Catalyst systems of the Ziegler-Natta type

Details Catalyst systems of the Ziegler-Natta type Catalyst systems of the Ziegler-Natta type

1997-06-05

2001-03-13

Wu, David W. (Department: 1713)

Catalyst, solid sorbent, or support therefor: product or process

Catalyst or precursor therefor

Plural component system comprising a - group i to iv metal...

C502S113000, C502S127000, C526S107000, C526S129000, C526S158000, C526S348000

Reexamination Certificate

active

06200922

ABSTRACT:

DESCRIPTION
The present invention relates to catalyst systems of the Ziegler-Natta type, comprising as active constituents
a) a titanium-containing solid component comprising a compound of titanium, a compound of magnesium, a halogen, an inorganic oxide as support and a carboxylic ester as electron donor compound,
and also, as cocatalyst,
b) an aluminum compound and
c) optionally a further electron donor compound,
wherein the inorganic oxide used has a pH of from 1 to 6, an average particle diameter of from 5 to 200 &mgr;m, an average primary particle diameter of from 1 to 20 &mgr;m and voids or channels having an average diameter of from 0.1 to 20 &mgr;m and a macroscopic share of the volume of the overall particle within the range from 5 to 30%.
The present invention also relates to a process for producing such Ziegler-Natta catalyst systems, to the production of polymers of propylene with the aid of these catalyst systems, to the polymers thus obtainable, and to films, fibers and moldings composed of these polymers.
Catalyst systems of the Ziegler-Natta type are known inter alia from EP-B 014523, EP-A 023425, EP-A 045975 and EP-A 195497. These systems are used in particular for the polymerization of C
2
-C
10
-alk-1-enes and comprise inter alia compounds of polyvalent titanium, aluminum halides and/or alkyls, and also electron donor compounds, especially silicon compounds, ethers, carboxylic esters, ketones and lactones, used on -the one hand in conjunction with the titanium component and, on the other hand, as cocatalyst.
Ziegler-Natta catalysts are usually produced in two steps. First the titanium-containing solid component is produced. It is then reacted with the cocatalyst. The thus-obtained catalyst is then used to carry out the polymerization.
Furthermore, U.S. Pat. No. 4,857,613 and U.S. Pat. No. 5,288,824 describe catalyst systems of the Ziegler-Natta type which, as well as a titanium-containing solid component and an aluminum compound, comprise organic silane compounds as external electron donor compounds. The catalyst systems in question are notable inter alia for good productivity and yield polymers of propylene having high stereospecificity, i.e.-high isotacticity, a low chlorine content and good morphology, viz. a low proportion of fines.
Propylene polymers obtained with the aid of the catalyst systems described in U.S. Pat. No. 4,857,613 and U.S. Pat. No. 5,288,824 still have certain proportions of xylene and heptane solubles, which is disadvantageous for some applications, for example in the food sector or in the hygiene sector.
It is an object of the present invention to develop, on the basis of the catalyst systems described in U.S. Pat. No. 4,857,613 and U.S. Pat. No. 5,288,824, an improved catalyst system of the Ziegler-Natta type which does not have the abovementioned disadvantages in respect of the presence of xylene and heptane solubles and which, what is more, shall be notable for the high production and stereospecificity of the polymers obtained.
We have found that this object is achieved by the initially defined catalyst systems of the Ziegler-Natta type.
The catalyst systems of this invention, as well as a titanium-containing solid component a), further comprise a cocatalyst. The cocatalyst may be an aluminum compound b). Preferably, the cocatalyst, as well as this aluminum compound b), additionally comprises an electron donor compound c) as further constituent.
The titanium-containing solid component a) is typically produced using halides or alkoxides of ter- or tetravalent titanium, preferably the chlorides of titanium, especially titanium tetrachloride. The titanium-containing solid component further comprises a support.
In addition, the titanium-containing solid component is produced using, inter alia, compounds of magnesium. Suitable magnesium compounds for this purpose include in particular magnesium halides, magnesium alkyls and magnesium aryls and also magnesium alkoxy and magnesium aryloxy compounds, of which magnesium dichloride, magnesium dibromide and magnesium di(C
