Abstract: Provided are polyvinylidene fluoride resin expanded beads which can be molded by in-mold molding and thus stably provide, without impairing excellent characteristics inherent in polyvinylidene fluoride resin, molded articles having excellent mechanical properties. Polyvinylidene fluoride resin expanded beads, characterized in that when 1 to 3 mg of the expanded beads are subjected to heat-flux type differential scanning calorimetry (DSC) wherein the beads are heated from 25° C. to 200° C. at a temperature rise rate of 10° C./min, the obtained DSC curve (of first heating) has both an inherent endothermic peak which is inherent in polyvinylidene fluoride resin and one or more higher-temperature endothermic peaks which appear on the higher-temperature side of the inherent endothermic peak, the quantity of heat of melting of the higher-temperature endothermic peaks being at least 0.5 J/g.

Abstract: An expanded bead of a polylactic acid resin, having an exterior surface, a surface region including the entire exterior surface and having a weight of one-sixth to one-fourth the weight of the expanded bead, and a center region located inside the surface region and having a weight of one-fifth to one-third the weight of the expanded bead, wherein the expanded bead, the surface region and the center region, after having been subjected to a pretreatment including a heat treatment at 110° C. for 120 minutes followed by cooling at a cooling speed of 2° C./min, have endothermic calorific values of (Br:endo), (Brs:endo) and (Brc:endo), respectively, when measured by heat flux differential scanning calorimetry at a heating speed of 2° C./min in accordance with JIS K7122(1987), and wherein (Br:endo) is greater than 25 J/g and (Brs:endo) is smaller than (Brc:endo) and is not smaller than 0 J/g.

Abstract: Multilayer expanded polypropylene resin beads that are heat moldable at low steam pressure and can provide an expanded mold with sufficient rigidity and heat resistance. The beads are formed from a polypropylene resin and a coating layer formed from a different polypropylene resin. The multilayer expanded resin beads can be molded in-mold at a steam pressure lower than the steam pressure for molding single-layer expanded beads made from the polypropylene resin which forms the core layer. The coating layer to core layer resin weight ratio in the multi-layer resin beads is not less than 0.001 and not greater than 0.040 and the expansion ratio of the expanded beads, the average value of the thickness of the coating layer of the expanded beads, calculated based on the coating weight ratio of the multi-layer resin beads, is not less than 0.1 ?m and not greater than 3.0 ?m.

Abstract: Foamed polyolefin resin beads having antistatic properties obtained by a process, which includes dispersing polyolefin resin beads into an aqueous medium, injecting a blowing agent, stirring and allowing the polyolefin resin beads to foam and expand. The polyolefin resin beads are composite resin beads comprising a core layer of a core layer polyolefin resin and a covering layer of a covering layer polyolefin resin.

Abstract: Provided are polyvinylidene fluoride resin expanded beads which can be molded by in-mold molding and thus stably provide, without impairing excellent characteristics inherent in polyvinylidene fluoride resin, molded articles having excellent mechanical properties. Polyvinylidene fluoride resin expanded beads, characterized in that when 1 to 3 mg of the expanded beads are subjected to heat-flux type differential scanning calorimetry (DSC) wherein the beads are heated from 25° C. to 200° C. at a temperature rise rate of 10° C./min, the obtained DSC curve (of first heating) has both an inherent endothermic peak which is inherent in polyvinylidene fluoride resin and one or more higher-temperature endothermic peaks which appear on the higher-temperature side of the inherent endothermic peak, the quantity of heat of melting of the higher-temperature endothermic peaks being at least 0.5 J/g.

Abstract: Foamed polyolefin resin beads having antistatic properties obtained by a process, which includes dispersing polyolefin resin beads into an aqueous medium, injecting a blowing agent, stirring and allowing the polyolefin resin beads to foam and expand. The polyolefin resin beads are composite resin beads comprising a core layer of a core layer polyolefin resin and a covering layer of a covering layer polyolefin resin.

Abstract: A polypropylene resin foamed bead from which a foamed bead molded article excelling in appearance, heat resistance and mechanical properties can be obtained at the molding temperature lower than that for conventional polypropylene resin foamed beads; and a foamed bead molded article obtained by molding the same. The polypropylene resin foamed bead is characterized by having such a crystal structure that in the first DSC curve obtained when the temperature of the foamed bead sample is raised from ordinary temperature to 200° C. at a temperature rising rate of 2° C/min by a differential scanning calorimetry, there appear a main endothermic peak of 100° to 140° C. endothermic peak apex temperature exhibiting 70 to 95% endothermic peak calorific value based on the total endothermic peak calorific value and two or more endothermic peaks exhibited on the high temperature side with respect to the main endothermic peak.

