METHOD OF PRODUCTION OF SULFURIZED CELLULOSE FIBER, SULFURIZED CELLULOSE FIBRE AND PAPER SHEET Russian patent published in 1999 - IPC

FIELD: wood-pulp and paper industry. SUBSTANCE: method includes oxidation of pulp by oxidizing agent forming aldehyde cellulose pulp and sulfurization of this pulp with sulfurizing agent. Oxidizing agent is selected from group consisting of sodium methaneriodate, sodium parapher iodate, periodic acid, sodium hypochlorite, hydrogen peroxide, ozone, potassium dichromate, potassium permanganate and sodium chlorite; pH is about 3.0 to 4.6. Pulp is washed with water and sulfurized with sodium bisulfite lye or sulfur dioxide in combination with sodium hydroxide at temperature about 25 C to about 90 C till sulfurized cellulose fibre is obtained; sulfur atom of this fibre is bound directly with cellulose and degree of substitution by sulfurized group is between 0.005 and 0.1. EFFECT: enhanced breaking strength both in dry and wet states; increased dry strength: wet strength ratio; enhanced reliability. 35 cl, 4 tbl, 4 ex