Interference pigments for preparing forgeryproof documents

• US 5,573,584 A
• Filed: 04/21/1995
• Issued: 11/12/1996
• Est. Priority Date: 12/11/1992
• Status: Expired due to Fees

• Current Assignee: BASF AG (BASF SE)
• Original Assignee: BASF AG (BASF SE)
• Inventors: Schmidt, Helmut, Ostertag, Werner
• Primary Examiner(s): Bell, Mark L.
• Assistant Examiner(s): Hertzog, Scott L.
• Application Number:
  US08/325,178
• Time in Patent Office: 571 Days
• Field of Search: 106/417, 106/415
• US Class Current: 106/417
• CPC Class Codes: B41M 3/14 Security printing securities B42D25/29
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: C09C 1/0015 Pigments exhibiting interference colours, e.g. transparent platelets of appropriate thinness or flaky substrates, e.g. mica, bearing appropriate thin transparent coatings
• CPC Class Codes: C09C 1/0081 Composite particulate pigments or fillers, i.e. containing at least two solid phases, except those consisting of coated particles of one compound C09C1/0015, C09C1/0078 take precedence
• CPC Class Codes: C09C 2200/24 Interference pigments comprising a metallic reflector or absorber layer, which is not adjacent to the core
• CPC Class Codes: C09C 2200/306 Thickness of an absorbing layer
• CPC Class Codes: C09C 2200/401 Inorganic protective coating
• CPC Class Codes: C09C 2200/403 Low molecular weight materials, e.g. fatty acids
• CPC Class Codes: C09C 2220/10 Wet methods, e.g. co-precipitation

Abstract

Interference pigments based on multiply coated plateletlike silicatic substrates comprising

A) a first layer comprising a colorless or selectively absorbing metal oxide with a high refractive index,

B) a second, non-selectively absorbing, semitransparent layer consisting essentially of carbon, a metal or a metal oxide, and optionally

C) a third layer comprising a colorless or selectively absorbing metal oxide in combination with scattering color pigments which are complementary in color to the reflection color of the interference pigments are useful for preparing valuable documents that are forgeryproof.

Claims

1. A process for preparing forgeryproof documents comprising printing said documents with interference pigments based on multiply coated platelet-shaped silicatic substrates comprising:

A) a first layer comprising a colorless or selectively absorbing metal oxide with a high refractive index,

B) a second, non-selectively absorbing, semitransparent layer consisting essentially of carbon, a metal or a metal oxide, and optionally

C) a third layer comprising a colorless or selectively absorbing metal oxide in combination with scattering color pigments which are complementary in color to the reflection color of the interference pigments.

2. The process as claimed in claim 1, wherein the layer (B) consists essentially of carbon.

3. The process as claimed in claim 1, wherein the layer (B) is from 1 to 30 nm in thickness.

4. The process as claimed in claim 1, wherein the interference pigment has 2 layers.

5. A forgeryproof document printed by the process of claim 1.