|
Preparation
No special preparation necessary other than a clean environment, proper screen, tools and substrate. Room temperature should be ~ 72°F. Before use, mix slowly by hand for 60 sec. Be careful not to create air bubbles or foam.
Screen Size and Squeegee
Use a 330 mesh and a medium hardness squeegee.Target screen tension at 25 Newtons per cm. For the more coarse matte finishes (such as GE Lexan™ 8B36-112 Suede) use a 280 mesh screen with a medium hardness squeegee.
Processing
WOW creates a clear window out of a matte substrate where a
see-through window is required. Dirt and other environmental
contamination will be visible if certain precautions are not
followed such as applying the coating in a clean room or using a HEPA filter enclosed unit over the printing area.
It is also best, to use automatic feed and take-off directly into a
drying oven with circulating filtered air, all enclosed leading to
the UV curing unit. There are no VOC’s to vent.
Coating Thickness
Maintain coating thickness at .3-.5 mils. (Use Tooke gauge or
equivalent to measure.)
Use of In-Line Heat
For ultimate results, it is recommended that prior to UV curing,
an in-line heater is used. This achieves two important objectives; first, it improves the flow of the coating and helps eliminate the screen mesh pattern which results in an improved appearance; secondly, it improves adhesion of the coating to the substrate.
At a substrate temperature of 90°F a good appearance and
100% adhesion is achieved (as per ASTM D-3359). At a substrate temperature of 140°F or higher, adhesion of 100% is
maintained after a twenty minute boiling test or the automotive
environmental tests which normally last for eight days.
The substrate can be heated by IR or gas fired jet dry. Test
the substrate temperature with an IR temperature gun. The
substrate need only be elevated for a second or so which means it can be done at usual production speeds.
Printing Over Ink
WOW has excellent flow and adhesion to non-silicone inks. Add 1% cyclohexanone for silicone inks.
UV Curing
One pass under a mercury vapor bulb at 800mj/cm2 will produce a complete through-cure without the use of nitrogen. Generally a 300 watt bulb will create this level of cure. Use a radiometer to read mj/cm2 intensity. Increase or decrease UV belt speed to reach the 800mj/cm2 level.
|
