Abstract: An inorganic filler-containing, polyolefin-based resin expanded bead having an expanded core layer of a first polyolefin-based resin, and a cover layer of a second polyolefin-based resin that covers the expanded core layer, wherein a weight ratio of the cover layer to the expanded core layer is 1:99 to 20:80, the expanded core layer contains an inorganic filler in a weight percentage amount of 5 to 90%, and the cover layer contains no inorganic filler or contains an inorganic filler in a weight percentage amount lower than that in the expanded core layer.

Abstract: An inorganic filler-containing, polyolefin-based resin expanded bead having an expanded core layer of a first polyolefin-based resin, and a cover layer of a second polyolefin-based resin that covers the expanded core layer, wherein a weight ratio of the cover layer to the expanded core layer is 1:99 to 20:80, the expanded core layer contains an inorganic filler in a weight percentage amount of 5 to 90%, and the cover layer contains no inorganic filler or contains an inorganic filler in a weight percentage amount lower than that in the expanded core layer.

Abstract: A hemispherical Luneberg dielectric lens including a hemispherical center layer having a hemispherical outer surface, and a plurality of hemispherical dome-shaped layers each having concentric hemispherical inner and outer surfaces, the outer surfaces of the center layer and dome-shaped layers having different diameters and the inner surfaces of said dome-shaped layers having different diameters. The center layer and dome-shaped layers are successively concentrically fitted into one another and integrated into a hemispherical shape. The center layer is a foam molding of ceramic-containing thermoplastic resin expanded beads, while each of said dome-shaped layers is a foam molding of thermoplastic resin expanded beads containing 0 to 80% by weight of a ceramic. The ceramic content per unit volume of the center and dome-shaped layers decreases from the center layer to the outermost dome-shaped layer, and the standard deviation of the apparent density of each of the center and dome-shaped layers is 0.

Abstract: A hemispherical Luneberg dielectric lens including a hemispherical center layer having a hemispherical outer surface, and a plurality of hemispherical dome-shaped layers each having concentric hemispherical inner and outer surfaces, the outer surfaces of the center layer and dome-shaped layers having different diameters and the inner surfaces of said dome-shaped layers having different diameters. The center layer and dome-shaped layers are successively concentrically fitted into one another and integrated into a hemispherical shape. The center layer is a foam molding of ceramic-containing thermoplastic resin expanded beads, while each of said dome-shaped layers is a foam molding of thermoplastic resin expanded beads containing 0 to 80% by weight of a ceramic. The ceramic content per unit volume of the center and dome-shaped layers decreases from the center layer to the outermost dome-shaped layer, and the standard deviation of the apparent density of each of the center and dome-shaped layers is 0.

Abstract: An expanded polypropylene bead for forming a dielectric material, including a polypropylene resin containing a ceramic in an amount of from 10 to 80 wt %, having an apparent density of from 0.03 to 1.7 g/cm3, having an intrinsic endothermic peak specific to the polypropylene resin on a DSC curve obtained by a differential scanning calorimetry, and also an endothermic peak at a higher temperature side of the intrinsic endothermic peak, and in that a caloritic value of the endothermic peak at the higher temperature side represents from 2 to 35% of a caloritic value of the peaks of the entire endothermic curve.

Abstract: The present invention relates to polyolefin resin expanded particles capable of demonstrating excellent flame retarding effects with a small amount of flame retardant content, despite the fact that carbon black is used as a colorant, and polyolefin resin in-mold foamed article obtained by the in-mold foaming of the expanded particles. More specifically, the present invention relates to polyolefin resin expanded particles and to a polyolefin resin in-mold foamed article obtained by the in-mold foaming of the expanded particles, which contain 0.5 to 20 wt % of carbon black, and which also contain 0.01 to 10 wt % of a hindered amine flame retardant shown by the general formula (I) below.

Abstract: An expansion-molded article is produced by filling prefoamed thermoplastic particles in a mold cavity formed in combination of mold sections, through each of which plural heating medium holes are defined, and then feeding a heating medium such as steam through the holes to heat and fusion-bond the particles into the article conforming with the mold cavity. Each of the mold sections is covered by a permeable porous sheet at least over the heating medium on a side of the mold cavity.