Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1998-12-21
2002-07-16
Wood, Elizabeth D. (Department: 1755)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S090000, C526S126000, C526S127000, C526S129000, C526S348000, C526S351000, C502S103000, C502S118000, C502S125000, C502S128000
Reexamination Certificate
active
06420499
ABSTRACT:
The invention relates to a process for the preparation of an olefin polymerization catalyst component containing magnesium, titanium, halogen and an electron donor. The invention also relates to such a catalyst component and its use for the polymerization of &agr;-olefins such as propene.
BACKGROUND OF THE INVENTION
Generally, so called Ziegler-Natta catalyst components of the above kind have been prepared by reacting a magnesium halide-alcohol complex with a titanium tetra-halide and an electron donor which usually is a phthalic acid diester. The preparation involves the use of large amounts of reagents and washing liquids, which are difficult to handle. Additionally, byproducts are formed, which cannot easily be regenerated or destroyed, but form an environmental problem.
For example, the preparation of a conventional polypropene catalyst component involves the reaction of a magnesium dichloride-alcohol complex with titanium tetrachloride to give reactive &bgr;-magnesium dichloride as intermediate and hydrogen chloride and titanium alkoxy trichloride as byproducts. Then, the reactive &bgr;-magnesium dichloride intermediate is activated with further titanium tetrachloride to give said catalyst component (the treatment with a titanium halide such as titanium tetrachloride is henceforth called titanation).
The titanium alkoxy trichloride byproduct formed in the titanation is a catalyst poison and must be carefully removed by extensive washing using large amounts of titanium tetrachloride. Further, the titanium alkoxy trichloride must be carefully separated from the titanium tetrachloride washing liquid, if the latter is to be reused e.g. for activating the reactive &bgr;-magnesium dichloride. Finally, the titanium alkoxy trichloride is a problem waste, which is difficult to dispose of.
Thus, in a typical propene polymerization catalyst component preparation involving two titanations and three heptane washes, one mol of produced catalyst component (mol Mg) requires about 40 mol of titanium tetrachloride e.g. as washing liquid to be circulated (see Table 15 below), and produces as problem waste about three mol of titanium alkoxy trichloride as well as about three mol of hydrogen chloride.
Sumitomo, EP 0 748 820 A1 (hereinafter referred to as “Sumitomo”), has prepared dialkoxy magnesium, reacted it with titanium tetrachloride to form an intermediate and then reacted the intermediate with phthalic acid dichloride to form a catalytically active propene polymerization catalyst component. The activity was raised by repeated titanations, as well as repeated washes with toluene and hexane. See page 10, lines 14 to 37, of said publication.
Said process of Sumitomo has avoided the reaction between the magnesium dichloride-alcohol complex and titanium tetrachloride, and thereby eliminated the formation of catalytically poisonous titanium alkoxy trichloride byproduct. However, as much as four titanations and hydrocarbon treatments are still needed to give satisfactory catalytic activity.
DESCRIPTION OF THE INVENTION
The purpose of the present invention is to provide a process which results in a catalyst component having satisfactory activity without producing harmful byproducts such as said titanium alkoxy trichloride or requiring the use of a large amounts of titanation reagent and/or washing liquid.
The problem described above has now been solved with a novel process for the preparation of a catalyst component of the above type, which is mainly characterized by the steps of:
(i) reacting a titaniumless magnesium compound (a) containing an alkoxy moiety, which titaniumless magnesium compound is selected from the group consisting of a compound or conplex containing halogen and alkoxide linked to magnesium, a complex containing a magnesium dihalide and an alcohol, and a non-complex magnesium dialkoxide, with a halogen compound (b) being capable of forming the electron donor by replacement of its halogen by said alkoxy moiety, to give an intermediate (ab); and
(ii) reacting said intermediate (ab) with a titanium halide (c), or
(i)′ reacting a titaniumless magnesium compound (a) containing an alkoxy moiety, which titaniumless magnesium compound is selected from the group consisting of a compound or complex containing halogen and alkoxide linked to magnesium, and a complex containing a magnesium dihalide and an alcohol, with a titanium halide (c), to give an intermediate (ac), and
(ii)′ reacting said intermediate (ac) with a halogen compound (b) being capable of forming the electron donor by replacement of its halogen by said alkoxy moiety.
It was found by the applicant, that the activity of a stoichiometric catalyst component, comprising a magnesium dihalide, a titanium tetrahalide and an electron donor, is the higher, the more magnesium dihalide it contains. Thus it is believed, that the purpose of the repeated toluene washes of e.g. Sumitomo has partly been to remove titanium tetrachloride and electron donor from the catalyst component precursor in order to raise the magnesium dichloride content and thus the catalytic activity, of the final catalyst component. The present invention solves the problem in another way. In the claimed process, magnesium dihalide is included or synthesized as part of the reacting material before any titanation takes place, and thus, the need for repeated cycles of titanation and washing is significantly reduced.
Preferably one, most preferably all of steps (i), (ii), (i)′ and (ii)′ are performed in solution. Then, the reaction product of step (ii) or (ii)′ is preferably recovered by precipitation.
According to one embodiment of the present invention, said compounds (a), (b) and (c) are in the claimed process contacted in essentially stoichiometric amounts. According to another embodiment, a stoichiometric excess, preferably a 5-20 fold excess, of said titanium halide (c) with respect to said magnesium compound (a), gives even better results.
Said halogen compound (b) used in the claimed process is an electron donor precursor, i.e. itself capable of forming the electron donor of the catalyst component by replacement of its halogen by an alkoxy group. By electron donor is in this connection meant an electron donor which forms a part of the titanous catalyst component produced by the claimed process and is in the art also called an internal electron donor. Such halogen compounds (b) are, e.g., C
1
-C
20
alkyl halides, C
7
-C
27
aralkyl halides and C
2
-C
22
acyl halides, which react with alkoxy compounds to replace their halogen with the alkoxy group of the alkoxy compound and form e.g. the corresponding ethers and esters acting as internal electron donors.
Preferably, said halogen compound (b) is an organic acid halide having the formula R″(COX′)
n
, wherein R″ is an n-valent organic group having 1-20 carbon atoms, preferably an n-valent benzene ring, X′ is a halogen, preferably chlorine; and n is the valence of R″ and is an integer 1 to 6, preferably 1, 2, 3 or 4, more preferably 2. Most preferably, said halogen compound is phthalic acid dichloride Ph(COCl)
2
, wherein Ph is o-phenylene. Correspondingly, the electron donor formed therefrom is preferably an organic acid ester having the formula R″(COOR)
n
, wherein R is an n-valent C
1
-C
20
aliphatic group or an n-valent C
7
-C
27
araliphatic group and R″ and n are the same as above, and more preferably a phthalic acid diester Ph(COOR)
2
, wherein R is a C
1
-C
20
alkyl or a C
7
-C
27
aralkyl, more preferably a C
1
-C
16
alkyl. Most preferably said electron donor is dioctyl phthalate.
The titanium halide (c) used in the claimed process is preferably a titanium halide of the formula (OR′)
k
TiX
4-k
, wherein R′ is an alkyl group having 1 to 10 carbon atoms or an aralkyl group having 7 to 16 carbon atoms, X is a halogen and k is 0 to 3. More preferably, said titanium halide (c) is a titanium tetrahalide TiX
4
, wherein X is the same as above, most preferably titanium tetrachloride TiCl
4
.
It is preferable, if said titaniuml
Ala-Huikku Sirpa
Garoff Thomas
Leinonen Timo
Borealis Technology Oy
Wood Elizabeth D.
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