Ashish S.,Thapar Center for Industrial Research 4 Development |
Shaveta K.,Thapar Center for Industrial Research 4 Development |
Chauhan Vipul S.,Thapar Center for Industrial Research 4 Development |
Bhardwaj Nishi K.,Thapar Center for Industrial Research 4 Development |
Varadhan R.,Thapar Center for Industrial Research 4 Development
IPPTA: Quarterly Journal of Indian Pulp and Paper Technical Association | Year: 2013
Due to the shortage of native fiber and environmental regulations, the demand of recycled fibers is increasing with time. Generally, the recycled fibers comprising alkaline sizing chemicals; alkyl ketene dimer (AKD) or alkenyl succinic anhydride (ASA) are imported for use in India. The dose of sizing chemicals depends upon various parameters such as type of raw material and filler. The present study deals with the use of AKD and ASA emulsions at different dose levels in bleached recycled fibers with three commercially available fillers; talc, ground calcium carbonate (GCC) and precipitated calcium carbonate (PCC) at 15% ash level. The Cobb60 and contact angle of the sheets were compared and the relationship between Cobb, vs. contact angle was developed and compared for both AKD and ASA with all fillers. Due to different particle size, shape and charge characteristics, the fillers affected the hydrophobicity of paper differently. It was observed that without filler and with talc filler, the Cobb, values were lower in AKD sizing whereas with GCC and PCC fillers those were lower in ASA sizing. The contact angles were higher in ASA sizing as compared with AKD sizing. The Cobb60 vs. contact angle relationship was also better in ASA sizing than AKD sizing which showed that the former is a better sizing chemical for such grade of bleached recycled fibers. The contact angle of 105°, which is considered fairly good for writing and printing paper grades, could be achieved at 25-30 and 38-48 g/m2 Cobb, values in AKD and ASA sizing, respectively with all three fillers. These results showed that there is no worth adding higher dose of sizing chemicals in pulp based on only Cobb60 values, rather it would be advisable to consider contact angle along with Cobb60 for the same.