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In a method for producing a plastic foam of a desired expanded dimension which is constituted by extruding a melt of a thermoplastic synthetic resin containing a blowing agent through a die of an extruder and passing the extrudate through a shaping device located outwardly of the extruder and secure

In a method for producing a plastic foam of a desired expanded dimension which is constituted by extruding a melt of a thermoplastic synthetic resin containing a blowing agent through a die of an extruder and passing the extrudate through a shaping device located outwardly of the extruder and secured to the discharge end of the extruder while expanding and solidifying the molten mass so that it fills the shaping device; the improvement wherein at least a part of that area of the inside surface of the shaping device with which the expanded resin makes contact is formed of a plate of a fluorocarbon resin, said plate being secured to the inside surface of the shaping device by fitting portions, said fitting portions having a sufficient space for absorbing an increase in the volume of the fluorocarbon resin plate at the temperature of extrusion molding; and an apparatus for use in the above described process.

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In a method for producing plastic foam by extruding a melt of a thermoplastic synthetic resin containing a blowing agent through an extrusion die on the end of an extruder, and forming and solidifying it by passing it through a shaping device having a metallic body secured to the discharge end of th

In a method for producing plastic foam by extruding a melt of a thermoplastic synthetic resin containing a blowing agent through an extrusion die on the end of an extruder, and forming and solidifying it by passing it through a shaping device having a metallic body secured to the discharge end of the extruder and extending away from said die in the direction of extrusion on the extruder opening into the inlet of the shaping device, the improvement comprising providing a plate of a fluorocarbon resin on at least a part of the inside surfaces of the metallic body, one of said body and said plate having recesses therein and the other of said body and said plate having projections thereon interfitted with said recesses, the inner surfaces of said recesses and the exterior surfaces of said projections being spaced from each other when the plate is unheated, said spaces being sufficiently large to just accommodate the resin plate at the temperature of extrusion from the heat of the resin for causing said projections to fit in said recesses for holding said plate securely on said shaping device.