Comparision of different coaters
1. Air knife coating
Advantage
1- It is possible to obtain a thicker coating amount, a more uniform layer, and less prone to paper breakage during coating.
2- Because it’s profiling coating, it has good cover performance.
3- There is mechanical contact, so will not cause scratches.
Disadvantage
1- This kind of coater the blade is invisible air knife, it is necessary to make the coating material soft and easy to control in order to scrape off excess coating material and smooth the coating layer.
2- During the coating process, it is easy to cause coating material splashing, which can cause blockage of the air knife gap, and it will cause uneven coating.
3- The solid content of the coating formula should not be too much, max. 48%. Too high solid content will cause high viscosity of the coating material and make it difficult to control the coating volume.
4- Low solid content of the coating material will cause high drying costs.
2. Blade coater
Advantage
1- It can make the paper achieve higher smoothness and gloss.
2- Operability is higher than air knife coater, and has higher adjustment accuracy.
Disadvantage
1- It has higher requirement of base paper (good flatness, smoothness, sizing etc.)
2- If it is used for surface coating (top layer), there are higher requirement for under top layer of the base paper.
3- Easy to scratch.
4-The covering performance is not so good as air knife coater and metering rod coater.
3. Metering rod coater
Advantage
1- Low requirement for base paper, suitable for rough base paper.
2- Suitable for high solid content coating.
3- It has good covering performance.
Disadvantage
1- The adjustable range of coating volume is worse than blade coater, generally 7-11gsm.
2- If use grooved rod, it will leave many rod marks.
3- When low coating volume, the metering rod is easy to get worn.
