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Polymerization of Ethylene Cross-reference to Related Applications
| Content Provider | Semantic Scholar |
|---|---|
| Copyright Year | 2017 |
| Abstract | X or an alkyl group from the metal atom. In that case a separate Lewis acid Strong enough to do the abstrac tion must be present. A preferred neutral Lewis acid, which can alkylate the metal, is a Selected alkyl aluminum compound, Such as RA1, RA1C1, RA1C1, and “R” Al O” (alkylaluminoxanes), wherein R' is alkyl containing 1 to 25 carbon atoms, preferably 1 to 4 carbon atoms. Suitable alkyl aluminum compounds include methylaluminoxane (which is an oligomer with the general formula Me AlO), (CH3)2AlCl, CHAlCland (CH)2CHCH-Al. Metal hydrides such as NaBH may be used to bond hydride groups to the metal M. In the third polymerization process described herein a nickel or iron complex of (I) is either added to the poly merization proceSS or formed in Situ in the process. In fact, more than one Such complex may be formed during the course of the process, for instance formation of an initial complex and then reaction of that complex to form a living ended polymer containing Such a complex. Examples of Such complexes which may be formed initially in situ include (III) and (IV), as defined above, and wherein the “parallel lines' are an ethylene molecule coor dinated to the metal. These complexes may be added directly to the process or formed in situ. For instance, (III) may be formed by the reaction of (II) with a neutral Lewis acid such as an alkyl aluminum compound. Another method of form ing Such a complex in Situ is adding a Suitable iron or nickel compound Such nickel II acetylacetonate, (I) and an alkyl aluminum compound. Other metal Salts in which anions Similar to acetylacetonate are present, and which may be removed by reaction with the Lewis or Bronsted acid. For instance metal halides and carboxylates (Such as acetates) may be used, particularly if they are slightly Soluble in the process medium. It is preferred that these precursor metal Salts be at least Somewhat Soluble in the process medium. After the ethylene polymerization has Started, the com plex may be in a form such as (V) as defined above wherein P may be a divalent (poly)ethylene group of the formula -(CH2CH2)— wherein X is an integer of 1 or more, and Zf is an end group (assuming no branching taking place during polymerization), for example the groups listed for Z above. Those skilled in the art will note that (V) is in essence a polymer containing a So-called living end. It is preferred that Mbe in +2 oxidation state in (III), (IV) and (V). Compounds such as (III), (IV) and (V) may or may not be stable away from an environment Similar to that of the polymerization process, but they may be detected by NMR spectroscopy, particularly one or both of H and 'C NMR, and particu larly at lower temperatures. Such techniques, especially for polymerization “intermediates' of these types are known, see for instance U.S. Pat. No. 5,880,241, especially Examples 197-203, which is hereby included by reference. (III), (IV) and (V) may also be used in the absence of any “co-catalysts’ or “activators' to polymerize ethylene in a third polymerization process. Except for the ingredients in the process, the process conditions for the third process, Such as temperature pressure, polymerization medium, etc., may be the same as for the first and Second polymerization processes, and preferred conditions for those processes are also preferred for the third polymerization process. In all the polymerization processes herein, the tempera ture at which the polymerization is carried out is about -100° C. to about +200° C., preferably about 0°C. to about 150° C., more preferably about 25° C. to about 100° C. A convenient ethylene preSSure to use in the polymerization is about 300 kPa to about 275 MPa, more preferably about 2 MPa to about 100 MPa. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://patentimages.storage.googleapis.com/34/ab/3b/1d37417e8d5d11/US6417364.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
