Patent ID: 7648658

Claim:
A method of alternate polymer extrusion comprising: (a) providing a first extruder including a first gear pump, (b) providing a second extruder including a second gear pump; (c) supplying a melt of a first material to the first gear pump; (d) supplying a melt of a second material to the second gear pump; (e) directing the melt of the first material along a first melt path from the first gear pump; (f) directing the melt of the second material along a second melt path from the second gear pump; (g) providing a convergence of the first and second melt paths; (h) directing the melt of at least one of the first and second materials from the convergence of the first and second paths to an outlet of a die; (i) extruding the melt of the at least one material by forcing through the die; (j) varying the speed of the first and second gear pumps to vary the rate of flow of the melts of the first and second materials to the convergence; and (k) providing constrictions constricting each of the first and second melt paths proximate the convergence sufficiently to at least substantially reduce drool of melt out of the first and second melt paths to the convergence upon substantial slowing or stopping of one of the gear pumps.