Polyurea is a truly remarkable coating , lining and joint sealant technology and can be used for a wide variety of applications. Polyurea coatings and linings are commonly applied over concrete and steel for corrosion protection and abrasion resistance. They also have numerous advantages over conventional materials due to their extremely fast setting times, high elongation, extreme resistance to atmospheric attack and their durability abrasion characteristics.
All About Polyurea
Polyurea is truly a remarkable coatings, linings and joint sealant technology. It is being used successfully for so many different applications today. Polyurea coatings and linings are more commonly applied over concrete and steel for corrosion protection and abrasion resistance.
They also have tremendous advantages over conventional materials for joint fill and caulk applications due to their fast set nature, high elongation and durability/abrasion characteristics. Polyurea can be molded and shaped by spraying it into molds.
Similarly, polyurea is also used as hard coat protective shell over expanded polystyrene (EPS) for architectural molded fascia applications.
The markets and applications are endless and rapidly on the rise. Polyurea’s future uses are limited only to one‟s imagination!
The main issue everyone must understand is that Polyurea by name is not a specific coating system or a specification, it is a description of a polymer TECHNOLOGY. A great technology that boasts so many different formulations and physical property ranges. There are pure polyureas (defined by the PDA) and there are hybrid polyurea systems, each possessing their own characteristics, advantages and disadvantages.
Polyurea cannot solve your protective coating or joint fill needs by itself. It must be specified and installed in combination with proper surface preparation and primers, correct manufacturer‟s material formulation, proper equipment, quality control inspection and trained applicators.
The content objective of this website is to bring real life polyurea information, success and failures into perspective. Users and specifiers must take into consideration that the proper combination of formulation, spray equipment, surface preparation, primers, training and application procedures is what leads to polyurea success.
Improper training, under-rated equipment and lack of material/substrate compatibilities and preparation is what leads to polyurea failure, and for that matter, failure of any protective coating and lining system. Always follow the system manufacturer’s written guidelines for the best results.
Polyurea Advantages and Benefits
No VOC‟s and Little to No Odor
Some Systems are USDA and Potable Approved
Weather Tolerant: Cures at -25ºF to >300ºF even in High Humidity Excellent Resistance to Thermal Shock
Flexible: Bridges Cracks Waterproof, Seamless and Resilient
Unlimited Mil Thickness in One Application Spray, Hand Mix and Caulk Grade Materials
Excellent Bond Strengths to Properly Prepared Substrates Resistant to Various Solvents, Caustics and Mild Acids Low Permeability, Excellent Sustainability
Markets and Applications for Spray Polyurea
Polyurea is a remarkable technology with a range of uses limited only by your imagination. As with any coating system, proper surface preparation, correct application equipment and the use of compatible primers is required. Read on to see where and how polyureas are being used successfully around the globe.
Pipe / Pipeline Coatings & Linings
Polyurea Coatings and linings are increasingly being used to protect steel pipes from corrosion. Polyurea has demonstrated its ability to last longer than paint and maintenance services and costs are reduced. Polyurea is a great protective coating system for pipes that are insulated with polyurethane foam. Polyureas are also being used to line the inside of water and sewer pipes for infrastructure rehabilitation work.
Polyurea’s ability to outlast paint and fight off corrosion is a major reason these systems are being specified for bridge deck and structure coating by State DOT’s around the nation. The most common applications of polyurea coatings on bridges are over steel and concrete.
Joint Fill / Caulk
Polyurea is being successfully used as a multi-purpose joint fill, caulking and sealant material. It can provide a flexible, durable, weather-tight and traffic resistant seal for all types of building joints, such as expansion joints and control joints in masonry floors, perimeter joints, panels and doors, water reservoirs, etc. It has
excellent crack-bridging properties with high elongation and tensile strength. The fast cure time and insensitivity to moisture allows for a quicker installation with a wider application window. Proper surface preparation and substrate condition is always necessary.
