Irreversibly magnetically induced images or patterns
US9724957B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 22, 2013 |
| Grant date | Aug 8, 2017 |
| Priority date | — |
| Expiry date | Dec 9, 2033 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB42D2033/20
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
The present invention relates to the field of the protection of security documents, especially banknotes, against illegal actions such as robbery or theft. In particular, the present invention relates to the field of ink compositions for producing irreversibly magnetically induced images or patterns, said inks comprising multichromal microspheres, preferably bichromal microspheres (1) that are orientable upon application of a magnetic field and that comprise at least a first portion (2) comprising one or more dyes and/or pigments and at least a second portion (3) comprising one or more magnetic or magnetizable materials, wherein said microspheres (1) comprise as the first portion a core (2) having a surface and comprising the one or more dyes and/or pigments and as the second portion a partial coating (3) covering at least a portion of the surface of said core (2) and comprising the one or more magnetic or magnetizable materials.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.