Abstract: An access authorization system comprising at least one arrangement of a plurality of microparticles and at least one identification unit. The arrangement of the microparticles is affixed to the identification unit. The arrangement of the microparticles forms a forgery-proof identification. A microparticle used in the arrangement has at least one first layer and at least one second layer.

Abstract: An access authorization system comprising at least one arrangement of a plurality of microparticles and at least one identification unit. The arrangement of the microparticles is affixed to the identification unit. The arrangement of the microparticles forms a forgery-proof identification. A microparticle used in the arrangement has at least one first layer and at least one second layer.

Abstract: A microparticle, particularly a microparticle for the counterfeit-proof marking of products, wherein the microparticle comprises at least one first layer and at least one second layer. The first layer forms an external side of the microparticle and at least one mark preaffixed to this side is arranged at least on said external side, and wherein none of the dimensions of the microparticle exceed approximately 100 ?m. A method is provided for producing at least one microparticle, tag and dispersion as well as a correspondent use.

Abstract: A process for producing multilayered microparticles for marking and later identifying substances or objects of any desired type, even animals and plants, has the following steps: several marking layers are successively applied in the liquid state onto a web-shaped or sheet-shaped substrate, each layer being dried and/or hardened before the next marking layer is applied, until a stack of layers of the desired type and in the desired order is obtained; the substrate is separated from the stack of layers; and the stack of layers is crushed into multilayered microparticles without affecting the integrity of the series of marking layers. A first disclosed process is characterized in that the individual marking layers are applied by a printing process. Alternative processes are characterized in that the individual marking layers are applied by bronzing, by spray painting or by roll coating.

Abstract: The invention relates to a method for protecting and marking products by using microparticles, which are to be attached or added to the product, each microparticle having several color layers forming a code, wherein for each individual product two or more differently coded microparticle groups are used, with the first microparticle group containing in its code the same information for a plurality of products, and with the second or subsequent microparticle group containing in its code an information which is individual for each individual product or for few products.