Can you tell me how paper is made?

Paper Generally speaking, the production of printing paper is divided into two basic processes: pulping and papermaking. Pulping is to dissociate plant fiber raw materials into natural pulp or bleached pulp by mechanical method, chemical method or a combination of the two. Papermaking is to combine pulp fibers suspended in water into sheets that meet various requirements through various processes.

Paper mills generally need to store enough raw materials for 4 ~ 6 months, so that the raw materials can naturally ferment during storage, which is beneficial to pulping and ensures the continuous production of paper mills. Raw materials such as reed, wheat straw and wood are cut into pieces (used to produce chemical pulp) or wood chips (used to produce ground wood pulp) in the material preparation section, and then small pieces of raw materials are put into a digester, added with chemical liquid, and steamed with steam to make the raw materials into pulp, or the wood chips are sent to a wood mill to be ground, or they can be ground after a certain degree of cooking. Then wash the pulp with plenty of clean water, and remove coarse chips, knots, stones and sand from the pulp through screening and purification. Then according to the requirements of paper types, the pulp is bleached to the required whiteness with bleaching agent, and then beaten with beating equipment. Then various auxiliary materials, such as fillers, sizing agents, sizing agents, etc., are added to the pulp, and then purified and screened. Finally, the paper pulp is sent to a paper machine, filtered for moisture in the wire section, squeezed and dehydrated, dried in a dryer, calendered and coiled, and then cut, rewound or cut to produce rolled paper and plain paper. If the production is to produce coated printing paper, it needs to be dried in the middle or produced into roll paper and then coated.

In addition to the above-mentioned basic procedures, it also includes some auxiliary procedures, such as the preparation of cooking liquid, the preparation of bleaching liquid, the boiling of rubber compound and the recovery of chemicals and heat energy from cooking waste liquid and waste gas.

Early papermaking methods

There are few historical records about the ancient papermaking methods in China, but the papermaking technology and its principle have not changed much since it was invented two thousand years ago. To sum up, the following points can be summarized:

First, cut plants, such as hemp plants, are soaked in water, peeled, chopped with a knife, boiled in a pot, soaked and trampled after cooling, and stirred with a stick to make their fibers break and thin.

Secondly, add auxiliary materials to make paper pulp.

Thirdly, it can be dried by a paper machine (bamboo curtain and the like) to make paper.

Although paper appeared earlier, it was really used for writing and popularization after Cai Lun made "Cai Hou Paper" with excellent texture. In 404 AD, Huan Xuan of the Eastern Jin Dynasty ordered the abolition of simplified paper, and the application of paper became more and more popular. From a historical perspective, any major technological invention in history is not accidental, and there is a development process from conception to prototype to perfection. Although there was paper in Cai Lun before, this does not detract from Cai Lun's great achievements as a major reformer and inventor who perfected the invention of papermaking. It was Cai Lun's invention that made paper enter the practical stage and spread quickly and widely, which provided a cheap and easily available substrate for improving printing and promoting its development. Cai Lun's achievements and his brilliant image as the inventor of the great invention of perfecting papermaking are undeniable. To sum up, the invention and improvement of the pen made China's characters develop in the direction of simplification, neatness, standardization and easy copying; The invention, development and application of fabric, paper and ink provide essential printing and transfer materials for printing. The continuous improvement and combination of embossing and rubbing technology based on hand engraving and transfer printing technology and fabric printing technology laid a technical foundation for the invention of printing; Social progress and the development of cultural undertakings have created social environment and objective requirements for the invention of printing. The possession and combination of these four made the invention of printing a historical necessity, and it began to be widely used in Sui and Tang Dynasties.

Paper type

Packaging paper: white board, kraft paper, corrugated board, paperboard, sheepskin, chicken skin paper, cigarette paper, silicone oil paper, paper cup (bag), base paper, coated paper, cellophane oil-proof and moisture-proof paper, transparent paper, aluminum foil paper trademark, label paper and fruit bag paper.

Printing paper: coated paper, newsprint, lightweight coated paper, lightweight paper, offset paper, writing paper and bible paper.

Industrial paper: release paper, copy paper, insulating paper, filter paper, test paper, capacitor paper, pressure plate paper, dust-free paper, impregnated paper, sandpaper, rust-proof paper, office and cultural paper: other copy papers from tracing paper and drawing paper, art paper, fax paper, printing paper, copy paper, Xuan paper, thermal paper, color jet paper, film paper and sulfuric acid paper.

Household paper: toilet paper, facial tissues, napkins, diapers, sanitary napkins and wet tissues.

Special paper: decorative base paper, watermark paper, leather paper, gold and silver cardboard.