Powder Coatings:

1. Powder Coatings: History, Types, and Applications James Baker

2. Outline • Conventional Coatings • Powder Coating History • Types of Powder Coatings • Advantages/ Disadvantages • Applications

3. Lacquers -Lack of durability -High maintenance -High VOC content + Fast Drying +Deep shine

4. Enamels • Long drying times • Oxidation + Good flexibility and durability + Cross-linking

5. Urethanes + Dry fast + Very durable and flexible - Isocyanate component is highly toxic

6. History • Late 1940’s- Flame spraying of thermoplastic powder developed • 1955- Dr. Erwin Gemmer patents fluidized bed application • 1962- Electrostatic spray method introduced • Late 1970’s- rapid growth in powder use in Europe • Early 1980’s- rapid growth in North America and Japan • Today- • Fastest growing finishing technology in North America • Powder coatings account for >10% of all industrial finishing applications • Powder coating engine blocks for automobiles is the largest volume job in the history of the powder industry

7. 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

8. 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

9. Powder Coating Types • In general powder coatings offer excellent: • Hardness • Corrosion protection • Chemical resistance

10. 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

11. Urethane Polyesters + Very good flexibility and weatherability + outstanding thin film appearance

12. Acrylics + Excellent color, gloss, weatherability + Excellent thin film appearance • Fair flexibility and corrosion resistance

13. TGIC Polyesters + Excellent exterior durability - Exposure limits when spraying due to TGIC

14. Advantages of Powder Coating • No VOC emissions • Improved durability • Over-spray may be reused • Lower operating and maintenance costs for finishing lines

15. 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

16. Automotive Applications • Engine Blocks • Frames • Suspension and Wheels • Trim and Moldings • BMW and Volvo have developed powder clearcoats • Chrysler, Ford, and GM have powder clearcoats in development

17. Metal 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 Other Common Applications

18. References • Industrial Paint and Powder Magazine http://www.ippmagazine.com/CDA/ArticleInformation/features/BNP__Features__Item/0,6897,119461,00.html • 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- http://www.powdercoating.org/media/pressreleases/