Patent ID: 6437089
Filing Date: 2002-08-20
Classification: C08G,Y02P

Abstract:
A process for the production of nylon 6 which comprises:a) (1) contacting either steam or water and 6-aminocapronitrile in the presence of a dehydration catalyst to produce a first feed stream comprising a major portion of caprolactam and a minor portion of 6-aminocapronitrile, or (2) contacting 6-aminocapronitrile and water at elevated temperature and superatmospheric pressure to produce a second feed stream comprising a major portion of nylon 6 prepolymer having more than about 40 gram equivalents of untreated nitrile end groups per million grams of nylon 6 prepolymer, and a minor portion of 6-aminocapronitrile; b) providing a vertical countercurrent multistage reactor having a top and a bottom, and having upper stages and lower stages, said reactor being equipped with internal perforated barrier means for establishing a plurality of stages and for effecting contact of said first and/or second feed stream with a countercurrently-flowing steam stream; c) introducing at least one of said first and second feed streams directly into said reactor at or near the top of said reactor; d) introducing steam into said reactor at at least one introduction point near the bottom of said reactor; e) maintaining a pressure within said reactor between 50 and 800 psig (0.34 and 5.52 MPa) and a temperature at the top of said reactor between 190 and 250 degrees C. and a temperature at the bottom of said reactor between 260 and 290 degrees C.; f) withdrawing a steam-containing overhead stream at the top of said reactor; and g) recovering a product stream from the bottom of said reactor, said product stream comprising nylon 6 polymer having less than about 20 gram equivalents of unreacted nitrile end groups per million grams of nylon 6.