KRAFT PAPER AND METHOD FOR MANUFACTURE THE SAME Russian patent published in 2003 - IPC

FIELD: pulp-and-paper industry. SUBSTANCE: method involves cleaning sulfate pulp only in case of high consistence (HC-cleaning) or in combination with milling at low consistence (LC-milling) while adding strengthening substance such as starch into resultant mass before feeding raw material onto wire net of papermaking machine; for HC-cleaning - supplying power and maintaining it at the level of at least 150 kW per ton of paper, for LC-milling - supplying power and maintaining it at the level, which does not exceed 50 kW per ton of paper, in both cases at the rate of 100% of dry paper; adding strengthening substance into resultant mass in at least two positions during processing, with strengthening substance being added in first and second positions in an amount of at least 5 kg. Method allows kraft paper having weight of 50-140 g/sq.m, tensile force absorption characteristic of 2.5-3.5 J/g and Garly porosity of less than 7 seconds to be produced. Such paper may be used for manufacture of air-permeable sacks, in particular, single- or multiple-layer cement sacks equipped with valve. EFFECT: increased strength and other characteristics of paper and products manufactured from said paper, reduced effect upon environment and enhanced reliability in operation. 25 cl, 2 dwg, 2 tbl