Abstract
Caking phenomenon of laundry granular detergent after a storage in the cartons under high temperature and high humidity was examined with regard to the change of humidity and temperature in the layers of detergent particles. It was disclosed that the humidity in the cartons varied with the atmospheric temperature and the caking of detergent had developed without moisture adsorption from the atmosphere. With rising temperature in the carton, the specific resistivity of conductance for the packed detergent decreased rapidly. So, it suggests that the number of ions in the water film increased due to the dissolved detergent components in the water film surrounding the surface of granular detergent. Meanwhile, SEM photographs showed the formation of solid bridges among the detergent particles.
It was concluded that the caking processes comprised the following steps: (1) dehydration of detergent components with temperature rising, (2) dissolution of the surface components of the granular detergent by water, and formation of the liquid bridges among the particles, (3) water uptake by crystalline materials with temperature reduction, and (4) transformation of liquid bridges to solid bridges.
