Method and composition for printing tactile marks and security document formed therefrom

摘要

Ultraviolet light-curable deposits are printed onto a substrate in a predetermined pattern to make tactile marks (e.g. Braille-like resin dots) for use by people with impaired vision to, for example, recognize the denominations of banknotes. The deposit demonstrates high adhesion due to: (1) presence of 20-80% (wt.) of a low viscosity acrylate component to provide a substrate-penetrating property; and, (2) 2-30% (wt.) of an adhesion-promoting acid acrylate. The deposit material further includes 1-30% (wt.) of urethane acrylate, 1-30% by weight of reactive diluent, photoinitiator and 1-10% (wt.) of rheological adsorbing additive. Optimally, the adhesion promoter is added after the other components have been mixed with the rheological additive. The printing step may be followed by heating before the curing step to increase penetration of the ink into the substrate. The deposit may comprise a taggant for use as a security feature.

主权项

1. A method for making a plurality of tactile marks on a security document substrate, comprising the steps:
(a) printing deposits onto the security document substrate in a predetermined pattern using an ultraviolet light curable deposit material comprising:
(i) 20-80% by weight of low viscosity acrylate having a viscosity below 200 cP at 25° C.;(ii) 1-30% by weight of urethane acrylate;(iii) 1-30% by weight of reactive diluent;(iv) photoinitiator in an amount sufficient to enable curing of the deposit material;(v) 1-10% by weight of rheological adsorbing additive comprising silica; and,(vi) 2-30% by weight of trifunctional acid ester, wherein the specified weight percentages of components (i)-(iii), (v) and (vi) are relative to a total weight of components (i)-(vi) combined, and the deposit material has a viscosity in the range of about 2,000 cP to 25,000 cP at 25° C.; and, (b) exposing the printed deposits to ultraviolet light to cure the printed deposits and form a plurality of tactile marks on the security document substrate wherein the tactile marks have easy-to-feel tactility for assisting the visually impaired to distinguish the printed, exposed security document substrate.