Release liner

comparing commercial release liners

What is a release liner?

There is a wide variety of products and intermediate, which have an adhesive layer or a reactive resin for a later application: adhesive films, labels, prepregs etc. The sticky surface of these materials is covered by a protective film, which is remove just before application. This film is called release liner. It is made of paper or a polymer film coated with an antiadhesive silicone resin.

Peel force of release liners
© Fraunhofer IAP
Peel test data obtained by two different test procedures (FINAT 10 and EN 1939) in comparison with the data sheet values of various release liners.

Comparing release liners from different suppliers

A wide range of release liners with different characteristics is commercially available for use in a large number of applications. Comparing the properties of the products from various suppliers is often rather difficult due to different testing methods.

Therefore, we compared release liners obtained from various suppliers. Typical test procedures for their anti-adhesive properties such as FINAT10 and EN1939 were applied for all the samples in the same way. The results of these two tests were compared with the data sheet values obtained from the supplier. Some of these data are shown in the figure for illustration.


ATR-IR spectra of silicone coatings
© Fraunhofer IAP
ATR-IR spectra of two kinds of silicone coatings and the structural information, which can be retrieved.

Analysis of release liner coatings

The testing of the mechanical properties was complemented by the analysis of the chemical properties. The chemical composition of the surfaces and their homogeneity was analysed by X-ray photoelectron spectroscopy XPS (LINK) and infrared spectroscopy IR. The first technique provides the elemental composition and information about the molecular structures of the surface. In this way the concentrations of crosslinks, linkages and linear siloxane chains can be estimated, for example.

IR spectroscopy was applied with the ATR (attenuated total reflectance) technique and it provides chemical information about the silicone coating and possibly a part of the underlying paper. In the figure the kind of information in the spectra is illustrated.