Abstract: Method and apparatus for producing a molded article of a foamed thermoplastic resin and articles produced thereby. A molten mass of an expandable thermoplastic resin is accumulated in an accumulator while it is prevented from foaming. A quantity of the accumulated formable melt is extruded through a die orifice having a shape adapted to reflect the shape of the desire finished product. The extruded foamable melt commences foaming as it comes in contact with the atmosphere. As the extruded thermoplastic resin foams, it is pulled vertically downward from the die orifice by gravity. The downward-hanging, foamed, thermoplastic material is captured between the halves of a vertically-oriented mold before the foaming expansion of the foamable melt has been completed. The foamed thermoplastic material is compressed by the vertically-oriented mold into the desired shape.

Abstract: An ultra low density polyolefin foam having a density of about 0.6 to about 1.5 pounds per cubic foot comprising a heat-plastified mixture comprising (1) a non-elastomeric olefin polymer resin selected from the group consisting of ethylene homopolymers, non-elastomeric copolymers of ethylene and a copolymerizable monomer, and propylene homopolymers; (2) an elastomer in an amount of about 3 to about 30 wt. parts per 100 wt. parts of said non-elastomeric olefin polymer resin; (3) polystyrene in an amount of about 1 to about 15 wt. parts per 100 wt. parts of said olefin polymer resin; (4) a stability control agent selected from the group consisting of partial esters of long chain fatty acids with polyols, higher alkyl amines, fatty acid amides, and olefinically unsaturated carboxylic acid copolymers, and (5) a hydrocarbon blowing agent having from 1 to 6 carbon atoms and a boiling point between -175.degree. C. and 50.degree. C.

Abstract: Method and apparatus for producing a molded article of a foamed thermoplastic resin and articles produced thereby. A molten mass of an expandable thermoplastic resin is accumulated in an accumulator while it is prevented from foaming. A quantity of the accumulated foamable melt is extruded through a die orifice having a shape adapted to reflect the shape of the desire finished product. The extruded foamable melt commences foaming as it comes in contact with the atmosphere. As the extruded thermoplastic resin foams, it is pulled vertically downward from the die orifice by gravity. The downward-hanging, foamed, thermoplastic material is captured between the halves of a vertically-oriented mold before the foaming expansion of the foamable melt has been completed. The foamed thermoplastic material is compressed by the vertically-oriented mold into the desired shape.

Abstract: A foamable composition for producing an ultra low density polyolefin foam having a density of about 0.6 to about 1.5 pounds per cubic foot comprising a heat-plastified mixture comprising (1) an olefin polymer resin selected from the group consisting of ethylene homopolymers and copolymers of ethylene and a copolymerizable monomer; (2) an elastomer in an amount of about 3 to about 30 wt. parts per 100 wt. parts of said olefin polymer resin; (3) polystyrene in an amount of about 1 to about 15 wt. parts per 100 wt. parts of said olefin polymer resin; (4) a stability control agent selected from the group consisting of partial esters of long chain fatty acids with polyols, higher alkyl amines, fatty acid amides, and olefinically unsaturated carboxylic acid copolymers, and (5) a hydrocarbon blowing agent having from 1 to 6 carbon atoms and a boiling point between -175.degree. C. and 50.degree. C.

Abstract: Method and apparatus for producing a molded article of a foamed thermoplastic resin and articles produced thereby. A molten mass of an expandable thermoplastic resin is accumulated in an accumulator while it is prevented from foaming. A quantity of the accumulated foamable melt is extruded through a die orifice having a shape adapted to reflect the shape of the desired finished product. The extruded foamable melt commences foaming as it comes in contact with the atmosphere. As the extruded thermoplastic resin foams, it is pulled vertically downward from the die orifice by gravity. The downward-hanging, foamed, thermoplastic material is captured between the halves of a vertically-oriented mold before the foaming expansion of the foamable melt has been completed. The foamed thermoplastic material is compressed by the vertically-oriented mold into the desired shape.

Abstract: Moldable shrunken foam beads comprising a foamable thermoplastic polymer, preferably a silane-crosslinked polyolefin foam, are produced by mixing a composition comprising a silane-modified polyolefin (such as a silane-grafted polyethylene) and a silanol condensation catalyst in an extruder to produce a melt, then projecting a blowing agent into the melt at a rate effective to produce a desired foam density in the extrudate; extruding and cutting the melt to form foam beads; allowing the beads to shrink; and exposing the foam beads to moisture to produce silane crosslinking of the polyolefin foam. In certain other embodiments the crosslinking of the thermoplastic polymer can be omitted, and/or shrinkage of the beads produced by vacuum treatment.