The object of the present invention is to provide an optical information medium having a colored glossy effect which is single- or multi-colored in regions where a reflective layer is present, but colorless in regions where the reflective layer is absent. The optical information medium of the present invention includes a bonding part (receiving layer), at least one image part, and an adhesive layer (protective layer) covering the at least one image part, wherein each of the image part includes a micro-protrusion/depression structure including part having a micro-protrusion/depression structure on at least a part of the surface opposite to the bonding part, a reflective layer, and a mask layer, in the order from the bonding part (receiving layer), the micro-protrusion/depression structure including part is colorless or colored in one or more translucent or opaque color, and at least one of the micro-protrusion/depression structure including part of the image part is colored in one or more translucent or opaque color.

The object of the present invention is to provide an optical information medium having a colored glossy effect which is single- or multi-colored in regions where a reflective layer is present, but colorless in regions where the reflective layer is absent. The optical information medium of the present invention includes a bonding part (receiving layer), at least one image part, and an adhesive layer (protective layer) covering the at least one image part, wherein each of the image part includes a micro-protrusion/depression structure including part having a micro-protrusion/depression structure on at least a part of the surface opposite to the bonding part, a reflective layer, and a mask layer, in the order from the bonding part (receiving layer), the micro-protrusion/depression structure including part is colorless or colored in one or more translucent or opaque color, and at least one of the micro-protrusion/depression structure including part of the image part is colored in one or more translucent or opaque color.

A method for manufacturing watermarked paper, comprising: a step of forming a first fibrous panel which comprises at least one watermark element; a step of forming a second, thin fibrous panel; a step of removal, by way of suction, of at least one portion of the second, thin fibrous panel in order to produce a localized reduction in thickness at a first face of the second, thin fibrous panel, so as to provide at least one accommodation seat intended to accommodate a security element; a step of coupling between the first fibrous panel and the face of the second, thin fibrous panel which lies opposite the first face.

A method for manufacturing watermarked paper, comprising: a step of forming a first fibrous panel which comprises at least one watermark element; a step of forming a second, thin fibrous panel; a step of removal, by way of suction, of at least one portion of the second, thin fibrous panel in order to produce a localized reduction in thickness at a first face of the second, thin fibrous panel, so as to provide at least one accommodation seat intended to accommodate a security element; a step of coupling between the first fibrous panel and the face of the second, thin fibrous panel which lies opposite the first face.

A method of forming a security document, comprises providing a thread comprising at least one region of heat-transformable material, this material having an optical effect which is transformable in response to applied heat. The thread is integrated with a document substrate material during a substrate forming process, so as to produce a security document substrate having at least one windowed region in which the thread is exposed at the substrate surface, and at least one bridge region in which the thread is not exposed. A patterned heat process is then applied, causing a structural modification in the heat-transformable layer of the thread so as to produce an observable optical effect representative of the heat pattern at one or more predetermined positions with respect to one or more of the said windowed region or bridge region. Security documents bearing threads with such optically transformable materials are also disclosed.

A method of forming a security document, comprises providing a thread comprising at least one region of heat-transformable material, this material having an optical effect which is transformable in response to applied heat. The thread is integrated with a document substrate material during a substrate forming process, so as to produce a security document substrate having at least one windowed region in which the thread is exposed at the substrate surface, and at least one bridge region in which the thread is not exposed. A patterned heat process is then applied, causing a structural modification in the heat-transformable layer of the thread so as to produce an observable optical effect representative of the heat pattern at one or more predetermined positions with respect to one or more of the said windowed region or bridge region. Security documents bearing threads with such optically transformable materials are also disclosed.

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 to a method of tagging a substrate with a covert, spectroscopically detectable security feature, wherein a liquid treatment composition comprising at least one acid is deposited onto a substrate, which comprises at least one external surface comprising a salifiable alkaline or alkaline earth compound.

The present invention relates to a method of tagging a substrate with a covert, spectroscopically detectable security feature, wherein a liquid treatment composition comprising at least one acid is deposited onto a substrate, which comprises at least one external surface comprising a salifiable alkaline or alkaline earth compound.