Orientation of talc particles in dispersion coatings

A novel approach was used for the determination of talc particle orientatio n. X-ray diffraction technique with the peak ratio method was utilized to o btain information on the ratio between misaligned and aligned crystals alig ned with the surface. Cross-sections of coatings were studied by scanning e lectron microscopy. Particle orientation was determined by image analysis. A laser profilometer and a glossmeter were used to obtain additional inform ation about surface properties. The effects of coating thickness, calenderi ng, base sheet roughness, and pigment size distribution on orientation were studied. Both calendering and base sheet roughness affected the orientatio n of talc particles significantly. In addition, the results indicated that good packing could be achieved with a proper pigment size.