1. Pulping and papermaking mechanism
Raw material structure, product quality and wastewater pollution are three major problems in the development of pulp and paper industry in China. Cork resources used for pulping and papermaking in China are extremely scarce, especially in the western region. The western region is sparsely populated and arid, but the climate is suitable for poplar growth, which is very suitable for planting fast-growing poplar in a large area. Non-wood materials, especially wheat straw, reeds, aquatic plants and Gracilaria lemaneiformis, are also abundant. Based on the present situation of raw materials in China's pulp and paper industry, this research direction focuses on the research of pulping mechanism, featuring new specialty paper, processed paper and functional paper, and studies the new technologies and related mechanisms of pulp and paper, providing theoretical basis and technical guidance for the practical application of new technologies, new processes and new equipment, so as to promote the progress and development of non-wood and fast-growing wood pulp and paper technologies in China. In recent 50 years, this research direction has focused on the biological structure and chemical composition characteristics of non-wood raw materials, especially grass raw materials such as wheat straw, reed, aquatic weed and Chinese alpine rush, and their pulping and papermaking mechanisms. The pulping characteristics of grass raw materials are different from softwood, and the theory of "low temperature rapid cooking" for alkaline pulping of grass is established. Through the study on the differences of pulping mechanism of different methods of grass raw materials, the most suitable pulping method for grass raw materials was put forward at the earliest in China, which provided a theoretical basis for better utilization of non-wood raw materials, reducing energy consumption and improving pulp quality.
In recent years, in order to cooperate with the smooth implementation of the "beautiful mountains and rivers" project in the western region and improve farmers' afforestation enthusiasm and economic income, this research direction has studied the pulping and papermaking mechanism and performance of fast-growing poplar, focusing on the chemical pulping and APMP pulping mechanism, and achieved phased results, providing ideas for the benign and sustainable development of forestry in the western region of China.
At present, the output of paper and paperboard in China is second only to that of the United States, but the types and quality, especially specialty paper and processed paper, are far from those of foreign countries. The development of papermaking in China is extremely unbalanced, and papermaking enterprises in the western region are generally small in scale, backward in equipment, low in product grade, poor in economic benefits and serious in pollution. In order to develop and survive, these enterprises must proceed from reality, adjust product structure according to local conditions, save energy and reduce consumption, and control pollution. Market-oriented, developing special products in market demand, improving product quality, increasing high value-added products represented by various kinds of processed paper, special paper and functional paper, and improving the economic benefits of enterprises are the road suitable for the development of small and medium-sized paper enterprises. The demand for specialty paper is small, but the technical content is high. How to improve the quality of specialty paper and processed paper, develop new specialty paper and processed paper products needed by society, improve the market competitiveness of products, and make these small and medium-sized enterprises survive and develop in the tide of paper industry development is an urgent problem faced by paper workers. Therefore, new specialty paper and processed paper are also important research fields in this research direction, and many achievements have been made. More than 20 kinds of special paper, such as copper-clad base paper for electrical appliances and new high-grade apple bagging paper, have been successfully developed, all of which have been transformed into productivity. Among them, the new technology of high-grade fruit bagging paper researched by doctoral supervisor Professor Zhang Meiyun has been popularized and applied in Shaanxi and surrounding provinces, which has produced good economic and social benefits. The popularization of these scientific research achievements has made outstanding contributions to the development of national and local paper industry and the improvement of economic benefits.
2. Paper chemicals and wet-end chemistry
A variety of chemicals need to be added in the paper-making process. Except fillers, the dosage of papermaking chemicals is generally 0. 1% ~ 2% of the total paper, but it can significantly improve the paper properties, improve the papermaking properties of fibers and the operation performance of paper machines, and reduce environmental pollution. China is a big papermaking country and one of the countries with the highest proportion of non-wood fiber pulp in the world, with 29% in 2004. Using a high proportion of non-wood fiber pulp makes the content of short fiber in pulp higher, which not only affects the quality of paper, but also increases the difficulty of papermaking. Therefore, relying more on chemicals, such as straw pulp using retention AIDS, will greatly reduce the loss of short fibers and fillers; The application of neutral sizing agent makes neutral papermaking a reality, which is of special significance for improving paper strength and reducing production cost. With the progress of society and the improvement of people's living standards, the demand for paper and paper products is increasing, and the application scope is getting wider and wider. The quality of paper is more stringent, and at the same time, higher requirements are put forward for papermaking chemicals.
