Applying Plural Component Spray Presented By Art Webb

Applying Plural Component Spray Presented By: Art Webb, Naval Research Laboratory

Scope n This webinar provides an introduction and overview of plural component spray methods of applying industrial/marine protective coatings.

Learning Outcomes n 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 n Economics n Environmental Compliance n Application Readiness n Safety n Application Quality

High-Solids Coatings n For our purposes, high-solids coatings are considered to be at least 90% solids

Various Names for A and B Components A Component Base Catalyst Resin Amines Prepolymer Isocyanate Polyol Accelerator or Promoter Activator

Plural Component Coatings n. Types − e. g. , Epoxies / Polyurethanes / Polyureas n. Components of a Typical Epoxy − Component (A): Resin or Base − Component (B): Co-reactant or Curing Agent n. Curing Mechanism − Reaction of Components A and B to form a chemically crosslinked protective film

Characteristics of Two Component Epoxies n Ratio − Volume by ratio of Components A to B (i. e. . 1: 1, 4: 1) n Induction Time (Sweat-in-Time) − Time mixed components must stand to allow for initial chemical reaction prior to application n Pot Life − Time mixed components remain usable without affecting applied coating performance

Characteristics of High Solids Epoxies n. Solids by Volume n. Primer Characteristics n. Topcoat Characteristics

Characteristics of High-Solids Epoxies n Viscosity (resistance to flow) − Generally twice that of solvent based epoxies − Higher pressure required to pump and atomize − Heating coating reduces viscosity n 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 n Polyurethane Coatings − Advantages − Limitations

Characteristics of Moisture. Cured Urethane Coatings n Moisture-Cured Urethane (MCU) Coatings − Advantages − Limitations

Polyurethane Advantages n Turn Around Time n 100% Solid n Ability to Apply During Winter Months n Unique “Self-Inspecting” Property

Plural Component Application Process - Summary n Components A and B are power mixed/agitated separately n 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 n Both components are pumped separately in their desired proportions (flow rates) toward the spray gun n Components are combined in a manifold/mixer immediately before reaching the gun

Examples of Plural Component Spray Units A B C

Plural Component Equipment Schematic Heater B Gun 1 “B” Heated Hose to Manifold 55 gal. “B” Supply Agitator and Elevator Proportioner Mix “A” To Catalyst (B) Inlet Gun 2 Heater A “A” Inlet 55 gal. “A” Supply Agitator and Elevator To Resin (A) Inlet “B” Inlet 30: 1 Solvent Flush to Mix Manifold

System Components n Feed system n Pump/proportioning system n Hoses n Heating system n Mixing manifold system n Spray gun

Feed System

Feed Pumps

Characteristics of Pump Systems n Available Spray Pressure n Normal atomization/spray pressure n Flow rate n Compatibility of wetted parts with materials pumped n Power source

Characteristics of Pump Systems - Impact on System n Feed pumps must be of a sufficient size n Need sufficient spray pressure

Power Sources for Pumps n Air-powered supply pumps n Hydraulic supply pumps

Photo of Proportioning (Metering) Pumps Courtesy of WIWA Courtesy of Graco, Inc.

Critical Nature of Mixing Ratio n Proper Ratio n Check Ratio n Off-Ratio n Monitoring System

Unit Control Panel Remote Mountable Controls - Up to 30. 5 m Digital Heat Controls Digital Pressure Control Park “A” pump PSI or Bar Target and Actual Temp F° or C° Stop Cycle Counter Error Codes

Heated/ Insulated Hoses

Portable Unit with Spray Hose

Heating System (In-line)

Coating Material Temperature Requirements n Too low a temperature will restrict flow n Too 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 Points n Storage Temperature n Reservoir/supply container n Pump n Manifold n Gun

Mixing Manifold System n The mix manifold is where the material components A & B are brought together to be mixed at proper ratio.

Manifold Mixer

Mix Manifold System n Mix Manifold Assembly and Connections n Mixing Manifold Maintenance & Care

Mixing Block (isolated)

Solvent Purge System n Used to flush mixed components from manifold, spray hose, and gun

Purging of Mixed Components After Interruption of Work n Mixed components must be solvent purged or flushed from the gun whenever application is interrupted for several minutes

Equipment Clean-up n 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 Atomization n Atomization occurs in airless spraying when coating is forced under high pressure through tip orifice

Factors Affecting Spray Pattern Size of tip orifice (typically 0. 017 to 0. 021) n Wear of tip n Fan angle n Distance of gun from substrate being painted

Tip Wear n High solids coatings wear tips more rapidly than traditional solvent borne coatings

Diagram of Changes in Airless Spray Pattern with Tip Wear

Application Thickness n Theoretically, wet film thickness of highsolids coatings is the same as the dry film thickness n Area with restricted working space can easily become coated with excessive film builds

Matching of System Components n All system components should be properly matched for size and capacity n The heating system should also match the components n Clean, lubricate and otherwise maintain equipment parts for best service n Never modify equipment without consulting with manufacturer

Plan the Work n Application team should be briefed about planned work before beginning it.

Summary n In 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?