| 摘要 |
PURPOSE:To obtain the title core for molding, low in a content of a volatile organic blowing agent and not forming pinholes in an unsaturated polyester layer, by impregnating a specified modified polyolefin resin with a volatile organic blowing agent and expanding the resin by heating in a mold. CONSTITUTION:A modified polyolefin resin is produced by impregnating a polyolefin resin (e.g., high-density polyethylene) with a vinyl monomer (e.g., styrene) and polymerizing the monomer. This modified polyolefin resin is expanded with a volatile organic blowing agent (e.g., propane) to produce pre-expanded particles. These pre-expanded particles are expanded by heating in a mold to produce a foam of a volatile organic blowing agent content <=0.5wt%. This foam is used as a core for molding an unsaturated polyester resin. The volatile organic blowing agent content of this core is so low that no loss of the strength of bond between the core material and the unsaturated polyester resin layer, etc., occurs. |
