Evaluation of surface coating properties with rice husk black liquor on handsheet

Abstract

The applicability of rice husk black liquor as coating material was evaluated in this study. Since the black liquor originated from the alkaline digestion of rice husk contained not only organic components such as lignin but also silica, the properties of the coated layer of rice husk black liquor before and after the silica extraction were evaluated. Although the contact angle of handsheet samples was not changed before and after the black liquor coating, the water absorption time was significantly increased before and after the black liquor coating. The higher improvement in the water absorption time was found in case of the black liquor coating after silica extraction. The addition of functional additives such as PVAm and AKD to the black liquor resulted in the different coating properties. Especially, the addition of AKD greatly increased the contact angle and the water absorption time of the black liquor coated layer. The black liquor after silica extraction, resulted in the greater increase of the contact angle than those of the black liquor before silica.