Surface pretreatment
The surface properties of materials are often crucial for their possible uses and areas of application. For printing, gluing and coating, a sufficiently high surface energy is the basis for good wetting and a subsequent good adhesion. For materials with a low surface energy, a surface pretreatment such as surface silicatization is compulsory. With this surface silicatization, an organosilicon compound (silane) is fed into a flame - known as flame pyrolysis - to create a thin, but very dense, moisture-stable and firmly adhering layer of silicate with high surface energy. Due to the short exposure time to the flame, the surface temperature of the workpiece remains low. This makes this process even suitable for very thin-walled plastics or heat-sensitive materials. The silicate layer itself adheres to basically all surfaces and forms a nanoporous surface structure which enables better mechanical anchoring of the subsequently applied polymers and also ensures optimal chemical bonding of organic components to the silicate layer.
The best results can be achieved on degreased, cleaned and mechanically roughened surfaces.
Compared to other pretreatment methods the silicatization process offers the substantial advantage of generating a uniform and solid layer, which can be individually adapted depending on the surface properties and requirements with regard to the layer deposition rate.
A silicate layer applied in this way has an average layer thickness of 5 - 40 nm (depending on the intensity of the flame). This layer is reactive for up to 1 week, which means that bonds or coatings can be carried out up to a week after the flame pyrolysis treatment.
With applying an additional coating with the Polytec PT adhesion promoters of the HP A-series using the sol-gel process, even “idle times” of up to two months can be achieved. With this method, not only adhesive promotion layers, but also corrosion protection, barrier layers and sealing coats can be achieved on a wide variety of surfaces.
Polytec PT’s surface silicatization is particularly suitable for the pre-treatment of metals, glass, ceramics, polar plastics (PVC, PET, PUR, PA etc.) and non-polar plastics such as PP, PE, POM, PTFE, PS, PFA etc.