Importance

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Abstract

A polymerization catalyst which exhibits a high activity and a good hydrogen response and thus is suitable for the production of an ethylene polymer having a wide molecular weight range can be obtained by a method using a chromium compound, an organic aluminum compound and a carrier and comprising the following steps (a) to (d): (a) contacting a chromium compound with a carrier in the presence or absence of a solvent; (b) adding an organic aluminum compound to said contacted substances at a temperature of not higher than 60.degree. C. in an amount such that the mixing ratio of said organic aluminum compound to said chromium compound falls within the range of from 0.5/1 to 100/1 as calculated in terms of the ratio of aluminum atom/chromium atom (Al/Cr molar ratio) and that the following relationship (1) is satisfied: log.sub.10 t.ltoreq.0.33log.sub.10 C+0.35 (1) wherein t represents the time (min) required until the organic aluminum compound is added to give an Al/Cr molar ratio of 10/1; and C represents the amount of the carrier used (Kg); (c) after the addition of the organic aluminum compound, stirring at a temperature of from 0.degree. C. to 60.degree. C. for 0.5 to 4 hours; and (d) removing the solvent used, unreacted matters and by-products at a temperature of not higher than 60.degree. C. in such a manner that the following relationship (2) is satisfied: log.sub.10 T.ltoreq.0.23log.sub.10 C+1.10 (2) wherein T represents the time required until the removal is completed; and C represents the amount of the carrier used (Kg).

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First Claim