Barrier properties OF inorganic-organic polymers: Influence of starting compounds, curing conditions and storage-scaling-up to industrial application

With a new kind of barrier coating material, namely inorganic-organic polym ers, it is possible to obtain high-barrier properties for oxygen, water vap or, and flavor permeation. These hybrid polymers can be synthesized by the sol-gel technique. Network forming reactions and degrees of condensation in the coating sols as well as in the cured coating materials were characteri zed using Si-29, C-13-NMR and FT-Raman spectroscopy. The oxygen barrier pro perties of the hybrid polymers were found to be strongly influenced by the inorganic and also by the organic network density. In order to scale-up the excellent laboratory results to pilot plant and production dimensions addi tional efforts were necessary. For optimization of the barrier coating comp ositions the influence of the starting compounds on the resulting barrier p roperties had to be investigated. A constant quality of the coating sols du ring the industrial processing had to be guaranteed so as to obtain reprodu cible barrier properties. The influence of storage conditions on chemical r eactions in the coating sols, indicated by changes of viscosity, was invest igated. Since the curing times of the laboratory system were not transferab le to the high speed of the production roll coating process more effective curing methods had to be found. The influence of the storage time of the cu red coating materials on the oxygen barrier properties was investigated. Ev en by storing at ambient temperature further improvement of the oxygen barr ier properties was obtained. Only by optimizing all of the above mentioned parameters can the excellent barrier properties result in marketable produc ts.