium halide is preferably MgCl
2
in active form which is widely known from the patent literature as a support for Ziegler-Natta catalysts. U.S. Pat. No. 4,298,718 and U.S. Pat. No. 4,495,338 were the first to describe the use of these compounds in Ziegler-Natta catalysis. It is known from these patents that the magnesium dihalides in active form used as support or co-support in components of catalysts for the polymerization of olefins are characterized by X-ray spectra in which the most intense diffraction line that appears in the spectrum of the non-active halide is diminished in intensity and is replaced by a halo whose maximum intensity is displaced towards lower angles relative to that of the more intense line.
The preferred titanium compounds used in the catalyst component of the present invention are TiCl
4
and TiCl
3
; furthermore, also Ti-haloalcoholates of formula Ti(OR)
n-y
X
y
, where n is the valence of titanium and y is a number between 1 and n, can be used.
The preparation of the solid catalyst component can be carried out according to several methods.
According to one of these methods, the magnesium dichloride in an anhydrous state, the titanium compound and the electron donor compound of formula (I) are milled together under conditions in which activation of the magnesium dichloride occurs. The so obtained product can be treated one or more times with an excess of TiCl
4
at a temperature between 80 and 135° C. This treatment is followed by washings with hydrocarbon solvents until chloride ions disappeared.
According to a further method, the product obtained by co-milling the magnesium dichloride in an anhydrous state, the titanium compound and the electron donor compound of formula (I) is treated with halogenated hydrocarbons such as 1,2-dichloroethane, chlorobenzene, dichloromethane etc. The treatment is carried out for a time between 1 and 4 hours and at temperature of from 40° C. to the boiling point of the halogenated hydrocarbon. The product obtained is then generally washed with inert hydrocarbon solvents such as hexane.
According to another method, magnesium dichloride is preactivated according to well known methods and then treated with an excess of TiCl
4
at a temperature of about 80 to 135° C. which contains, in solution, an electron donor compound of formula (I). The treatment with TiCl
4
is repeated and the solid is washed with hexane in order to eliminate any non-reacted TiCl
4
.
A further method comprises the reaction between magnesium alcoho

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