The invention relates to a humidity sensor of electric resistance type whose electric resistance changes in accordance with an ambient humidity, characterized by a protective film (6) of silicone resin provided on the surface of a humidity-sensitive material (3), and to a method for preparing the same. The protective film (6) of silicone resin is formed by applying a varnish of siloxanes to the humidity-sensitive material and subjecting the varnish to reaction. The varnish can be of one-pot type or two-pot type, and desirably the reaction of siloxanes is a cross-linking reaction. The formed protective film is not influenced by swelling or shrinking of the humidity-sensitive material, and is prevented from flowing off due to a temperature rise, or from deposition of dusts, etc.
本发明涉及一种电阻式湿度传感器,其电阻随环境湿度的变化而变化,其特征在于在湿度敏感材料(3)的表面上有一层
硅树脂保护膜(6),本发明还涉及一种制备方法。
硅树脂保护膜(6)是通过在湿度敏感材料上涂敷
硅氧烷清漆并使清漆发生反应而形成的。 清漆可以是一锅型的,也可以是二锅型的,
硅氧烷的反应最好是交联反应。 形成的保护膜不受湿度敏感材料膨胀或收缩的影响,并能防止因温度升高而流掉,或防止灰尘等沉积。