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

1999-11-10

2001-11-06

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...

C502S102000, C502S103000, C502S118000, C502S127000, C502S125000, C502S123000, C502S348000

Reexamination Certificate

active

06313238

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.
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 as an internal donor 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-2-methylmalonate, diethyl-2-butylmalonate and diethyl-2-phenyl-malonate. Only the use of a catalyst containing diethyl-2-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.
It has now surprisingly been found that if specific esters of malonic acid are used as internal donor, catalyst components capable to give an excellent balance between polymerization yield and isotactic index of the polymer are obtained.
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 hydrocarbyl 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 is selected from esters of malonic acids of formula (I):
wherein R
1
is a C
5
-C
20
linear or branched alkyl, a C
5
-C
20
cycloalkyl, a C
7
-C
20
arylalkyl or alkylaryl group; R
2
and R
3
, equal to or different from each other, are C
1
-C
3
alkyl, cycloalkyl. Preferably R
1
is a C
5
-C
20
primary alkyl, a C
5
-C
20
cycloalkyl, a C
7
-C
20
or arylalkyl, group.
Specific examples of compounds are diethyl-2-dodecylmalonate, diethyl-2-(2-pentyl)malonate, diethyl-2-cyclohexylmalonate, diethyl-2-cyclohexylmethylmalonate, dimethyl-2-cyclohexylmethyl-malonate.
It has been found that if R
1
belongs to one of the above defined categories, the yields in the polymerization process are much higher than in the prior art wherein C
1
-C
4
alkyl or phenyl substituents were used.
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. Patents 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 chloride 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 a 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 alcoholates or chloroalcoholates (in particular chloroalcoholates prepared according to U.S. Pat. No. 4,220,554) and an excess of TiCl
4
containing the electron donor compound (I) in solution at a temperature of about 80 to 120° C.
According to a preferred method, the solid catalyst component can be prepared by reacting a titanium compound of formula Ti(OR)
n−y
X
y
, where n is the valence of titanium and y is a number between 1 and n, preferably TiCl
4
, with a magnesium chloride deriving from an adduct of formula MgCl
2
.pROH, where p is a number between 0.1 and 6 and R is a hydrocarbon radical having 1-18 carbon atoms. The adduct can be suitably prepared in spherical form by mixing alcohol and magnesium chloride in the presence of an inert hydrocarbon immiscible with the adduct, operating under stirring conditions at the melting temperature of the adduct (100-130° C.). Then, the emulsion is quickly quenched thereby causing the solidification of the adduct in form of spherical particles. Examples of spherical adducts prepared according to this procedure are described in U.S. Pat. No. 4,399,054. The so obtained adduct can be directly reacted with the Ti compound or it can be previously subjected to thermal controlled dealcoholation (80-130° C.) so as to obtain an adduct in which the number of moles of alcohol is generally lower than 2.5 preferably between 0.1 and 1.5. The reaction with the Ti compound can be carried out by suspending the adduct (dealcoholated or as such) in cold TiCl
4
(generally 0° C.); the mixture is heated up to 80-130° C. and kept at this temperatur

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