Modern papermaking process in papermaking enterprises
Paper making is one of China's four great inventions. With the continuous progress and development of science and technology, papermaking technology is also constantly upgrading,
and is gradually moving towards technological and modernization. How do paper mills produce paper today? YIDAFA PAPER MACHINERY takes everyone to understand the entire papermaking process.
Overall, a paper mill consists of two major systems: the pulp system and the paper machine.
The modern papermaking process can be divided into main steps such as raw material - cooking - washing - beating - pulping - papermaking - finished paper storage:
1. Raw materials: Wheat straw, coniferous wood, and broad-leaved wood are the main raw materials for papermaking. Bamboo, reed, and sugar cane are used in remote areas of my country.
2. Cooking: Cooking means that the raw materials are cooked for 1 hour under a certain pressure, temperature and humidity, so that the medicinal liquid can fully penetrate into the raw materials
and decompose the raw materials. (In pressure vessels, cooking aids and chelating agents are generally added to reduce cooking time).
3. Washing: washing pulp with water, repeating the cycle of water absorption and dehydration, and finally only fibers are left. The washing section is also called the washing, sorting, and bleaching section:
washing means washing with water; washing means using grading and screening to select grades according to different fiber lengths after washing; bleaching means bleaching, and the classified pulp is
bleached with various bleaching agents. (Bleaching aids are aerobic oxygen bleaching aids, chlorine gas, hydrogen peroxide, etc., and reducing sodium carbonate and thiourea dioxide, etc.).
4. Beating: After washing, the slurry becomes lumpy and irregular. In the beating section, the pulp is beaten into a free suspension required by the standard through kneading, rubbing, and spinning.
5. Pulp mixing: The preparation of paper materials in the process of pulp mixing is another key point of papermaking. The strength, color tone, printability of the finished paper, and the length of the shelf
life of the paper are directly related to it. Therefore, papermaking generally has a saying of 7 points for pulping and 3 points for paper making.
Generally, 3 to 5 kinds of pulp are used, and the pulp is prepared according to the requirements of different types of paper.
6. Papermaking: The main work of the papermaking department in the papermaking section is to evenly interweave and dehydrate the thin paper materials, and then dry and calender them.
The function of the wet part in the papermaking section is the forming of the paper sheet. Add retention aids, filter aids, defoamers, etc. during the paper sheet forming process. The purpose of the retention
aids is to promote the retention of fillers (talcum powder, china clay, calcium carbonate, etc.). (In the papermaking tank between the pulp preparation and the wet end, if there is special demand, color dyes,
color fixing agents, fluorescent agents, anhydrous aluminum sulfate, fluorescent whitening agents, etc. can be added. If white paper needs to be improved in the process of making white paper value, you can add purple, blue or violet colors.)
After the wet section is the press section in the cadre, where the pulp is dehydrated, and about 60% of the water should be removed. The dehydrated slurry enters the drying section, where oxidized starch,
cationic starch, etc. are added. Then enter the sizing department, add surface sizing agent, amylase, dry strength agent, wet strength agent, starch enhancer and other chemicals as needed.
7. Finished paper storage: The paper has to be rewinded, cut, packed, and stored.
In addition, different papers require different papermaking machinery and associated different papermaking processes. It is customary to divide the paper machine into long wire, rotary wire, folder wire
and long circular wire hybrid according to the type of paper former; it is also divided into cultural paper machine (including newsprint), board according to its main product variety. Paper machine (including
packaging paper), toilet paper machine, special paper machine; or divided into thin paper machine, cardboard machine and conventional paper machine according to the thickness of the paper produced