Current situation and development of the hottest p

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The current situation and development of papermaking chemicals (Part 2)

recently, the fastest growing is lotion rosin sizing agent. This kind of sizing agent was first developed and mass produced by Hercules company in the United States in the mid-1970s, and is widely used in the papermaking industry. The content of free rosin in lotion rosin sizing agent reaches 100% (the content of free rosin in traditional saponified rosin sizing agent is below 40%, generally 20% - 30%), the dosage is reduced in the sizing process, and the usage of alum is also reduced by about 50%, thus reducing the papermaking cost of paper, which is welcomed by papermaking enterprises. In recent years, the rise of neutral (alkaline) sizing has made the product functional characteristics: rosin sizing is facing a new situation. However, due to the reliability and low price of rosin sizing, rosin sizing also has the advantages of processing wood pulp and no bleaching and cooking for low-grade papermaking, so there are still many countries that use rosin sizing. For example, rosin sizing is the main sizing agent in Japan, accounting for about 84%. The technical trend of rosin sizing is to change the acidic sizing system with a pH value of about 5 to a near neutral sizing system with a pH value of 6-7. Cationic rosin lotion, which is currently used abroad, was first introduced by herculs company of the United States in 1984. The advantages of cationic lotion rosin size are that it can size at a pH value close to neutral, can tolerate a certain amount of calcium carbonate filler, reduce the cost of fiber raw materials, and can reduce equipment corrosion and waste water pollution. The transformation of acidic papermaking into alkaline (neutral) papermaking is a great change in the history of papermaking in the world. At present, the papermaking industry in Western Europe and North America has turned to alkaline sizing. At present, 60% of Western Europe is alkaline sizing, and more than 50% of alkaline papermaking in the United States. The main products of alkaline sizing agents are AKD and ASA. Because AKD and ASA have defects such as easy decomposition and poor stability of lotion, and it is difficult to store them, foreign countries have developed AKD modified fibers while improving AKD and ASA neutral sizing agents. They only need to add them directly to pulp, which has better sizing effect and fundamentally solves the problem of AKD instability

the commonly used sizing agents in pulp in China include rosin sizing agent, paraffin gum, stearic paraffin gum, modified starch, casein and synthetic resin. Among them, rosin gum and paraffin rosin gum are widely used. At present, most domestic paper mills still use ordinary saponified rosin size (the content of free rosin is less than 40%), and a small number of paper mills use strengthened rosin size anionic lotion rosin size, which has entered the stage of production and application, and neutral sizing agent AKD has also entered the stage of trial production. At present, cationic resin sizing agents are normally produced, such as CS neutral sizing agent produced by Hunan Xiangtan fine chemical plant and Sr neutral sizing agent produced by Hangzhou Institute of chemical industry. As the most important neutral sizing agent, AKD has entered the stage of production, promotion and application. Because of its high price, AKD is mainly used in some high-grade paper, and the proportion of its expected dosage is much lower than that of rosin sizing type

v. paper enhancers

paper enhancers are chemicals used to improve the internal and surface strength of paper, which are divided into dry enhancers and wet enhancers

① dry reinforcer is used to provide tensile strength, bursting stress, folding resistance and stiffness of paper, and its main function is to enhance the internal binding force of fiber surface. Abroad, the chemicals used for the internal dry reinforcement of paper mainly include polyacrylamide, cationic starch, etc., and the chemicals used to provide the surface strength of paper mainly include polyvinyl alcohol, carboxymethyl cellulose and starch. The dry reinforcing agent is mainly modified starch and PAM. In Western Europe, cationic starch and double modified starch are mainly used. 2. The oil pump of hydraulic universal experiment is commissioned, and the consumption of vegetable gum is significantly reduced. PAM is the main dry reinforcing agent in Japan, and there has been a trend that PAM gradually replaces various types of starch. The United States is dominated by cationic starch, followed by PAM, and the market is occupied by nationalstarch

at present, the dry enhancers used in China are mainly modified starch and PAM, including hc-1, hc-2 anionic and cationic modified starch compound common dry enhancer produced by Hangzhou Institute of chemical industry, ccs-02 cationic starch, bd-01 anionic starch of Beijing industrial additives science and technology development center, ct-700 quaternary ammonium cationic starch of Zhengzhou petrochemical materials factory, Sam polyacrylamide starch graft copolymer developed by Guangzhou Fine Chemical Company, xanthate starch SX developed by Sichuan Seiko Research Institute, hc-3 amphoteric starch, hc-4 polybasic modified starch of Hangzhou Institute of chemical industry, nbz-2 Cationic PAM of Ningbo Institute of chemical industry, etc. At present, China has produced many varieties of paper dry reinforcers, but the promotion has not yet been popularized and needs to be improved. In the future, we should produce and develop high-performance reinforcers according to the characteristics that China's paper fiber raw materials are mainly straw pulp, such as straw pulp reinforcer hc-3 developed by Hangzhou Institute of chemical industry

② there is a huge space for the market development of recycled plastic granulators with wet reinforcers

under normal circumstances, when no additives are added, the strength of paper wetted is only 5% - 10% of the dry bath strength. The addition of wet reinforcers can greatly improve the strength of paper wetted. Paper wet enhancers are divided into permanent and temporary types. The permanent type is mostly used in corrugated box boards. The commonly used resins for packaging fresh vegetables and frozen products are urea formaldehyde resin (UF), modified melamine formaldehyde resin (MF), polyamide epichlorohydrin resin (PPE) and acrylamide polymers. Most of the temporary types are paper varieties that are short-term and discarded after use, such as baby paper, diapers, handkerchiefs, etc. they should be maintained regularly and forced. The commonly used resins include PPE, reaction products of glyoxal modified acrylamide dialkyl dimethylammonium chloride, etc

the annual growth rate of wet strength agents in the United States is 4.5%. The largest amount of wet strength agents in the United States are UF and PPE, followed by MF and acrylamide polymers. Due to the gradual transformation of the American paper industry into neutral and alkaline paper making processes, coupled with strict environmental protection, the UF and MF resins with high free aldehyde content and need to be cured under acidic conditions are gradually reduced, while the amount of PPE and polyamide polyamine resins (PAA) has increased significantly, UF, MF and PPE are the main wet enhancers in Western Europe. Due to the increasingly strict requirements of environmental protection and health departments on the content of free aldehyde in wet enhancers, many departments are committed to the development and application of glyoxal or aldehyde free products

in China, urea formaldehyde resin and melamine formaldehyde resin were first used as wet enhancers, and then modified urea formaldehyde resin and modified melamine formaldehyde resin were developed. In the 1980s, PPE and polyamine wet enhancers were successfully developed in China. PPE wet enhancers are water-soluble cationic thermosetting polyamine epichlorohydrin resin, which has good reinforcement effect, can cooperate with neutral sizing, and has no free formaldehyde. It has been widely promoted in China

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