Good paper requires quality raw materials. Cellulose forms a basis of paper. Fibers of cellulose can be received from various materials, such as wood, straw, reed, hemp, rice and so on.
Paper production secrets
The main source of cellulose for production of paper is wood now. Practically all grades of paper are developed from mix firm, such as birch, and soft breeds of wood, such as fir-tree or pine. And from soft breeds receive long fibers which give to paper rather high strength characteristics. However the general quality indicators of the paper made of strong breeds of wood, above in spite of the fact that fibers are applied much shorter here.
Except wood, as raw materials for obtaining the paper cotton can serve. Thin and long fibers of cotton in combination with wood fibers allow to receive paper of the highest quality. Besides, for giving of special characteristics to paper fibers of asbestos, wool, and also various other fibrous materials are used.
Except primary initial materials by production of paper also secondary, for example, waste paper, rag semi-weight, semi-cellulose and so on are widely used. Modern technologies allow to receive from these semi-finished products paper of rather high quality, newspaper, packing and other. To become the only restriction for use of waste paper gradual shortening of fibers and the loss of durability connected with it and also decrease in printing properties of paper.
How many it is necessary wood for obtaining the sheet of paper
If to speak about primary receiving cellulose directly from wood, then it is necessary to consider that an exit of pure cellulose makes from 25% to 38%, therefore, from kilogram of wood it is possible to receive 240-375 grams of paper. In other words, with a weight of a standard sheet of A4 five grams, are spent for it from 15 to 21 grams of a tree. Here it is necessary to tell about how there is a transformation of a birch log into the sheet of paper a little. First of all the office of fibers of cellulose is made. There are two methods, mechanical and chemical. Each of them allows to receive fibers with quite certain properties. The mechanical method is most widespread. The mechanical method consists in crushing of wood and a vyshchepleniya of fibers. The way is characterized by high extent of the processing of raw materials reaching 98 percent. Unfortunately, it is a way extremely highly expensive on energy consumption. Besides, the received weight contains high percent of lignin. In further the received raw materials arrive on bleaching. Process this multistage, in particular for obtaining the paper of high degree of whiteness. And only after full bleaching from ready cellulose paper cooks.