초록 ▼

Improved compositions useful for the production of rotomolded articles having a foamed interior and non-foamed exterior skin are provided. The compositions of the invention are comprised of a first thermoplastic resin component which is an ethylene polymer in pellet form containing a chemical foamin

Improved compositions useful for the production of rotomolded articles having a foamed interior and non-foamed exterior skin are provided. The compositions of the invention are comprised of a first thermoplastic resin component which is an ethylene polymer in pellet form containing a chemical foaming agent, an organic peroxide and, optionally, a metal-containing activator compound and a second resin component which is a powder and can be a thermoplastic ethylene polymer or ethylene copolymer having less than 30% crystallinity. An improved one-step process for producing foamed rotomolded articles having foamed interiors and non-foamed exterior skins is also provided.

대표청구항 ▼

[ I claim:] [1.] A process for rotationally molding articles having a foamed interior and a non-foamed exterior skin which comprises introducing a rotomolding composition comprising polymers to a mold and heating the mold and its contents to a temperature above the melt temperature of the polymers a

[ I claim:] [1.] A process for rotationally molding articles having a foamed interior and a non-foamed exterior skin which comprises introducing a rotomolding composition comprising polymers to a mold and heating the mold and its contents to a temperature above the melt temperature of the polymers and above decomposition temperatures of a chemical foaming agent and an organic peroxide while biaxially rotating, said rotomolding composition comprising:(a) 25 to 75 wt. %, based on the weight of the total composition, ethylene polymer pellets ranging in size from about 1/16 inch to about 3/16 inch in diameter and containing 0.25 to 7.5 wt. % chemical foaming agent, based on the weight of the ethylene polymer and 0.1 to 2.0 wt. % organic peroxide, based on the weight of the ethylene polymer, said ethylene polymer having a melt index from 0.25 g/10 mins to 25 g/10 mins; and(b) 75 to 25 wt. %, based on the weight of the total composition, ethylene polymer powder containing:(i) a major proportion of fractional melt index ethylene polymer powder wherein 80 percent or more of the powder particles are greater than 250 microns in size and(ii) a minor proportion of ethylene polymer powder wherein 80 percent or more of the powder particles are less than 250 microns in size and the ethylene polymer has a melt index greater than 1 g/10 mins., and with the proviso that the mean particle size of (b)(i) and (b)(ii) differ by at least 100 microns.