| abstract |
Easily pourable polyolefin granules are obtained by polymerizing an olefin in the presence of a polymerization catalyst system comprising a compound having a main catalyst component supported on a spheroidal particle, 1 to 1,000 μ in diameter, of a high molecular compound used as a carrier, and an organometallic compound under a pressure of 100 kg/cm 2 or less and at a temperature lower than both of the melting points of the resulting polymer and the said high molecular compound used as a carrier. The granule diameter of the said polyolefin can be controlled very easily by changing the particle size of the high molecular compound used as a carrier, the loading rate of the main catalyst component on the high molecular compound used as a carrier, or the catalyst efficiency. The granule size distrubution can be controlled by controlling the particle size distribution of the high molecular compound used as a carrier. The polyolefin granules obtained have a bulk density of 0.4 to 0.6 g/cc, containing little of fine powders of the polyolefin, and are uniform in size and shape, so that they are directly usable in the same way as in the case of ordinary pellets as a material for common molded articles such as, for example, injection-molded articles, blow-molded articles, or films. When sprinkled with a foaming agent, the granules can be used directly in expansion molding to manufacture structural materials. |