As you already know, paper was invented in China. The Chinese did it from the soaked plant fibers. In Europe, the paper fell between 1000 and 1100 years. It turned out that it can be made from wood, rags, and even... from the old paper - waste paper. So it turned out that the paper can be used twice!
How do the paper today?
The paper is produced at paper mills.
The main raw material for production of paper is wood pulp. Cellulose obtained from wood species: mainly of spruce, pine and birch, but also use eucalyptus, poplar, chestnut and other trees.
At the factory the machine is stripped from them bark, crushed into pieces.
The most economical method of obtaining wood pulp mechanical: woodworking mill timber are crushed to a powder which is mixed with water. The paper made on the basis of such pulp, fragile and often goes to production, for example, Newspapers.
The paper of higher quality are made from pulp obtained by a chemical process. Of such wood pulp manufacture of paper and books, leaflets, fashion magazines, as well as strong wrapping materials.
In this case, the chips are sorted by size on special screens and send in cooking. Cook the tree in special machines where add acid.
Peeled and boiled wood filtered and washed to remove impurities.
To the processed paper weight can be added to the paper, but only after removal of ink. At this stage, the production of processed weight, consisting of wood fibers and water, called paper raw materials.
Then on a special processing machine change the shape and structure of the paper fibers. For this paper raw materials add additional substances. For example, adhesives is their presence in the writing paper repels moisture. Or resin - thanks to them, written on paper with ink, water-based, does not leak and can be easily detected by the human eye. The paper used for printing, does not require this ring, as a writing, because printing inks are prepared not water-based and do not spread.
After that, the paper paint in the mixer where add dyes or pigments, for example, finely crushed substances for coating. So, additives kaolin make the paper white and opaque.
Paper pulp, made into a paste gets into the paper machine.
First, the slurry is poured on grid paper machine. This grid is stretched to the two shafts and moves, shifting the paper mush forward. On a grid plot begins the formation of the paper web, called the molded sheet. This is due to the removal of water from the fibrous material. Advancing paper pulp on the tape conveyor portion of the contained water flows through the mesh holes, and paper fibers start to be weaved with each other, forming a so-called tape and reel.
Raw paper tape passes through a series of rollers. Some rollers wring out the water, the other, the heated steam from inside, dried it, others polished.
At the end of the grid area still wet paper web is moved in the pressing section, which is also called "wet pressing". There the paper web is mechanically dewatered and even more condensed.
Finally smooth white ribbon out of the car and wrapped in a huge roll.
Then these rolls are sent in the printing or cut into sheets.
So, moving from car to car, the tree turns into white and clean paper.
Did you know that...
For the manufacture of 1 ton of paper you need to 5.6 m3 of wood. When you consider that the average volume of one tree (tree) - 0.33 m3, to produce 1 ton of paper requires 17 trees.
As of 1 ton of paper you can make about 30 thousand ordinary school exercise books.