Electrostatic pinning of extruded thermoplastic film
AssigneeImperial Chemical Industries PLC
InventorDavid J. Groves
Life of this patent
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Abstract
Apparatus and process for the extrusion and quenching of thermoplastics films wherein the film is electrostatically pinned to a cooled quenching surface by means of a blade electrode having a charge-emitting edge which is non-linear and conforms substantially to the transverse curvature in the edge portions of the film.
Claims14
An apparatus for extruding and quenching a thermoplastics film, which comprises a movable casting surface arranged to receive a web of continuously-extruded thermoplastics film, an electrostatic pinning electrode supported transversely across and in spaced relation to the path of the molten film in the proximity of or prior to the region of first contact of the film with the casting surface, said electrostatic pinning electrode comprising a blade having a charge-emitting edge which is non-linear and conforms during extrusion and quenching substantially at least to the transverse curvature of the marginal portion of the film adjacent each of the film edges in said proximity of or prior to the region of first contact of the film with the casting surface.
A process for extruding and quenching a thermoplastics film, which comprises continuously extruding a molten thermoplastics film onto a moving casting surface, depositing electrostatic charges upon the molten film by means of an electrostatic pinning electrode supported transversely across and in spaced relation to the molten film in the proximity of or prior to the region of first contact of the film with the casting surface, said electrostatic pinning electrode comprising a blade having a charge-emitting edge, which is non-linear and conforms during extrusion and quenching substantially at least to the transverse curvature of the marginal portion of the film adjacent each of the film edges in said proximity of or prior to the region of first contact of the film with the casting surface.
Dependencies are inferred from the claim text.