Optically variable multilayer film and optically variable pigment obtained therefrom

  • US 5,437,931 A
  • Filed: 10/20/1993
  • Issued: 08/01/1995
  • Est. Priority Date: 10/20/1993
  • Status: Expired due to Term
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First Claim
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1. An optically variable multilayer film, comprising:

  • (1) a metallic reflective layer M'"'"';

    (2) two sub-unit multilayer stacks symmetrically mounted onto opposite surfaces of the metallic reflective layer M'"'"';

    each of the stacks having a structure of D'"'"'MD, wherein D'"'"' and D are a protective layer and a color-presenting layer, respectively, and both are composed of low refractive index, high hardness, chemically stable silicon dioxide;

    said protective layer D'"'"' further has an optical thickness which is 1/2 of the wavelength of the desired reflected light; and

    M is a semi-transparent metallic layer;

    said optically variable multilayer film being deposited on a flexible substrate S with a release layer R made of a neutral detergent, soluble in water or a solvent, deposited between said optically variable multilayer film and said flexible substrate S so as to form a structure of S-R-D'"'"'-M-D-M'"'"'-D-M-D'"'"'.

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