History of paper: from rags to wood
Since the invention of paper in China more than 2000 years ago it was used for writing and printing. Up to mid of the 19th century paper was made out of rags taken from used textiles (flax, hemp and later of cotton wool tissue). The rags were cut to strings and soaked in water. Then separate sheets (deckle-edge-paper) were taken off and got air-dried. Around 1800 the invention of a paper making machine enabled the manufacturer of endless webs to improve their productivity. The increasing demand led to a shortage of raw material mid of 19th century and people succeeded to gain fibres from wood by grinding and pulp by adding chemicals. Wood is the most important raw material for the paper production apart from waste paper.
»Recycling-collapse« . Processing of waste paper 
Raw material wood  In germany less trees are cut down than are growing again in the same period. In the past approx. 30 million metres had been felled per year. Wood reserves in germany had been estimated 1961 for the last time. That time: 826 million metres.Considering the annual net-growth ( growth deducting cut off and natural damage) there should be much more than 900 million metres today. The annual growth in bavaria is estimated to be around 14 million metres whereby the annual cut off is just around 9 million metres. The situation in the other parts of germany is supposed to be similiar. The difference between growth and cut off could be felled without reducing the forest. Only 1843 the raw material wood was found out to be useful for the paper-industry. Today it is an important grain- rawmaterial for the production of paper. Coniferes are preferred to deciduous trees as they got longer grains. Mechanical wood-pulp production  Thermomechanical wood-pulp production  Raw material "Hadern" =rags 
Up to the 18th century rags were the only raw material for the paper production.Today less than 1 % of the used raw material is made out of textiles. "Hadern" is used for fibres that consist out of pure cellulose not containing any lignified parts. Such material is used for papers of special demands, e.g. banknotes, record-paper as well as especially thin papers like for bibles. Straw cellulose Is gained by chopping, mechanical treatment and chemical splitting of straw (cellulose). In terms of volume it is just about 0,2 % of the material used in german paper production. pulp Material gained from vegetable fibres by chemical splitting. Apart from its main constituent cellulose it consists also "Hemicellulose", "Remnats lignin" and oragnic substances. First wood ( deciduous trees and coniferes) is mechanically chopped. Those get impregnated in special liquids by boiling under pressure and temperature for several hours using several possible processes. Finally the pulp gets dried and is pressed to layers or will directly by supplied to the paper-plant by using pipelines. Pulp Production  Other aid-substances and fillers Fillers, dyes and glue are used as aid-substances. Others like resins are used in order to produce papers with special features. Fillers are additives for the paper production. They fill space between the paper fibres, improve the opacity, the printing-features as well as the smoothness of the paper. Most of the fillers are dissolved in water and added to the semi-finished product in the mixing-vat. Usually mineral nutrients like kaolin and calciumcarbonate are used as fillers.  Herstellung des Halbstoffes Nachdem die Rohstoffe durch Holzschleifer, Hackmaschine, Kocher, Sortierung, Eindicker und Bleicherei gelaufen sind, kommt der Halbstoff/ Holzschliff in die sogenannte Bütte/ Vorratsbütte. Stock metering section  Following the preparation process, all raw material components are fed to the stock metering station. Depending on the manufacturing formula, they are precisely batched with the help of high-precision regulating systems. Base papers usually consist of approx. 90 % fibre and 10 % fillers and process materials. All the raw materials together, the so-called paper stock, are diluted with the cycle water from the papermaking machines, purified and freed from air bubbles. The stock is then fed into the head box. At this stage all the accumulated waste is reintroduced to the production cycle. Paper machine  A "normal" paper machine is equipped as follows.: Stock metering station / Headbox Screen section / Press section Dryer section / Reeling Headbox  In the paper making machine the papers‘ constituents are mixed to form a homogenuous fibre compound. 100,000 litres of fibre-water mixture with a fibre content of only 500 kg enter with one minute and at a speed pf 72 km/h through precisely 1,254 honeycombed openings. This method ensures the best possible fibre orientation. An automatic crossprofile control system ensures uniform paper quality. Screen section  The headbox is followed by a drainage process. In contrast to the conventional Fourdrinier machine, liquid transport is effected by two continuously running, finemesh plastic screens. This results in an almost syemmetrical paper structure and largely uniform surfaces. Only one second after the stock jet strikes the double screen, the fibre web leaves the screening section with a solids content of approx. 18 %. Press section  In the press section, mechanical pressure rollers are used to extract water from the web, which is still moist and sensitive to tension. The paper structure is compacted, its strength increased and surface stability greatly enhanced. After the press section, the paper’s solids content goes up from 16 to 45 %.Dryer section  In the dryer section the remaining water in the paper is evaporated without damaging the fibres. The paper web runs at a speed of 72 km/h through 50 labyrinth-type steam-heated dryer cylindres. The resultant base paper has a homogenuous moisture profile with a solids content of approx. 96-98 %.Size press section The glue press of a papermaking machines enables the application of watery glue (resin) on both side of the web. Among others this improves the stability inside the paper. In order to enable writing on the paper as well as to give othe features glue is added to the papermass before the further process. For other types glue gets applied on the surface during the drying-process. Reeling  In the final section of the papermaking machine, the reelsing section, sheets thickness is equalized by a two-roll calender and the thickness profile of the paper optimised. Such papers are machine-glazed.Reeling  Roughly 14 seconds after the fibre suspension has reached the screen, the base paper for coating, with a width of 7,60 metres, is reelsed up to form reels weighing over 20 tonnes: approx. 10,000 sqm per minute – 500 tonnes per day.Further Processes When leaving the papermaking machine the paper obtains its final form by further processes like claycoating, calendering, slitting as desired by the customer. Coater  The production of base paper for coating is followed by the finishing process coater. At the specialist for coated printing paper, the top-quality consists of different components. Its essential elements are extra-white China clay (Kaolin) and calcium carbonate. An excess layer is applied to the base paper in the coater at speeds up to 85 km/h by a jet applicator. A coating blade – the so-called dynamic blade – with a specific geometry and a laser-controlled deflection adjustment of the ductor bar is responsible for correct coating weight and spread. Supercalander  In the calender the coated paper is glazed to give it the required smoothness and brilliant gloss. The paper web is compacted under pressure and heat and its thickness is reduced. One 12-roll supercalender units use state-of-the-art-technology. The rolls can be controlled zone by zone, resulting in a complete uniform paper thickness over the entire width.Slitter  At the slitter the reels up to 30 tonnes can be slit at speeds of 120 km/ h into widths desired by the customer. Advanced winding technology ensures uniform tension of paper wheels with a diameter up to 1,5 m. Free from over-elongation. ...and the siliconrawpaper is finished |
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