Method of preparing expandable polystyrene
OwnerRichard P. Crowleyinventor
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Abstract
A process for the expansion of an expandable, polymeric, bead material by exposing the bead material to steam at an elevated temperature, to effect the expansion of the bead material into a polymeric bead material form, while tumbling the bead material during expansion to prevent fusion, the improvement which comprises: employing as a lubricant for the bead material a lubricant material which, on exposure to the steam and prior to the end of the expansion of the bead material, is changed in lubricant characteristics, to provide an expanded, polymeric foam bead material having a reduced surface lubricity.
Claims15
In a process for the expansion of an expandable, polymeric, bead material by exposing the bead material to steam at an elevated temperature, to effect the expansion of the bead material into a polymeric, free-flowing foam, particulate, bead material, while tumbling the bead material during expansion to prevent fusion, the improvement which comprises:
- employing as a lubricant for the bead material a steam-degradable lubricant material which, on exposure to the steam and prior to the end of the expansion of the bead material, is substantially diminished in lubricant characteristics, to provide an expanded, polymeric foam bead material having a reduced surface lubricity.
In a process for the expansion of expandable polystyrene bead material by exposing the polystyrene bead material to steam at a pressure of less than 100 psi and at a temperature of from about 95.degree. C. to 99.degree. C. for a period of time of from about 1 to 5 minutes, while tumbling the polystyrene bead material within a revolving drum having an inlet and an outlet, the tumbling of the drum preventing the fusion of the polystyrene bead material during the expansion of the bead material within the drum, and wherein the expandable polystyrene bead material is introduced into the inlet and an expanded, polystyrene foam material, suitable for use as loose-fill packaging, is withdrawn from the outlet, the improvement which comprises:
- employing as an exterior surface coating on the expandable polystyrene bead material a steam-hydrolyzable, long-chain, quaternary-ammonium lubricant material, which material, on exposure to steam and prior to the withdrawal of the expanded polystyrene foam material from the outlet of the revolving drum, loses a substantial portion of its lubricity characteristics, thereby providing for the recovery of an expanded, free flowing, polystyrene foam bead material suitable for use as a packaging material.
Dependencies are inferred from the claim text.