To improve the water repellency of glass fiber by treating the glass fiber under a condition of equal to or above a specific temp. and equal to or above a specific humidity.
The glass fiber is treated at ≥60°C and ≥55% RH. The treating temp. is preferably 80-150°C and the humidity is suitably ≥80% RH. The treating time is different with the temp. and the humidity and is fixed by previous testing. The treating time lasts usually a whole day and night. The treatment is performed by leaving the glass fiber in a room kept at a high temp. and high humidity. After the treatment, the glass fiber is taken out of the room, washed and then used. A water repellent agent is unnecessary for the glass fiber because the water adsorption property is decreased without deteriorating the air permeability even if the glass fiber is heated and humidified. Any kinds of short fiber and long fiber are applicable as the glass fiber. The glass fiber is widely utilized, e.g. as a heat insulating material, a sound proof material, an electrical insulating material, FRP, a filter and the like by giving water repellency in addition to the air permeability, the heat insulating property, the heat resistance or the like.
YAZAWA KENICHIRO
ITO TOSHIFURU
