Paper production process

The production of general printing paper involves two basic processes: pulping and papermaking. Pulping involves the dissociation of plant fiber materials into raw pulp or bleached pulp through mechanical, chemical, or a combination of both methods. Papermaking, on the other hand, involves the suspension of pulp fibers in water and the subsequent processing to produce paper that meets various requirements.

Paper mills generally need to store raw materials sufficient for 4 to 6 months, allowing the raw materials to undergo natural fermentation during storage to facilitate pulping, while ensuring continuous production in the paper mill. In the preparation section, raw materials such as reeds, wheat straw, and wood are cut into chips (for the production of chemical pulp) or wood chips (for the production of groundwood pulp). The small chips are then placed in a digester and mixed with chemical liquor, and steamed using steam to boil the raw materials into pulp, or the wood chips are sent to a groundwood machine to grind into pulp, or they can be ground into pulp after a certain degree of steaming. The pulp is then washed with a large amount of clean water, and coarse pieces, knots, stones, and sand are removed from the pulp through screening and purification.

According to the requirements of the paper type, the pulp is bleached to the desired whiteness using bleaching agents, and then beaten using a beating device. Various auxiliary materials such as fillers, sizing agents, and sizing agents that improve paper performance are added to the pulp, and purification and screening are performed again. Finally, the pulp is sent to the paper machine for wire drainage, press dewatering, drying cylinder drying, calendering and winding, and then cut and rewound or cut to produce roll paper and flat paper. If coated printing paper is to be produced, it needs to be dried in the middle section or processed into roll paper after coating.

In addition to the above basic processes, there are also some auxiliary processes, such as the preparation of cooking liquor, the preparation of bleaching liquor, the boiling of glue materials, and the recovery of chemicals and heat energy from cooking waste liquor and waste gas.

New papermaking technology for modern paper
Due to continuous breakthroughs in papermaking technology, a sanitary paper manufacturing plant in the United States has adopted such a new papermaking technology; the raw materials for producing sanitary paper are used writing paper and discarded printing paper, which are first crushed into pulp. Then, the pulp is filtered, gradually bonded, and subjected to water extraction treatment, and finally cut and packaged. After these processes are completed, the produced sanitary paper can be reused. This technology not only facilitates waste utilization and resource conservation, but also simplifies the paper-making process compared to traditional methods.

Invent

Papermaking is one of the Four Great Inventions of ancient China. The invention of paper has greatly facilitated the storage and exchange of information, and has epoch-making significance in promoting the development of world civilization. Before the invention of papermaking, people inscribed characters on tortoise shells, animal bones, bamboo strips, wooden strips, and silk. Tortoise shells and wooden strips were bulky and inconvenient to use; silk was too expensive for ordinary people to afford. Around the early Western Han Dynasty, people made paper from hemp and ramie. This early paper was relatively rough and not suitable for writing.