Newsprint paper grades

Principal Uses. Groundwood pulp contains a considerable proportion (70—80 wt %) of fiber bundles, broken fibers, and fines in addition to the individual fibers. Principal uses of paper-grade pulps are in newsprint, magazine papers including coated pubHcation grades, board for folding and molded cartons, wallpapers, tissue, and other similar products. 

While mechanical pulps are used mostly in low-quality paper grades and assortments, e.g. for newsprint or packing papers, Kraft pulps are the strongest pulps used in all-quality papers and paperboards where high strength properties are required. 

A much improved ORC-process can be obtained with heat recovery steam (HR-steam) from the TMP-steam reboilers. An integrated mill with a TMP-plant combined with a paper machine is taken here as an example. Paper grade is newsprint with a basis weight of 40 g absolute dry web/m. With a machine speed of 1700 m/min and a sheet width of 10 m the production of paper is 12.3 kg/s air-dry paper with 92 % dry solids. The paper... 

The cahper is the thickness in p.m of a single sheet measured under specified conditions (TAPPI T411). CaUpers for a number of common paper and board grades are capacitor tissue, 7.6 p.m facial tissue, 65 p.m newsprint, 85 p.m offset bond, 100 p.m linerboard, 230—640 p.m and book cover, 770-7600 pm. 

Mechanical and ultra-high yield pulps are used primarily for low-value, short-life grades of paper such as newsprint and advertising, catalog, and directory papers. Their use in more valuable paper products is severely restricted by the rapid yellowing which occurs upon exposure to daylight, a phenomenon which is attributed to the photooxidation of lignin. 

The furnish of a paper machine varies widely, depending on the grade of paper being made. Newsprint usually consists of about 80 percent groundwood and 20 percent chemical fiber (sulfite or semibleached kraft). Bag papers and linerboard are usually 100 percent unbleached softwood kraft. Printing papers are made from bleached pulps and contain both hardwoods and softwoods. By selecting the proper pulps and refining conditions, a wide variety of paper qualities can be achieved. 

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