Polyacrylamide is one of the most widely used papermaking aids in the papermaking industry, and has now been called the standard "papermaking aid". It is a water-soluble polymer compound. Because of the chemical properties of its double bond and amide group, it can carry out a series of chemical reactions. Due to the different raw materials and reaction conditions during preparation, polypropylene with different molecular weights and different functions can be prepared. Amide series products. According to the degree of polymerization, it can be divided into high molecular weight PAM, medium molecular weight PAM and low molecular weight PAM; it can be used as a retention aid, reinforcing agent, filter aid and dispersant, etc. Polyacrylamide for papermaking.
Application of Polyacrylamide in Paper Industry
1. Retention and Drainage Aid
Used as retention and drainage aids in papermaking are usually polyacrylamide modified products, including anionic polyacrylamide (APAM), cationic polyacrylamide (CPAM) and amphoteric polyacrylamide (AmPAM), with a relative molecular mass of 2 million ~4 million.
APAM generally forms a composite system with other cationic compounds to play a strong role in retention. For example, in combination with aluminum sulfate, APAM can be closely combined with fibers, fine fibers, fillers, etc., thereby greatly improving the retention of fine fibers and fillers. The rate.
CPAM is one of the more commonly used retention aids in papermaking. Generally, products with high polymer quality and low charge density are used. The charge is opposite to that of the fiber. It can be used alone or in combination with bentonite, anion, etc., in the paper material, the bridging mechanism causes the paper material to flocculate, and can increase the retention rate of the paper filler and promote The concentration of white water under the net is reduced. When using CPAM and negatively charged bentonite to form a particulate retention and filtration aid system, the flocs of the paper material formed by adding CPAM are large in size, and then subjected to high shearing force after being passed through a slurry pump and other devices. It is broken down into small pieces, and the negatively charged bentonite will bridge the small pieces again, and form flocs smaller than the flocs initially formed by CPAM. Thereby increasing the retention rate of the paper material, and relatively improving the evenness and water filtration performance of the finished paper.
When AmPAM is used as a retention and drainage aid, the anionic groups repel the anionic trash in the pulp, and the ionic groups are combined with fibers and fine fibers. So as to improve the retention rate of fine fibers.
CPAM is used as a reinforcing agent. Through the formation of ionic bonds between the cations and the anions on the fibers, it can be adsorbed to the pulp fibers, and the amide groups combine with the hydroxyl groups on the fibers to form hydrogen bonds, which enhance the bonding force between the fibers. Increase paper strength. The order of APAM plus rosin plus aluminum sulfate can also be used in paper pulp to obtain a better reinforcement effect, but the reinforcement effect of APAM will decrease as the amount of filler increases.
AmPAM is also commonly used as a dry strength agent for paper in the paper industry. Compared with cationic polyacrylamide strengthening agents, AmPAM has a better effect and can effectively improve paper strength. Studies have shown that amphoteric polyacrylamide type dry strengthening agent has a better strengthening effect for papermaking from waste paper pulp. Papermaking aid polyacrylamide.
3. Dispersant, flocculant
Polyacrylamide-based dispersants in the paper industry are mainly cationic polyacrylamides with low relative molecular weight. Because of the carboxyl group contained in the molecular chain, they have a dispersing effect on negatively charged fibers, which can increase the viscosity of the pulp, facilitate fiber suspension, and are effective Improve the uniformity of the paper, it is a high-efficiency dispersant for long fibers. The flocculant used in the water treatment of the paper industry is amphoteric polyacrylamide. Its amide group can form a hydrogen bond with many substances in the wastewater, so that the particles dispersed in the water can be absorbed together to form agglomerates. Promote the sedimentation and filtration of particles. Compared with other inorganic flocculants, amphoteric polyacrylamide has the advantages of complete variety, less dosage in production, fast settling speed, less production sludge, and simple post-treatment. It can meet the requirements of different wastewater treatment.
In summary, polyacrylamide also plays an important role in the paper industry. It can be used as paper leveling agent, strengthening agent, dispersant, filter aid, etc. Its function is to improve the uniformity of paper, effectively improve the quality and strength of paper, and also increase the retention rate of fillers and fine fibers, and reduce The loss of raw materials can improve filtration and recovery efficiency and reduce environmental pollution.
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Record number：Guangdong ICP No. 16127109-1