In the history of human civilization, the creation of writing is an important milestone, and the development of human civilization relies on the carriers that record writing. The emergence of paper was an epoch-making revolution in the history of the development of human writing carriers.
Papermaking in China has a long history, dating back over 1,900 years. In 105 AD, CAI Lun invented papermaking, laying the foundation for plant fiber paper and its manufacturing process technology. The invention of papermaking in ancient China also laid the foundation for the history of world papermaking engineering technology.
The core principle of papermaking - processing fibers into thin sheets - has remained unchanged for thousands of years. Modern technology has developed it into a large-scale and highly efficient industry with diverse production lines.
Today, the papermaking industry mainly relies on two raw materials: wood fiber and recycled paper, both of which need to go through different processing procedures.
The entire process of wood pulp papermaking begins at the pulp mill.
First, the logs are peeled and then processed into pulp through mechanical or chemical methods.
Mechanical pulping is made by directly grinding wood into fibers. This method is low-cost, but the paper produced is relatively weak in strength and is only suitable for newsprint and toilet paper.
Chemical pulping involves boiling wood chips together with chemical agents to dissolve lignin - a natural substance that originally binds wood fibers together.
The slurry obtained in this way has higher strength and better quality, and can be used to manufacture printing paper and writing paper.
During the process of waste paper recycling, it is necessary to collect and classify waste paper such as newspapers, cardboard boxes and magazines.
The key step is the deinking process, which removes ink and impurities from the paper fibers through chemical agents and mechanical stirring.
The cleaned fibers will be reprocessed into pulp.
This recycled pulp is often used to manufacture packaging materials such as corrugated cardboard, which not only reduces the demand for logs but also effectively lowers the generation of waste.
After the pulp preparation is completed, the next step is the papermaking process.
Dilute the pulp with a large amount of water to make slurry, and pour it into mobile screens such as Polyester forming fabric and Woven dryer screen. The water is discharged through the screen, leaving behind a thin layer of fibers.
Subsequently, the fiber layer is pressed to remove excess moisture and thoroughly dried through heating rollers.
For high-end printing paper, a coating process will also be added to form a smooth surface, thereby enhancing the printing quality.
Bleaching is a key process in manufacturing white paper.
Traditional processes use chlorine, but to reduce environmental impact, modern paper mills are gradually adopting environmentally friendly technologies.
For instance, the Sapoxal oxygen bleaching process pioneered by Sapi Company is now widely adopted by many factories as chlorine-free (ECF) or completely chlorine-free (TCF) bleaching technologies to protect the ecosystem.
