A surface study of cellulose fibres impregnated with alkyl ketene dimers via subcritical and supercritical carbon dioxide

Impregnation of Alkyl Ketene Dimers (AKD) into filter paper substrates was investigated using subcritical and supercritical carbon dioxide (scCO2) over a range of operating conditions, in order to assess the possibility of this novel technique as an alternative method of sizing for the paper industry. The key findings were that AKD was uniformly distributed within the paper matrix at five times greater than the concentration observed via conventional means, and that sizing development (i.e., a contact angle >90° for water on the substrate) occurred at a similar rate to that of other more conventional techniques. It is believed that lower quantities of AKD could be used with this technique, reducing the overall quantity of AKD required for a particular level of sizing.