Polymer coating by spraying

Polymer coatings are one of the main protection methods against corrosion and are also widely used to decorate articles, equipment, and structures for industrial and domestic use. These coatings are films made of high-molecular-weight compounds formed on a solid surface. 

The preparation of polymer materials for coating requires the choice of a suitable composition, depending on the expected use, followed by composition preparation and processing. The choice of polymer depends on the physical, chemical, and mechanical properties of the materials themselves and on the intended purpose of the coating being applied. 

To achieve the main process requirements (ability to be applied by different methods by hand, spray, electropaint), and to provide the necessary decorative, physical, and mechanical properties, organic solvents are used in concentrations up to of about 50% to modify the viscosity and other rheological characteristics of the some polymer compositions. During the application and formation of the coating, the solvents evaporate into the atmosphere as pollutants. This serious disadvantage of formulations based on the use of solvents as intermediate carriers has provided the incentive to develop polymer compositions and application technologies which yield the required rheological characteristics either without solvents, or at least with low concentrations of them. 

When preparing coatings from reactive compositions, a thin layer of material is first applied to the item. The coating material adheres to the item by gravitational, magnetic, centrifugal or adhesion forces. The prepared article with its reactive layer is then placed in a chamber where the final polymeric coating is formed. 

Successful solution of these technical problems depends on the initial viscosity of the material in the sprayer, the surface tension of the material, changes in the rheokinetic properties during the process, sprayer design, and jet configuration. 

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