ALKALI-METAL SALTS OF HYDROXY-ACIDS AS CATALYSTS IN DURABLE PRESS FINISHING WITH BUTANETETRACARBOXYLIC ACID

Alkali metal salts of hydroxy acids have been investigated as catalysts for esterification cross-linking of cotton with 1,2,3,4-butanetetracarboxylic acid to produce cotton fabrics with smooth drying properties. Of the sodium salts of several acids studied, the sodium citrates produce fabrics with the best appearance properties. The sodium citrates serve both as donors of citric acid for cross-linking and of sodium ions for catalysis of the esterification of cotton cellulose by the two polycarboxylic adds. Although the use of citric acid as an extender for the more expensive butanetracarboxylic acid has been reported in non-formaldehyde finishing of cotton fabrics for smooth drying properties, the catalyst used was sodium hypophosphite. Comparisons are made between fabrics finished with the phosphorus-containing system and the butanetetracarboxylic acid/sodium citrate systems. Textile properties, fabric whiteness, effect of pad bath pH. and extent of esterification are discussed.