Abstract: A stamped plastic sheet manufacturing method includes immersing a molten extruded thermoplastic sheet into a liquid refrigerant just prior to passing through a pair of stamping rolls having tooth-like or vane-like projections. In this manner, a skin layer is formed on the surface of the molten plastic sheet prior to stamping. Upon stamping, the sheet is tensioned by the confronting crests of the above tooth-like or vane-like projections and then removed from the liquid refrigerant after the interior of the sheet has been hardened to form a stamped sheet having a substantially uniform thickness.

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 .mu. in diameter, of a high molecular compound used as a carrier, and an organometallic compound under a pressure of 100 kg/cm.sup.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.