Durable Press Finishing of Cotton with N-Methylolacrylamide Using Non-Peroxidic Polymerization Initiators

Abstract

A study is presented of the use of the water-soluble azo compound 4,4'-azobis(4- cyanovaleric acid) and its salts as nonoxidative free radical polymerization initiators for durable press finishing of cotton with N-methylolacrylamide. The azo initiators show less tendency to tender and discolor cotton fabric during high temperature curing than does ammonium persulfate. Two-stage curing at 110° and 160° was used to induce vinyl polymerization, foltowed by cellulose crosslinking in the pres ence of zinc salts serving both as co-catalysts for polymerization and as Lewis acid catalysts for cellulose crosslinking by poly(NMA). Phosphoric acid-monosodium phosphate buffer also served to minimize tendering. Adding catalytic amounts of phosphonium salts such as THP sulfate or phosphate as oxygen scavengers, in the presence and absence of azo initiator and co-catalysts, increased the efficiency of NMA polymerization in air. It is possible to eliminate completely the loss of flex abrasion resistance normally encountered in printcloth finishing to durable press appearance ratings of 4.0-4.2, and to improve Accelerotor abrasion resistance relative to conventionally treated fabric. Increased tearing and breaking strength retention were also imparted. The treated fabrics were more supple and possessed a lower bending moment than did the original untreated printcloth.