Graphic Papers,Wood-containing Natural Printing Papers

11.2.1
Graphic Papers
The term graphic papers refers to a large range of different papers that are suitable for printing and writing and are made from virgin or recycled fibers or mixtures of them.
11.2.1.1 Printing and Press Papers

[13] Printing and press papers are divided into the following four subgroups:
1. 1. newsprint
2. 2. wood-containing natural printing papers
3. 3. Wood-free natural printing papers
4. 4. Coated printing papers (wood-containing and wood-free).

11.2.1.1.1 Newsprint
Newsprint represents an important subgroup. It consists primarily of a mixture of primary and secondary fibers (0–100 %). The primary fibers include groundwood and small amounts of chemical pulp, which are used to increase strength. The main field of application is newspaper production. Other uses are, e. g., paper¬backs, calculating-machine rolls, and interleafing paper.
Newsprint has a basis weight of 40–49 (in certain cases up to 54) g m–2. It is machine-finished or supercalendered. Standard newsprint should have an ISO brightness of 57–60 %.
Improved newsprint has a high filler content and is calendered to obtain a more closed surface. It is used, e. g., for book and offset printing. The ISO brightness is about 10 units higher than the mean brightness of standard newsprint [14].

11.2.1.1.2 Wood-containing Natural Printing Papers
The term wood-containing indicates that these printing papers consist mainly of mechanical pulp along with chemical pulp, while “natural” refers to the fact that they are not coated. Fillers, e. g. kaolin or calcium carbonate, are used to produce high smoothness and good opacity. This important group of printing and press papers includes gravure printing paper, also called SC paper (supercalendered). Here SC-A+, SC-A, SC-B and SC-C are the subgrades (with decreasing quality demands).
Natural magazine papers have high lignin content, are filled and highly super¬calendered. Their main use is the production of magazines and catalogs.

Gravure papers (SC-A. SC-A+) have the same properties as natural magazine paper, they are specially suited to gravure printing. ISO brightness is > 67 %.
Improved newsprint (SC-B, SC-C), improved for gravure printing containing up to 25–30 % recycled pulp has the same properties as natural magazine paper; ISO brightness is < 67 %.
SC offset paper has the same properties as natural magazine paper. The ISO brightness is > 67 % and the surface strength is optimized for offset printing.
Wood-containing thin printing papers have a basis weight of ) 45gm–2. They are used for telephone, railroad timetables, and address books.
Book papers are used in the production of books. They have a groundwood con¬tent of 5–20 %. The filler content depends on the desired specific volume.
Voluminous book papers are produced with a * 1.4-fold specific volume compared with book papers.