Use of stretched, at least two-layer foil as window foil for letter envelopes

摘要

In the present invention there is disclosed the use of a stretched, at least two-layer foil consisting predominantly of polypropylene and having at least one surface with reduced reflection that was subjected plasma pretreatment during a low-pressure process with oxygen as a processing gas and that exhibits excellent adhesive property for letter envelope windows. The foil surface luster is less than 60 luster units and its cloudiness is less than 40 percent.