Polyurea coatings protect steel tanks from corrosion, chemicals, and other natural weather and jobsite elements. With proper surface preparation, substrate condition, formulation choice, primers, and installation procedures, polyurea goes on fast and stays on long. Polyureas are great for extending the life of older tanks and can offer limited structural characteristics as well. These systems can be applied during primary construction or in a retrofit environment. With their fast cure times they are ideal for retrofit since down time is significantly minimized compared to some competing materials.
Polyurea linings are resistant to many chemicals and industrial liquids. With their fast application advantages and ability to adhere to properly prepared substrates, polyureas are ideal for new storage tank primary lining and rehabilitation projects.
Above the water line and below, polyurea can be very effective in protecting steel, aluminum, and fiberglass in a variety of water sport and commercial marine applications. From sound attenuation for fishing canoes, to fish hold liners, to hull protection and bilge liners, polyureas are used in many abrasion, chemical and corrosion resistant marine applications
Polyurea coatings make an excellent protective covering for polyurethane foam roofs. Polyurea can be formulated to meet specific performance requirements due the wide range of physical properties that can be formulated. Some systems have the “Cool Roof” rating for color and reflectivity. These reflective coatings can help reduce the amount energy consumption buildings use for heating and cooling. The fast cure time and insensitivity to moisture allows for a quicker installation with a wider application window. Proper surface preparation and substrate condition is always necessary.
Waste Water Treatment Linings
Fast cure, chemical and abrasion resistant, concrete primary and secondary containment linings. What more can you say about Polyurea applications for the Wastewater Treatment industry?
Manhole & Sewer Linings
Polyurea manhole lining is a rapidly growing market due to polyurea‟s ability to solve many current issues with groundwater infiltration and installation speed. Many municipal and private water systems are in great need of lining and structural repair. With proper surface preparation and substrate conditions, primers and Polyurea can be applied fast to return the cavity to service faster than most competitive systems. Polyurea‟s ability to form a monolithic, durable liner protects the cavity from sediment and groundwater infiltration into municipal wastewater systems.
Truck Bed Liners
Polyurea truck bed liners form a durable, water and air-tight, permanent liner for the exterior of pick up trucks, dump trucks and steel containers. These durable, easy to clean and abrasion resistant liners protect utility trucks from their harsh duty environments. They also protect against rust and corrosion from damaging trucks and containers. Polyurea liners can also be applied in varied thickness to meet any specific application demand. Sprayed on truck bed liners are available in many colors and can be wrapped over the top edge of the truck bed to provide added protection from impact and abrasion.
Theme Park & Decorative Design
Theme Parks often use polyurea as a protective coating over foam, EPS and other structures to create ornamental building fascia, themed characters, artificial rocks, pools and environments.
Flooring and Parking Decks
Polyurea flooring systems are most popular for their rapid turnaround installation capabilities. Other benefits are available with polyurea flooring systems as well. Polyureas are very durable and great for use in areas of high traffic. They are used in clean/dirty rooms as a waterproofing and protective coating from daily pressure cleaning operations. Polyurea can be formulated to be flexible and resilient allowing the flooring system to protect objects that may fall upon them.
Aquariums have also found benefits with polyurea. The ability to form to properly prepared custom shaped walls and themed ornaments make this system desirable. A spray applied, water resistant liner, available in a variety of colors with rapid return to service installation is why facility owners are turning to polyurea.
Landscape & Water Containment
Landscape designers and contractors have found similar benefits with polyurea. Polyurea is often used to contain water for ponds and pool decorations to form a primary containment liner. Use of geotextile material is common when applying polyurea over dirt. Proper surface condition is vital when applying over concrete and most other substrates.
Polyurea has much the same uses in architectural design as it does in theme park applications. Polyurea is used as a protective coating over foam, EPS and other structures to create ornamental building fascia, themed characters, artificial rocks, pools and environments. There are many uses for movie set and theater stage design as well.
