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Coating operations are divided into in-machine and out-machine types according to the relationship between the coating machine and the papermaking machine, and into single-layer coating and double-layer coating according to the number of coating times. In-machine coating is to install a coating machine on the papermaking machine so that papermaking and coating are carried out continuously; out-machine coating is to install the coating machine and the papermaking machine independently. There are three main types of coating machines on the market: roller coating machine, air knife coating machine and scraper coating machine.
Roller coating machine uses a coating roller to apply coating to the paper surface, and in-machine coating is mainly based on this type of coating machine. The coating amount can be adjusted by measuring the pressure between the rollers. When the pressure is increased, the amount of coating passing through will decrease, and the coating amount will also decrease. As an in-machine coating machine, the roller double-sided coating machine has a simple structure, can carry out double-sided coating at the same time, has a more suitable coating speed, and is not easy to produce coating streaks.
The air knife coater mainly uses pressurized air to adjust the coating amount and smooth the coating layer. Air knife coating can obtain a thicker coating amount, and its coating layer is more uniform. It is not easy to break the paper during coating, which is particularly suitable for the coating of pressure-sensitive coatings. However, its disadvantage is that it cannot be coated with high solid content, and the air knife is easily blocked by dry coating, which causes coating marks.
The principle of the scraper coater is basically the same as that of the air knife coater. The difference is that the scraper coater uses a steel scraper for coating and flattening. The scraper coater can make the coating surface very smooth, which is not affected by the surface state of the base paper, and does not require the coating to be soft, etc. It can be coated with high solid content and high speed, but the thickness uniformity requirements of the base paper are also relatively strict.
If you want to know more about the coating machine, please search the official website of Wenzhou Feihua Printing Machinery Co., Ltd. for consultation!
