A Brief Analysis of the Development History and Future Prosp

The invention of papermaking has ushered in a new era for the dissemination and inheritance of human civilization, transforming the medium of writing from heavy bamboo slips to lightweight and portable paper. It can be said that the emergence of paper has changed the way culture is transmitted, allowing culture and historical materials from thousands of years ago to be preserved to this day. However, due to technological limitations, the quality of paper was very poor when papermaking was first invented. With the continuous development of human technology, papermaking technology is also constantly undergoing changes, with the quality of paper becoming higher and more functional. At present, China has become a country with a high ranking in the manufacturing and consumption of paper products worldwide. Therefore, researching and improving pulp making techniques to control production costs, improve paper quality, and address environmental pollution issues during the production process has become an urgent issue that needs to be studied and solved. As professionals in the papermaking industry, we must strive for innovation, absorb advanced domestic and international papermaking techniques, further innovate existing papermaking technology, and improve the quality and efficiency of papermaking.

Introduction

Pulping has a significant impact on the quality of paper forming, so in order to obtain high-quality paper, it is necessary to improve the process quality of pulp making. Generally speaking, pulping includes three methods: mechanical pulping, chemical pulping, and semi chemical pulping. Pulping generally refers to the process of turning wood into pulp required for papermaking, using special methods (usually mechanical, chemical, or a combination of two methods) to extract fiber raw materials from trees and other plants into natural pulp or further bleaching. In the nearly a thousand years since the emergence of papermaking, due to limited technological level, mechanical pulping has been widely used. However, in recent years, with the development of technology, the application of chemical pulping has become increasingly widespread, greatly improving the efficiency of pulping and the quality of pulp. This article mainly introduces the increasingly widely used chemical pulping technology, and introduces the relatively advanced chemical bleaching methods. It analyzes the advantages and development prospects of chemical pulping technology.

2. Types and uses of chemical pulping technology

The common methods of chemical pulping technology include alkali method and sulfite method, among which alkali method mainly includes caustic soda method and sulfate method, while sulfite method usually includes acidic bisulfite method, bisulfite method, slightly acidic sulfite method, neutral sulfite method, and alkaline sulfite method. Chemical pulping technology is an advanced technology that has developed rapidly in recent years, mainly used for producing advanced cultural paper, paper bag paper, national defense paper, and fiber composite materials. In order to improve the quality of papermaking, save production costs, and solve the environmental pollution problems caused by papermaking, countries around the world are striving to innovate pulp technology. At the end of October 2014, the 9th China International Paper Chemical Technology and Pulping Equipment Exhibition was held at the Shanghai World Expo Exhibition Center. At this exhibition, advanced chemical pulp raw materials and equipment from various countries were exhibited, and the application of papermaking chemicals in the papermaking industry was introduced, as well as their significant impact on controlling production costs, improving environmental pollution issues, and improving papermaking quality. This allowed people to deeply understand the important role of chemical pulp technology in papermaking technology.

3. Current Development Status of Chemical Pulping Technology

As is well known, pulping is a series of processes, including raw material selection, cooking and fiber separation, concentration, pulping, storage of logs, sawing, peeling, knot removal, chipping, cooking, washing, screening, purification, bleaching, impregnation, and pulping to obtain natural pulp boards. With the development of chemical technology, more and more chemical techniques are being applied to these production processes, making significant contributions to the development of the papermaking industry. Below, we will introduce the application of chemical processes in several production processes. When cooking wood, tower continuous cooking systems and low energy consumption displacement intermittent cooking equipment are generally used. During the cooking process, an appropriate amount of caustic soda is added to increase the rate of wood removal, which separates most of the lignin and continuously diffuses into pulp, while also slowing down the dissolution of carbohydrates. However, it should be pointed out that the acquisition rate using this method is relatively low, generally around 50%.

In the previous grinding process, whether it was disc grinding or stone grinding, logs or wood chips were simply placed in the grinding disc or stone machine to promote fiber separation by applying physical pressure. This processing method has low efficiency and requires a large amount of construction investment. Currently, a commonly used method is to first perform chemical pretreatment, using chemical agents to make the tissue of the logs more relaxed, while also softening the fibers. After chemical pretreatment, the grinding process becomes much simpler, while greatly improving processing efficiency and quality, and increasing yield.

Bleaching is also a common process in the papermaking industry. Before the birth of ancient bleaching technology, the quality of paper was poor. We all know that lignin and extracts are the reasons why pulp has other colors, and the purpose of bleaching is to add chemical agents to improve the whiteness of the pulp. There are two common bleaching methods. One is to only allow the chromophore to decolorize while retaining lignin. Disulfite and sodium borohydride are commonly used for this type of bleaching. Another type is to not retain lignin and use bleach to oxidize and dissolve it. The two types of bleaching methods are as follows: the former has a higher yield, but the resulting pulp has a lower whiteness; The latter has significant losses and low yield, but can produce pulp with high whiteness. In the actual production process, the bleaching method can be reasonably selected based on the different paper yield and whiteness.

In addition to the two traditional bleaching methods mentioned above, the application of hydrogen peroxide bleaching has become increasingly widespread in recent years. In traditional bleaching methods, the reducibility of chloride ions is often utilized for bleaching, and hydrogen peroxide, as a chlorine free bleaching agent, has its unique advantages. Using hydrogen peroxide as a bleaching agent utilizes its HOO functional group to passivate and even eliminate chromophores, but it can maintain the original structure of lignin. Due to its unique chemical properties, it is sometimes used as a multi-stage bleaching process to change the structure of chromophores and maintain the whiteness of pulp. However, its drawback is that hydrogen peroxide has limited performance in improving the whiteness of pulp, usually around 8% -10%.

4. Application prospects of chemical pulping technology

The role of chemical technology in improving pulp technology is self-evident. With the continuous development of technology, new technologies will continue to be applied to pulp technology. Objectively speaking, although China is a major producer and consumer of paper products, there is still a certain gap between China's equipment manufacturing industry and developed Western countries, and the pollution problem caused by the paper industry to the environment is still severe. Simply using mechanical pulping has relatively low efficiency, high production cost investment, and will inevitably cause serious environmental pollution. Therefore, it is foreseeable that chemical pulping technology will be increasingly applied. The Scientific Outlook on Development requires us to develop environmentally friendly industries. As an industry with significant environmental pollution, the paper industry needs to constantly innovate, analyze various problems that arise in the paper making process, and use chemical methods to solve them. Overall, chemical pulping technology is bound to have increasingly broad development and application prospects in the future.

5. Conclusion

The maturity of pulp technology determines the quality of paper, so improving pulp technology is very important. Compared to traditional mechanical pulping, chemical pulping technology has its unique advantages. However, in the production process, we should also pay attention to absorbing the advantages of mechanical pulping technology, integrating the advantages of chemical and mechanical pulping technology, continuously improving pulping technology, catching up with international advanced levels, continuously improving pulping level, improving papermaking quality, and solving the environmental pollution problem caused by the papermaking process, Develop environmentally friendly industries. Persist in conducting research on chemical agents in processes such as cooking and bleaching, improve yield, and explore methods to further improve pulp whiteness. Practitioners in the paper industry should continuously improve their professional competence, enhance their professional quality, constantly understand and learn advanced pulp technology from abroad, and apply it to production, striving to achieve significant development of China's paper industry at a relatively low cost, and continuously improve China's existing pulp technology.