Automotive Fascia OEM Molded Parts
Polyurea can be spray, open pour or reaction injected into molds. Many automotive fascia parts have been molded from polyurea RIM systems. Now many spray in mold uses are becoming popular in replacing parts commonly made from fiberglass. Water park chutes, plaques, automotive aftermarket fascia and spoilers, architectural decorative molding, and more…
Water Parks & Playgrounds
Molded slides, protective coating of seats for wet/dry amusement rides, tank linings, water containment, aquariums, concrete stadium seats are just a few of the many applications polyureas are commonly used for in the amusement and theme park industry. Polyureas usage is rapidly growing in applications to replace paint and fiberglass due its fast cure and ability to reduce maintenance cycles.
Railcar Lining & Track Containment
Polyureas are commonly used to line liquid containment railcars for their waterproofing and chemical resistance benefits. Hopper style rail cars have benefited from the strength of polyurea and its ability to resist abrasion. These cars often carry coal, sand, and other abrasive materials. Polyurea can be applied quickly and it will last longer than many other conventional systems if properly applied.
Polyurea is a very fast set material, which makes it ideal for use in line striping and pavement marking. It can be returned to service for traffic and pedestrian use in only a few minutes (depends on formulation) after application.
Polyurea is is much more durable than paint and typically lasts much longer between maintenance cycles. Polyurea is the clear choice when it comes to cost/performance payback and operation.
The use of Polyureas for spray in mold processes are gaining momentum with the advent of low output spray guns. Polyureas have very fast reaction times and are meter mixed and dispensed through plural component equipment. These materials are dry to the touch within seconds after application reducing demold time dramatically. Physical properties of these materials can be altered by the system formulator to meet application requirements.
- Race Car Body Parts
- Mold Making
- Artificial Rock
Fuel Storage & Containment
Polyurea is resistant to many fuels and chemicals. It is commonly used in fuel pits and pipeline secondary containment. Polyurea is not resistant to all chemicals and necessary compatibility tests and surface preparation are always required.
What Is Polyurea?
Polyurea is an organic polymer that is the reaction of isocyanate with an amine terminated polyether resin, forming a plastic-like or rubber-like compound that may be used in many of the same ways as older technologies – polyurethane, epoxy, vinyl ester, neoprene; to name a few.
What is Polyurea? – As defined by the PDA
A polyurea coating/elastomer is that derived from the reaction product of an isocyanate component and a resin blend component. The isocyanate can be aromatic or aliphatic in nature. It can be monomer, polymer, or any variant reaction of isocyanates, quasi- prepolymer or a prepolymore. The prepolymer, or quasi- prepolymer, can be made of anamine-terminated polymer resin, or a hydroxyl- terminated polymer resin.
The Resin blend must be made up of amine-terminated polymer resins, and/or amineterminated chain extenders. The amine-terminated polymer resins will not have any intentional hydroxyl moieties. Any hydroxyls are the result of incomplete conversion to theamine-terminated polymer resins. The resin blend may also contain additives, or non-primarycomponents. These additives may contain hydroxyls, such as pre-dispersed pigments in a polyol carrier. Normally, the resin blend will not contain a catalyst(s).
Polyurea Formulations & Raw Materials
Part A is a dark colored viscous liquid called isocyanate. Part B is commonly called the amine resin blend. It is often colored, or pigmented, and normally requires agitation or stirring before use.
When the liquids are thoroughly mixed, they result in an immediate chemical reaction that becomes viscous and ultimately solid. This reaction is very fast and typically sets up dry to the touch within seconds. Ultimate cure usually takes up
to 24-48 hours, however longer and shorter cure time durations are quite possible depending on specific formulation and characteristics of mix.
The use of different types, and/or different volumes, of isocyanates, polyether, or polyester amines, chain extenders and other additives can have a significant effect on the ultimate physical properties and final characteristics of the polyurea coating/lining system.
