CARDBOARD FOR FLAT LAYERS OF CORRUGATED CARDBOARD AND METHOD FOR PRODUCTION THEREOF Russian patent published in 2022 - IPC D21F11/12 D21H27/18 

FIELD: paper.

SUBSTANCE: group of inventions relates to the pulp and paper industry, namely to cardboard for flat layers of corrugated cardboard, which consists of not less than 70 wt. % of waste fibre, as well as to a method of making said fibre. Such cardboard is intended for manufacture of packing containers in the form of boxes and trays for packing vegetables, fruits, as well as cooled and frozen products. Cardboard contains hydrophobic adhesive and reinforcing starch in the mass and/or on the surface and moisture-resistant polyamide-polyamine-epichlorhydrin resin in the mass. Cardboard additionally contains a polyacrylamide-based cationic resin. Method of producing cardboard consists in the fact that hydrophobic adhesive and moisture-resistant polyamide-polyamine-epichlorhydrin resin are diluted with water and mixed with each other. Obtained mixture, cationic starch and cationic resin based on polyacrylamide are then added to the paper mass. Layer of cardboard is formed and subjected to surface treatment with a composition containing hydrolysed starch and hydrophobic glue.

EFFECT: technical result of the invention consists in providing an increase in the strength of the cardboard in a wet state due to the acceleration of the reaction of formation of moisture-resistant chemical bonds, increase in the number of such bonds between the fibres of the raw material, without increase in the consumption of the moisture-resistant polyethylene resin, as well as in the reduction of water absorption during prolonged contact therewith.

4 cl, 1 tbl, 11 ex, 2 dwg