Olefin polymerization catalyst based on magnesium chloride complexes

#The present invention relates to novel magnesium chloride compositions in which magnesium chloride is complexed with an ether. The present invention also relates to the use of these complexes in manufacturing high performance alpha-olefin polymerization catalysts. Further a process is provided for producing alpha-olefins polymers having a controlled morphology by using the magnesium chloride complexes of this invention.

#Activated magnesium chloride has long been important in the manufacture of high performance catalysts for making polyethylene and polypropylene. It is known in the art that anhydrous magnesium chloride must be activated by mechanical or chemical methods in order to obtain active polymerization catalysts.

#Such activation methods typically include:

#The Applicant has unexpectedly found that polymerization of alpha-olefins in the presence of a Ziegler-Natta catalyst prepared according to the present invention results in a high polymerization activity per unit quantity of the catalyst component. Further the polymer fluff obtained according to the present invention is under the form of spherical particles. It is another advantage of the present invention because this is synonymous with an improved plant operability and this permits to transform the polymer directly into manufactured items, thus avoiding the expensive process of pelletizing.

#The Ziegler-Natta catalysts of the present invention utilizes a magnesium chloride complex of this invention together with a compound of a metal selected from Groups IV-B and V-B of the Periodic Table of the Elements. Preferred metal compounds are those of titanium, vanadium and zirconium. Examples of the titanium compound used in the present invention include halides, alkoxyhalides, alkoxides and halogenated oxides, of titanium. As preferred examples of the titanium compound, there may be mentioned tetravalent and trivalent titanium compounds. As tetravalent titanium compounds, those represented by the general formula Ti(OR).sub.y X.sub.4-y are preferred wherein R is a hydrocarbon radical such as an alkyl, aryl or aralkyl group having 1 to 24 carbon atoms, X is a halogen atom and 0.ltoreq.y.ltoreq.4, such as titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, monomethoxytrichlorotitanium, dimethoxydichlorotitanium, trimethoxymonochlorotitanium, tetramethoxytitanium, monoethoxytrichlorotitanium, diethoxydichlorotitanium, triethoxymonochlorotitanium, tetraethoxytitanium, monoisopropoxytrichlorotitanium, diisopropoxydichlorotitanium, triisopropoxymonochlorotitanium, tetraisopropoxytitanium, monobutoxytrichlorotitanium, dibutoxydichlorotitanium, monopentoxytrichlorotitanium, monophenoxytrichlorotitanium, diphenoxydichlorotitanium, triphenoxymonochlorotitanium and tetraphenoxytitanium. As trivalent titanium compounds, there may be used, for example, titanium trihalides obtained by reducing titanium tetrahalides such as titanium tetrachloride and titanium tetrabromide with hydrogen, aluminum, titanium or an organometallic compound of a Group I-III metal in the Periodic Table, as well as trivalent titanium compounds obtained by reducing tetravalent alkoxytitanium halides represented by the general formula Ti(OR).sub.s X.sub.4-s with an organometallic compound of a Group I-III metal in the Periodic Table, in which formula R is a hydrocarbon radical such as an alkyl, aryl or aralkyl group having 1 to 24 carbon atoms, X is a halogen atom and 0<s<4.

#More preferably the catalyst used according to the present invention is a TiCl.sub.4 /MgCl.sub.2.xE compound.