abstract
In paper manufacture, many colloidal particles are added to improve with a pulp suspension on paper. Under the right conditions, these various colloids flocculate and interact. Examples of colloids papermaking fillers and internal sizing agents, opacity and hydrophobicity to improve the paper, respectively. Internal sizing agents (added in the wet end of a paper machine) together emulsion droplets stabilized by cationic starch and other stabilizers solidified. We studied the interaction of a common internal sizing agent, alkyl ketene dimer (AKD), with calcium carbonate fillers. AKD is a liquid over 50-65 ° C (depending on the alkyl chain length) which can be emulsified above its melting point in the presence of a stabilizer, which include, after cooling in the solid colloidal particles to 1 micron in size. We have investigated the interaction of AKD particles stabilized by cationic starch, with precipitated calcium carbonate (PCC) particles. Pure PCC particles are positively charged, but they are in the process water is negative. Flocculation experiments with positively charged and negatively charged AKD were PCC with a photometric dispersion analyzer. Instead of the expected heteroflocculation between AKD and PCC, we observed homoflocculation PCC and AKD homoflocculation, results confirmed by SEM. The results from the transfer of starch from AKD to PCC explains what to PCC flocculation by starch and AKD destabilization due to depletion of the stabilizer.
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