In order to meet the needs of some special uses of paper, various types of non-fibrous additives are often mixed in pulp or paper. According to its purpose, it can be roughly divided into the following categories:
1.Wet strength agent. Wet strength agents are additives added to increase the wet strength of the paper, such as urea-formaldehyde resins and phenolic resins.
2.Dry strength agent. Such as cationic starch, polyacrylamide and so on.
3.Retention aid. Additives added to reduce the loss of fillers and fine fibers in the papermaking process, such as polypropylene amine, polyethylene oxide, and polyethylene imine.
4. Defoamer. Used to eliminate bubbles in the papermaking process. Such as silicone oil, turpentine, tridecyl alcohol, tributyl phosphate, pentanol and octanol.
5.Water repellent. Mainly used in paper with high requirements for water resistance. Such as paraffin, metal soap, glyoxal, melamine formaldehyde resin and dimethylamino ethyl acrylate, etc.
