By Kevin Biller
The powder coating industry had
been asleep for nearly a decade.
Two recessions, off-shoring,
over-capacity and slim profit margins
cast this outstanding coating technology
into a funk. R&D budgets were decimated
and far too many experts either
retired or got out of the business.
Fortunately, in the last four to five
years the industry has experienced a
resurgence in innovation. Technologists
are finally heeding the call to
develop new materials and processes to
meet the emerging needs of the manufacturing
The following is a summary of
some of the latest trends in the manufacturing
sector and the innovations
powder coating technologists are
developing to meet these transformations.
Powder on Plastic
Manufacturing processes are evolving
and not surprisingly, methods and materials to coat manufactured goods
are evolving as well. The use of lighter
weight materials in fabrication continues
to displace traditional substrates
like steel and aluminum and hence
coating technology must advance to
meet the finish required for these
Plastic substrates encompass a wide
spectrum of materials and processes.
Each product has its own unique
characteristics that strongly influence
which coating technology is most suitable
for protection and aesthetics.
How does powder coating fit into
these trends? Some conventional
powder technology is suitable for high
temperature plastics. The only requirements
are making the plastic surface
conductive and achieving adhesion.
These requirements are rather easily
Low Temperature Cure
LTC powders have been touted as
energy savers however their real value
is in delivering a coating for heat sensitive
substrates. For years these types
of powder coatings have been applied
to medium density fiberboard. There
are basically two schools of thought.
One uses LTC thermoset powder and
the other uses UV curable powder
There are advantages and disadvantages
with both. Thermoset types
require higher temperatures and
longer process time but can be used
on complex part geometries with ease.
UV curable types can be processed
at relatively low temperatures (e.g.
~220ºF) and very short time cycles
(30 to 90 seconds) however require
line-of-sight curing with high intensity
UV light. This is a compact but more
complex process requiring a high level
Bio-Based Polymer Systems
Formulating powder resins with renewable
chemical feedstocks is a laudable
goal and many researchers have
attempted this. Derivatives of soybean
oil, corn, sugar cane and cellulose have
been incorporated into polyester resin
backbones with limited success. The
state-of-the-art is deficient in providing
a cost/performance balance that is acceptable
to the coatings industry. These
lab synthesized products are more
costly than petroleum based counterparts
and provide less durable coatings.
Regardless research continues in this
area with the hope of developing more
High Density Low Velocity
One of the most gratifying developments
in powder coating application
technology is the new feed systems
that deliver more powder with less air.
This accomplishes a few very beneficial
properties. The powder feed to the gun
is more consistent with virtually no
surging and spitting. In addition the
lower air velocity makes penetration
into tight corners and Faraday cages
significantly easier. This development
which is available from all the major
equipment suppliers gives a more even
and consistent film thickness range
which translates into better economics
and higher finish quality.
Robotic application of powder
coatings has been around for decades
however recent advances in design and
software have made this once cost prohibitive
technique affordable to a wider
market. Robot manufacturers have developed
high quality units that sell for
under $50,000 making them accessible
to mid-range finishers. In addition the
software to operate this equipment has
been made much more user friendly.
Hence the high capital cost and need
to employ a full-time robotic engineer
have vanished which will help introduce
this technology beyond the high
end OEM finishing shops and into the
custom coater mainstream.
Powder application to non-conductive
substrates has been a bit of
a mystery for the novice coater. For
years a few shops relied on in-house
proprietary techniques to electrostatically
apply powder to their plastic
substrate of choice. Recently chemical
companies have developed new
conductivity solutions that allow for
excellent transfer efficiency of powder
coatings. These products are now
available to the coating industry.
With the availability of conductive
preps powder coating technologists
can explore novel approaches
to finish a wide variety of plastic
Infrared curing equipment
technology is seeing a renaissance
in development. A broad array of
techniques are being refined and
promoted to cure powder coatings.
The finisher now has medium, long
and short wave electric IR options to
heat and cure their powder coating.
In addition gas catalytic IR technology
has been dusted off and is being
specifically designed to cure powder
NEW TECHNOLOGY EFFECT ON
Significant changes are swirling
in the markets traditionally served
by powder coatings. The Powder
Coating Institute reports that the
(ACE), architectural, appliance and
automotive industries account for
approximately 40% of the powder
coating volume in North America.
The following will analyze some of
the major trends in these industries
and how powder coatings are affected.
Powder coatings have been well
ensconced in the European architectural market since
the early 1990s. Powder performance meets all the major
European specifications and has an excellent track record
of durability in European climates. Architectural market
penetration in North America has been significantly less
successful than that in Europe.
There are two drivers responsible for this. First the
durability requirements in southern regions of the United
States are far more stringent than most of Europe. This dictates
the use of polymer types beyond the traditional polyester
and superdurable polyester materials commonly used
to meet European durability requirements. Consequently
novel resin chemistry is needed to meet commercial quality
Fluoropolymers are the resin chemistry of choice to
meet the highest quality U.S. architectural specifications
(American Architectural Manufacturers Association 2605).
