Catalysts and process for the preparation of catalysts which may

Details Catalysts and process for the preparation of catalysts which may Catalysts and process for the preparation of catalysts which may

1994-06-07

1996-02-20

Delmendo, Romulo H.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymerizing in tubular or loop reactor

5261247, 526139, 526141, 526142, 526143, 526148, 526160, 502104, 502110, 502115, 502117, C08F 414

Patent

active

054929830

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to catalysts and to a process for the preparation of polymerization catalysts, as well as to a process for the polymerization of ethylene using the said catalysts.
It is known to polymerize ethylene in a wide range of temperatures and pressures using catalysts and catalytic systems containing transition metal derivatives and organometallic derivatives. These catalytic systems, known as Ziegler-Natta catalytic systems, have been continuously improved in order to increase their activity. As a result, the catalytic residues only persist in trace amounts in the polymer, which it would be uneconomical to wish to remove by processing. The contents present are, at the present time, ecotoxicologically acceptable.
However, insofar as the presence of the catalytic residue in the polymer is inevitable, even at extremely low contents, at the detection limit, a search has been made for catalysts which could be selected such that their residues, as infinitesimally small as they are, present no health or environmental risk.
The elements of the lanthanide family feature among those whose salts and derivatives are known to display no toxicity. The Applicant has thus attempted to replace the Ziegler-Natta catalytic systems by catalysts containing compounds of lanthanides or of related metals.
It is known from document WO-A-86 05788 to polymerize olefins at a pressure of approximately 1 bar and at a temperature between -78.degree. and +80.degree. C. using a catalyst comprising a compound of the Cp'.sub.2 MR or Cp'.sub.2 MH type in which Cp' is the pentamethylcyclopentadienyl radical, M is chosen from lanthanum, neodymium, samarium and lutetium, R is a very bulky alkyl radical such as the bis(trimethylsilyl)methyl radical of formula --CH[Si(CH.sub.3).sub.3 ].sub.2 or such as the mesityl radical of formula: ##STR1##
The synthesis of these compounds is very complicated. In particular, that of the compounds of formula Cp'.sub.2 MH requires a hydrogenation, followed by a filtration, washing and drying.
With an aim of simplification, the Applicant has sought to rid itself of the latter steps of the synthesis of these compounds, particularly the separation steps. It has also sought to avoid the use of reactants possessing bulky groups (trimethylsilyl or mesityl). The Applicant has thus attempted to develop a polymerization catalyst from the product of the first step of the reaction sequence described in the document WO-A-86 05788, or from an analogous product.
The subject of the present invention is thus, first of all, a catalyst for the polymerization of ethylene, characterized in that it consists of the reaction product, with at least one reactant chosen from organomagnesium compounds and organolithium compounds of formula R.sup.1 Li in which R.sup.1 is an alkyl radical containing not more than 12 carbon atoms, or of formula ArLi in which Ar is the phenyl ring or the benzyl radical C.sub.6 H.sub.5 --CH.sub.2 --, of the product of reaction of a compound of formula (I): by a divalent radical; providing a suitable catalyst for the polymerization of ethylene, in particular a bidentate ligand which is capable of bonding to the metal M of the compound (I) by forming a ring with it, in particular a 5-6 membered ring, via two bonds each between the metal M and an oxygen and/or phosphorus and/or nitrogen atom.
Neodymium, samarium, lanthanum, lutetium and ytterbium may in particular be mentioned as metal M entering into the definition of the compounds of formula (I). Preferably, (Cp) is the pentamethylcyclopentadienyl radical, R is the ethyl radical and X is chlorine.
The bidentate ligands are in particular chosen from .beta.-diketones or .beta.-keto imines of the formula (IIa): ##STR2## in which: the Z groups may be identical or different and are independently chosen from halogen, alkyl radicals, in particular C.sub.1 -C.sub.6 alkyl, and hydrogen; and C.sub.1 -C.sub.12 alkyl, or aryl, in particular phenyl; ##STR3## in which: the R.sup.2 groups may be identical or different and are independently chosen from al

REFERENCES:
patent: 4575538 (1986-03-01), Hsieh et al.
patent: 4665046 (1987-05-01), Campbell, Jr.
patent: 5066739 (1991-11-01), Pettijohn et al.
patent: 5270274 (1993-12-01), Hashiguchi et al.
Webster's II New Riverside University Dictionary, The Riverside Publishing Co., Boston, 1984, p. 171.

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