Coatings World - April 2016

LED Curing Technology for Coatings

formulation is usually very small, less than 5%. PIs typically absorb across a range of wavelengths, not a narrow band. Many existing UV formulations developed for curing with a typical UV lamp use a broad spectrum PI. While there is often some absorption within the LED output range, it is clear that much of the PI absorption range is wasted. A more efficient cure is possible with a formulation designed specifically for LED curing using a PI with more concentrated absorption in the UV-A range.

New LED Innovation

Last year, Sherwin-Williams announced a
new LED innovation aimed at manufac-
turers within the wood finishing industry
– Full Curing LED. This breakthrough
technology makes it possible to imple-
ment LED throughout the entire cur-
ing line, allowing for even more energy
savings and quality improvements than
before.
“We´ve been working toward a solu-
tion like this since we first introduced
LED curing in 2012. However, there
was always a problem with unwanted
yellowing effects due to difficulties with
the topcoat. For a while, it seemed that
a combination of LED and UV lamps
was the only way to go, but we pushed
forward and the R&D division finally
came up with the right formula to make
it work. It’s now pos-
sible to use LED
lamps in every
step of the cur-
ing process,
eliminating
the need for
conventional
UV lamps al-
together. This will
allow for a much more effec-
tive production”, says Lars Sandqvist,
Sr. Technical Application Manager at
Sherwin-Williams.
Due to the low curing temperatures
of LED, it´s possible to coat materials
such as pine and other resinous woods
with significantly lower reject rates. The
LED lamps also last thousands of hours,
which decreases the overall maintenance
cost compared to using conventional UV
lamps and, without a warm up cycle,
there is less down time. Additionally, LED
lamps do not produce high temperatures
or harmful ozone, which reduces the en-
vironmental impact. Several companies
worldwide have already implemented
LEDs in their curing lines and there are a
variety of LED solutions available today,
with interest booming.
“Our participation at the LIGNA ex-
hibition last year really reinforced our
belief that the market is ready; LED was
everywhere. It´s only logical that we take
this last step to facilitate a 100% LED
curing line. Since we conducted this as
an internal project without any client
involvement, we now have to test Full
Curing LED together with our machine
suppliers and present it to our current
LED customers. We´re very excited about
this”, says Lars Sandqvist.

LED Technology Benefits

Less Heat

With no IR heat, LED curing technology significantly reduces work-piece surface temperature. With the ability to cure heat sensitive substrates, LED technology can add new capability and higher yields to coating applications.