Chemical resistance

Generally GE films make up with most chemical materials which are met in the typical living- and office environment, when there are normal temperatures and a low stress level. Films under tension – like cold-formed, bended or embossed applications – tend to tension cracks in contact with certain substances.

Increased temperatures can pander or accelerate this kind of defects.

Some chemicals, like acetone, toluol and halogenised hydrocarbons act soluble to GE films. Because of that dichloromethane is used as a solvent adhesive for GE films.

Whenever influences of potential aggressive or incompatible materials are possible, only covered films should be used.

Chart 18 states relevant information about the general chemical compatibility of GE films. Generally the concrete resistance against specific substances during processing and/or using should be pre-tested under practical conditions in every individual case.

In case of doubt please do not hesitate in contacting our application engineering.

Behaviour after immersion in water

During laboratory tests no notable changes in tensile- and stretch behaviour at the films have been determined after the immersion in water for several weeks. But the immersion in boiling water has a significant and rapid influence to the elongation of Lexan® films. The values of the tensile strength up to the liquid and elastic limit change insignificantly. Long-term immersion in seawater at normal temperatures also has insignificantly influences to Lexan® films. Valox® and Ultem® films are even more resistant under the same conditions.

Gas- and vapour permeability

The specific gas- and vapour permeability of polymer films can play a major role in packaging applications. The particular permeability depends on the diffusion rate or the solubility of the gas in the barriers and their wall thicknesses.
Chart 20 states typical values for Lexan® and Ultem® films with a wall thickness of 0.025mm at 23°C.

Chart 20: Gas- and vapour permeability in controlled atmosphere

Gas- and vapour permeability Lexan Ultem

Weather resistance

Permanent direct solar radiation on unprotected GE films leads to a (removable) chalky covering and yellow colour. The time till a visible change depends on the intensity of the radiation as well as on the film thickness and can vary between months and years. Because of this unprotected GE films should not be used for outdoor applications at which good appearance and mechanical properties are essential. Generally GE films are well-resistant against temporary outdoor weathering or constant lightning with fluorescent lamps.

UV stability

The Lexan® film HP92W has a GE developed special covering for protecting against yellowness and turbidity so that graphics behind the films remain well-readable. Lexan® HP92W is a common choice for special ambitious outdoor applications because of its yellow value of <0.25 after 1,000 hours of accelerated UV lightning.

Diagram 8: accelerated UV lightning (ASTM G53 – UV313 BB)