The whole purpose of a coating is to attach uniform layer of pigment to the base sheet. A Binder is used to adhere the pigment to the fibers. There are additional additives in the coating formula to help in processing or enhance final sheet properties.
Clay Interest : paper & ink gloss, rotogravure printability, stiffness. Draw back : lack of brightness, closed coating. GCC Interest : brightness, low viscosity, high solid, ink porosity. Draw back : gloss, low water retention, fiber coverage. TiO 2 Interest : opacity, brightness, whiteness Draw back : cost, latex demanding.
Plastic Pigment Interest : high gloss, brightness, low specific gravity. Draw back : price, more latex demand. PCC Interest : brightness, viscosity, low abrasivity. Draw back : cost, more latex demand. Silica Interest : brightness, high specific area, opacity. Draw back : cost, need higher cohesion binder.
Talc Interest : smoothness, non abrasive, best for gravure. Draw back : gloss. Satin White Interest : high gloss. Draw back : work ability.
Latex Hard Latex : Higher gloss, low binding power, mainly for top coat. Web Offset Latex : Blistering resistance, low binding power. Soft Latex : Lower cost, high binding power, best for pre coat. Starch Interest: Stiffness, price. Draw Back: Mottling, low binding power, rheology at high speed.
CMC Interest: Water retention, rheology, binding power. Draw Back: Handling. PVA Interest: Excellent binding power, gloss, brightness. Draw Back: Price, rheology at high level. Protein Interest: Water retention, binding power, bulkier coating layer. Draw Back: Handling, rheology at high level, microbiology control.