Jsp Corporation

Kazuo Tsurugai

Masaharu Oikawa

Hisao Tokoro

Hidehiro Sasaki

Hideki Kuwabara

Satoru Shioya

Taizo Kitahara

Michitoshi Ono

Masato Naito

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).

Propylene resin foamed particle and foamed particle molded body

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).

Propylene-based resin foam particle and foam particle molded body

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/cm , 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. The high-temperature peak b is a peak appeared on the temperature side higher than a temperature corresponding to the inherent peak a, and the quantity of heat at the high-temperature peak is at least 25 J/g.

Shock absorbing material

Expanded particles of polyolefin resin and process for preparing the same

Foamed particles of polypropylene homopolymer and molded article of the

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.

Flame-retardant foamed particles of polyolefin resin

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.degree. C./min and during the second heating the measurement for the DSC curve is carried out, q.sub.1 /q.sub.total .gtoreq.0.5 wherein q.sub.1 stands for the quantity of heat absorbed in the range of the DSC curve of from 50.degree. C. to (the melting point-10) .degree. C. in terms of J/g and q.sub.total stands for the total quantity of absorbed heat of the DSC curve of from 50.degree. C. to the temperature at which the melting is completed in terms of J/g is satisfied, and the temperature width at 1/2 of the peak height h of the endothermic peak whose apex is at 115.degree. C. or higher is 5.degree. C. or more. Further, the present uncrosslinked polyethylene expanded particles are obtained by impregnating the above resin particles with an expanding agent, dispersing the resin particles in a dispersing agent in a closed vessel, and discharging the resin particles and the dispersing medium from the vessel at a temperature equal to or over the softening temperature of the resin particles into a low-pressure region.

Uncrosslinked polyethylene particles for the production of expanded

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. An aliphatic hydrocarbon and/or an alicyclic hydrocarbon and carbon dioxide are used in admixture as the foaming agent in amounts satisfying the following equations (1) and (2) at the same time:

Production method of foamed particles of uncrosslinked ethylene-based

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.

Process for the production of foamed poymer particles

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.

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Utsunomiya, Japan

Kazuo Tsurugai