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.

Magnetic ink and toner compositions traditionally comprise magnetic materials in fine particulate form, either as a dry composition or a liquid suspension. Often such materials are black or dark in color. Disclosed herein are particles compositions suitable for use as inks or toners, that exhibit desirable magnetic properties, and furthermore which include particles coated so they appear white substantially white, or colored. Such compositions present new opportunities for the production of corresponding magnetic layers, when the compositions are deposited in an appropriate manner to a substrate.

A security device is disclosed that has an image formed upon a substrate. The image has a first printed region and a second different printed region both printed with a same ink formulation of field alignable flakes. At least one of the printed regions has optically variable effects. One of the first and second printed regions at least partially surrounds the other. The second printed region is formed of thin parallel lines and the first printed region has substantially wider lines than are printed in the second printed region. The area density of the ink in a line in the first group of wider lines is greater than the area density of a line in the second group of narrower lines. A surprising effect of this image is that particles or flakes in the ink are field aligned so as to produce a visible kinematic dynamic effect visible in the first region and not visible in the second region when the image is tilted or rotated.

A nanoparticle sized between 10-180 nm composed of M(III).sub.2O.sub.3, M(II)O and M(II)M(III).sub.2O.sub.4, wherein M(III) is a trivalent metal and M(II) is a divalent metal, or Fe.sub.2O.sub.3, MnO and M(II)O, wherein M is a divalent metal selected from the group consisting of Fe, Ni, Co, Cu, Pt, Au, Ag, Ba and a rare earth metal.

The invention relates to anisotropic, reflective, magnetic flakes. In a liquid carrier and under influence of an external magnetic field, the flakes attract to one another side-by-side and form ribbons which provide higher reflectivity to a coating and may be used as a security feature for authentication of an object.

A composite security device is provided that is made up of a first polymer film that constitutes or embodies a security feature in the form of at least one high value material, and a second polymer film that constitutes, embodies, or is coated with one or more additional security features. The first polymer film is positioned on and adhered to a surface of the second polymer film, which has a width or diameter greater than the width or diameter of the first polymer film By way of the present invention, the high value material is applied to only a part of the security device, leaving remaining parts of the device available for one or more additional materials that do not impact upon the effect of the high value material.

The invention relates to a method of aligning magnetic flakes, which includes: coating a substrate with a carrier having the flakes dispersed therein, moving the substrate in a magnetic field so as to align the flakes along force lines of the magnetic field in the absence of an effect from a solidifying means, and at least partially solidifying the carrier using a solidifying means while further moving the substrate in the magnetic field so as to secure the magnetic flakes in the carrier while the magnetic field maintains alignment of the magnetic flakes. An apparatus is provided, which has a belt for moving a substrate along a magnet assembly for aligning magnetic flakes. The apparatus also includes a solidifying means, such as a UV- or e-beam source, and a cover above a portion of the magnet assembly for protecting the flakes from the effect of the solidifying means.

A fluid for ink jet printing characters on a substrate that become magnetized in the presence of a magnetic field, the fluid HAVING a suspension of nanoparticles dispersed in a solvent, wherein the fluid comprises a viscosity from 1 to 50 cps and a surface tension of 20-45 dynes/cm, further wherein each nanoparticle is sized between 10-180 nm and comprises M(III).sub.2O.sub.3, M(II)O and M(II)M(III).sub.2O.sub.4, wherein M(III) is a trivalent metal and M(II) is a divalent metal, or Fe.sub.2O.sub.3, MnO and M(II)O, wherein M is a divalent metal selected from the group consisting of Fe, Ni, Mn, Co, Cu, Pt, Au, Ag, Ba and a rare earth metal.

Magnetic pigments containing a transparent flaky homogeneously composed substrate having two parallel major surfaces and a coating containing maghemite, a process for the production of said pigments as well as their use.

A printed image is disclosed wherein the image may be in the form of an array of magnetically aligned platelets or flakes that may by uniform in shape and size and wherein the flakes are arranged in a particularly manner to form optically illusive images useful as security devices, or useful in beam steering applications. In one embodiment of this invention printed array is disclosed a plurality of concentric rings of magnetically aligned platelets disposed upon a substrate in the form of a Fresnel structure, preferably a Fresnel reflector. Advantageously, since the magnetic field can be controlled with respect to strength and direction, one can easily design a field that will correct for spherical aberration that would otherwise be present in a typical Fresnel reflector. In other embodiments of the invention optically illusive images of funnels, domes and cones are printed.