METHOD OF PRODUCING NON-WHITE PAPER FOR PRINTING AND NON-WHITE PAPER FOR PRINTING Russian patent published in 2025 - IPC D21H11/10 D21H17/66 D21C3/02 D21C9/16 

FIELD: pulp and paper industry.

SUBSTANCE: method of producing non-white paper for printing involves sulphate pulping of hardwood pulp to obtain hardwood pulp with Kappa number of 13-14. Then, the obtained hardwood cellulose is subjected to oxygen-alkaline treatment to obtain hardwood cellulose with Kappa number of 7.5-8.5. After that, oxygen-alkaline bleaching is carried out in the presence of hydrogen peroxide (EOP) of the obtained hardwood cellulose to obtain semi-bleached hardwood cellulose having whiteness of 38-40% ISO. Obtained semi-bleached hardwood pulp is combined with hardwood chemical-thermomechanical wood pulp (CTMP) and precipitated calcium carbonate (PCC) at ratio of 70 pts. wt. hardwood pulp, 27-33 wt.pts. hardwood CTMP and 19-21 wt.pts. PCC to obtain a paper pulp composition. Paper for printing is formed from the obtained paper mass.

EFFECT: obtaining non-white paper for printing, having acceptable whiteness and at the same time optimum mechanical and printing properties.

19 cl, 1 dwg, 10 tbl, 1 ex