Processing aid for polymers

DETAILED DESCRIPTION OF THE INVENTION In accordance with the present invention it has been discovered, surprisingly, that for the improvement of extrusion behavior, difficultly melt-processible polymers which contain combinations of fluorocarbon polymers (hereinafter called type (1) fluorocarbon polymers) that are above their melting points if crystalline, or above their glass transition temperatures if amorphous, and are thus molten and fluid at the polymer-processing temperatures, and crystalline or amorphous fluorocarbon polymers (herinafter called type (2) fluorocarbon polymers) that are solid at the polymer melt-processing temperatures, have significant advantage over such difficultly melt-processible polymers which contain equivalent, or even greater, amounts of extrusion-modifying additives of the art, as in U.
S.
Pat.
No.
3,125,547 (supra).
The term "extrusion behavior" is intended to include such parameters as the operating melt temperatures, die pressure reached during extrusion, maintenance of a steady die pressure during extrusion, maximum extrusion rates that can be achieved, maintenance of a steady extrusion rate, dimensional stability of the melt, absence of deposits of decomposed polymer or additives at the exit of the die surface and good surface quality of the extruded part.
In some cases the invention may provide a means for carrying out the extrusion at a lower temperature.
Blow molding, tubing manufacture and fiber spinning represent examples of extrusion processes that may be improved by means of this invention.
Thus, the compositions of this invention, compared to polymers not containing both types (1) and (2) fluorocarbon polymers will show improved extrusion behavior, incorporating improvements in at least some of the parameters noted above.
With respect to the fluorocarbon polymer process aid of this invention, it has been independently discovered that there must be present an effective amount of polar functional groups selected from --COF, SO.
sub.
2 F, --SO.
sub