290 likes | 475 Views
Dry, Chemical-Free Surface Treatment for Powder Coated Substrates. June 17-18, 2013 – Columbus, OH. Question:. “Is there a way to improve adhesion of two-component polyurethane adhesives to polyester- and epoxy-based powder–coated surfaces?”.
E N D
Dry, Chemical-Free Surface Treatment for Powder Coated Substrates June 17-18, 2013 – Columbus, OH
Question: “Is there a way to improve adhesion of two-component polyurethane adhesives to polyester- and epoxy-based powder–coated surfaces?” Source: Products Finishing Magazine, Powder Coating Clinic, April 2013 PC Summit, 2013
Answer: “It is possible to apply an adhesive over a powder. The challenge is to find an adhesive/powder combination that works. You need to select a powder that meets the performance and appearance properties you need, and then work with an adhesive supplier to find the correct adhesive…” Source: Products Finishing Magazine, Powder Coating Clinic, April 2013 PC Summit, 2013
Answer: “…Polyester powder is more likely to provide adhesion than epoxy powder. You can roughen the surface where you need the adhesion, but that may not be feasible. Talk to an adhesive supplier and you should be able to make it work.” Source: Products Finishing Magazine, Powder Coating Clinic, April 2013 PC Summit, 2013
Problem Statement Powder coated materials present downstream bonding issues. Potential Applications • adhesive bonding • label application • decoration (pad printing, silk screening) • foam gaskets PC Summit, 2013
Fundamentals of Paint Adhesion • The molecules in the paint film wet or flow freely over the substrate • Chemical bonds are formed at the interface • The paint film penetrates the roughness on the substrate surface, resulting in mechanical interlocking once the paint dries. Source: www.metalfinishing.com, Fundamentals of Paint Adhesion, Ed Petrie PC Summit, 2013
Surface Wetting PC Summit, 2013
Surface Energy Measurement Low Surface Energy High Surface Energy PC Summit, 2013
Surface Modification Options PC Summit, 2013
Is There a Perfect Solution? PC Summit, 2013
* ions + + + + free electron e- e- * gas molecule * gas molecule (excited) e- * * * e- + + Plasma: The 4th State of Matter Plasma Solid Liquid Gas Plasma molecule fragment (high- energy) PC Summit, 2013
Flame Treatment • Low ion density • Activation only- little or no cleaning • Thermal distortion • Inconsistent-ambient conditions • Contamination • Liability – open flame • High consumable cost • Metals/mixed materials not possible PC Summit, 2013
Corona Discharge • Better ion density • Activation only- little or no cleaning • Tight application tolerances • Liability - ozone • High voltage at interface • Metals/mixed materials not possible PC Summit, 2013
Vacuum Plasma • High ion density • Cleaning & activation • Complex chemistries possible • Offline process • Not selective PC Summit, 2013
Openair™ Plasma • High ion density • Cleaning & activation • Simple inputs – power/air • In-line process • Selective treatment • Low/no voltage • No ozone • $0.10 to $0.25/hour PC Summit, 2013
Source: Guideline to Bonding Plastics, ANTEC-2013 Michael Oliveira, Henkel PC Summit, 2013
Openair™ Plasma Jet High voltage Current Ionization Gas Inner Electrode Discharge Chamber Ring Electrode (SS casing) Plasma Substrate PC Summit, 2013
* * * * * * * C C C C C C C H H H H H H H H H H H H H H O O O O O O O N N N N N N N N Attack Surface Contamination C PC Summit, 2013
* * * * * * * C C C C C C C H H H H H H H H H H H H H H O O O O O O O N N N N N N N N Remove Surface Contamination C PC Summit, 2013
H C C C C C C C H H H H H H H H H H H Form Functional Sites N * * N O N N * H O O H * O * O N N * N * N C O O PC Summit, 2013
Straight Jet • Focused plasma cleaning & activation • Long term stability • Low consumable parts • Flexible with different nozzles • Speed: up to 70m/min • Gap: 5 to 20 mm • 15 mm max treatment width PC Summit, 2013
Rotational Jet • Wide area plasma cleaning & activation • Long term stability • Low consumable parts • Flexible with different nozzles • Speed: up to 35m/min • Gap: 5 to 20 mm • 50 mm max treatment width PC Summit, 2013
Openair™-Plasma Jet Heads – Rotating Jet PC Summit, 2013
Continuous Monitoring If you can’t see the treatment, how do you know it’s there? Control the Inputs • Voltage • Amperage • Air Flow • Air Pressure • Pulse Frequency • Duty Cycle • Jet Rotation (if required) PC Summit, 2013
Advantages of Openair™ PlasmaCleaning & Activation • Reliable, repeatable, fast • No dilution effect, steady state • No expensive consumables • Surface cleaning of the complete structure of the material • In-line integration = small footprint • Economical and environmentally friendly • No change in bulk properties of substrate PC Summit, 2013
Powder Coating on Plastic! What’s Next? PC Summit, 2013
Q & A/Discussion jeff.leighty@plasmatreat.com 847.783.0622 Ext. 2121 PC Summit, 2013