june 17-18, 2013 – columbus, oh. question: “is there a way to improve adhesion of two-component...
TRANSCRIPT
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 adhesivesto polyester- and epoxy-based
powder–coated surfaces?”
PC Summit, 2013
Source: Products Finishing Magazine, Powder Coating Clinic, April 2013
Answer:“It is possible to apply an adhesive over a powder.
The challenge is to find an adhesive/powdercombination that works. You need to select a powder
that meets the performance and appearanceproperties you need, and then work with an adhesive
supplier to find the correct adhesive…”
PC Summit, 2013
Source: Products Finishing Magazine, Powder Coating Clinic, April 2013
Answer:“…Polyester powder is more likely to provide adhesion
than epoxy powder. You can roughen the surfacewhere you need the adhesion,but that may not be feasible.Talk to an adhesive supplier
and you should be able to make it work.”
PC Summit, 2013
Source: Products Finishing Magazine, Powder Coating Clinic, April 2013
Problem StatementPowder coated materials present
downstream bonding issues.
Potential Applications• adhesive bonding• label application
• decoration (pad printing, silk screening)• foam gaskets
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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.
PC Summit, 2013
Source: www.metalfinishing.com, Fundamentals of Paint Adhesion, Ed Petrie
Surface Wetting
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Surface Energy Measurement
Low Surface Energy High Surface Energy
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PC Summit, 2013
Contamination
Anti-oxidants
Cross-linkers
Fillers
UV Modifiers
Pigments
Slip Agents, Waxes
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Wet
Che
mic
al CleanerSolventPrimer
Mec
hani
cal
ScuffSandBlast
Phys
ical
FlameCoronaPlasma
Surface Modification Options
Is There a Perfect Solution?
PC Summit, 2013
• Reliable• Repeatable• Easy to useRobust Process
• In-Line• Easy to automate• Easy to integrateLabor Reduction
• No chemicals• No ozone• No wasteSafe
• Material savings• Labor savings• Reduced liabilityCost Effective
Plasma: The 4th State of Matter
Solid Liquid Gas
+
+
**
e-
e-
e-
**
gas molecule
*gas molecule(excited)
*
ionsfree electron
+e-
–
+–
–
+
+
Plasma
moleculefragment (high-energy)
Plasma
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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
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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
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Vacuum Plasma High ion density Cleaning & activation Complex chemistries possible Offline process Not selective
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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
PC Summit, 2013
Source: Guideline to Bonding Plastics, ANTEC-2013Michael Oliveira, Henkel
Openair™ Plasma Jet
Substrate
Inner Electrode
Ionization GasHigh voltage Current
Plasma
Ring Electrode (SS casing)
Discharge Chamber
PC Summit, 2013
Attack Surface Contamination
C
O
O
N*
* *
*N N
O
N
N
N
ON
O
O
N
O
*
*
*
C C C C C C C
HHHHHHH
H H H H H H H
PC Summit, 2013
Remove Surface Contamination
C
C C C C C C C
HHHHHHH
H H H H H H H
O
O
N*
* *
*N N
O
N
N
N
ON
O
O
N
O
*
*
*
PC Summit, 2013
C O
N
C C C C C C C
HHHHH
H
H
H
H
H
H
H H H
OO
O
O
O
O N
N
N
N
NN
N
*
**
*
*
**
Form Functional Sites
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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 & activationLong term stabilityLow consumable partsFlexible with different nozzlesSpeed: up to 35m/minGap: 5 to 20 mm50 mm max treatment width
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Openair™-Plasma Jet Heads – Rotating Jet
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Continuous MonitoringIf you can’t see the treatment, how do you know it’s there?
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• Voltage• Amperage• Air Flow• Air Pressure• Pulse Frequency• Duty Cycle• Jet Rotation (if required)
Control the Inputs
Reliable, repeatable, fastNo dilution effect, steady stateNo expensive consumablesSurface cleaning of the complete structure of the
materialIn-line integration = small footprintEconomical and environmentally friendlyNo change in bulk properties of substrate
Advantages of Openair™ PlasmaCleaning & Activation
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Powder Coating on Plastic!
PC Summit, 2013
What’s Next?
•Plasma Cleaning & Activation
•Conductive Agent
•Powder Application
•Heat (IR or Convection)
•UV Cure
