EXPERIMENTAL-STUDY OF INFRARED OR CONVECT IVE DRYING OF CAR MODEL PAINTINGS COATED ONTO A PLASTIC OR IRON SUPPORT

This work aims to study car paint drying and to better understand the complex physico-chemical transformations which occur during this proce ss. Two different model painting systems were studied: a water-based e poxy-amine paint applied on steel support; a solvent based polyurethan e paint applied either on sheet molding compound support (SMC) or on s teel support. In these two cases, drying is an important step and dete rmines significantly the final paint film quality. Indeed, water is a solvent which is difficult to evaporate and SMC supports are plastic a nd porous materials which can induce the apparition of bubbles on the dry paint film. After the description of the two paint systems and of the near infrared and convective laboratory drier, we will sum up the different results obtained for different experimental conditions, in t erms of drying kinetics and dry paint film quality. These experiments show the influence of the physical process parameters (air temperature and velocity), of the infrared flux density, of the paint system (fil m thickness, chemical properties...) and of the supports properties.