First solution: Use of Up-Converting (anti-Stokes) security pigments.
These luminescent materials convert near infrared (NIR) laser light to visible (VIS) light.
The anti-Stokes shift occurs when the emission is a shorter wavelength than the original excitation wavelength. Generally, the excitation wavelength is a sharply determined near infra-red laser light (980 nm or, in some cases, 940 nm). The effect shows up as a concentrated bright color spot. Luminochem is able to provide anti-Stokes luminescent security pigments in the single digit micron and sub-micron range in order to enable offset printing.
These properties make anti-stokes pigments highly effective for special applications in the field of authentication such as security printing, ceramics, paper, ink or polymer industries.
This is probably the most economically efficient way of marking surfaces. The laser or a special „beeper” will identify the presence of a few milligrams of such pigment, but it will be absolutely invisible to the human eye under normal light conditions.
Second solution: Use of Near Infra-Red absorbing materials.
When a print containing Near Infra-Red (NIR) pigment or dye is viewed through an infrared camera, a black or dark grey area will be seen. Specialised infrared detectors pick up this effect so a machine-readable feature can be created. Since counterfeits made with color printers or copy machines can be filtered out in this way, there is no need for separate verification of origin.
LuminoChem offers three types of near-infrared absorbing products: the water-soluble LUWSIR4 and the solvent soluble LUNIR5 dyes, and the insoluble LUNIR6 pigment.
Brand protection and prevention of counterfeiting
Luminescent pigments and fluorescent dyes are used for invisible security features which get printed on the product surface, packaging and labels.
Find out more by registering for your free delegate pass and say 'hello' to LuminoChem at booth 408.