We claim:
1. Process for extracting from poly-e-caproamide the
hot water-soluble materials remaining therein after polym
erization is complete, which process comprises
continuously and countercurrently contacting a downward
moving bed of particles of said poly-e-caproamide, at least
one of the dimensions of said particles being not over
0.25 inch, with an upward moving body of water in weight
ratio of water feed per hourzpoly-e-caproamide feed per
hour ‘of at least about 0.8, thereby ‘forming an extraction
zone containing an aqueous extraction medium; main
taining the average temperature at the bottom of the
extraction zone in the range between about 90° C. and
about 140° C.; supplying to said moving bed of particles the heat required to maintain said temperature range of
90° C.—140° C. by the heat content of the incoming
water and thus maintaining a negative temperature gradient
from bottom to top of the extnaction zone and maintain
ing temperatures at the top thereof at-least 5° vC. below
the average temperatures at the bottom thereof; and main
taining an atmosphere over the extraction zone
consisting essentially of vapors evolved from said aqueous
extraction medium and of an inert gas, said gas being at
pressure of at least 5 degree p.s.i.; and the total pressure of said
atmosphere over the extraction zone plus the hydrostatic
pressure due to: the aqueous‘ extraction medium therein
being at least about 5 p.s.i. greater than the vapor
pressure exerted by water at the average temperature
prevailing at the bottom of the extraction zone.