Development status and future prospects of paperma

2022-10-02
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The development status and future prospects of papermaking chemicals in China (I)

in the early 1980s, papermaking chemicals in China were still almost blank, but with the continuous improvement of material living standards, people have higher and higher requirements for the quality of paper, and the demand for paper is increasing, which makes China's papermaking industry develop continuously and at a high speed. Because papermaking chemicals can promote the scientific and technological progress of the papermaking industry and bring huge economic and social benefits to the papermaking industry, they have attracted great attention from relevant national departments, colleges and universities, and scientific research institutes. According to the preliminary investigation, there are many beneficial conditions for China's extruder industry in terms of foreign trade export. The actual sales volume of papermaking chemicals in China at the end of the ninth five year plan is about 300000 tons, and it may reach 600000 tons by the end of the tenth five year plan. Therefore, China's paper chemicals industry is a promising sunrise industry

1 current situation and development trend of papermaking chemicals

papermaking chemicals have different classification methods. This paper briefly describes the current situation and development trend of five special chemicals classified by China Paper Chemicals Industry Association - modified starch, sizing agent, water-soluble polymer, special paper chemicals and fillers

1 1 because the molecular structure of modified starch is similar to that of fiber, its affinity is good, its effect is obvious, and it comes from natural resources, and its price is cheap. It is deeply welcomed by the papermaking industry. It is the most important papermaking chemical, and its dosage accounts for more than 80% of the total fine chemicals in papermaking. In developed countries, the amount of modified starch accounts for about 2% of the output of paper and paperboard, and some kinds of paper are even as high as 5% - 6%. It is mainly used for wet end addition, interlayer spray, surface sizing and coating bonding. It is reported that the annual use of various kinds of modified starch in the United States is more than 1.3 million tons, and that in Japan is more than 500000 tons. China started relatively late, but it has developed rapidly in recent years, with an annual consumption of more than 150000 tons. There are many varieties of modified starch for papermaking, mainly including enzyme conversion, oxidation, cationic, phosphate esterification, hydroxyalkyl, carboxymethyl, acetate and other varieties, of which cationic starch is still the mainstream product

main development trends of paper modified starch in the new century:

(1) pay more attention to environmental protection and develop high retention products. Taking surface sizing starch as an example, high retention surface sizing starch will replace oxidized starch in a large amount, mainly because the retention rate of oxidized starch on fiber is low (about 40%), which is easy to cause environmental pollution during pulping. Several paper mills in Europe have been closed by the government because they did not use high retention starch

(2) pay more attention to the development of products with strong specificity. New special-purpose products continue to emerge, such as the successful development of amphoteric, polydenatured, complex functions and other products. The traditional modified starch has crossed a new level in technology. Special reinforcing agents, retention and drainage aids and other products are more easily accepted by paper mills, which can obtain better benefits at a lower cost

(3) pay more attention to the research of applied technology. The application technology of modified starch on paper has developed from the application of a single variety to the comprehensive application of multi variety coordinated application and optimization of paper machine production process. At the same time, the research on the relevant application theory and mechanism, such as the application theory and mechanism of wet end chemistry for fear of poor contact between the sample and the anvil, will be more thorough and perfect. Through the research on the application mechanism and theory, we can guide the practical application in turn, so as to achieve the best application effect of papermaking chemicals and maximize the economic benefits of papermaking enterprises

1 2 sizing agents referred here mainly refer to chemicals that provide water resistance to paper and paperboard, which mainly fall into two categories:

(1) natural type, mainly using rosin as raw material. The saponified rosin size used in the early stage has been gradually replaced by dispersed rosin size. Dispersed rosin size can be divided into anions and cations according to their ionic properties. Anions are still the main products at present. Cationic products have certain advantages due to their intrinsic properties. New products that directly connect cationic substituents to rosin molecules have also been reported. Among rosin sizing agents, the key technical index is the adaptability to pulp pH. acidic rosin sizing agents with pH value of 4.5 ~ 5.5 are still the current mainstream products. Near neutral sizing agents with pH value of 5.5 ~ 7.0 are developing rapidly, and neutral sizing agents that can accommodate calcium carbonate as filler are also being developed

(2) synthetic, mainly including alkyl ketene dimer (AKD) and alkenyl succinic anhydride (ASA). AKD has been widely used in high-end cultural paper in China, but the hysteresis and skid resistance of AKD sizing are not suitable for in-machine coated products and high-speed paper machines. ASA can make up for the shortcomings of AKD, so ASA will be gradually promoted in China. Of course, new AKD series and ASA series products are still in the process of development

in addition to the products used in pulp, the research on products and application technologies that improve water resistance through surface sizing has gradually been paid attention to. Synthetic polymer surface sizing agents such as styrene maleic anhydride copolymer and styrene acrylic acid copolymer can share surface sizing with modified starch. They can not only improve the surface strength of paper, but also improve the water resistance, which is more effective and popular for weak sizing paper in pulp and AKD sizing paper

1 3 water soluble polymers

such products are also widely used, such as polyacrylamide (PAM), anionic, non-ionic, zwitterionic and various products with relative molecular weight and degree of polymerization. When used in wet end, it can be used as reinforcing agent, retention and drainage aid, etc. However, due to certain difficulties in the dissolution of PAM solid particles and the transportation and preservation problems of liquid products, the current application of PAM in paper mills is not widespread enough. Its new trend is to share it with modified starch, which can achieve better results than the single application, and is conducive to the reduction of addition cost. In neutral papermaking, the binary retention system composed of special cationic starch and PAM with a certain relative molecular weight has been generally accepted by paper mills. Polyethyleneimine (PEI) is a good retention aid, drainage aid and water treatment agent, and polyethylene oxide (PEO) is an excellent fiber dispersant, which also has a good retention and drainage aid when matched with modified starch, urea formaldehyde resin (UF), etc. Polyvinyl alcohol (PVA) is a common surface sizing agent from the perspective of single vehicle aluminum in North America. In addition, synthetic latex as coating adhesive also belongs to this kind of products. Due to the adjustable relative molecular weight and multi ion characteristics of water-soluble polymers, new products are still emerging, and their special products are welcomed by paper mills. The research on the application technology of water-soluble polymers is more urgent. The research on special equipment, synthesis technology and compounding application technology is still an important content of scientific research and development in the chemical and paper industry. This kind of products also have important uses in the process of papermaking wastewater treatment, but the research in this field in our country needs to be deepened

1 4 special papermaking chemicals

these products mainly refer to products with special functions in some aspects, which are characterized by a wide variety but small market capacity. Some people also call these products functional chemicals. For example, the main type of wet strength agent that can give paper wet strength is polyamide epichlorohydrin resin (PPE), and 3. The range of tensile speed: 1mm/min-500mm/min (special requirements are determined separately) modified products. Temporary wet strength agent is still under development; Another example is waste paper deinking agent, which is mainly a composite formula product of surfactant. According to different kinds of paper inks, the deinking methods have different process formulas, and the products deinked by biological enzyme technology have also been successfully reported; Whitening agent is also an important product. At present, VBL type is still the main product, but many new products have been reported. Others, such as stripping agents, resin barrier control agents, bactericidal preservatives, defoamers, softeners, and various dye products, are colorful. In the new century, with the development of new paper products and new processes, special paper chemicals will continue to emerge

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