Security or Tamper-evidence Applications
“Thermoprint” Irreversible Colour-change Inks
We offer an ink/lacquer, a “chemithermal”, which can either be coated down onto label stock to produce the familiar “thermal-label”, or can be printed down as a heat-sensitive patch on a printed label. As the surface area required for the variable information (batch-code, sell-by date, bar code), is frequently only a small proportion of the total, it will be cost effective to print this patch when the rest of the label is printed. Compared with the use of thermal label stock, the printing of a small patch of our chemithermal ink can produce much improved margins for the printer.
The normal colour change would be white to black, e.g. TFBK90 (Thermoprint, Flexo, Black, 90C), although other colours and temperatures can be offered.
Thermoprint inks are also used in the manufacture of Security packaging. As tamper-evidence (TE) inks, they offer improved colouration characteristics, better printability, better colour stability, and savings on ink consumption of up to 50% compared with other TE inks.
Let us offer you a FREE sample of Thermoprint; and let us offer a FREE demonstration of how you can get a better TE effect and save on cost.
“Thermoswell” Volume Change Inks
We offer inks (for flexography, screen or gravure), either water-based or solvent-based, which, after coating and drying, will expand when heated. The temperature of the expansion is 100-130C, and this produces a tactile effect or a “soft-touch” feel. Volume increases of a few percent up to several hundred percent are possible. The swelling could be accompanied by a colour change such that “intaglio” text (and codes) could be written by a laser beam. A special form of Thermoswell ink is under development, as a means of printing Braille.
Thermochromic Inks
Thermochromic inks change colour, reversibly when heated. The lifetime of these inks is normally very limited because of the degradation caused by exposure to the UV in sunshine. However, Siltech offers a range of UV protected Thermochromic inks with increased lifetime of up to 10 times. A range of colours and change-temperatures is available.
“Thermocheck” Thermal-cure Indicators
Indicator labels are offered for showing when a baking or annealing process at an elevated temperature has taken place. A typical colour change would be red to black.
Transparent UV Protective Lacquer
This is a polymer lacquer, which to the eye, is perfectly transparent. At wavelengths above 400nm, it therefore absorbs very little radiation. However, at lower wavelengths, e.g. between 390nm and 370nm, the lacquer absorbs strongly and below 360nm across the UV range, its absorbance is approaching 100%.
This technology lends itself to numerous applications: the lacquer could be coated onto PET bottles to protect beverages, or onto film to protect food stuffs. It could be the basis of transparent shop-window blinds that protect textiles and other goods from deterioration in sunshine (UV) or it could be incorporated into an overprint varnish to give outdoor posters a longer life.
UV Colouring Inks and Labels
We can offer a UV sensitive formulation and make it available as a coated or printed label. The sensitive chemistry will change colour in one of two ways:
a) it may change it’s optical density in a manner dependent on the received dose, i.e. act as a dosimeter, or
b) it may change colour rapidly following receipt of a threshold dose of UV, in this case the label would act as an indicator, for example to show that a product has been through the UV sterilisation process.
We are able to offer the process colours, and so the technology could be the basis of a full-colour photoprinting process. Contact us for further information.
“Relacsil” Release Lacquer
We offer lacquers which modify the adherence of adhesives. If adhering films are “peeled-apart”, and a message has been back-printed with Relacsil, then that message remains readable even if the adhesive has been heated or cooled.
Thus, attempts to enter a sealed package by freeze-hardening the adhesive will still result in the visible evidence when peeled apart.
A variant of Relacsil can be radiation-activated to show the same effect, without the need for back-printing, when exposed to the beam of a low-power CO2 laser. In this way on-demand, variable information can be stored in a covert way until revealed by peeling-apart.
Relacsil is solvent-based.
“Silmark”
Silmark is a form of high-speed, non-contact, printing that uses the beam from an IR laser to “write” onto the special substrate. The speed of writing (printing) is very high, as also is the quality. Silmark has numerous advantages over conventional techniques for coding which makes it cheaper, better, and greener. Silmark is the coding technology of the future.
Siltech Limited offers a benefits analysis service and is prepared to produce a “turn-key” system or simply provide the consumable ink.