The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 26, 1994
Filed:
May. 06, 1993
Thomas Muehlenbernd, Tokyo, JP;
Roger Klimesch, Alsbach-Haehnlein, DE;
Gernot Koehler, Meckenheim, DE;
Ernst Fischer, Speyer, DE;
BASF Aktiengesellschaft, Ludwigshafen, DE;
Abstract
Novel ethylene homopolymers and ethylene copolymers which are suitable for film production and have a density from 925 to 940 kg /m.sup.3, a melt flow index (MFI) of <1 g/10 min at 190.degree. C. and at an applied force of 2.16 kp can be prepared by free radical polymerization of the monomers at from 500 to 5000 bar and reaction temperatures T of from 40.degree. to 320.degree. C. by means of an initiator with virtually complete exclusion of oxygen in at least n=3 polymerization stages. In the first stage, the total amount or the predominant part of the monomers is subjected to the polymerization by means of part of the required initiator until the polymerization virtually comes to a stop. A further part of the initiator and, if required, of the monomers is then added to the mixture cooled to 20.degree.-60.degree. C. This process is repeated in the subsequent stages until the n th stage, at least the initiators used in the n th stage having a half-life temperature of from 90.degree. to 260.degree. C., and that the maximum reaction temperature T.sub.max being 270.degree. C. or higher, at least in the n th stage.