Method and means for producing a magnetically induced design in a coating containing magnetic particles

A method for magnetically transferring predeterminable indicia onto a printed document, comprising the steps of

• a) applying a layer of an ink or a coating composition to at least a part of a first surface of a sheet or web, said ink or coating composition comprising at least one type of magnetic or magnetizable particles;
• b) exposing the sheet or web of step a), while the ink or coating composition is wet, to a magnetic field at a surface of a body of permanent-magnetic material, said body of permanent-magnetic material being either a flat plate, or a cylindrically curved plate, and said surface of said body of permanent-magnetic material is carrying predeterminable indicia in form of engravings, thereby allowing the said magnetic or magnetizable particles to orient in the said magnetic field;
• and
• c) hardening the ink or coating composition, thereby irreversibly fixing the orientation of said magnetic or magnetizable particles of step b);
• wherein the body of permanent-magnetic material is permanently magnetized in a direction substantially perpendicular to said surface of said body of permanent-magnetic material and said predeterminable indicia in said surface cause perturbations of said magnetic field.

A method for continuously magnetically transferring, on a printing press, predeterminable indicia onto a printed document, comprising the steps of

• a) mounting a device around a rotatable cylinder, said device comprising a body of a permanent-magnetic material carrying the predeterminable indicia in the form of engravings at a surface, such that said surface is located at an outer surface of the rotatable cylinder;
• b) imprinting at least part of a first surface of a sheet or web with an ink, said ink comprising at least one type of magnetic or magnetizable particles;
• c) exposing the sheet or web of step b), while the ink is wet, to a magnetic field at said surface of said body of permanent-magnetic material thereby allowing said magnetic or magnetizable particles to orient in said magnetic field;
• and
• d) hardening the ink, thereby irreversibly fixing the orientation of the magnetic or magnetizable particles of step c);
• wherein the body of permanent-magnetic material is either a flat plate or a cylindrically curved plate and is permanently magnetized in a direction substantially perpendicular to said surface of said body of permanent-magnetic material, and said predeterminable indicia in said surface cause perturbations of said magnetic field.