A flat security element with optical security features includes at least one first surface region with a first sub-wavelength structure. The structure elements that define the first sub-wavelength structure periodically repeat in the plane of the security element. In order to be able to convey a motif with increased forgery protection using at least two different color impressions, which motif is easy to produce, the first sub-wavelength structure of at least one partial region of the first surface region is additionally provided with an interference coating for producing a color-shifting effect.

A method for producing security elements, security elements, a security document with at least one security element as well as a transfer film with at least one security element, wherein a three-dimensional object is recorded and a surface profile of the three-dimensional object, described by a function F(x,y), is determined, wherein the function F(x,y) describes the distance between the surface profile and a two-dimensional reference surface spanned by co-ordinate axes x and y at the co-ordinate points x and y. A first microstructure is determined in such a way that the structure height of the first microstructure is limited to a predetermined value smaller than the maximum distance between the surface profile and the two-dimensional reference surface, and the first microstructure provides an observer with a first optical perception which corresponds to the surface profile of the three-dimensional object described by the function F(x,y).

A method for producing security elements, security elements, a security document with at least one security element as well as a transfer film with at least one security element, wherein a three-dimensional object is recorded and a surface profile of the three-dimensional object, described by a function F(x,y), is determined, wherein the function F(x,y) describes the distance between the surface profile and a two-dimensional reference surface spanned by co-ordinate axes x and y at the co-ordinate points x and y. A first microstructure is determined in such a way that the structure height of the first microstructure is limited to a predetermined value smaller than the maximum distance between the surface profile and the two-dimensional reference surface, and the first microstructure provides an observer with a first optical perception which corresponds to the surface profile of the three-dimensional object described by the function F(x,y).

An object of the present invention is to provide a thin volume hologram sheet to be embedded sufficiently resistant to a mechanical stress such as a stress including a tensile stress, a shear stress and a compression stress at the time of processing even under a heating condition, a forgery prevention paper and a card using the same. The object is achieved by providing a volume hologram sheet to be embedded comprising a volume hologram layer, and a substrate disposed only on one side surface of the volume hologram layer using an adhesion means, wherein a peeling strength of the volume hologram layer and the substrate is 25 gf/25 mm or more.

An object of the present invention is to provide a thin volume hologram sheet to be embedded sufficiently resistant to a mechanical stress such as a stress including a tensile stress, a shear stress and a compression stress at the time of processing even under a heating condition, a forgery prevention paper and a card using the same. The object is achieved by providing a volume hologram sheet to be embedded comprising a volume hologram layer, and a substrate disposed only on one side surface of the volume hologram layer using an adhesion means, wherein a peeling strength of the volume hologram layer and the substrate is 25 gf/25 mm or more.

The present invention relates in particular to a security element (1) for a valuable document, which comprises an array (R) of at least two contiguous or adjacent lines (2, 2′, 2″), at least one of these lines (2) being raised and having two opposing and at least partially inclined sides (20, 21) that each originate along one of the longitudinal and opposing edges (200, 210) of the line (2), characterised by the fact that the two opposing inclined flanks (20, 21) meet at a single, uninterrupted, sinuous junction area (22), that extends in the longitudinal direction of the line (2), the sides (20, 21) having no discontinuities or interruptions at least in the longitudinal direction.

The present invention relates in particular to a security element (1) for a valuable document, which comprises an array (R) of at least two contiguous or adjacent lines (2, 2′, 2″), at least one of these lines (2) being raised and having two opposing and at least partially inclined sides (20, 21) that each originate along one of the longitudinal and opposing edges (200, 210) of the line (2), characterised by the fact that the two opposing inclined flanks (20, 21) meet at a single, uninterrupted, sinuous junction area (22), that extends in the longitudinal direction of the line (2), the sides (20, 21) having no discontinuities or interruptions at least in the longitudinal direction.

A method for producing flakes of a resin thin film including: a step (1) of forming a resin thin film on a substrate film to obtain a multilayer film; a step (2) of pressing the multilayer film by a member having a concavo-convex shape to form cracks in the resin thin film; and a step (3) of stripping the resin thin film from the substrate film to obtain flakes. The step (2) is preferably performed with a pressing pressure of 100 MPa or less. The resin thin film is preferably formed of a cured product of a photocurable liquid crystal composition. The resin thin film is preferably a cholesteric resin layer.

A method for producing flakes of a resin thin film including: a step (1) of forming a resin thin film on a substrate film to obtain a multilayer film; a step (2) of pressing the multilayer film by a member having a concavo-convex shape to form cracks in the resin thin film; and a step (3) of stripping the resin thin film from the substrate film to obtain flakes. The step (2) is preferably performed with a pressing pressure of 100 MPa or less. The resin thin film is preferably formed of a cured product of a photocurable liquid crystal composition. The resin thin film is preferably a cholesteric resin layer.

A security element includes a first transparent film, on which a holographic layer is formed having a holographic surface structure, a reflective layer arranged in contact with the holographic layer having a pattern of non-transparent regions and transparent regions, a color changing layer, and a photoactive layer having dark regions and transparent regions. In first regions, parts of the non-transparent regions of the reflective layer are not overlapped by the dark regions of the photoactive layer. In second regions, the color changing layer is backed by the dark regions of the photoactive layer. In third regions, the transparent regions of the photoactive layer are at least partly in register with the transparent regions of the reflective layer so that the third regions are continuous when passing from patterns outside the non-transparent regions of the reflective layer to patterns outside the dark regions of the photoactive layer.