| 摘要 |
PURPOSE:To obtain the titled foamed article having improved toughness and moldability, composed essentially of a polyethylene having the coefficients representing the toughness and the moldability of higher than specific levels and having a specific gel fraction, and applicable even to the field requiring high performance. CONSTITUTION:A copolymer of ethylene and preferably a 5-20C alpha-olefin (e.g. 1-butene) having a melt flow rate of preferably 0.5-20g/10min, a density of 0.915-0.935g/cm<3> and a melting point of 115-127 deg.C, and obtained by the medium- or low-pressure polymerization process is mixed with a decomposition-type foaming agent (preferably an azodicarbonamide having a decomposition point of >=196 deg.C), to obtain the objective foamed article composed of a polyethylene having the toughness coefficient (r) of the formula of >=5.5, the moldability coefficient (R) of the formula of >=0.55, and a gel fraction of 10-60%. The ratio of ethylene to the alpha-olefin is adjusted to give the polymer having desired density. USE:Heat-insulating steel plate for building use, etc. |
