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US 2007/0164467 A1Published application
Process for reducing surface aberrations
OwnerDavid Smith, Michael Andrewsinventors
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OwnerDavid Smith, Michael Andrewsinventors
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The processes and resins of the present invention allow the extrusion of polymer products, such as polymer films, that have a reduced occurrence of surface aberrations, e.g., surface melt fracture and/or haze bands and/or haze. Preferably, the polymer products produced in accordance with the present invention are substantially free of surface aberrations even when manufactured under conditions of high sheer stress such as those conditions that occur at commercial production rates. In part, the present invention provides processes for polymer extrusion wherein the resins employed are treated using heat in an atmosphere sufficient to substantially eliminate the tendency to create surface aberrations. The resins can have reduced or substantially eliminated concentrations of low molecular weight components. In some embodiments, both the polymer resins and the extruded polymer products have reduced concentrations of processing aid(s), e.g., the polymer resins and the extruded polymer products are substantially free of processing aid(s).
A process for substantially eliminating the occurrence of surface aberrations during extrusion of a thermoplastic polymer, comprising:
(canceled)
A process for substantially eliminating surface aberrations during extrusion of a thermoplastic polymer, comprising extruding the thermoplastic polymer through a die wherein the thermoplastic polymer is substantially free of low molecular weight compounds, including organic compounds, and processing aid.
A process for producing a thermoplastic film, comprising:
A low density polyethylene extrusion resin for blown film extrusion, comprising polyethylene that is substantially free of low molecular weight species, including organic compounds, and substantially free of processing aid.
A thermoplastic polymer resin wherein the resin has been treated by the application of heat in an atmosphere for a time sufficient to remove low molecular weight components, including organic compounds, to substantially eliminate the tendency to create surface aberrations during extrusion of the resin.
An extruded thermoplastic polymer film comprising a thermoplastic polymer resin wherein the extruded thermoplastic polymer film is substantially free of low molecular weight species, including organic compounds, substantially free of surface aberrations, and substantially free of processing aid.
A process for treating a thermoplastic polymer resin susceptible to surface melt fracture comprising heating the thermoplastic polymer resin for a period of time sufficient to remove low molecular weight components, including organic compounds, to substantially eliminate surface melt fracture upon subsequent extrusion under conditions which would otherwise produce surface melt fracture.
Dependencies are inferred from the claim text.