Process and apparatus for reducing die drips and for controlling surface roughness during polymer extrusion
OwnerJoseph E. Kotwis, Donald L. Rymer +1inventors
InventorsJoseph E. Kotwis, Donald L. Rymer, Christopher J. Nesbitt
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Abstract
Provided is a method of reducing the incidence of defects caused by die drool or die drips on extruded polymeric products such as films and sheets. The method includes the step of directing a flow of gas towards the die. The flow of gas is substantially parallel to one or more surfaces of the extrudate, and the temperature of the gas is about 50° C. to about 300° C. when it impinges on the surface of the die. Moreover, selecting the temperature or flow rate of the gas provides a method of determining the surface roughness of the extruded polymer.
Claims31
A process for reducing the incidence of die drips in a polymeric extrusion, said process comprising the steps of:
- a) extruding a molten polymer composition through a die to produce an extrudate;
- and
- b) directing a flow of gas towards the die along a surface of the extrudate, wherein the gas flow is substantially parallel to the surface of the extrudate, and wherein the temperature of the gas is from about 50° C. to about 300° C. when it impinges on the surface of the die.
A process for reducing the incidence of die drips in a polymer extrusion, said process comprising the steps of:
- a) extruding a molten polymer composition through a die to produce a molten extrudate, wherein the die is a sheet-forming or film-forming die, and wherein the molten extrudate has a front surface and a back surface, and the front and back surfaces are substantially parallel;
- and
- b) directing a flow of gas towards the die along the front surface, the back surface, or both surfaces of the molten extrudate, wherein the gas flow is substantially parallel to the front surface, the back surface, or both surfaces of the molten extrudate, and wherein the temperature of the gas is from about 50° C. to about 300° C. when it impinges on the surface of the die.
A process for attaining a targeted surface roughness in an extruded polymer, comprising the steps of:
- a) extruding a molten polymer composition through a die under melt fracture conditions to produce an extrudate;
- b) directing a flow of gas towards the die along a surface of the extrudate, wherein the gas flow is substantially parallel to the surface of the extrudate;
- and
- c) selecting the temperature of the gas or the gas flow rate to attain the targeted surface roughness.
An apparatus for reducing the incidence of die drips in a polymer extrusion process, said apparatus comprising a gas flow manifold that is reversibly connected to a support structure, wherein the gas flow manifold is removably and repeatably positioned in an air gap of a polymer extrusion apparatus.
Dependencies are inferred from the claim text.