High speed extrusion
AssigneeE. I. Du Pont de Nemours and Company
InventorsMarlin Dwight Buckmaster, Donald Leonidas Henry, Stuart Karl Randa
Life of this patent
Estimating the term…
Abstract
Extrusion theology of thermoplastic polymer as manifested by surface smoothness is improved by incorporating foam cell nucleating agents into the polymer and extruding the polymer under laminar flow to form unfoamed extrudate.
Claims13
Process comprising steady state melt extruding unfoamed extrudate of molten thermoplastic polymer, said melt extruding being carried out wherein (i) said polymer has foam cell nucleating agent incorporated therein and (ii) said extrudate is formed from laminar flow of said polymer, said melt extruding being carried out at a shear rate which is at least 1.2 times the shear rate at which the onset of surface roughness for said extrudate occurs in the absence of said foam cell nucleating agent and laminar flow, said extrudate being free of surface roughness, the amount of said foam cell nucleating agent being effective to provide said surface free of surface roughness, said foam cell nucleating agent being thermally stable during said extruding, and obtaining said unformed extrudate as a result thereof, whereby articles obtained from said unfoamed extrudate are also unfoamed.
Dependencies are inferred from the claim text.