STUDIES OF SOME BASIC ASPECTS IN EASY-CARE COTTON FINISHING .3. CATALYSTS

A balance between wet/dry crease recovery and strength properties could be achieved by treating cotton fabrics with dimethylol dihydroxy ethylene urea (DMDHEU) with a new technique. The latter involves padding with an aqueous solution containing DMDHEU and a specific concentration of an ammonium salt. The ammonium salts examined were: ammonium chloride, ammonium mono‐ and dihydrogen phosphate, ammonium nitrate, ammonium sulphate, ammonium oxalate and ammonium citrate. Of particular interest were the results obtained with fabrics catalyzed by ammonium dihydrogen phosphate. While these fabrics show crease recovery angles of 298° and 304° the loss in tensile strength amounts only to ca. 14%. It was postulated that the catalytic system used is based on two phases; the first is the initial acidity which induces crosslinking in the wet state thus enhancing the wet crease recovery; the second phase involves decomposition of the ammonium salt during curing with generation of acid which catalyzes crosslinking in the dry state thereby improving the dry crease recovery. The relatively lower losses in strength properties suggest that this catalytic system brings about a uniform distribution of crosslinks in the cellulose structure. © 1979 Hüthig & Wepf Verlag, Basel