Wood-free and wood-containing paper
The terms woodfree and wood-containing relate papers not to the wood content of the paper , but on its content of pulp .
So - called wood - free paper is made from bleached cellulose . The proportion of wood pulp in the total fiber content of the paper must not exceed 5%. In addition to fibers, paper often also contains fillers, various additives and, if necessary, an application of binding agent on the surface. A more precise description would be wood pulp-free paper .
Wood-free papers do not yellow and are therefore suitable for long-lasting print products such as books. Wood-free papers are considered to be of high quality due to their higher resistance to aging.
Wood-free uncoated paper - in English WFC (woodfree coated) or WFU (woodfree uncoated) - is wood-free paper without a binding agent (see also coated paper ). The surface of uncoated paper may well have been treated with chalk to increase the whiteness . Wood-free uncoated paper is mainly used for office applications ( copy paper , printer paper), exercise books, writing pads, but also in book printing and in some cases in the graphics industry. The printability is not as good as with art paper, but the paper is more pleasant to the touch . The printability can be improved by satinizing . Wood-free, uncoated, highly satin-finished paper belongs to the class of natural art paper .
So - called wood - containing paper contains more than 5% wood pulp in the total pulp mass. A more precise name would be paper containing wood pulp .
Wood-containing papers tend to yellow and are therefore used for short-lived printed products such as newspapers and magazines.
Wood pulps are obtained from wood by mechanical defibration or at least partially mechanically. Cellulose is produced by chemical pulping - for the most part also from wood. Wood pulp contains much more lignin than wood pulp. That is why wood-containing papers contain much more lignin than wood-free papers. In terms of lignin content, wood pulp and wood-containing papers are more similar to wood than wood pulp or wood-free papers. The higher lignin content of the wood-containing papers causes them to yellow quickly.
- ↑ a b Jürgen Blechschmidt (Ed.): Pocket book of paper technology. Fachbuchverlag Leipzig in Carl Hanser Verlag, Munich 2013, ISBN 978-3-446-43802-6 , p. 33.