company news about Modern papermaking process flow and steps

Papermaking is one of the four great inventions of China. With the continuous progress and development of science and technology, papermaking technology is also constantly upgrading and gradually moving towards technological and modern directions. How do paper mills produce paper nowadays? What is the papermaking process flow?

The modern papermaking process can be mainly divided into several steps:

• Raw materials
• Cooking
• Washing
• Pulping
• Pulp mixing
• Papermaking
• Paper storage

1. Raw materials:

   The raw materials for papermaking are mainly wheat straw, coniferous wood and broad-leaved wood. In remote areas of China, bamboo, reeds, sugarcane and other materials are used.

2. Steaming and boiling:

   Steaming and boiling refers to the process where raw materials are steamed and boiled for one hour under certain pressure, temperature and humidity conditions, allowing the medicinal liquid to fully penetrate the raw materials and decompose them.

   In pressure vessels, cooking AIDS and chelating agents are generally added to reduce the cooking time.

3. Washing:

   It involves washing the pulp with water, continuously repeating the cycle of water absorption and dehydration, and eventually only the fibers remain.

   The washing section is also known as the washing, selection and rinsing section: "washing" means water washing. The selection is based on the different lengths of the fibers after water washing, and the grades are sorted through a grading screen. Bleaching means bleaching. The pulp after classification is bleached with various bleaching agents.

   (Aerobic bleaching AIDS include oxygen bleaching AIDS, chlorine gas, hydrogen peroxide, etc., and reducing ones include sodium carbonate and urea dioxide, etc.)

4. Pulping:

   After washing, the slurry forms lumps and is irregular.

   In the pulping section, the pulp is processed into a free suspension that meets the standard requirements through kneading, rubbing, and spinning.

5. Pulp mixing:

   The preparation of paper materials during the pulp mixing process is another key point in papermaking. The strength, color tone, printability of the paper after completion, and the length of the paper's shelf life are directly related to it.

   So there is generally a saying in the papermaking industry that 70% is about pulping and 30% is about papermaking.

   Generally, 3 to 5 types of pulp are used, and the pulp is mixed according to the requirements of different types of paper.

6. Papermaking:

   During the papermaking process in the papermaking section, the main task of the papermaking department is to evenly interweave and dehydrate the thin paper material, followed by drying and calendering.

   The wet-end function in the papermaking section is to form the paper sheet. During the paper sheet forming process, retention AIDS, filter AIDS, defoamers, etc. are added. Among them, the purpose of retention AIDS is to promote the retention of fillers (talcum powder, kaolin, calcium carbonate, etc.). In the forming tank between the slurry preparation and the wet end, if there are special requirements, color dyes and fixatives, fluorescent agents, anhydrous aluminum sulfate, fluorescent brighteners, etc. can be added.

   If it is necessary to increase the whiteness value during the process of making white paper, purple, blue, or violet colors can be added.

   After the wet section comes the pressing section in the cadre, where the slurry is dehydrated, approximately 60% of the water needs to be removed. The dehydrated slurry enters the drying section, where oxidized starch, cationic starch, etc. are added.

   Then enter the sizing section and add chemicals such as surface sizing agent, amylase, dry strength agent, wet strength agent, and starch enhancer as needed.

7. Paper storage:

   The paper needs to go through rewinding, cutting, packaging and storage.