How Mixed Catalysts Differ'

Abstract

Catalysts from combinations of Lewis-acid salts, or from a Lewis-acid salt and a Bronsted acid, have been used in crosslink finishing of cotton textiles for many years. Whereas the effect on formaldehyde release was not a major factor in the early use of these catalysts, this effect presently influences the selection of the integral components of the mixture as well as the component ratio within the mixture. Interactions of physical property variables with formaldehyde release are given for mixtures of magnesium chloride and zinc nitrate with organic acids and with other salts, and for aluminum sulfate and selected alum salts. When proton donors are added to catalysts possessing considerable Bronsted activity, antagonism can occur. When proton donors are added in correct proportion to catalysts exhibiting little Bronsted activity, improvements can be realized in appearance-related properties while low formalde hyde release is maintained. Both pH of the crosslinking bath and of the fabric during cure influence property modification.