Formic Acid Colloid of Methylolmelamine as a Weather and Rot Resistant Finish for Cotton

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Abstract
A study of application techniques of methylolmelamine resins to cotton has revealed a practical method for producing cotton fabric with outstanding rot resistance and im proved weather resistance. This method is based upon the use of an acid colloid of methylolmelamine. The method of application of the colloid is the same as that con ventionally used for resin finishing; that is, pad, dry, and cure. The main difference is the use of formic acid to produce a colloid. Photomicrographs show that methylol melamine colloids (1-4 hr. old) are deposited in the outer portion of the cell wall of the fiber, whereas the conventional process deposits resin about halfway through the cell wall and the wet-cure Arigal 3 process deposits uniformly throughout the cell wall. Colloids five hours or older are deposited in much the same position as obtained by the conventional process. Only the fresh (1-4 hr.) colloids give outstanding rot resistance. Cotton fabric finished with the acid colloids compares favorably with partially acetylated, fully acetylated, cyanoethylated, and Arigal fabrics which are known to have excellent resistance to rot. Experimental evidence indicates that the mechanism through which rot resistance is acquired by the acid colloid is "controlled penetration" rather than a continuous surface film. Several acids were evaluated for colloid production; formic was the only acid which produced suitable colloids. A number of metal halides have been used as catalysts with the colloids. Small amounts of the metals become tenaciously bound in the fabric, and some of the metals alter outdoor weathering and other properties of the fabric.