PAPER BASES CONTAINING SURFACTANT PIGMENTS AND METHODS FOR MAKING AND USING THE SAME Russian patent published in 2022 - IPC B42D25/373 D21H21/48 

FIELD: paper bases.

SUBSTANCE: paper bases are proposed that contain latent marking pigments (CMP), which are one or more infrared (IR) anti-Stokes pigments. Also proposed is a method for obtaining a paper base with hidden markings and a method for determining whether a sheet paper base is a genuine document. A latent marking pigment is used, characterized by a particle size in the range from about 0.1 mcm to about 5 µm and introduced into the paper base in an amount detectable in the IR range from about 2 mg/m² to about 10 mg/m², while the latent marking pigment is one or more IR anti-Stokes shift pigments selected from one or more of: yttrium oxide; double sodium-yttrium fluoride; lanthanum oxide; lanthanum fluoride; yttrium oxysulfide; lanthanum oxysulfide; gadolinium (Gd2O2S); ytterbium (Yb) or mixtures thereof.

EFFECT: elimination of visible staining and discoloration of IR inks.

20 cl, 2 tbl