Coating process: drying method of coating film

Core tip: in the coating construction, the water-based coating occupies a certain proportion In order to make the drying and curing of coating film (layer) faster, three methods of natural drying, drying and radiation curing are generally used 1 Natural drying Under natural conditions, the method of evaporation, oxidation and polymerization of solvent by air convection to react with curing agent to form film becomes natural drying It is suitable for volatile coating, air drying coating, curing agent curing coating and other self drying coating Natural drying is greatly affected by environmental conditions When the ambient humidity is high, the solvent volatilization is inhibited, the drying is slow, and the formation of Paint knowledge how about Akzo Nobel Powder Coating Recommended introduction: powder coating is a kind of coating with different form from general coating, which is in powder form It is a new type of coating, because of its own advantages and more and more known by 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greatly affected by environmental conditions When the environmental humidity is high, the solvent volatilization is inhibited, the drying is slow, and the defects such as white coating are formed Therefore, the operating environment should be low rather than high When the temperature is high, the solvent volatilizes quickly, the curing reaction is fast and the drying is fast At this time, it is advantageous to reduce the dust adhesion, but it may be the poor leveling Therefore, it is better to set air filtration system in the natural drying area to ensure the film quality 2 Drying (1) according to the low drying temperature, it can be divided into low temperature drying, medium temperature drying and high temperature drying ① Dry at low temperature The curing temperature lower than 100 ℃ is called low-temperature drying, which is mainly to dry the self-drying coating to dry the coating on the surface of the material with poor heat resistance The drying temperature is usually 60 ℃ ~ 80 ℃, which can greatly shorten the curing time of the self-drying coating, so as to meet the industrial flow line operation mode ② Dry at medium temperature The medium temperature drying temperature is 100 ℃ ~ 150 ℃, which is mainly used for condensation polymerization and film-forming coatings When the temperature is too high, the film turns yellow and brittleness increases The best curing temperature of this kind of coating is generally between 120 ℃ and 140 ℃ ③ Dry at high temperature Curing temperature above 150 ℃ is high temperature curing, such as powder coating, electrophoretic coating, etc As the primer only requires protection, there is no requirement for the color of the film, so it is all dried at high temperature In order to prevent pinhole, orange peel and other defects in the drying process of the film, the wet film should be dried for 3-8 minutes in advance according to the thickness of the film before drying (2) According to the way of heating and curing, drying can be divided into three ways: hot air convection and far infrared radiation ① Hot air convection drying In this method, the combustion gas produced by the heat source or the heated high-temperature air is introduced into the drying chamber by the fan, and circulates in the drying chamber, so that the coating is convective and heated The application of high-quality coating is not affected by the shape and structure complexity of the workpiece, and the heating temperature range is wide, so this method is widely used ② Far infrared radiation drying Far infrared radiation drying The far-infrared radiation electric heating device includes far-infrared heating plate, far-infrared electric heating belt, far-infrared heating lamp, etc it is easy to install, debug and maintain It is suitable for workpieces with simple shape ③ Hot air convection plus radiation drying Hot air convection heating and far-infrared radiation heating have their own characteristics In order to give full play to their respective advantages, they can be combined in the design of drying room Generally, radiation is first followed by convection, and the advantages of rapid radiation heating are used to heat up the workpiece and volatilize the solvent Then, hot air convection is used for heat preservation to ensure the drying quality 3 Radiation curing radiation curing is a new type of curing method which uses electron beam and ultraviolet radiation to cure coating This method has the advantages of short curing time (seconds, tens of seconds to minutes), room temperature curing and relatively low equipment price But the radiation has blind spot, which is only suitable for the workpiece with simple shape, and the radiation distance is strictly controlled Home of coatings is specialized in coatings, diatom mud, paint coating, coating technology, fire retardant coating news and coating, diatom mud, paint coating, coating technology, fire retardant coating decoration knowledge and decoration renderings,