Abstract The invention relates to a novel method for making improved packaging components of thermoplastic foam. Recesses of predetermined size, shape and depth are pressed into sheets of the foam material by the combined effect of a die or hob structure maintained at a temperature which will not melt, but will substantially soften the material, such structure being forced into the material by a pressure which would be inadequate to effect penetration if the material were not progressively softened as the die advances. Each work piece is pre-coated on the face to be recessed with an appropriate release agent. The lateral walls of the recess are protected against heat shrinkage by limitation of temperature and by speed of penetration together with limitation of lateral die area. The material displaced by recess formation is all usefully employed through fusion and condensation to reinforce the wills of the components in the very areas where they are thinned and where the merchandise is to be nested in them.
The method of die molding an integral, recessed packaging component of the thermoplastic foam type as set forth in claim 1 which further includes the preliminary coating of the face of the foam work piece which is to be directly engaged and fused by the die with a suitable release agent, whereby the die and the recessed component are caused to leave contact with one another readily and without imposing damaging strain upon the recessed component.
Claim 2
Dependent Claim
67 words
The method of forming a recessed packaging component of the thermoplastic foam type as set forth in claim 2 in which the release agent employed is carried in water as a vehicle, the water serving also in the areas not actually engaged by the die to limit heating of the work piece surface in such areas, thereby to prevent heat damage to the surface in such areas.
Claim 3
Dependent Claim
55 words
The method forming a recessed packaging component of the thermoplastic foam type as set forth in claim 2 in which the release agent applied consists essentially of water as a vehicle, a detergent and zinc stearate in the proportions by weight of substantially 1,000 parts water to 8.5 parts detergent to 88 parts zinc stearate.