Technical Aspect of Polyurea Formulations
Polyureas have been described as the resin from a polyurethane reacted with the curative of an epoxy. This is a good description, as polyurea coatings do seem to take the best from both of these polymer technologies. They have improved chemical and solvent resistance, and higher temperature resistance compared with the polyurethanes. They also have better impact resistance and higher
elongation vis-à-vis the epoxy.
A polyurea is formed when amines react (cure) with the isocyanate. This reaction is fast,auto-catalytic (that means it does not need a catalyst to react – even at cold temperatures) and leads to many of the special properties that allow polyureas to distinguish themselves from the other polymers.
There are three main properties:
Polyurea reactivity is independent of the ambient temperature. Polyurea reacts fast – and it will react at the same speed regardless of the temperature. It can be 100 F or -25 F and the reactivity is almost the same. Polyurethanes can be catalyzed to also react very fast, but a system designed for 70 F, will take forever to cure at -20 F. A polyurethane system that will cure properly (fast) at -20 F will be too fast to handle at 70 F. Epoxy cannot cure at these very low temperatures.
Polyurea reactivity is independent of the ambient humidity. It can be 98% RH and the polyurea coating will spray bubble-free. (Be careful of the dew point – that’s a different story) A polyurethane must have catalysts to complete the reaction. These catalysts are designed to catalyze either the polymer reaction (gelation) or the “blowing” reaction (many polyurethanes use this well known use of water to react with the isocyanate to release CO2 to use as the blowing agent in polyurethane foams). Unfortunately, either types of catalyst will catalyze BOTH reactions – to some degree. The choice of a good gelation catalyst will still catalyze the ISO/water (from the humid air) reaction – and when it does you WILL have bubbles.
Polyurea develop their physical properties FAST. This gives the polyurea “FAST RETURN TO SERVICE”, that is you can drive on the coated floor; use the coated product within 12 hours of application. Polyurethanes take up to 14 days to fully develop their physical properties. Epoxy require several days.
As mentioned before, polyureas have improved chemical and solvent resistance and higher temperature resistance compared with polyurethanes. They have improved impact resistance and elongation compared with epoxies. All of the properties can be impacted by the formulating chemist.
The formulating chemist will always want to know the application for which his polyurea system is intended. The proper selection and amount of raw material components will effect the performance – both processing and physical properties.
A-Side Polyisocyanate Pre-Polymer
The selection of the isocyanateprepolymer will influence most of the properties of the polymer. The % of NCO will influence hardness, stiffness, strength properties, speed of reactivity. The “backbone” will influence the type of chemical/solvent resistance, as well as strength properties. The functionality (number of reactive sites per molecule) of the prepolymer will affect the temperature resistance, hardness, stiffness, impact resistance and elongation. The isocyanate can be aliphatic or aromatic. This selection will affect the UV stability, as well as other physical properties. The formulator may add other chemicals to the prepolymer, especially a diluent to lower the viscosity, and slow down the reactivity of the system. The viscosity of the system will greatly affect the processing of the polyurea.
B-Side: Resin Blend Formulation
The Resin blend consists of various amine terminated molecules of varying sizes and types.
The choice of which amines to include and the ratio among the amines, will determine the performance and the processing of the polyurea. To be a “pure polyurea” there can be NO (zero) “intentional hydroxyls” added to the system. If there are hydroxyl containing products (polyols) it will be a „hybrid‟ coating.
Hybrid systems have their place. They are good systems for certain applications. There has been significant confusion in the marketplace between a true “Pure” polyurea and a hybrid. A coating system with hydroxyls (hybrid) will require a catalyst to complete the reaction. This catalyst will cause the polymer to have the difficulties sited above.
In all polyurea applications, the coating formulation is only 1/3 of the critical success. Proper substrate preparation is necessary and proper equipment and mixing at proper temperatures and pressures is critical.