| Ground-breaking new technology from Whitford Worldwide, manufacturer of the largest, most complete range of fluoropolymer coatings in the world, claims it is revolutionising the coating and curing of extruded rubber seals across the automotive industry.
Extruders can now dramatically improve their on-line curing process
using new UV-cured Xylan 2525. This new coating not only improves performance
but also offers a range of other benefits:
- Reduces overheads by slashing energy consumption
- Minimises waste materials and cuts disposal costs
- Significantly reduces the footprint of the extrusion line needed for curing
- Permits coating of TPEs and TPVs
- Increases productivity by curing the coating in less than a second
Xylan 2525 is a waterborne, UV-cured coating that has all the advantages
of a thermally-cured coating -- with none of the many disadvantages of
a conventional thermal-cure process (which is costly and inefficient,
with high overheads.
Conventional thermally-crosslinked coatings are usually cured in a series
of large, long convection "tunnel" IR ovens that, on average,
account for 30 per cent of the length of the extrusion line. Not only
does this take up floor space, but the ovens are very expensive to run,
consuming huge amounts of energy. This is exacerbated by the fact that
these ovens can take a long time to "warm up", so they are often
left on, even when not in use, thus wasting additional energy.
In contrast, the Xylan 2525 curing system requires much less space because
it cures the coating very rapidly. A set of IR lamps removes the water-based
carrier in the coating before a small UV-curing oven achieves cross-linking.
An extrusion line using a Xylan 2525 curing system is:
- 25-30 per cent shorter than a conventional line
- ready to operate after almost instantaneous “warming up” of the UV-lamps
- significantly cheaper to run
- easily turned off to save energy when not in use.
The shorter line also saves money by reducing waste. Obtaining the correct
wet-film/dry-film thickness of a coating sometimes requires several spray-gun
adjustments that can only be assessed after a 3-minute cure cycle in a
conventional process. So, with a conventional extrusion speed of 15m per
minute, at least 45 metres of waste material is produced. Obviously, the
longer the line, the more waste is produced. Using Xylan 2525 reduces
waste by at least 80 per cent, due to the massive reduction in the length
of the line. This saves raw materials and reduces disposal costs dramatically.
Steve Butler, Whitford's European sales manager for flexible finishes,
is already taking enquiries for the new system. "Naturally, companies
in the competitive automotive industry are always keen to improve production
while cutting overheads. Xylan 2525 allows them to do just that. Extensive
trials show that the UV-cured coating performs equally as well as a thermally-cured
coating, if not better. Xylan 2525 is exciting the industry because it
cures very quickly, slashing overheads and wastage. There is another important
advantage: this revolutionary coating can also be used on Thermoplastic
elastomers (TPEs) and Thermoplastic Vulcanisates (TPVs), substrates that
are recyclable but cannot tolerate the high temperatures associated with
conventional curing."
The high cure speed of Xylan 2525 also offers opportunities to improve
productivity. Modern extrusion lines for EPDM processes are capable of
running at five times the speed at which they are usually operated. The
limiting factor is the inability to cure conventional coatings at such
speeds. The Xylan 2525 curing system makes operation at these speeds possible.
Daniel Sydes, Whitford's managing director, Worldwide Flexible Finishes
Group, said: "Xylan 2525 marks a breakthrough for the automotive
industry. Our research department has worked to develop a coating system
that brings substantial cost benefits for car manufacturers and extruders.
In addition to rationalising production space, improving working conditions
and reducing environmental impact, this coating also allows them to coat
a wider range of environmentally friendly substrates and operate at higher
speeds. We are confident the industry will move to this revolutionary
product quickly."
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