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Epoxy Powder Coating

Epoxy Powder Coating. EMAC 276 April 15, 2009 Alexander Frayna, Leben Tefera , Amol Shetti , Lyle Zyra Case Western Reserve University, Cleveland OH . Background. Coating Covering aimed to improve surface properties or appearance Applied as a liquid, gas, or solid Powder Coating

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Epoxy Powder Coating

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  1. Epoxy Powder Coating EMAC 276 April 15, 2009 Alexander Frayna, LebenTefera, AmolShetti, Lyle Zyra Case Western Reserve University, Cleveland OH

  2. Background Coating Covering aimed to improve surface properties or appearance Applied as a liquid, gas, or solid Powder Coating Durable finishing method for metals Uses dry, powdered plastic Heat-fused onto surface Epoxies Thermosetting Polymer Excellent adhesion, chemical and heat resistance, mechanical properties

  3. Epoxy Powder Coating Introduction in early 1960’s Applications and Properties Excellent protection in several environments Prevention of corrosion Heat Resistance Increased Mechanical Strength Electrical Insulation Increased adhesion

  4. Polymer Structure Diphenol + epoxide Structure of a Bisphenol A-epichlorohydrin type epoxy prepolymer Key features Number of monomers range from 0 to 25 Glycidyl ether end groups http://tinyurl.com/cfqjja

  5. Reaction Reaction step 1 Reaction step 2 http://pslc.ws/macrogcss/eposyn.html

  6. Synthesis BPA and ECH added to reactor in 1:1 ratio (slight excess of ECH) Aqueous caustic soda Reaction lasts one hour Taffy-like mass Inert solvent added to cause phase separation Solvent removed by vacuum distillation http://pslc.ws/macrog/epoxy.htm

  7. Synthesis Cross-linking between prepolymers using secondary polyamine as curing agent http://pslc.ws/macrogcss/eposyn.html

  8. Synthesis Large cross-linked network Properties of resin determined by R group of amine http://pslc.ws/macrogcss/eposyn.html

  9. Processing Coated objects are typically conductive metals Cleaning and surface preparation is essential Typical pre-treatment process includes: Clean Rinse Etch Rinse Conversion coating Demineralized rinse

  10. Powders contain resin, curing agent, and pigments Two application techniques Electrostatic gun application Fluidized bed dipping Powder is electrostatically charged before application Electrical potential difference attracts powder to metal Coatings are cured in ovens (160-210°C)

  11. Cost and Competition Typical powder coating installation (~$120,000) Includes two wash booths, one dry filter booth, four automatic guns, one manual gun, and two reciprocators Conventional solvent paint system (~$150,000) Material costs Powder- $27,000 per 1,000,000 sq.ft. Solvent- $35,000 per 1,000,000 sq.ft. Applied coating cost Powder- $3.80/100 sq.ft. Solvent- $5.66/100 sq.ft.

  12. Advantages ∙ Excellent adherence to surface ∙ High corrosion/chemical resistance ∙ Convenient Storage ∙ Environmentally Friendly: No volatile diluter or solvent ∙ Near zero waste during application: Overspray may be gathered and recycled

  13. Advantages ∙ Running/Sagging/Flow Eliminated ∙ Low gloss, matte finish ∙ F – 5H Pencil Hardness

  14. Disadvantages ∙ Difficult to produce smooth, thin layer -Orange peel texture due to particle size ∙ UV degradation - chalking -less color retention/fade resistance -White coatings tend to ‘yellow’ -Mostly for indoor use/out of sun ∙ High energy consumption in processing

  15. RecentTechnologies ∙ Supercritical carbon dioxide used as solvent, eliminating the melt-mixing step and significantly reducing processing temperature. (Ferro, 1995) ∙ Electromagnetic brush coating (DSM Resins, 2004) ∙ Increased running speed ∙ Reduce Cost ∙ Decrease environmental impact ∙ Meet demand of high-tech market

  16. Thanks! References 1. Attar, M., Naderi , R., Moayed, M., (2005). Investig. on effect of various surface prep. on corrosion perform. of powder coated steel by EIS., Materials and Corrosion, 56, No.5, 325-328. 2. Li, G., Yuan, C., Chen, B. (2007). Explosion risk eval. during production of coating powder, J. of Haz. Mat., 149, 515-517. 3. Lothongkum, A., Nonthapone, R. (2006). Powd. charac. and coating conditions of fresh and reused polyester resins for electrostatic powd. coating: powd recycling and loss prev., Adv. Powd. Technol., 18, No.2, 175-186. 4. Misev, T., van derLinde, R. (1997). Powd. coatings technol.: new dev. at the turn of the century.. Progress in Organic Coatings. 34, 160-168. 5. Parra, D., Mercuri, L., Matos, J. (2001). Therm. behav. of the epox. and polyester powd. coat. using thermogravimetry/differential therm. anal.. Thermochimicaacta. 368, 143-151. 6. Shah, U., Zhang, C., Zhu, J. (2005). Compar. of electrostatic fine powd. coat. and coarse powd. coat. by numerical sim., J. of Electrostatics. 64, 345-354. 7. Stevens, M. Polymer Chemistry: An introduction. Oxford, New York. (1999). pp. 326-327.

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