涂料生产和工艺(英文版).ppt

Backgrounds on production What is Paint? A fluid, paste of powder product, mend to be applied in thin layers on a surface, where, by film formation, a solid layer is formed, which serves aesthetic, protective or special purposes. What is Paint? Paint is a dispersion of solid (pigment) particles in a solution of polymers. Grade of dispersion Effects: Optical properties Flow Durability Hiding power Gloss (Can) stability Paint consists of: Binder Solvent Thinner Additives Pigments Fillers etc. Fluid / solid Fluid Fluid Fluid / solid Solid Solid ... Primary processes Wetting Separation of agglomerates Stabilization Wetting Removal of air, water and/or pollution from the surface of a particle. Wetting Surface tension ? liquid phase ? pigment phase Capillary forces Speed is mainly viscosity dependent (fluid phase) Breaking down agglomerates Agglomerates Aggregates Primary particles Breaking down agglomerates Shear stress (?) dependent Shear stress = shear rate x viscosity Shear rate, equipment dependent Viscosity, as high as possible for used equipment. Stabilization Prevent flocculation Entropical stabilization Steric hindrance Osmotic hindrance Electrical stabilization Production process De-agglomeration Actions Stabilization Oil absorption Amount of binder, sufficient to completely wet a known amount of pigment. Daniel : Wet point titration Gardner-Coleman : Oil absorption (OA) Daniels titration Wet point Just completely wetted (dry paste) Flow point Binder solution is added, until flow is achieved on a vertical spatula Flow point titration Production process The letdown Add while homogenizing Prevent temperature and viscosity differences Search the proper composition of dispersion and let down phase Finishing of Intolerance (solvent - binder) pH-shock Temperature-shock Flocculation Extraction - migration Solvability Pigment-shock Solvents Alternative production routes Possible production problems Productionequipment Which Equipment? Production e