The Powder Coating
Technology
What is Powder Coating?
Powder coating is a
finishing technology where a decorative and highly protective coating can be
applied to a wide range of products. The process involves spraying finely
ground, electro-statically charged particles of pigment and resin onto a
surface to be coated. The charged powder particles adhere to the electrically
grounded surfaces and then are heated and fused into a smooth coating in a
curing oven.
 |
Fig. 1.1: Spray gun for
powder coating.
What
does Powder Coating Offer?
·
Superior
Appearance
·
Mechanical
Resistance Properties
·
Corrosion
Resistance
·
Solvent
Resistance
·
Highly
durable: chip, scratch, fade and wear resistant
·
Ready
to use and require no mixing, solvent or catalysts
Liquid Finishes vs. Powder Coating
·
Solvents
Necessitate venting, filtering, and solvent recovery systems that is not
necessary in powder coating.
·
Liquid
Spray Coating achieve material usage of 20-85% while powder coating has a
Material usage of 95-98%
·
Liquid
overspray is lost in filters while 99% of Powder overspray is collected and
reused
Fig.
1.2: The powder coating lab.
Powder Types
·
Thermoplastic:
o
Powder
melts and flows to form a film.
o
Continues
to have the same chemical composition when it solidifies
o
Will
re-melt when heated.
o
Thick
coating surface and not in same market as liquid paint.
o
Examples
Ø Polyethylene
Ø Polypropylene
Ø PVC
·
Thermoses:
o
Powder
melt flow and cross-link chemically to products
o
Cured
coatings have different chemical structures than the basic resigns.
o
Will
not re-melt when reheated
o
Can
produce thin paint like coating of 0.001 – 0.003 inch thick.
o
Examples
Ø Epoxy
Ø Hydroxyl
polyester (urethane)
Ø Acrylic Urethane
Process
Fig. 1.3: The
powder coating gun.
Fig. 1.4: Stages
of powder coating.
By : Anshul Gupta
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