PAPER AND CARDBOARD PRODUCTS Russian patent published in 2020 - IPC D21H11/18 D21H19/52 D21H11/14 

FIELD: paper.

SUBSTANCE: invention relates to paper and cardboard products containing a cellulose substrate and a coating layer. Cellulose substrate contains recycled pulp. Coating layer contains 67–92 wt. % of inorganic solid particles and 5–30 wt. % of microfibrillar cellulose. From 20 % to 95 % by weight of inorganic solid particles have equivalent spherical diameter of less than 2 mcm. Brightness of cover layer makes at least 65 %. Cover ply grammage is 15–40 g/m². In method of producing paper or cardboard product, microfibrillar cellulose and inorganic material in form of particles are applied at stage, when wet substrate is in process of forming on wire mesh of paper-making machine, which allows to avoid additional costs for more large-scale equipment and equipment, as well as for separate drying of coating.

EFFECT: providing low porosity and good strength characteristics of paper and cardboard products.

32 cl, 4 tbl, 4 ex, 7 dwg