Reagents for Low-Formaldehyde Finishing of Textiles

Abstract

The most important reactants for finishing textiles are the N-methylol compounds. They not only crosslink with the cellulose but also split up to form formaldehyde. To decrease the content of formaldehyde on the fabrics finished with N-methylol compounds, a very efficient fog-chamber technique using solutions of special formal dehyde-binding substances was developed, which reduces the liberation of formalde hyde on finished fabrics to levels below 100 ppm, according to the AATCC Sealed Jar Test Method 112—1975. Low-formaldehyde finishing agents can be prepared by etherifying the methylol groups with alcohols. Fabrics finished with N-alkoxymethyl compounds give off less formaldehyde than those finished with the corresponding unetherified methylol compounds. A few examples are demonstrated. Using the basics of statistical experi mental designs, it was possible to optimize a finishing process with a partly etherified dimethylol-4.5-dihydroxyethyleneurea to obtain simultaneously all desired levels of properties, including a low level of formaldehyde release. A new class of crosslinking agents is described with a nonformaldehyde-containing reactive group beside a N-methylol or N-alkoxymethyl group as a second reactive group on the base of 4-hydroxy- and 4-alkoxy-cycloalkyleneureas. The optimum of application conditions to obtain the desired properties was derived from the results of experimental designs. Another class of crosslinking agents for easy-care, antipilling, and hydrophilic finishing of polyester/cotton fabrics, where cotton is equal or less than 50% in the blend, was developed on the base of polyfunctional carbamates. In comparison to the methylol compounds of cyclic ureas, these products show a higher molecular weight. They are ideal for the swelling and crosslinking of cellulose under heat conditions and provide a smooth, pleasing hand to the finished fabric. This class of reactants exhibits lower abrasion loss than glyoxal reactants and shows less development of unpleasant formaldehyde odor on treated fabrics than most of the usual glyoxal-based reactants.