Paper-making process is a complex process, and there are interactions and influences among the components in the paper, which will further affect the running performance of the paper machine and the final performance of the products. In order to keep the paper machine in suitable papermaking chemical conditions and reduce the change of production technology, paper-making enterprises need to strengthen the wet-end chemical control, improve the running performance of the paper machine and improve the cleanliness of the paper machine. Modern papermaking technology marked by high speed and intelligence can improve the sizing degree and strength of paper, reduce the difference between two sides of paper, reduce the fluctuation of basis weight and ash content, and improve the uniformity of paper and appearance, but it is necessary to establish a suitable wet-end chemical system. The basic research contents of wet-end chemistry include studying the basic theory and application mechanism of various wet-end additives needed by paper industry, determining the best use process, ensuring the chemical balance of wet-end papermaking, and obtaining the best use effect, thus improving the operability of paper machine and paper quality, and increasing the economic benefits of enterprises.
This research direction systematically studies the cooking mechanism, washing mechanism, bleaching mechanism, waste paper deinking mechanism, paper physical strength enhancement mechanism, paper adhesion mechanism and neutral sizing mechanism of pulp and paper chemicals, which provides theoretical guidance for the research and development of paper chemicals and avoids inaction waste. In the research of wet-end application of chemicals, focusing on the retention mechanism of chemicals, combined with the development of current technical level, various retention system theories are supplemented, perfected and developed, and the grey system theory is introduced into the optimization of wet-end chemical factors for the first time, and ideal results are achieved.
The research direction is also devoted to the research and application of chemicals for processing paper and specialty paper, focusing on the development of coating additives and coating preparations for specialty paper. At present, the color development mechanism and coating formula of carbonless carbon paper particle capsules and color inkjet printing paper are being studied, which will replace foreign products. At present, special waterproofing agent and polymer fiber adhesive with independent intellectual property rights have been successfully developed.
Since 1980s, this research direction has been devoted to the modification and application mechanism of papermaking chemicals. A series of high-efficiency dry strength agents, retention AIDS and filtration AIDS for papermaking, such as modified starch, polyacrylamide and chitosan with different charges, different molecular weights and different degrees of substitution, were prepared by ourselves. Emphasis is placed on neutral sizing agents, functional additives with drainage and retention, deinking agents, softeners and finishing agents. Many mature achievements have been made, among which cationic starch, hydroxypropyl quaternary ammonium salt and polyacrylic acid grafted starch have been popularized and applied in many domestic paper enterprises, and good social and economic benefits have been achieved. In recent years, it has undertaken 3 national projects, 8 provincial and ministerial projects, and more than 0 enterprise cooperation projects/kloc-0, and many achievements have won provincial and ministerial awards. Among them, the national "Ninth Five-Year Plan" key project "Research, development and application of high-efficiency neutral sizing agent, dry strength agent and retention and drainage aid for papermaking" has achieved good expected results and attracted the attention of papermaking enterprises. During the research process, researchers in this research direction combined theory with production practice, and compiled and published many books on papermaking chemicals and papermaking wet-end chemistry, which were used by many researchers and manufacturers as books to guide scientific research or production, and formed a certain influence in the papermaking industry at home and abroad.
3. Low pollution pulping and environmental protection
Under the situation that the processing and manufacturing industries in China are generally overcapacity, the paper industry is one of the few industries with increasing demand. Its development potential is huge, but it is necessary to prevent pollution, protect the environment, implement the strategy of sustainable development, take the road of circular economy, maximize the use of resources, minimize waste and make it harmless. The present situation of raw material structure, enterprise scale and technical equipment level of China paper industry makes the wastewater pollution situation of China paper industry still not optimistic. Paper industry wastewater accounts for 15% of the national industrial wastewater discharge, and COD discharge accounts for 40% of the total discharge, and the pollution caused by small and medium-sized paper mills is more serious. Among them, cooking waste liquid and bleaching waste water are the main pollution sources of China's paper industry. Combined with the reality of China's paper industry, it is one of the keys to develop China's paper industry to carry out research on low-pollution pulping and environmental protection.
Large paper mills must implement clean production to fundamentally solve the pollution problem. Cleaner production is to reduce pollution from the source. By selecting raw materials, optimizing technology and strengthening scientific management, the utilization rate of resources in the production process can be improved as much as possible and the pollution discharge can be reduced as much as possible. Cleaner production can not only obtain environmental benefits, but also obtain economic benefits, which has been proved to be an effective way by foreign practice. In China, cleaner production has been included in one of the key research directions supported by the government.
This study focuses on the mechanism and new technology of low-pollution cooking and bleaching and the treatment of pulping and papermaking wastewater, especially the mechanism of autocatalytic ethanol pulping and chlorine-free (TCF) and chlorine-free (ECF) bleaching, which provides a basic theoretical basis for reducing and eliminating the pollution of cooking and bleaching wastewater in China and optimizing the production process. The research focuses on oxygen delignification technology, bleaching mechanism, and low-pollution bleaching chemicals such as hydrogen peroxide, ozone and methyl iminosulfonic acid.
