POLYETHYLENE FOR LOW-TEMPERATURE EXTRUSION-COATING APPLICATIONS

A new polyethylene has been developed for use in low-temperature (400-480-degrees-F) extrusion-coating applications. Originally designed to function as a biodegradable coating on a paper substrate, it is loaded with starch nutrients. When the coated paper enters the waste stream, microorganisms feed on these nutrients and break down the synthetic coating. Starch nutrients are destroyed at temperatures above 480-degrees-F, so a biodegradable polyethylene must extrude satisfactorily at temperatures below this threshold. By establishing the correct melt index and modifying polyethylene chemistry, the developers were able to obtain a low-temperature polyethylene with satisfactory extrusion and adhesion properties. The new low-extrusion-temperature polyethylene should be useful in applications involving direct extrusion coating of thermally-sensitive components such as ethylene-vinyl alcohol copolymer (EVOH).