Method of producing cellulose and paper from straw, esparto, reed, and similar raw materials

摘要

269,154. Rinman, E. L. April 7, 1926, [Convention date]. Pulp, preparation of.-In the production of cellulose and paper from the straw of rye, wheat, barley, oats, reeds, Indian corn straw, rice straw, esparto, sugar cane, sunflower stalks, cotton plants, papyrus, and similar raw materials, the material is boiled at a temperature above 100‹ C. but not exceeding 140‹ C. with caustic soda lye, with or without the addition of sodium sulphide. At this temperature glutinous substances are not destroyed. After boiling, the mass is cooled to about 30‹ C.-50‹ C. and the separation of waste liquor carried out at that temperature, the washing being done at a temperature not above 30‹ C., preferably in a rotary filter, petroleum or other oil of high boiling point being added to prevent the formation of scum. Pulp parchment paper or greaseproof paper is obtained from the pulp so produced by grinding to 65‹-80‹ Schopper- Riegler. Thicker papers may be obtained by heating the pulp to 40‹ C. before feeding on to the wire cloth of a paper machine. Kraft paper equal to that of the best sulphate pulp is obtained by grinding to 55‹-60‹ S.R., and the strength thereof may be increased by adding 10 per cent of ordinary kraft pulp, strong sulphite pulp, or jute, hemp, or cotton fibres. The cellulose obtained may be mixed'with 3 parts of mechanical pulp in the production of newsprint paper, the yellow colour being covered by adding suitable dyes. The pulp may be bleached with ordinary bleaching liquids such as chloride of lime, preferably at a temperature of 25‹ C., and the product may be used wholly or partly in place of bleached sulphite pulp in the production of fine papers of all grades. In an example, 150-170 kilos. of caustic soda are used for boiling 1000 kilos of chopped rye straw. The bleaching which is effected at a temperature not exceeding 30‹ C. may take place during the grinding, which is preferably done with beaters having very broad knives.