Preparation And Application Of AKD Emulsions Stabilzied By Modified Laponite Particles

Alkyl ketene dimer (AKD) as a reactive sizing agent, which is prepared by emulsifiers of starch, surfactants and polymers into oil-in-water AKD emulsions, has been widely used in alkaline papermaking. Pickering emulsions mechanism enables the inorganic nanoparticles capable of forming oil-in-water emulsion. Under the mechanism, AKD emulsions are prepared by modified laponite with dodecyl trimethyl ammonium chloride (DTAC) and L-lysine (Lys), respectively. Sodium alginate (SA) and hydrochloric acid are studied for the stability and sizing performance of emulsions in order to achieve efficient use of AKD emulsions. ASA emulsions were prepared by nano-alumina and laponite particles or nano-silica and laponite particles. In the experiment, when the dosage of sodium alginate based on AKD as 0.054%, AKD emulsions have a good sizing and stability performance, which are prepared by laponite particles modified DTAC.Laponite particles modified by dodecyl trimethyl ammonium chloride have changed the uniform dispersion of the laponite suspensions, made the distance of spacing of 001 larger, an infrared absorption spectrum appearing a methylene (-CH2-) absorption peak, so DTAC molecules have successfully modified laponite particles. Under the mass ratio of AKD and water phase was 1:7 and 1:9 two conditions, with the increasing amount of DTAC based on laponite, the average particle size of AKD emulsion droplets decreased, and the sizing performance of AKD emulsion gradually improved. DTAC based on laponite in an amount of 1.0%, we have achieved optimal sizing performance, and the papers sizing degree at a relatively bone-dry pulp added in an amount of 0.05% were 305 seconds and 350 seconds, repectively. Meanwhile, the adding of sodium alginate as the protective colloidal agent improves the stability of AKD emulsion in the appropriate dosage, helping to improving the sizing efficiency of AKD emulsions. When the dosage of sodium alginate based on AKD exceeded 0.054%, the sizing degree of AKD emulsions began to decrease, which is not conducive to play effectively sizing roles of AKD emulsions.Laponite particles modified by L-lysine have made the distance of spacing of 001 larger, an infrared absorption spectrum appearing a carboxyl (-COOH) functional groups absorption peak, so L-lysine molecules have successfully modified laponite particles. Under the mass ratio of AKD and water phase was 1:7 and 1:9 two conditions, the dosage of L-lysine based on laponite was 0.6%, and we got the minimum value of AKD emulsons average particle diameter, which was 3.96μm and 3.56μm. The papers sizing degree at a relatively bone-dry pulp added in an amount of 0.05% were 133 seconds and 263 seconds, repectively. The adding of hydrochloric acid (HCl) affected the sizing roles of AKD emulsions. We got the maximum sizing performance when the mass fraction of hydrochloric acid reached 4.3%.ASA stability emulsions were prepared via two particles of nano alumina particles and laponite under the ratio of ASA and and aqueous phase volume ratio of 1:2.4. The adding of nano alumina could improve the sizing performance. The sizing degree of ASA emulsions prepared by the pristine laponite was 30seconds. When the dosage of nano alumina reached to 0.2%, we got the the minimum sizing value of ASA emulsons, which was 37seconds. The most sizing efficient emulsions of ASA under different mass fractions of ASA was 22%. The stability and sizing roles of ASA emulsions prepared by nano-silica and laponite particles were not ideal.