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Frequently Asked Questions on our Products

Q: What Is Polyurea? 

A: A typical polyurea consists of a multi-ingredient chemical formulation commonly
shipped in 55-gallon drum sets or 5-gallon pales. 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.

Polyureas develop their physical properties FAST. This gives the polyurea “FAST
RETURN TO SERVICE” — meaning you can drive on the coated floor and/or
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.

Q: How Must A Polyurea Coating Be Applied? 

A: Polyurea is applied using commercially available plural-component proportioning
equipment. It should be applied by trained, professional contractors.
The amine resin blend and isocyanate material components are typically
supplied in 55-gallon drum sets. The materials must be shipped and stored
according specific procedures. Once in use on the jobsite, they are transferred
from 55-gallon drums to the machine using special pumps called transfer pumps.
Typical equipment used to apply Polyurea has two metering, or proportioning
pumps (one for each component) that heat and proportion the isocyanate and
polyol resin through heated hoses to the spray gun in a 1:1 ratio. The two
materials are kept separate through this entire system until they come together in
the gun, where they are mixed and spray applied to the substrate.
Proportioning Machines
The drive system is what forces the metering pumps to go up and down, or back
and forth. The metering pumps are the pumps that proportion, or ratio, the
materials and move them out through the machine and hoses to the gun. Most
drive systems are pneumatically, electrically, or electric-hydraulically driven.
Pneumatically driven machines are typically less expensive, but because air is
compressible, hydraulic drives are considered to be of higher performance. Read
more >>
Spray Guns
Most every commercial Polyurea Spray Gun uses impingement-mixing
technology to mix the chemicals inside the gun. Pouring and injection
applications can incorporate a variety of different mixing technologies including
static and dynamic mix, however, in this section we will focus on spraying.
It is important to understand that once the two materials come together inside the
gun to mix, they begin to react immediately as they mix and exit the spray gun. If
the all of the reacted material is not expelled from the gun once the trigger is
released, the material will set-up and harden inside the gun, rendering it non-
usable. The design function within the spray gun that assures this does not
happen is called purging. There are three basic purge systems offered by the
various manufactures that offer different degrees of advantages and
disadvantages, mechanical purge, air purge and solvent purge.
Heated Hoses
However, the most common Polyurea applications are in the construction market
with commercial roofing and perimeter wall insulation leading the pack. It is not
always practical to lift the machine and all its auxiliary components onto a roof or
into a residential home. For this reason, most Polyurea machines use several

hundred feet of hose to deliver the raw materials to the spray gun for applying to
the remote roof or wall surface. As mentioned previously, Polyurea needs to be
heated to 140°F-160°F for optimum processing. Heating the material is the job of
the pre-heaters located on the proportioning machine. Heated hoses are used to
maintain the chemicals at the required temperature until they are mixed and
applied with the spray gun.
Auxiliary Equipment
This auxiliary equipment, in addition to the proportioning machines need
electrical power to run and are typically powered by a mobile generator, unless
power is available at the jobsite or building facility. The generator needs to be
sized to handle the full load amperage draw of all jobsite equipment it is intended
to power.
The transfer pumps that supply the material to the machines from the 55-gallon
drums are typically air driven and require a supply of compressed air to run. Most
every spray gun is air actuated, which requires yet more air. Pneumatic
machines also require compressed air in specific volumes to drive their pump
drive systems. A large capacity air compressor located on the jobsite or OEM
facility typically satisfies these air requirements.
Mobile Spray Rigs
In any given Polyurea application, you will typically find much more equipment
and power utilities in addition to the proportioning machine, spray gun and
heated hoses. Many different power tools are used to prepare the substrates and
perform set-up, operational and clean-up duties.Mobile Spray Rigs integrate all of
the necessary tools and equipment needed for Polyurea application into a
turnkey trailer system. Most of these trailers are tag along style, however, you will
also see them integrated into a box truck style as well. The benefit with a mobile
spray rig is that all equipment is always set-up and stored in one place. The
power utilities are also included in the rig so you always have electrical power
and air. Proportioning machines come in all shapes and sizes from several
manufacturers. There are several major distinctions to consider when specifying
and purchasing a machine: type of drive system, output and pressure capacity,
heating capacity, and electrical system are the majors. Maximum and minimum
hose lengths may be affected by the choices made in these major component
areas.

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