Patent ID: 6127034
Filing Date: 2000-10-03
Classification: B42D,D21H,G07D,Y10S,Y10T

Abstract:
A method of manufacturing a composite security thread comprising the steps of:a) coating a plastics film with an aluminium film to form a laminated film;b) coating selected regions of the aluminium film with magnetic material so as to produce spaced apart groups of regions along the length of the aluminium film which can be detected by a magnetic reading head, to generate electrical readings for decoding;c) in registry with selected groups of the magnetic material, printing characters which are to appear visible to the naked eye along a parallel region of the laminated film using a photo resist material so as to protect the aluminum film in those regions in which the characters are to appear in the final thread;d) applying a chemical to the said parallel region to remove the aluminium film except where protected by the resist material;e) coating the region containing the groups of spaced apart magnetic material with an obscuring layer; andf) coating the entire surface of the laminated film containing the magnetic depositions and the visually readable characters with a transparent or semitransparent material to provide a barrier to prevent chemical contamination and provide physical protection to the magnetic regions and the visually readable characters, to reduce the risk of damage to the laminated film during the subsequent paper making and printing processes to which the laminated film is subjected.