1
-C
10
-alkyl) compounds are preferred. In addition, the titanium-containing solid component can further contain halogen, preferably chlorine or bromine.
The titanium-containing solid component a) further comprises electron donor compounds, for example mono- or polyfunctional carboxylic acids, carboxylic anhydrides and carboxylic esters, also ketones, ethers, alcohols, lactones and also organophosphorus and organosilicon compounds. Preferred electron donor compounds for inclusion in the titanium-containing solid component are phthalic acid derivatives of the general formula (II)
where X and Y each represent a chlorine atom or a C
1
-C
10
-alkoxy radical or together represent oxygen. Particularly preferred electron donor compounds are phthalic esters in which X and Y are each C
1
-C
8
-alkoxy, for example methoxy, ethoxy, propyloxy or butyloxy.
Further preferred electron donor compounds for inclusion in the titanium-containing solid component include diesters of 3- or 4-membered, substituted or unsubstituted cycloalkyl-1,2-dicarboxylic acids and also monoesters of substituted or unsubstituted -benzophenone-2-carboxylic acids. The hydroxy compounds used for these esters are the alcohols which are customarily used in esterification reactions, for example C
1
-C
15
-alkanols , C
5
-C
7
-cycloalkanols which may in turn bear C
1
-C
10
-alkyl groups, and also C
6
-C
10
-phenols.
The titanium-containing solid component can be produced by methods known per se. Examples thereof are described inter alia in EP-A 45 975, EP-A 45 977, EP-A 86 473, EP-A 171 200, GB-A 2 111 066, U.S. Pat. No. 4,857,613 and U.S. Pat. No. 5,288,824.
The titanium-containing solid component a) is preferably produced using the following two-stage process:
In the first stage, an inorganic oxide, which generally has a pH of from 1 to 6, an average particle diameter of from 5 to 200 &mgr;m, especially of from 20 to 70 &mgr;m, a pore volume of from 0.1 to 10 cm
3
/g, especially of from 1.0 to 4.0 cm
3
/g, and a specific surface area of from 10 to 1000 m
2
/g, especially of from 100 to 500 m
2
/g, is admixed with a solution of the magnesium-containing compound in a liquid alkane, and the mixture is stirred at from 10 to 120° C. for from 0.5 to 5 hours. From 0.1 to 1 mol of the magnesium compound is preferably used per mole of the support. Subsequently, while the mixture is stirred continuously, a halogen or a hydrogen halide, especially chlorine or hydrogen chloride, is added in an at least twofold, preferably at least fivefold, molar excess, based on the magnesium-containing compound. After from about 30 to 120 minutes, this reaction product is admixed at from 10 to 150° C. with a C
1
-C
8
-alkanol, especially ethanol, a halide or an alkoxide of the ter- or tetravalent titanium, especially titanium tetrachloride, and also with an electron donor compound. The amounts used are, per mole of magnesium in the solid obtained in the first step, from 1 to 5 mol of the ter- or tetravalent titanium and from 0.01 to 1 mol, especially from 0.1 to 0.5 mol, of the electron donor compound. This mixture is stirred at from 10 to 150° C. for at least 30 minutes, and the resulting solid substance is subsequently filtered off and washed with a C
7
-C
10
-alkylbenzene, preferably with ethylbenzene.
In the second stage, the solid obtained from the first stage is extracted for some hours at from 100 to 150° C. with excess titanium tetrachloride or an excess solution of titanium tetrachloride in an inert solvent, preferably an alkylbenzene, in which case the solvent comprises at least 5% by weight of titanium tetrachloride. The product is then washed with a liquid alkane until the titanium tetrachloride content of the wash liquor is less than 2% by weight.
The titanium-containing solid component obtainable in this way is combined with a cocatalyst to form a Ziegler-Natta catalyst system. The cocatalyst used includes an aluminum compound b).
Aluminum compounds b) suitable for use as cocatalysts are trialkylaluminums and trialkylaluminum

Affiliated with

Also associated with

Rating

Catalyst systems of the Ziegler-Natta type does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Catalyst systems of the Ziegler-Natta type, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Catalyst systems of the Ziegler-Natta type will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2465981