JAPAN EXLAN (a subsidiary company of TOYOBO) has developed acrylate fiber which generates 3 times more heat than rayon by moisture absorption. Newly developed acrylate fiber “eks hyper” contains more chemical groups which bond with water molecules. “eks hyper” absorbs more moisture generated from a human body, and converts the absorption energy to heat energy after decomposing smell. The water absorption of rayon for moisture-absorbing/heat-generating underwear is about 11 % by weight, while newly developed acrylate fiber “eks hyper” absorbs about 35 % where the temperature increases up to 30 for 10 minutes in the atmosphere of 20℃/90 %.

JCFA News Letter (No.7) February, 2014/Japan Chemical Fibers Association