R-AND-D NEEDS IN THE DRYING OF COATINGS

The key technologies involved in the drying of coatings are first revi ewed and then the factors that influence the drying process are identi fied, leading to a discussion of future R&D needs. The drying mechanis ms in the constant and falling rate periods are discussed, Present and anticipated restrictions on the use of solvents will result in aqueou s systems replacing some solvent systems, and in wider use of high sol ids coatings and 100% solids coatings. Cross-linking reactions to soli dify monomers and low-molecular polymers now become important. Dryers will become chemical reactors. Further development of models of drying , of diffusion, of surface solvent levels, and of solvent vapor pressu res will be needed, along with those of dryer defects and drying stres ses. To accurately simulate a wide range of coating systems more physi cal property data is needed. Non-convection heating and environmental concerns complete the discussion.