Bleaching, continuous manufacture

Cellulose acetate is manufactured by a batch process (see Fig. 12.9). There has been mention in the patent literature of a continuous system, but its utilization as a production process has not been announced. The charge of cellulose, purified, bleached, and shredded, is of the order of 800-1500 lb. It is pretreated with about one third its weight of acetic acid and a very necessary amount of water, about 6 percent of its weight. If it is too dry at the time of use, more H20 must be added to the acetic acid. A small amount of sulfuric acid may be used to assist in swelling the cellulose and to make it accessible to the esterifying mixture. 

Materials and Regents. Paper samples employed in this study were 8- X 10-in. sheets cut from a continuous portion of a single roll or JCPA-60 bleached kraft paper. This paper had been manufactured from a pulp mixture consisting of 70 bleached southern kraft and 30 bleached hardwood kraft. The paper contained 13 clay materials, which are composed mainly of titanium dioxide. It also contained 212 ppm of iron and 66 ppm of copper and had a pH of 5.4. All chemicals employed were analytical reagent grade. Water used for the washing of paper samples and the preparation of solutions had a minimum resistivity of 15 Mil. 

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