Experimental Investigate Of Coated Film By Infrared Drying

Drying coated film is a complicated process that refers to the chemical engineering, chemical thermodynamics, macromolecule chemistry and physics. The choice of drying method is not unique as the different coated films. Because of low drying efficiency of the traditional hot air convection, the process needs much time, the layer surface has asymmetric superficial temperature, it affects the product quantity. So the choice of the drying manner and research of the drying process is very important. The infrared technique has much advantage such as the energy saving, well heat effective, easy control etc. For some thin material as paint layers, the infrared ray can radiate to the being heated material as electromagnetic wave modality, penetrate in the film and finish the mass and heat transfer, so the influence to the effect layer induced by not enough penetrating depth will not appear, and the application will highly spread.This works selected alkyd varnish, which involves in the oxidation thermohardening polymerization paint and black ester-gum ready-mixed paint, which involves in the crude resinousness thermoplastic paint as experimental material. But the two kinds of materials both need long drying time (the alkyd varnish: seemingness drying out 6hours, drying completely 12 hours; the black ester-gum ready-mixed paint: seemingness drying out 6hours, drying completely 24 hours). Intended for searching for the drying behavior, we ground plan to use infrared technique to drying the two films. We use a electronics weighing scale to measure the changes of the quantity of a coated film on a metal plank in the drying process at different operation condition and analyzed each factor to the influence of the infrared drying process. Then we survey the superficial temperature of coat and analysis all the main factors to the influence of the process. So we gained the best condition for the two paints and build a drying model for the whole process, which could provide the experimental base for the infrared application in industry. The experimental result indicate: with the certain distance between the paint layer and the heat plank, the drying process will be influenced by the radiant temperature, the higher radiant temperature is, the quicker drying process and higher superficial temperature are; with the certain radiant temperature, the dry process will be influenced by the distance, the nearer distance is, the quicker drying process and higher superficial temperature are; The high temperature and low distance radiates are beneficial to the paint layer drying. Because the infrared drying process of paint is a match absorption process, it is best to dry material at the match temperature range. But we should consider the species of the coating and the coat support in case they will be destructed by high temperature. The best experimental condition for infrared drying paint is: for the black ester-gum ready-mixed paint is 232℃ of radiant temperature and 11.4cm distance between paint layer and heat plank ; for the alkyd varnish is 151℃ of the radiant temperature and 11.4cm distance between paint layer and heat plank.