Continuous aqueous dyeing process for high-tenacity industrial nylon fabrics

Claim 1

A continuous process for uniformly dyeing high-tenacity industrial nylon fabrics composed of high tensile strength nylon 6,6 yarn having a draw ratio of at least 4.0 to about 5.1 comprising the successive steps of: (1) applying to the nylon fabric in open width an aqueous dyebath volatile at elevated temperatures containing a tinctorial amount of an acid dyestuff, a wetting agent and a dye transport system active at elevated temperatures and composed of (a) a retarding and leveling agent to facilitate rapid penetration of the nylon filament bundles and (b) a mono, di- or tri- lower (C 1 -C 4 ) alkylene glycol having a molecular weight in the range of about 50 to about 200; (2) drying the dyed fabric of step (1) to reduce migration of the dyebath liquid on the fiber, to heat activate the dye transport system and promote uniform penetration of the filament bundle; (3) thermofixing the treated fabric of step (2) at elevated temperatures in the range of about 375° to about 425° F. to penetrate the dyestuff into the fibers and to volatilize the aqueous dyebath then (4) enhancing dye penetration by exposing the fabric to a wetting agent and a nylon swelling agent, to swell the nylon fibers and further penetrate the dyestuff into the nylon fibers; (5) subjecting the fabric to saturated steam maintained at a temperature in excess of 200° F. for a period of time sufficient to completely fix the dyestuff in the fabric; and thereafter (6) washing the fabric to remove any unattached dye and any remaining processing agents.