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Development Of Four Common Protective Coating Methods
- Sep 03, 2018 -

The technical methods of protective film coating are as follows: 1. Guangkun coating, 2. Mesh coating, 3. Scraper coating, 4. Spray coating and curtain coating. The development of these technologies can not be smooth and must face many technical challenges. High solid content of scraper coating will produce such as scraper scar, scraper pressure, scraper paint precipitation (commonly known as turning material) and scraper wear fast and other operational problems. Metrological sizing and pressing coating must face many problems caused by high speed, high solid content and high coating amount.


Including spray at the exit of the coating roll pressing area, orange peel marking paper disease on the coating surface and so on: the new coating method should also solve the new problems that have not been encountered in the conventional coating.


The progress of coating technology needs the continuous development of pigments, adhesives and additives to adapt to, and the paint additives more and more highlight their 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 results in the structuralization of the wet coating, which shows obvious viscoelastic characteristics. It would be beneficial if this structure of the coating could be effectively broken under shear and quickly restored after measurement. On the one hand, it has good performance. On the other hand, the paint adhesive has less migration and good coating coverage. However, the viscoelastic structure can not be eliminated to the desired level at a high solid content, resulting in the above problems of scraper coating and sizing press coating.


With theoretical knowledge and technological breakthroughs, WRRM, which can obviously reduce the viscoelasticity of coatings, has begun to appear. The addition of WRRM not only makes the coating exhibit low viscoelastic properties, but also helps to eliminate viscoelasticity rapidly under shear and makes the coating viscoplastic at high shear rate. Such a coating can obtain better scraper and ink sizing press coating runnability, and solid content can be increased by 2-3'70, and high shear viscosity is the same or lower. Spray coating and curtain coating require new paint additives to achieve good operation.


For example, a wetting agent is needed to spread the sprayed paint droplets and stabilize the curtain.


More importantly, spray coating requires a low viscosity of the coating, curtain coating requires appropriate coating properties such as stretching viscosity may also need appropriate additives to match.


In addition, coating auxiliaries also present a trend of versatile development. Rheological and water-holding modifiers have some of the lubricant's functions, and even some companies claim to be able to act as water-resistant modifiers, with new lubricants showing flow.

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