Continuous dyeing process

Claim 1

A PROCESS COMPRISING CONTINUOUSLY TREATING A RUNNING LENGTH OF MATERIAL, SAID MATERIAL CONSISTING ESSENTIALLY OF (1) A POLYMER CONTAINING AT LEAST 85% OF ACRYLONITRILE IN THE POLYMER MOLECULE AND (2) FROM ABOUT 1 TO 40% BY WEIGHT OF SAID MATERIAL OF A WATER-SOLUBLE DYE ASSISTANT SELECTED FROM THE GROUP CONSISTING OF WATER SOLUBLE AMINE SALTS, QUATERNARY AMMONIUM SALTS, SULFONIUM SALTS, PHOSPHONIUM HALIDES, POLYMERIC N-VINYL FATTY ACID AMIDES AND POLYMERIC N-VINYL LACTAMS, IN AN AQUEOUS DYE SOLUTION HAVING A PH NOT EXCEEDING ABOUT 7 AND A TEMPERATURE OF ABOUT 175-212*F. AND CONTAINING PER GALLON ABOUT 0.25-8 OZ. OF AN ACID DYESTUFF AND ABOUT 2-16 OZ. OF A WATER-MISCIBLE, ACID-STABLE, HIGH BOILING ORGANIC SOLVENT FOR SAID DYESTUFF FOR ABOUT 20-90 SECONDS, REMOVING EXCESS SOLUTION FROM THE DYED RUNNING LENGTH AND THEN STEAMING THE DYED RUNNING LENGTH AT A TEMPERATURE OF ABOUT 212-225*F. SAID SOLVENT BEING SELECTED FROM THE GROUP CONSISTING OF N-LOWER ALKYL-2PYRROLIDONES, N,N-DI-SUBSTITUTED FORMAMIDES, GAMMALACTONES, AND LOWER ALIPHATIC POLYHYDRIC ALCOHOLS AND PARTIAL ALKYL ETHERS OF SUCH ALCOHOLS.