Preparation of dunnage material

Claim 1

A method for the preparation of foamed dunnage in the form of particles, the method comprising providing a heat plastified mass of synthetic resinous material containing an expanding agent, the heat plastified mass being capable of expansion to form a mass containing a plurality of closed gas-filled cells, maintaining the heat plastified foamable material under pressure, subsequently cooling the heat plastified mass below the foaming temperature thereof, to provide a cooled heat plastified mass extruding the cooled heat plastified mass to form elongate strands, the mass being extruded from a shaping configuration without significant foaming occurring in the strands, subsequently severing the strands to form a plurality of elongate elements of relatively high bulk density the elongate elements being heatable to an elevated temperature sufficient to cause them to expand and form foamed strandular particles having a plurality of gas-filled cells therein, the improvement which comprises introducing, prior to severing, asymmetric foamability into the strandular particles involving altering the cross-sectional expansibility of these particles to cause one side of the strand to expand to a lesser degree, if at all, than the other, to thereby cause curling to a desired degree to form a generally nonlinear configuration upon subjecting the elements to foaming conditions.

Claim 2

A method for the preparation of foamed dunnage in the form of particles, the method comprising providing a heat plastified mass of synthetic resinous material containing an expanding agent, the heat plastified mass being capable of expansion to form a mass containing a plurality of closed gas-filled cells, maintaining the heat plastified foamable material under pressure, subsequently cooling the heat plastified mass below the foaming temperature thereof, to provide a cooled heat plastified mass extruding the cooled heat plastified mass to form elongate strands, the mass being extruded from a shaping configuration without significant foaming occurring in the strands, subsequently severing the strands to form a plurality of elongate elements of relatively high bulk density the elongate elements being heatable to an elevated temperature sufficient to cause them to expand and form foamed strandular particles having a plurality of gas-filled cells therein, the improvement which comprises introducing, prior to severing, asymmetric foamability into the strandular particles involving altering the cross-sectional expansibility of these particles to cause one side of the strand to expand to a lesser degree, if at all, than the other, to thereby cause curling to a desired degree to form a generally nonlinear configuration upon subjecting the elements to foaming conditions.