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 process of producing a foamed molding, wherein expanded, substantially non-crosslinked polypropylene-based resin beads are heated in a mold to fuse-bond the beads together into a unitary body. Each of the expanded beads has been surface-modified with an organic peroxide.

Abstract: A process of producing a foamed molding, wherein expanded, substantially non-crosslinked polypropylene-based resin beads are heated in a mold to fuse-bond the beads together into a unitary body. Each of the expanded beads has been surface-modified with an organic peroxide.

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: A process of producing a foamed molding, wherein expanded, substantially non-crosslinked polypropylene-based resin beads are heated in a mold to fuse-bond the beads together into a unitary body. Each of the expanded beads has been surface-modified with an organic peroxide.

Abstract: Expanded, substantially non-crosslinked polypropylene resin beads capable of producing a high rigidity foamed molding at a relatively low temperature. The beads are produced by a process including a step of dispersing substantially non-crosslinked polypropylene resin particles in a dispersing medium containing an organic peroxide to obtain a dispersion, a step of heating the dispersion to decompose the organic peroxide and to modify the surface of the surface-modified polypropylene resin particles, and a step of expanding the non-crosslinked, surface-modified polypropylene resin particles using a blowing agent.

Abstract: An expansion-molded article (foamed body) produced by using foamed and expanded beads, and having open voids has sound absorbing qualities, and can be used as a sound absorbing material. However, a sound absorbing material comprising such an expansion-molded article has been unable to attain a high sound absorption coefficient in a wide acoustic frequency range. The invention relates to a molded article produced by using resin particles, and having sound absorbing qualities. The resin particles used have through hole(s) and a porosity of 45 to 80% in a most densely packed state. The void content of the molded article is 10 to 60%, and the bulk density thereof is 0.01 to 0.6 g/cm3.

Abstract: A method for producing expanded polypropylene resin particles wherein polypropylene resin particles impregnated with a physical blowing agent are heated along with an aqueous medium and a dispersant and are released and expanded at reduced pressure from the interior of a pressure-tight vessel, wherein the aforementioned aqueous medium has an electrical conductivity of from not less than 0.00 ms/m to not more than 20.00 mS/m. The resulting particles obtained are without inconsistencies caused by differences in the amount of dispersant adhering to the particles or the amount of dispersant added to prevent the particles from fusing together during the heat treatment step of the method.

Abstract: A process of producing a foamed molding, wherein expanded, substantially non-crosslinked polypropylene-based resin beads are heated in a mold to fuse-bond the beads together into a unitary body. Each of the expanded beads has been surface-modified with an organic peroxide.

Abstract: An expansion-molded article (foamed body) produced by using foamed and expanded beads, and having open voids has sound absorbing qualities, and can be used as a sound absorbing material. A sound absorbing material which is able to attain a high sound absorption coefficient in a wide acoustic frequency range is provided by a molded article produced by using resin particles, having through hole(s) and a porosity of 45 to 80% in a most densely packed state. The void content of the molded article is 10 to 60%, and the bulk density thereof is 0.01 to 0.6 g/cm3.

Abstract: Expanded, substantially non-crosslinked polypropylene resin beads capable of producing a high rigidity foamed molding at a relatively low temperature. The beads are produced by a process including a step of dispersing substantially non-crosslinked polypropylene resin particles in a dispersing medium containing an organic peroxide to obtain a dispersion, a step of heating the dispersion to decompose the organic peroxide and to modify the surface of the surface-modified polypropylene resin particles, and a step of expanding the non-crosslinked, surface-modified polypropylene resin particles using a blowing agent.

Abstract: Expanded, substantially non-crosslinked polypropylene resin beads capable of producing a high rididity foamed molding at a relatively low temperature. The beads are produced by a process including a step of dispersing substantially non-crosslinked polypropylene resin particles in a dispersing medium containing an organic peroxide to obtain a dispersion, a step of heating the dispersion to decompose the organic peroxide and to modify the surface of the surface-modified polypropylene resin particles, and a step of expanding the non-crosslinked, surface-modified polypropylene resin particles using a blowing agent.

Abstract: A method for producing expanded polypropylene resin particles wherein polypropylene resin particles impregnated with a physical blowing agent are heated along with an aqueous medium and a dispersant and are released and expanded at reduced pressure from the interior of a pressure-tight vessel, wherein the aforementioned aqueous medium has an electrical conductivity of from not less than 0.00 ms/m to not more than 20.00 mS/m. The resulting particles obtained are without inconsistencies caused by differences in the amount of dispersant adhering to the particles or the amount of dispersant added to prevent the particles from fusing together during the heat treatment step of the method.

Abstract: An expansion-molded article (foamed body) produced by using foamed and expanded beads, and having open voids has sound absorbing qualities, and can be used as a sound absorbing material. However, a sound absorbing material comprising such an expansion-molded article has been unable to attain a high sound absorption coefficient in a wide acoustic frequency range.

Abstract: An expansion-molded article (foamed body) produced by using foamed and expanded beads, and having open voids has sound absorbing qualities, and can be used as a sound absorbing material. However, a sound absorbing material comprising such an expansion-molded article has been unable to attain a high sound absorption coefficient in a wide acoustic frequency range.

Abstract: A shock-absorbing material composed of an expansion-molded article of polypropylene resin particles is excellent in shock-absorbing property and impact resilience compared with shock-absorbing materials composed of other resin materials, but has not been said to be satisfactory in stiffness and energy absorption efficiency. The present invention relates to a shock-absorbing material composed of an expansion-molded article produced by using foamed particles comprising, as a base resin, a polypropylene homopolymer obtained by using a metallocene polymerization catalyst. The base resin has a tensile modulus of at least 15,000 kgf/cm2, and the expansion-molded article has a crystal structure that an inherent peak a and a high-temperature peak b appear as endothermic peaks on a DSC curve obtained by the differential scanning calorimetry of the molded article.

Abstract: Propylene resin beads for molding expansion molded articles having improved high temperature resistance include as base resin metallocene-catalyzed copolymers of propylene with at least one or more of ethylene and ∝-olefins of 4 to 20 carbon atoms. The metallocene-catalyzed propylene copolymers are isotactic random copolymers characterized by a melting point higher than 140° C. to 160° C. and a melt flow rate (MFR) of not higher than 12 g/10 minutes, especially, 0.5 to 12 g/10 minutes. Expansion molded articles produced by expansion molding the expanded beads have a high temperature degree of deflection which is lower than that of metallocene-catalyzed propylene homopolymers and lower than that of Ziegler-Natta-catalyzed random propylene copolymers having the same comonomers and melting point.

Abstract: A polycarbonate resin foamed molding having a density D of 0.6 g/cm3 or less and at least 30 (kg·cm/cm3)/(g/cm3) of a value E80/D obtained by dividing an amount of energy absorbed through 50% compression of the molding at 80° C. (E80 kg·cm/cm3) by the density of the molding. A shock absorber for a vehicle includes a core of the above molding, and a skin covering a surface of the core.

Abstract: When it is intended to obtain foamed particles having a high expansion ratio upon the production of foamed particles of a polyolefin resin, there has been a problem that foamed particles uneven in cell diameter are produced. Any molded article produced with such foamed particles has involved a drawback that it is poor in dimensional stability, and its surface profile becomes uneven.The invention relates to foamed particles comprising a polyolefin resin as a base resin, wherein the base resin contains a metal salt (excluding alkali metal salts) of boric acid in such a manner that the content of the metal salt of boric acid in the raw resin amounts to 50-50,000 ppm. Zinc borate, magnesium borate or the like is used as the metal salt of boric acid.