Processes for producing optical effects layers
AssigneeSicpa Holding SA
InventorsEvgeny Loginov, Mathieu Schmid, Claude-Alain Despland, Pierre Degott
Life of this patent
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Abstract
The invention relates to the field of the protection of security documents such as for example banknotes and identity documents against counterfeit and illegal reproduction. In particular, the invention relates to processes for producing optical effect layers (OELs) comprising a motif made of at least two areas made of a single hardened layer on a substrate comprising a photomask.
Claims18
A process for producing an optical effect layer (OEL) on a substrate comprising a photomask, said OEL comprising a motif made of at least two areas, preferably at least two adjacent areas, made of a single hardened layer, said process comprising the steps of:
- a) applying on the substrate comprising the photomask a radiation curable coating composition comprising one or more photoinitiators and a plurality of magnetic or magnetizable pigment particles so as to form a coating layer, said coating layer being in a first state and said coating layer at least partially facing the photomask;
- b)
- b1) hardening one or more first substrate areas carrying the coating layer through the substrate, said hardening being performed by irradiation with a UV-Vis irradiation source to a second state so as to fix or freeze the magnetic or magnetizable pigment particles in their positions and orientations;
- and
- c)
- c1) exposing at least one or more second substrate areas carrying the coating layer which are in the first state due to the presence of the photomask of the substrate to a magnetic field of a magnetic-field-generating device thereby orienting the plurality of magnetic or magnetizable pigment particles so as to follow any magnetic or magnetizable pigment particles orientation pattern except a random orientation;
- and
- c2) simultaneously, partially simultaneously or subsequently hardening by irradiation with a UV-Vis irradiation source at least the one or more second substrate areas carrying the coating layer to the second state so as to fix or freeze the magnetic or magnetizable pigment particles in their adopted positions and orientations,
- wherein the photomask has an optical density DM equal to or higher than 1.0.
An optical effect layer (OEL), wherein the OEL is disposed on a substrate comprising a photomask, said OEL comprising a motif made of at least two areas made of a single hardened layer, the OEL comprising a radiation cured coating composition comprising a plurality of magnetic or magnetizable pigment particles fixed or frozen in the coating composition by radiation curing so as to form a coating layer, said coating layer at least partly overlapping with the photomask to provide a masked area and an unmasked area thereof;
- wherein the magnetic or magnetizable pigment particles of the masked area of the coating layer are oriented so as to follow any magnetic or magnetizable pigment particles orientation pattern except a random orientation;
- and
- wherein the magnetic or magnetizable pigment particles of the unmasked area of the coating layer follow a random pattern or are oriented so as to follow a different orientation pattern than that of the magnetic or magnetizable pigment particles of the masked area to provide visually distinct optical impressions as determinable by the human eye.
Dependencies are inferred from the claim text.