Newsprint chemical additives

This has historically involved only minimal use of chemical additives. The product is usually unsized and, because of its low cost, the use of polyelectrolytes for retention is not usually cost-effective. However, this situation is changing as a result of the trend towards limited filler inclusion and also the increased use of deinked waste paper. Newsprint is usually made in an acidic system due to the naturally low pH of groundwood pulp but, as more recycled fibre is used, the process may eventually become neutral. 

Retention and drainage aids are chemicals which are added to the fibre and filler suspension to assist the efficiency of the filtration process. Growth in recent years in the use of retention aids has been greater than that of almost any other paper chemical additive. It has been caused by a combination of factors increased machine speeds, the increased use of filler in alkaline systems, the increased use of recycled paper and the growing tendency to use fillers in newsprint. Retention aids are water-soluble polymers which may be cationic,... 

In the paper industry, PEO is widely used as a retention aid and pitch control agent in the newsprint industry (118—135). Typically, a phenol formaldehyde-type resin is added to the substrate before the addition of PEO. The chemical that is added before PEO has been referred to as an enhancer. Recent pubHcations on designing enhancers that work with PEO have resulted in expanding the use of PEO in flocculation of several substrates (128,129). 

The processes occurring in a high-speed newsprint paper machine have been discussed above. There are several additional considerations of note in the overall process picture. Paper for the most part is a commodity item (i.e., production costs are more economical per unit when large tonnages of uniform specifications are produced). Most mills have a break-even point at an 85% capacity so it is vital to operate mills at design capacity. Economies of scale are also found for pulp and paper mills at levels of about 1000 tonnes of paper per day for full chemical mills and 200—400 tonnes of paper per day for semichemical or mechanical mills. Thus, the outputs of paper mills are... 

Table II shows the calcium content in paper from the chemical feeder process. With the addition of 9.2 ppm Ca in DI water, the treated newsprint papers calcium content doubled in comparison with the control. The treated Foldur Kraft paper contained three times more calcium than did the unwashed paper. The more calcium that was added in the DI water, the higher the amounts of calcium absorbed in the papers during the washing and deacidification process. However, the absorption of calcium in the paper reached a saturation point. This is the reason why newsprint and Foldur Kraft papers that are treated with 36.4 ppm Ca in the Dl-Ca water imbibed the same amount of calcium as the papers washed with 112.8 ppm Ca in the Dl-Ca water.

Monthly data on newsprint paper, chemicals, and power generation, including production, consumption, foreign trade, foreign tariffs, foreign markets, and new products, processes and equipment, are assembled by the Newsprint Service Bureau, Inc., of New York. In addition, information on production facilities is issued annually. 

Since newsprint contributes about 30 % to the municipal waste of industrial countries and only parts of it can be recycled into paper, Richards and Zheng [28] studied the possibilities to increase the pyrolysis yields of this matter by addition of ferrous sulfate (see also the section 20.4 about Pyrolysis). The production of levoglucosan was stimulated fivefold and that of levoglucosenone also. The authors point to the fact that - instead of enlarging the waste mountains of modem society - pyrolysis of newsprint generates a chemical feedstock (of these two compounds) and forms char at the same time which already contains ferrous ions as an efficient catalyst [28]. 

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