Abstract: The present invention relates to foamed polyolefin resin beads. Further, the present invention provides foamed resin beads obtained by foaming and expanding composite resin beads which include a core layer constituted by a polyolefin resin and a covering layer which covers the core layer constituted by a polyolefin resin, wherein (a) the polyolefin resin constituting the core layer is a crystalline polyolefin resin, (b) the polyolefin resin constituting the covering layer is a crystalline polyolefin resin which has a lower melting point (B) than a melting point (A) of the polyolefin resin constituting the core layer, wherein a temperature difference [(A)?(B)] between the melting point (B) and the melting point (A) is more than 0° C. and 80° C.

Abstract: Expanded polypropylene resin beads having a melting point of not less than 120° C. but less than 140° C., the melting point being determined from a DSC curve obtained by heat flux differential scanning calorimetry in accordance with JIS K7121-1987 in which a sample of 1 to 3 mg of the expanded polypropylene resin beads is heated to 200° C. at a heating rate of 10° C./minute, then cooled to 30° C. at a rate of 10° C./minute, and again heated from 30° C. to 200° C. at a heating rate of 10° C./minute to obtain the DSC curve. The expanded polypropylene resin beads has an apparent density ?1 before heating and an apparent density ?2 after being heated for 10 seconds with steam at a temperature higher by 5° C. than the melting point thereof, wherein a ratio of ?1 to ?2 is not greater than 1.5.

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.

Abstract: The molded articles of foamed particles, which are produced by using foamed particles composed of a polypropylene-based polymer, have had excellent cushioning characteristics and impact resilience, but have been not always satisfactory in stiffness such as compressive strength.The invention is directed to foamed particles comprising a polypropylene homopolymer as a base resin and having a tensile modulus of 15,000-25,000 kg/cm.sup.2 and a crystal structure that an inherent peak and a high-temperature peak appear as endothermic peaks on a DSC curve obtained by differential scanning calorimetry of the foamed particles. A quantity of heat at the high-temperature peak is 30-60 J/g.A molded article of foamed particles according to the invention is obtained by using the foamed particles as described above and molding them, and has a density of 0.01-0.3 g/cm.sup.3 and a tensile modulus of 15,000-25,000 kg/cm.sup.2.

Abstract: Flame-retardant foamed particles of a polyolefin resin, which contain a bis(alkyl ether)tetrabromobisphenol A flame retardant and/or a bis(alkyl ether)tetrabromobisphenol S flame retardant, and a synergist of the flame retardant, are disclosed. The flame retardant has a bromine content of at least 50 wt. %. The alkyl group in the alkyl ether moiety of the flame retardant is any one of ethyl, propyl, bromoethyl and bromopropyl. The synergist of the flame retardant is selected from the group consisting of antimony oxides, metal oxides, boric acid salts and metal hydroxides. An expansion-molded article is obtained by filling the flame-retardant foamed particles into a mold and molding the foamed particles.

Abstract: The present invention relates to uncrosslinked polyethylene particles for the production of expanded particles that can easily and securely produce expanded particles which can be molded without applying a special internal pressure, are excellent in moldability, such as secondary expansion, fusion and dimensional accuracy, and have a high expansion rate and to uncrosslinked polyethylene expanded particles made of said uncrosslinked polyethylene particles. The present uncrosslinked polyethylene particles for the production of expanded particles are resin particles whose base resin is an uncrosslinked polyethylene having a density of over 0.920 g/cm.sup.3 and up to and including 0.940 g/cm.sup.3 and wherein, in the DSC curve that is obtained by using a differential scanning calorimeter in such a manner that after 1 to 10 mg of the resin particles is heated to 200.degree. C. at 10.degree. C./min and then is cooled to room temperature at 10.degree. C./min, heating is again carried out to 200.degree. C. at 10.

Abstract: Disclosed herein is a method of producing foamed particles of an ethylene-based resin, which have a high expansion ratio and are free from the formation of fine cells, by dispersing particles of the uncrosslinked ethylene-based resin, which are obtained using, as a base resin, an ethylene/.alpha.-olefin copolymer containing, as a comonomer component, 1.0-10 wt. % of an .alpha.-olefin having 4-10 carbon atoms, in a dispersion medium in the presence of a foaming agent in a closed vessel, heating the resultant dispersion to impregnate the resin particles with the foaming agent, and then releasing the resin particles into a region of a pressure lower than the internal pressure of the vessel at a foaming temperature not lower than the softening temperature of the resin particles, thereby expanding the resin particles.

Abstract: Disclosed herein is a production process of foamed polymer particles, wherein particles of a polymer, which contain a silica-alumina absorbent in which the molar ratio of SiO.sub.2 Al.sub.2 O.sub.3 is at least 1.15:1 are dispersed in a dispersion medium in the presence of carbon dioxide in a closed vessel, the resultant dispersion is heated to a temperature not lower than the softening temperature of the polymer to impregnate the polymer particles with carbon dioxide, and the polymer particles and the dispersion medium are then released into an atmosphere of a pressure lower than the internal pressure of the vessel, thereby expanding the polymer particles. The polymer may be an uncrosslinked propylene polymer, uncrosslinked, linear low-density polyethylene or crosslinked polymer.