Magnetic thin film interference device or pigment and method of making it, printing ink or coating composition, security document and use of such a magnetic thin film interference device
AssigneeSicpa Holding SA
InventorsMyron Seto, Thomas Tiller, Edgar Müller
Life of this patent
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Abstract
The invention discloses magnetic OVP, said pigment consisting of thin layer flakes having a basic metal-dielectric-metal structure to result in a viewing-angle dependent color appearance, and having, in addition to said viewing-angle dependent color appearance, incorporated magnetic properties, to make them distinguishable from OVP of similar appearance but not having said magnetic properties. The invention discloses as well methods for obtaining such pigments and the use of such pigments as security elements in inks, coatings and articles.
Claims15
Magnetic thin film interference device, showing a viewing-angle dependent color-appearance, comprising a multi-layer stack including at least one light-reflecting reflector layer (3, 3′), at least one light-transmitting dielectric layer (2, 2′), at least one light-absorbing absorber layer (1, 1′), and at least one magnetic layer (4), wherein said magnetic layer (4) being separated from a dielectric layer (2) by a reflector layer (3).
Method for producing a magnetic thin-film interference device, made of optically variable pigments showing a viewing-angle dependent color-appearance, comprising a multi-layer stack including at least one light-reflecting reflector layer (3, 3′), at least one light-transmitting dielectric layer (2, 2′), at least one light-absorbing absorber layer (1, 1′), and at least one magnetic layer (4), comprising the steps of:
- a) depositing a dielectric layer (2, 2′) on one side of an absorber layer (1, 1′),
- b) depositing a reflector layer (3, 3′) on said dielectric layer (2, 2′), and
- c) depositing a magnetic layer (4) on said reflector layer (3, 3′).
Thin film interference device, such as a foil or a pigment, comprising a first layer which comprises a ferromagnetic material and a second layer comprising material selected from the group of material having reflecting properties for light and wherein the ferromagnetic properties of the first layer are greater than the ferromagnetic properties of the second layer, and wherein the reflecting properties of the second layer are greater than the reflecting properties of the first layer.
Dependencies are inferred from the claim text.