Abstract: The present invention is concerned with expanded propylene resin beads including a core layer being in a foamed state, having a tubular shape, and being constituted of a propylene-based resin composition (a) satisfying the following (i) and (ii) and a cover layer being constituted of an olefin-based resin (b) satisfying the following (iii) or (iv). (i) A mixture of 75% by weight to 98% by weight of a propylene-based resin (a1) having a melting point of 100° C. to 140° C. and 25% by weight to 2% by weight of a propylene-based resin (a2) having a melting point of 140° C. to 165° C. (ii) A difference between the melting point of the resin (a2) and the melting point of the resin (a1) is 15° C. or more. (iii) A crystalline olefin-based resin having a melting point TmB that is lower than a melting point TmA of the composition (a) and having a relation of 0° C.<[TmA?TmB]?80° C. (iv) A non-crystalline olefin-based resin having a softening point TsB that is lower than TmA and having a relation of 0° C.

Abstract: The present invention is concerned with expanded propylene resin beads including a core layer being in a foamed state and constituted of a propylene-based resin composition (a) and a cover layer constituted of an olefin-based resin (b), the propylene-based resin composition (a) satisfying the following (i) and (ii), and the olefin-based resin (b) satisfying the following (iii) or (iv). (i) A mixture of 75% by weight to 98% by weight of a propylene-based resin (a1) having a melting point of 100° C. to 140° C. and 25% by weight to 2% by weight of a propylene-based resin (a2) having a melting point of 140° C. to 165° C. (ii) A difference between the melting point of the resin (a2) and the melting point of the resin (a1) is 15° C. or more. (iii) A crystalline olefin-based resin having a melting point TmB that is lower than a melting point TmA of the composition (a) and having a relation of 0° C.<[TmA?TmB]?80° C.

Abstract: The present invention is concerned with expanded propylene resin beads including a core layer being in a foamed state, having a tubular shape, and being constituted of a propylene-based resin composition (a) satisfying the following (i) and (ii) and a cover layer being constituted of an olefin-based resin (b) satisfying the following (iii) or (iv). (i) A mixture of 75% by weight to 98% by weight of a propylene-based resin (a1) having a melting point of 100° C. to 140° C. and 25% by weight to 2% by weight of a propylene-based resin (a2) having a melting point of 140° C. to 165° C. (ii) A difference between the melting point of the resin (a2) and the melting point of the resin (a1) is 15° C. or more. (iii) A crystalline olefin-based resin having a melting point TmB that is lower than a melting point TmA of the composition (a) and having a relation of 0° C.<[TmA?TmB]?80° C. (iv) A non-crystalline olefin-based resin having a softening point TsB that is lower than TmA and having a relation of 0° C.

Abstract: The present invention is concerned with expanded propylene resin beads including a core layer being in a foamed state and constituted of a propylene-based resin composition (a) and a cover layer constituted of an olefin-based resin (b), the propylene-based resin composition (a) satisfying the following (i) and (ii), and the olefin-based resin (b) satisfying the following (iii) or (iv). (i) A mixture of 75% by weight to 98% by weight of a propylene-based resin (a1) having a melting point of 100° C. to 140° C. and 25% by weight to 2% by weight of a propylene-based resin (a2) having a melting point of 140° C. to 165° C. (ii) A difference between the melting point of the resin (a2) and the melting point of the resin (a1) is 15° C. or more. (iii) A crystalline olefin-based resin having a melting point TmB that is lower than a melting point TmA of the composition (a) and having a relation of 0° C.<[TmA?TmB]?80° C.

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: 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: 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.

Abstract: A process for the production of expanded resin particles is disclosed, wherein an aqueous dispersion containing expandable particles of a polyolefin resin is discharged at a temperature higher than the softening point of the resin from a high pressure condition to a low pressure condition to expand the expandable particles and wherein the expandable particles contain fine particles of an inorganic material coated with an agent selected from isopropyltriisostearic titanate, tetraoctadecyl titanate, acetoalkoxyaluminum diisopropylates, stearic acid, methyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, phenyltriethoxysilane and vinyltriethoxysilane.