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Powder Coatings:. History, Types, and Applications. James Baker. Outline. Conventional Coatings Powder Coating History Types of Powder Coatings Advantages/ Disadvantages Applications. Lacquers. -Lack of durability -High maintenance -High VOC content. + Fast Drying + Deep shine. - PowerPoint PPT Presentation
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Powder Coatings:History, Types, and Applications
James Baker
Outline
Conventional Coatings Powder Coating History Types of Powder Coatings Advantages/ Disadvantages Applications
Lacquers
-Lack of durability-Lack of durability-High maintenance-High maintenance-High VOC content-High VOC content
+ + Fast DryingFast Drying++Deep shineDeep shine
EnamelsEnamels
- Long drying timesLong drying times- OxidationOxidation
+ + Good flexibility and Good flexibility and durabilitydurability+ + Cross-linkingCross-linking
UrethanesUrethanes
+ Dry fast+ Dry fast+ Very durable and + Very durable and
flexibleflexible
- Isocyanate - Isocyanate component is highly component is highly toxictoxic
HistoryHistory Late 1940’s- Flame spraying of thermoplastic powder developedLate 1940’s- Flame spraying of thermoplastic powder developed 1955- Dr. Erwin Gemmer patents fluidized bed application1955- Dr. Erwin Gemmer patents fluidized bed application 1962- Electrostatic spray method introduced1962- Electrostatic spray method introduced Late 1970’s- rapid growth in powder use in EuropeLate 1970’s- rapid growth in powder use in Europe Early 1980’s- rapid growth in North America and JapanEarly 1980’s- rapid growth in North America and Japan Today- Today-
• Fastest growing finishing technology in North AmericaFastest growing finishing technology in North America• Powder coatings account for >10% of all industrial finishing Powder coatings account for >10% of all industrial finishing
applicationsapplications• Powder coating engine blocks for automobiles is the largest volume job Powder coating engine blocks for automobiles is the largest volume job
in the history of the powder industryin the history of the powder industry
Application Methods
Electrostatic spray- Most common method High voltage, low amperage field generated by spray
gun imparts electrostatic charge on powder Charged powder sticks to grounded substrate Object is heated in oven to cure, powder flows to form
a continuous film
Application Methods (cont) Fluidized Bed
Heated object is dipped into an air fluidized bed of powder Electrostatic Fluidized Bed
Similar to above, but powder particles are charged Flame Spray
Powder is air fed through a propane flame Molten polymer is deposited on substrate Suitable for non-conductive substrates or very large objects
Tribocharge Similar to electrostatic spray, but no high-voltage system Friction between powder and barrel induces weak static charge
Powder Coating TypesPowder Coating Types
In general powder coatings offer excellent:In general powder coatings offer excellent:• HardnessHardness• Corrosion protectionCorrosion protection• Chemical resistanceChemical resistance
Epoxy
+ Excellent flexibility- Fair resistance to over-
baking- Poor exterior durability
(low UV resistance) Epoxy-urethane hybrids
• Similar to epoxy+ Improved flow
properties- Lower hardness
OOH2C C
H
H2C
OHO O
H2C
O
H2C
O
Urethane Polyesters
+ Very good flexibility and weatherability
+ outstanding thin film appearance
RN
CO
R'O
NCO
* O
n
Polyurethane
N
N
N
O
OO
NC
O
NC
ON
CO
tris(6-isocyanatohexyl) isocyanurate
O CO
R'R CO
On
Polyester
Acrylics
+ Excellent color, gloss, weatherability
+ Excellent thin film appearance
- Fair flexibility and corrosion resistance
C C
CH3
C
**
OOCH3
H
H n
Poly(methyl methacrylate)
TGIC Polyesters
+ Excellent exterior durability
- Exposure limits when spraying due to TGIC
N
N
N
O
O
O
O
O
O
TGIC
O CO
R'R CO
On
Polyester
Advantages of Powder Coating
No VOC emissions Improved durability Over-spray may be reused Lower operating and maintenance costs for
finishing lines
Disadvantages
Material must be able to withstand curing temperatures, >260º F (~125ºC)
Forming films thinner than 1.5mil is difficult Electrostatic spraying may only be used for
electrically conductive materials Powder is highly flammable Conversion from conventional to powder coating
line requires large capital investment
Automotive ApplicationsAutomotive Applications
Engine BlocksEngine Blocks FramesFrames Suspension and WheelsSuspension and Wheels Trim and MoldingsTrim and Moldings
BMW and Volvo have developed powder clearcoats BMW and Volvo have developed powder clearcoats Chrysler, Ford, and GM have powder clearcoats in developmentChrysler, Ford, and GM have powder clearcoats in development
Other Common ApplicationsMetal Objects Appliances Highway signs Tools Lawn and garden
equipment Office furniture A/V furniture and
equipment Sports equipment
Non-metal Objects Home-office furniture Kitchen cabinets Sinks/shower stalls Ceramics
ReferencesReferences• Industrial Paint and Powder Magazine Industrial Paint and Powder Magazine
http://www.ippmagazine.com/CDA/ArticleInformation/features/BNP__Features__Item/http://www.ippmagazine.com/CDA/ArticleInformation/features/BNP__Features__Item/0,6897,119461,00.html0,6897,119461,00.html
• North Carolina DENR Division of Pollution Prevention and Environmental Assistance North Carolina DENR Division of Pollution Prevention and Environmental Assistance http://www.p2pays.org/ref/01/00777/alternat.htm#General%20Description%203
• The powder coating institute- The powder coating institute- http://www.powdercoating.org/media/pressreleases/