These polymers are expensive and have less of a track
record than their polyester counterparts. Second, the liquid
coating producers have served the American architectural
industry far longer than the powder producers and have
lobbied hard against powder’s incursion into their market
In spite of these barriers powder coatings have been
developed and qualified to meet the AAMA 2605 specification.
Powders capable of meeting this specification and
the lesser residential specs (AAMA 2603 and AAMA 2604)
are being sold to a few architectural product manufacturers
to coat mainly aluminum extrusion window profiles and
Recently window and door manufacturers have initiated
a move from aluminum extrusion profiles to pultruded
profiles for construction of their products. Composites
Technology magazine (May 2012) notes: “Pultruded fiberglass
windows offer greater dimensional stability, impact
resistance, strength and color fastness than the vinyl and
wood windows that still dominate the residential construction
market. But the dramatically improved thermal
performance of fiberglass windows is promising gains in
once out-of-reach commercial building construction, where
fiberglass windows are increasingly seen as an attractive
and viable alternative to aluminum windows.” Not only
do fiberglass window frames perform better dimensionally,
but they offer significantly lower thermal transmission and
require 57 times less energy to produce than aluminum
The use of fiberglass profiles in the architectural industry
is forecast to grow at double digit rates at the expense
of aluminum extrusions. The impact on powder coating
use cannot be understated. The hard-fought acceptance
of powder coatings for architectural aluminum extrusions
appears to be for an ever-shrinking market. Technologists
are now refocussing efforts on developing novel powder
solutions for pultruded profiles consisting of fiberglass
reinforced polymers. These will have to be applied to this
non-conductive substrate with a process temperature limitation.
In addition the qualification process is somewhat
complicated and lengthy.
Powder coating’s heyday in the automotive market
seems to have passed. The spectacular growth in the
1990’s has given way to market decline at the hands of
innovations in liquid coating materials and processes. At
its pinnacle powder coatings were being applied as body
coats at approximately twenty-three automotive finishing
lines. This includes twenty-one primer surfacer lines and
two clear topcoat lines. Since then eleven powder lines
have been discontinued. Some are due to a consolidation of
automotive product lines and others have been replaced by
liquid paint technology.
New installations are all based on liquid paint technology.
This includes assembly plants from North America to
Europe and even Asia. The reasons? Liquid paint technology
has evolved into a “compact” process by applying
wet-on-wet processes that have eliminated one or more
curing steps. In addition waterborne paint technology
has been developed that meets the VOC (volatile organic
compound) targets established by the EPA. Consequently
non-powder technology is available that satisfies both economic
and environmental requirements of the automotive
Powder coatings used as body coats will continue to
lose automotive market share. A sliver of good news is that
automotive wheels production is growing and continues to
use powder as a finish.
In the quest for lighter and more fuel efficient vehicles
the overall composition of automotive products is becoming
more and more polymer based at the expense of steel
and aluminum. For powder coatings to experience any
growth in the automotive industry new technologies for
plastic substrates will have to be developed and refined.
Agricultural and Construction Equipment (ACE)
Powder coatings have been used to finish ACE components
for decades. Most of the coating process is carried
out at certified custom coater shops using products
approved by the respective OEM’s. As with the automotive
industry engineers are transitioning components traditionally
built out of sheet metal and metal castings to injection
molded and compression molded parts. This again displaces
powder coating finishing processes with liquid paint systems.
For powder coating technology to grow in the ACE
world low temperature cure products for plastic substrates
need to be developed and optimized for production.
The appliance industry was one of the first adopters
of powder coatings back in the 1980’s when their industry
was replacing the inefficient and energy consumptive
porcelain enameling process. Powder coatings have
enjoyed a solid share of the appliance coating market ever
since. Some of this share has been eroded by high quality
coil coatings mainly for kitchen and laundry equipment
As the appliance industry replaces components with
molded and compressed plastic substrates. In some cases
these plastics are high temperature materials and can be
made conductive and coated electrostatically with powder.
However the lower temperature resistant commodity plastics
will require innovative powder technology.
The methods and materials of manufacture are changing.
Metal bending, casting and extrusion are being
replaced by injection molding, compression molding and
pultrusion. Powder coating technology will have to evolve
to meet the needs of these new processes and materials.
High temperature resistance plastics such as Nylon,
PMMA, PEEK and to a lesser extent fiberglass reinforced
polymers (FRP) can be powder coated with relatively
conventional powders with minimal process modifications.
However it will take significant effort to develop
novel powder materials to finish commodity type plastics.
Material scientists and equipment engineers are diligently
working to make this a reality in the not-to-distant future.
Kevin Biller is technical editor of Powder Coated Tough and
the president of The Powder Coating Research Group. He can be
reached at firstname.lastname@example.org.