Abstract:
Caprolactam and process water (up to 10 percent) are charged to an autoclave
reactor. The vessel is purged with nitrogen, heated to 2100C and is
pressurised to a maximum of 18 bar when polymerisation occurs. The pressure
is maintained by bleeding steam. When the temperature rises to 270-280'C,
the pressure is reduced to atmospheric after about 1 hour.
Pressure is reduced to below atmospheric (at the same temperature' when the
unreacted monomers and oligomers (cyclotriamide etc) are
removed. The polymer product is finally removed by pressurising the vessel
with nitrogen and extruding the polymer from the autoclave base. The
polymer is quenched with water and cut into chips.