METHOD OF MAKING PAPER WITH TRANSPARENT AREAS AND PAPER WITH TRANSPARENT SECTIONS, MADE USING THIS METHOD Russian patent published in 2020 - IPC D21H19/00 D21H21/26 

FIELD: pulp and paper industry.

SUBSTANCE: invention relates to pulp and paper industry, in particular, to production of paper for making banknotes and other valuable documents, which require high protection against falsification. Disclosed is a method of making paper with transparent sections, which includes obtaining a paper base, forming an opaque region which increases contrast of the transparent portion, and applying a composition to increase transparency in the region of the transparent portion. According to the invention, an opaque region is formed by applying on the paper base at least two overlayer layers arranged one above the other on one or two sides of the paper base, note here that lower cover layer is colored by dark dye so that paper whiteness, measured on lower cover layer, is not more than 2 % less than paper whiteness measured on top cover layer.

EFFECT: high opacity of the paper on the entire area of the printed article, with the exception of the transparent section, while maintaining high whiteness, good physical and mechanical properties and the ability of the paper to receive printing inks when sealing is subsequently printing.

7 cl