Magnetic pigment flake, optically variable ink, and anti-falsification article

An optically variable ink, comprising:

• an ink body;
• and
• magnetic pigment flakes, each of the magnetic pigment flakes comprising:
• a filtering film layer, with a magnetic or magnetizable material;
• and
• a metal nanoparticles layer, formed on a surface of the filtering film layer;
• wherein each of metal nanoparticles layer has a light scatter-enhancing property with a wavelength selectivity for incident light, the each of the metal nanoparticles layers is configured to generate scattered light enhanced by a local surface plasmon resonance under an irradiation of visible light exceeding a predetermined intensity, and the filtering film layer has a Fabry Perot interference cavity;
• a color of the metal nanoparticles layer under the local surface plasmon resonance in response to the metal nanoparticles layer being irradiated by the visible light exceeding the predetermined intensity is different from a color of the metal nanoparticles layer under the local surface plasmon resonance in response to the metal nanoparticles layer being irradiated by the visible light below the predetermined intensity and
• wherein the magnetic pigment flakes are doped in the ink body.

An anti-falsification article, comprising:

• an article body;
• and
• an optically variable ink, coated on the article body, and comprising an ink body and magnetic pigment flakes;
• wherein each of the magnetic pigment flakes comprises:
• a filtering film layer, with a magnetic or magnetizable material;
• and
• a metal nanoparticles layer, formed on a surface of the filtering film layer;
• wherein each of metal nanoparticles layer has a light scatter-enhancing property with a wavelength selectivity for incident light, the each of the metal nanoparticles layers is configured to generate scattered light enhanced by a local surface plasmon resonance under an irradiation of visible light exceeding a predetermined intensity, and the filtering film layer has a Fabry Perot interference cavity;
• a color of the metal nanoparticles layer under the local surface plasmon resonance in response to the metal nanoparticles layer being irradiated by the visible light exceeding the predetermined intensity is different from a color of the metal nanoparticles layer under the local surface plasmon resonance in response to the metal nanoparticles layer being irradiated by the visible light below the predetermined intensity and
• wherein the magnetic pigment flake of the optically variable ink is magnetically oriented, such that a bright and dark areas are generated with a viewing angel changing under an irradiation of visible light below the predetermined intensity;
• and under an irradiation of visible light exceeding the predetermined intensity, light with a color different from that of the bright area is generated on a corresponding position of the dark area.