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Iowa State University researchers have developed a thin transparent ink coating with UV-blocking properties and high transparency.

Ultra-violet (UV) light is a high-energy light that can cause damage to organic matter, including the degradation of foods and beverages. As such, UV-blocking coatings are typically applied to the outside of transparent plastic food and beverage packaging in order to prevent degradation and extend the shelf life. ZnO nanoparticles have been used in polymeric matrices for UV protection due to their scattering properties. However, due to aggregation of the nanoparticles when the coatings dry, the UV-blocking capabilities significantly decrease when using thin layers of coating, since aggregations are unavoidable. Studies have shown that the polymeric binder has a strong influence on how the aggregation occurs, but there is insufficient information on how different binder polymers change the UV-blocking and transparency of the composites. Iowa State University researchers have developed a transparent ink coating that has thicknesses of 0.2 to 2 microns while maintaining efficient UV-blocking capabilities. This ink utilizes hydroxyethyl cellulose as a bio-based binder that provides fractal aggregation of the ZnO nanoparticles, which keeps the particles disperse even in thin layers. Additionally, ZnO is generally recognized as safe (GRAS) by the FDA and has antimicrobial properties as well, which makes it ideal for food and beverage packaging.

• Efficient (>90% UV-blocking and ~70% transparency)

• Ultrathin (thicknesses of 0.2-2 micrometers)

• Bio-based (hydroxyethyl cellulose binder)

• Waterborne (no oil-based emulsions required)

Food and beverage packaging.