UV Coating

UV Coating Also known as radiation-cured coating, ultraviolet (UV) coating is a surface treatment method that is cured by ultraviolet radiation or protects the material below from the harmful effects of UV. UV radiation is frequently used for various purposes in industrial processes as well as in medical and dental environments, including phototherapy, bacterial elimination, fluorescence, curing inks and resins, and tanning. Compared to these applications, UV coating as a surface treatment method is a recent development. However, due to the distinct advantages of UV coating, which will be detailed below, its use has become widespread, particularly in printing.

What is Ultraviolet (UV)?

The term ultraviolet derives from the Latin words ultra (meaning "beyond") and violet (meaning "purple") and refers to a form of electromagnetic radiation that has a longer wavelength than X-rays but shorter than the violet end of the visible spectrum. The sun emits electromagnetic radiation transmitted in waves and particles of various wavelengths and frequencies. Some artificial sources, such as arc lamps and tanning beds, also produce ultraviolet (UV) radiation. The electromagnetic (EM) spectrum refers to this broad range of wavelengths. In this spectrum, ultraviolet (UV) light lies between visible light and X-rays. Exposure to UV rays has both beneficial and harmful effects on human health. Vitamin D production, improved mood, and higher energy are among the positive effects of UV exposure. Moderate exposure to UV radiation is a good way to obtain vitamin D. This vitamin helps regulate blood pressure, immunity, insulin secretion, calcium metabolism, and cell division. However, excessive exposure to high UV radiation, particularly UVB (medium-wave UV), can lead to certain types of skin cancer as well as premature aging and eye damage.

UV Coating Application Areas

UV coating consists of a compound applied to wet paper and then instantly cured with ultraviolet light. Paper used for UV coating is coated with various chemicals, including polyethylene, calcium carbonate, and kaolin. These materials are refined and combined with viscosifiers that help them adhere to the paper. After printing, coating is applied using a UV coating machine. Depending on the application, UV coatings can vary in thickness and reflectance, but high-gloss or soft matte UV coatings are often used for high-quality print applications. UV coating can be applied to the entire product, both front and back, or to only one side. It can be used as spot coating to highlight only specific areas or applied to the entire printed piece (a process known as flood coating). Spot UV coating is a highly effective method for adding dimension to the printed area and deepening the area's color. UV curing is used in situations where inks, adhesives, and coatings need to be converted or cured. UV-cured adhesive has rapidly replaced two-component adhesives, eliminating concerns about solvent removal, mixing ratios, and material shelf life. UV curing systems are used in flexographic, offset, pad, and screen printing processes to polymerize images on screen-printed products, including t-shirts, 3D and cylindrical parts. Beyond printing, UV coating is also frequently used in sectors where glass and plastic are manufactured and used. Glass and plastic can be coated to reduce the amount of ultraviolet radiation exposure. This coating is also commonly used in automotive window and eyeglass applications. Photography filters eliminate ultraviolet to prevent the film or sensor from being exposed to invisible light. Gloss reduction, abrasion and scratch resistance, anti-fogging, microbial and chemical resistance, are among the properties that UV-curable coatings can provide to polymeric surfaces. Many personal electronic devices, including keyboards and computer screens, contain some form of UV-cured coating. Coatings are typically applied to plastic substrates using various methods, including spraying, dipping, rolling, and flow. UV technology is also used in the finishing, varnishing, and lamination of furniture and woodwork.

Advantages of UV Coating

UV coating provides protection against staining, rubbing, abrasion, and scratching. Thus, materials maintain a better appearance and last longer, which helps manufacturers maximize profits. This is particularly important when direct mail such as postcards mixed with other cargo needs protection and when posters, brochures, or similar materials are placed in crowded public areas where people are likely to handle them. UV coatings and varnishes increase product quality and line speed thanks to the rapid formation rate of the curing process, create more floor space due to shorter finishing lines, and reduce fire risk. By reducing the wetting time of an ink or coating, the curing or drying stage in the process can be accelerated, which can reduce defects and errors. Additionally, less space is required to store items that must wait until the drying process is complete, which is another advantage of shortening production time. Besides these, they provide superior hardness and solvent resistance. UV coatings are solvent-free and emit no volatile organic compounds when cured, so they can be said to be environmentally friendly and their application can contribute to environmental sustainability. Sources • https://www.psprint.com/resources/what-is-uv-coating/ • https://www.formaxprinting.com/blog/2010/09/printing-lingo-what-is-uv-coating • https://www.autoprint.net/blog/what-is-uv-coating-and-benefits-of-uv-coating • https://www.digikey.com/en/articles/ultraviolet-radiation-attributes-and-benefits • https://www.alpha-cure.com/applications/the-applications-of-uv-coating-finishing • Images by: https://pixabay.com/ Translation and Compilation: Murat Soygür