Development of coater coating technology
In recent years, the development of coater coating technology, coating technology in the future will have three important characteristics:
1. It is worth mentioning that scraper coating is still the most important coating method for a long time, and it is developing towards high speed and high solid content;
2. Metering sizing press coating method is widely used and developed rapidly;
3. the new coating method (spray coating and curtain coating) has attracted wide attention and will have bright prospects for development.
However, it does not mean that the above-mentioned development will be very smooth and may face many technical difficulties and challenges. High solid content blade coating will produce some operational problems, such as blade marks, high blade pressure, coating precipitation on the blade (commonly known as turning material) and rapid blade wear; metering sizing press coating must face many difficulties caused by high speed, high solid content and high coating weight coating. The new coating method also needs to solve the new problems not encountered in the conventional coating.
Progress of coater coating technology
The development of coater coating technology also needs the development of pigments, adhesives and additives to match. At this time, coating additives highlight its unique important value. With the increase of solid content, the viscoelastic properties of coatings become more and more important. The interaction between the components in the coating leads to the structure of the wet coating, which shows obvious viscoelastic characteristics. If the structure of the coating can be broken effectively under the action of shear, and at the same time, it will be very beneficial to recover quickly after measurement. In this way, it can not only present good workability, but also have less migration of coating adhesive and good coating coverage. However, the viscoelastic structure can not be eliminated to the ideal level at high solid content. As a result, there may be problems in blade coating and metering sizing press coating. Spray coating and curtain coating require new paint additives to achieve good operation. For example, wetting agents should be added to spray paint to spread and stabilize curtain coatings. More importantly, spray coating requires low viscosity of the coating, and curtain coating requires proper coating extensional viscosity and other properties may also require suitable additives to match. In addition, coating additives also show a multi-functional development trend. Rheological and water retaining modifiers have some functions of lubricants, and some companies even claim that they can play the role of water resisting agent; new lubricants show many characteristics of rheological modifiers, etc.