The research and application of biotechnology in the treatment of pulping and papermaking wastewater is one of the hot spots at present. The research direction focuses on the principle and technology of anaerobic biological treatment of high-concentration organic wastewater. The third-generation internal circulation anaerobic reactor technology, membrane bioreactor (MBR) technology, high-efficiency compact aerobic bioreactor (HCR) technology and supercritical oxidation technology of wastewater are very effective for the treatment of black liquor and middle-stage wastewater in small paper enterprises. This research direction started earlier in China in terms of the structural principle, reaction mechanism, equipment development, treatment mechanism and technology of high-concentration organic wastewater from pulp and paper, and achieved some achievements and breakthroughs, which accelerated the process of designing and manufacturing the internal circulation anaerobic reactor in China and laid the foundation for its application in wastewater treatment of pulp and paper enterprises. The treatment technology of cooking black liquor, middle-stage wastewater and white water, which is successfully studied in this research direction and suitable for small and medium-sized pulp and paper enterprises with grass as the main raw material, has been popularized and applied in many domestic paper enterprises and achieved good economic, environmental and social benefits.
4. Pulping and papermaking process control and new equipment
Paper-making equipment and its automation technology are the main components of modern paper-making enterprises and one of the main sources to improve the efficiency of paper-making enterprises. All papermaking countries in the world attach great importance to the development of papermaking equipment and its automation. The research of pulp and paper process control and new equipment has always been the characteristic research direction of our institute, which has a wide influence at home and abroad.
Under the leadership of Professor Wang, a national expert with outstanding contributions and doctoral supervisor, this research direction has achieved fruitful results for more than 20 years and is growing day by day. In the field of pulp and paper measurement and control, a number of domestic leading scientific research achievements have been completed. Has developed 10 products and patented technologies. Professor Wang presided over the research on the national key scientific and technological projects in the Ninth Five-Year Plan, namely, the development of optimal control system for washing and bleaching process of eucalyptus pulp high-quality printing paper and the development of optimal control system for papermaking process of eucalyptus pulp high-quality printing paper, and won the third prize of Shaanxi Science and Technology. This research direction has obvious characteristics and advantages in the field of domestic papermaking technology and equipment automation.
With the continuous improvement of paper machine speed and the rapid increase of single machine output, consumers' requirements for paper product quality are becoming more and more strict, and paper production cannot be separated from automation. In the past 20 years, our school has invested a lot of manpower, material resources and financial resources in the research and promotion of totally integrated automation in pulping and papermaking process, and has successively undertaken 7 national projects such as the National Natural Science Foundation and international scientific and technological cooperation projects, 6 provincial projects such as the State Administration of Foreign Experts Affairs and major scientific and technological projects in Shaanxi Province, and departmental projects such as the Shaanxi Provincial Education Department and xi 'an Science and Technology Support Plan 10. Enterprises have entrusted more than 500 horizontal projects, and 7 scientific research achievements have passed the appraisal at or above the provincial and ministerial level, and won all levels of scientific and technological awards 14. Board machine's headbox control, alkali recovery process control, quantitative moisture control system and other scientific research achievements have reached the domestic leading level. At present, the following research directions are summarized:
1)APMP pulping process control and integrated optimization;
2) Control and integration optimization of 2)PRC-DDS cooking process;
3) Air cushion and hydraulic headbox control system;
4) Steam condensate thermal control system based on adjustable heat pump;
5) Quantitative Moisture Control System (BQCS) in board machine;
6) Control and integrated optimization of alkali recovery process based on field bus;
7) Process control and integration optimization of wastewater biochemical treatment;
8) Drive control of high-speed paper machine;
9)CIPS； Computer integrated process system based on PCS/MES/ERP three-tier architecture;
10) paper industry energy information system.
5. Research on paper printing.
1) study on printability of paper-based materials: deeply study and analyze the structure, composition and performance of materials, explore the relationship between printing materials and printing quality, and further develop green and efficient new packaging and printing materials; This paper studies the relevant mechanism and color management in the process of printing color reproduction, so as to truly realize the "what you see is what you get" of printing.
2) Paper-making and printing chemicals: Study the new production technology and related mechanism of water-based and new anti-counterfeiting ink, provide theoretical basis and technical guidance for the development of water-based ink and new anti-counterfeiting, and promote the progress and development of water-based ink and new anti-counterfeiting production technology in China. Really realize environmental protection printing and meet the market demand of different environmental protection inks.
3) Digitization technology of printing graphic information: According to the current digital development trend of printing technology, the key technologies such as color theory, color management and image quality control are deeply studied, and theoretical models and technical parameters suitable for different production environments are established to lay the foundation for personalized printing.
4) Printing equipment and technology: mainly study the basic structure principle, working performance, technical specifications and development trend of printing equipment and binding equipment, and study the automatic control principle and system of printing equipment; Combining new printing materials and other printing elements, explore the best production process. In printing technology, it is to deepen the pollution problem in existing printing technology and study and implement printing quality standardization; Study the new printing technology at home and abroad, test and study the parameters of the new technology, and provide strong data support for the promotion and use of the new printing technology in the domestic market.