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In the modern paper industry, the air and small air bubbles contained in the white water and the slurry have a huge impact on the papermaking of the paper machine, the formation of the paper web, and the quality of the paper after paper production. The generation of air bubbles depends on many reasons, such as the use of wet end chemicals, the jet agitation of stock in the size tank flow system, the addition of air during the suction process of the vacuum roll and the recovery of white water on the screen, etc. These air bubbles from all sides can easily lead to various production problems. The common ones are: the pulp is unstable in the flow delivery system, and the paper weight fluctuates; the dehydration ability of the paper is reduced during the forming process, and the fibers and undispersed fillers are easy to agglomerate, thereby reducing the evenness of the paper sheet; the air bubbles are also easy to cause foam dots, needle holes and other common paper defects. Therefore, the paper industry has high requirements for defoaming, and it is very important to control the air content in the headbox of the high-speed paper machine.

In the method of eliminating foam, only mechanical degassing is often not enough. Most modern paper mills use defoamers to more efficiently defoam pulp. Regarding the mechanism of action of the defoamer, it is generally believed that the defoamer with low surface tension enters the part of the bimolecular oriented bubble film, which destroys the mechanical balance of the oriented bubble film, resulting in foam breaking or foam suppression. There are mainly three types of defoamers mainly used in the paper industry in the market: silicone defoamer, fatty alcohol defoamer and polyether defoamer. Since the silicone defoamer contains silicone oil, it cannot meet the requirement of not affecting production in the papermaking industry. Therefore, fatty alcohol defoamer and polyether defoamer are generally used in the papermaking process.