METHOD FOR PRODUCING EXTRUSIVE THERMOMECHANICAL MASS Russian patent published in 2022 - IPC D21B1/16 D21B1/30 

FIELD: paper.

SUBSTANCE: invention relates to the pulp and paper industry, namely, to a method for producing thermomechanical wood mass for office paper, writing and printing paper, packaging paper and packaging cardboard applying twin-screw extrusion. The method herein includes operations for processing chips of foliiferous, coniferous wood, or a mixture thereof with a sodium hydroxide solution; grinding the chips in a Bi-Vis twin-screw extruder while simultaneously treating with solutions of hydrogen peroxide, liquid glass, and sodium diethylenetriamine pentaacetate (DTPANa₅) into a fibrous-shivey mass; grinding the fibrous-shivey mass in disk refiners into a coarse mass, holding said mass in the first reactor before the first grinding stage and in the second reactor after the third grinding stage; diluting the coarse mass with circulating water; holding the diluted coarse mass in order to remove latency; grinding the diluted coarse mass in disk refiners; thickening the resulting mass, wherein the chips are treated with a sodium hydroxide solution with a consumption rate of 4% of completely dry weight (MASD) at a concentration of 5% and the first half of the sodium diethylenetriamine pentaacetate (DTPANa₅) introduced in the process with a consumption rate of 0.2% MASD, at a concentration of 5%, while heating the reaction mixture with steam to a temperature of 70 to 80°C and holding for 4 to 5 hours; the wood chips are ground in the Bi-Vis twin-screw extruder at a temperature of 95 to 100°C while simultaneously treating with solutions of the first half of the 27% hydrogen peroxide introduced in the process with a consumption rate of 1.5% MASD, 29% liquid glass with a consumption rate of 4% MASD, and the second half of the sodium diethylenetriamine pentaacetate introduced in the process, with a consumption rate of 0.2% MASD, at a concentration of 5%, into the fibrous-shivey mass at a concentration of 32 to 37%; the fibrous-shivey mass is ground into a coarse mass in the disk refiners at a concentration of the mass of 32 to 37% consecutively in 3 stages, the mass is held in the first reactor before the first grinding stage for 20 minutes, the mass is held in the second tower reactor after the third grinding stage for 20 minutes; the fibrous-shivey mass before the first stage of grinding is supplied with the second half of the 27% hydrogen peroxide introduced in the process with a consumption rate of 1.5% MASD; the coarse mass is diluted to a concentration of 8 to 9% with circulated water heated to temperatures of 70 to 80°C, wherein the diluted mass is held in order to remove latency for 15 to 20 minutes; the diluted coarse mass is ground to a degree of fineness in the range of 30 to 40°SR at a concentration of 8 to 9% in the disk refiners consecutively in 3 stages; the resulting mass is thickened to a dryness of 37 to 50%.

EFFECT: increase in the mechanical strength and whiteness — the "breaking length" and "whiteness" indicators of the chemical thermomechanical mass made of aspen, birch, spruce, and pine wood, due to the reduction in the intercellular bonding forces in the wood tissue in the area of the "layer S₃ - layer P - layer S₃" complex middle lamella, reduction in the strength of the "carbohydrates - lignin" bond in the cellular walls (layers S₁ S₂ S₃), deepened decoloration reaction of the forming chromophore groups in the structure of lignin.

1 cl, 5 ex