PURPOSE: To easily and simply produce a moisture exchanging material at a low cost by impregnating a sheet or the like with a silica sol containing such silica fine particles that have strong coupling force and silanol groups on the particle surface, drying to change the sol into a gel to be fixed, and specifying the diameter and amt. of the silica particles.
CONSTITUTION: The silica sol used contains such silica particles by ≤30 % that have about ≤120 particle diameter, stable silanol groups on the particle surface, and extremely strong coupling force between particles and with other material. This silica sol is applied on a sheet or a laminated body having lots of small pares by impregnating or coating, then the sol is dried to be changed into a gel so that silica fine particles are fixed to the space in the fibers and on the surfaces of fibers of the laminated sheet. Thus, a moisture absorbing sheet or a moisture exchanging honeycomb element of high performance can be obtd. without using a binder but by impregnation and fixing of a special silica gel. Moreover, an inorg. material such as zeolite and calcium salt, and an org. moisture absorbing agent such as a hydrophilic org. polymer electrolyte may be added to the silica sol.
SHIRAHAMA MASUAKI
IZUMI HIROAKI
KUMA TOSHIMI