Applying Plural Component Spray Applying Plural Component Spray Presented By: Art Webb, Naval...
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Transcript of Applying Plural Component Spray Applying Plural Component Spray Presented By: Art Webb, Naval...
Applying Plural Component Applying Plural Component SpraySpray
Presented By: Art Webb, Naval Presented By: Art Webb, Naval Research LaboratoryResearch Laboratory
ScopeThis webinar provides an
introduction and overview of plural component spray methods of applying industrial/marine protective coatings.
Learning Outcomes At the end of this webinar the student will
be able to: Recognize the use of plural component
application Define a high solids coating Identify plural component application systems
available Recognize the methods for properly mixing
material or coating components (e.g., Part A, Part B)
Why the Interest in Plural Component Application
EconomicsEnvironmental ComplianceApplication ReadinessSafetyApplication Quality
High-Solids CoatingsFor our purposes, high-solids coatings
are considered to be at least 90% solids
A Component B Component
Base Catalyst
Resin Amines
Prepolymer Isocyanate
Polyol Accelerator or Promoter
Activator
Various Names for A and B Components
Plural Component CoatingsTypes
e.g., Epoxies / Polyurethanes / Polyureas
Components of a Typical Epoxy Component (A): Resin or Base Component (B): Co-reactant or Curing
Agent
Curing Mechanism Reaction of Components A and B to
form a chemically crosslinked protective film
Characteristics of Two Component Epoxies Ratio
Volume by ratio of Components A to B (i.e.. 1:1, 4:1)
Induction Time (Sweat-in-Time) Time mixed components must stand to allow
for initial chemical reaction prior to application
Pot Life Time mixed components remain usable
without affecting applied coating performance
Characteristics of High Solids Epoxies
Solids by Volume
Primer Characteristics
Topcoat Characteristics
Characteristics of High-Solids Epoxies Viscosity (resistance to flow)
Generally twice that of solvent based epoxies Higher pressure required to pump and atomize Heating coating reduces viscosity
Pot Life Measured in minutes vs. hours (ex. 45 minutes
@ 77°F) Exothermic reaction (heat generated by mixed
components in container)
Characteristics of Polyurethane Coatings
Polyurethane Coatings Advantages Limitations
Characteristics of Moisture-Cured Urethane Coatings
Moisture-Cured Urethane (MCU) Coatings Advantages Limitations
Polyurethane Advantages
Turn Around Time100% SolidAbility to Apply During Winter
MonthsUnique “Self-Inspecting” Property
Plural Component Application Process - Summary Components A and B are power mixed/agitated
separately Components are heated to reduce their
viscosities and re-circulated uncombined from the reservoir to the mixer and back until the desired temperatures and viscosities have been reached and maintained
Both components are pumped separately in their desired proportions (flow rates) toward the spray gun
Components are combined in a manifold/mixer immediately before reaching the gun
Examples of Plural Component Spray Examples of Plural Component Spray UnitsUnits
A B C
55 gal. “B” SupplyAgitator and Elevator
55 gal. “A” SupplyAgitator and Elevator
To Catalyst (B) Inlet
To Resin (A) Inlet
30:1 Solvent Flush toMix Manifold
Heated Hose to Manifold
“A” Inlet
Gun 2
Mix
Gun 1
“B” Inlet
“B”
“A”
Proportioner
Heater A
Heater B
Plural Component Equipment SchematicPlural Component Equipment Schematic
System Components
Feed systemPump/proportioning systemHosesHeating systemMixing manifold systemSpray gun
Feed System
Feed Pumps
Characteristics of Pump SystemsAvailable Spray PressureNormal atomization/spray pressure Flow rate Compatibility of wetted parts with
materials pumpedPower source
Characteristics of Pump Systems - Impact on SystemFeed pumps must be of a sufficient
size Need sufficient spray pressure
Power Sources for PumpsAir-powered supply pumpsHydraulic supply pumps
Photo of Proportioning (Metering) Pumps
Courtesy of WIWA
Courtesy of Graco, Inc.
Critical Nature of Mixing RatioProper RatioCheck RatioOff-Ratio Monitoring System
Unit Control Panel
Digital Heat Controls Digital Pressure Control
Cycle Counter
PSI or Bar
F° or C°
Park “A” pump
Target and Actual Temp
Error Codes
Stop
Remote Mountable Controls - Up to 30.5 m
Heated/ Insulated Hoses
Portable Unit with Spray Hose
Heating System (In-line)
Coating Material Temperature Requirements
Too low a temperature will restrict flowToo low a temperature may also cause
amine blush or amine bloom as it is sometimes called
Amine Blush on Steel
Taking Material Temperature Using Infrared Gun
Critical Material Temperature Check PointsStorage Temperature Reservoir/supply container Pump Manifold Gun
Mixing Manifold System
The mix manifold is where the material components A & B are brought together to be mixed at proper ratio.
Manifold Mixer
Mix Manifold SystemMix ManifoldMix Manifold Assembly and
ConnectionsMixing Manifold Maintenance & Care
Mixing Block (isolated)
Solvent Purge SystemUsed to flush mixed components
from manifold, spray hose, and gun
Purging of Mixed Components After Interruption of WorkMixed components must be solvent
purged or flushed from the gun whenever application is interrupted for several minutes
Equipment Clean-up Plural-component application
equipment must be thoroughly cleaned after use, especially interiors of pumps, manifold, hoses, guns and tips
Cut-away of plural component impingement gun with component hoses joined at the tip
Airless Spray Gun
Proper AtomizationAtomization occurs in airless
spraying when coating is forced under high pressure through tip orifice
Factors Affecting Spray Pattern Size
Size of tip orifice (typically 0.017 to 0.021)
Wear of tipFan angleDistance of gun from substrate
being painted
Tip WearHigh solids coatings wear tips more
rapidly than traditional solvent borne coatings
Diagram of Changes in Airless Spray Pattern with Tip Wear
Application ThicknessTheoretically, wet film thickness of
high-solids coatings is the same as the dry film thickness
Area with restricted working space can easily become coated with excessive film builds
Matching of System Components All system components should be
properly matched for size and capacity The heating system should also match the
components Clean, lubricate and otherwise maintain
equipment parts for best service Never modify equipment without
consulting with manufacturer
Plan the WorkApplication team should be briefed
about planned work before beginning it.
SummaryIn this Unit, we covered:
Why industrial/marine customers are considering use of plural component spray technology to apply 100% solids coatings
Brief introduction to high solids material Plural component application systems Mixing methods
Questions?