Influences of surfactants on copper carbamate stain formation

Abstract

Latex clipping industrial process uses zinc dibutyldithiocarbamate (ZDBC) as an accelerator for increasing cure rate of natural rubber. During leaching step, ZDBC can react rapidly with copper ion and causes dark-brown stain on the product. In order to reduce the stain due to copper carbamate formation, several surfactants were introduced; sodium dodecyl benzene sulfonate, benzethonium chloride, coco aminopropylbetaines and nonyl phenoly ethoxylate. The effect of surfactant concentration, pH and temperature of aqueous solution on the effectiveness of binding were studied. The result showed that when the surfactant concentration was greater than critical micelle concentration(CMC), there was insignificant effect on the copper binding in aqueous phase as the concentration increased regardless of the type of surfactant. In contrast, the pH effect was more pronounced in the case of benzethonium chloride and sodium dodecyl benzene sulfonate. It was found that the suitable pH of aqueous solution that benzethonium chloride can prevent copper carbamate stain reaction was less than 6 and more than 6 in the case of sodium dodecyl benzene sulfonate. Nonyl phenoly ethoxylate and coco aminopropylbetaines can prevent copper carbamate stain for all pH. The suitable temperature that can prevent copper carbamate stain is 20℃.