Wet-Fixation Process for Improved Durable-Press Cotton1

Abstract

This paper is concerned with a new research development for imparting durable press to cotton in which finishing resins are deposited inside the wet, swollen cotton fiber. This is accomplished by padding an N-methylol resin-mineral acid solution on the fabric, heating the fabric in a closed or semi-closed container for 15 min at 180° F, neutralizing in sodium carbonate solution, washing, and drying. The heating results in deposition of the resin in the fiber in such a manner that it is not removed by washing and so sustains the fibers in a somewhat swollen condition. Subsequent application of cross-linking catalyst followed by a high-temperature dry cure results in only modest loss of fabric strength compared with conventional pad-dry-cure processing. The key to arriving at good strength properties of the finished fabric and high levels of fabric performance, both in resistance to wrinkling and good crease retention, lies in the use of two resin components. One of these, called a polymer builder, acts to swell the fibers and keep them in a swollen state (melamines are particularly effective in this regard) ; the second component is primarily a cross-linking agent for cotton, contributing only moderately to the swelling of the fiber but enhancing wet wrinkle recovery and, once catalyzed and dried, imparting high dry wrinkle recovery to the fabric (dihydroxy dimethylolethylene urea and methylol carbamates are good examples of this class). A total dry resin add-on of 8% to 15% is required to achieve the enhancement of fabric properties. Resin combinations for use on colored goods and white fabrics have been developed. A twill fabric treated by this process in the laboratory gave breaking strength retention values of 60% (filling), dry wrinkle recovery values of 300 degrees, and wash- wear ratings of 5. This fabric, converted to simulated trouser cuffs, showed less wear in laundering than cuffs conventionally finished by pad-dry-cure at comparable perform ance levels. In 20 laundering and tumble-drying cycles, most of the wet-fixed samples were not worn, whereas the pad-dry-cure controls all failed, on the average, at the sixth cycle. Similar results have been obtained in other abrasion tests.