Application of urea-intercalated kaolinite for paper coating

Kaolinite was successfully intercalated by urea in a static and sealed condition at 95 °C for 3.5 h. The urea-intercalated kaolinite was applied for paper coating. The high shear rate rheologies were used to study the flowing properties of them and to stimulate the realistic coating paper at ultra high shear rate. The structure, morphology, chemical constitution, particle size distribution and rheological properties of the samples were measured by XRD, SEM, ICP-MS, particle size analyzer and by rheometer, respectively. The particle size of urea-intercalated kaolinite became finer with the growth of intercalation ratio. The rheological properties of slurries were changed from pseudo plastic behavior to complex flow and the solid content of slurries at the viscosity of 500 mPa·s increased from 70.84 % to 74.09 % due to intercalation of urea. The urea-intercalated kaolinite improved slightly the properties of papers, while the better rheology could enhance the process of coating paper with ultra high speed.