Want to know more about ThermaShield’s products? We’ve collected the answers to some of the questions that our Texas customers ask us most often here.
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Frequently Asked Questions about Our Products
Q: What Is Polyurea?
A: Polyurea is a multi-chemical formulation. It is usually shipped in 55-gallon sets of drums or 5-gallon containers. Typically, part A of the combination is isocyanate,
a liquid. Part B is usually an amine resin blend, which is pigmented. When these two compounds are mixed together, a chemical reaction occurs that turns the mixture into a solid. The reaction occurs instantly, and the compound is dry to the touch within seconds. The final cure takes up to 48 hours, but longer and shorter cure times do occur, depending on the exact base compounds used. Different types of isocyanate, amine, resin blends, chain extenders, and other materials can be used, which all can lead to different curing times and affect the physical properties of the coating and lining system.
Q: What Are the Technical Aspects of Polyurea Formulations?
A: Polyureas are sometimes explained as the resin of polyurethanes mixed with an epoxy, and this is a good explanation, since polyureas generally take the best from both of these types of formulations. They have better chemical and solvent resistance than polyurethanes and better impact resistance than epoxy formulations
Polyureas are formed by an auto-catalytic reaction between amine resin and isocyanate, which leads to three qualities that make them different from other forms of polymers:
• Reactivity occurs regardless of and independent of the temperature, and the speed of the reaction occurs no matter what the temperature is. With polyurethanes, fast reactions occur when the substance is at the temperature for which it is designed, but they will be dramatically slowed outside of those conditions.
• Reactivity occurs regardless of the ambient humidity. Although dew points matter, ambient humidity has no impact on the application and reactivity of polyureas.
• Polyureas offer a fast return to service. The surfaces to which they are applied can be used within 12 hours of application. With polyurethanes, it can take 14 days for the surface to be ready. The person in charge of creating a polyurea will need to know what the formulation will be used for before creating the mixture, so that it is able to provide the best and fastest results for the particular type of surface.
Q: How Are Polyurea Coatings Applied?
A: Plural component portioning equipment is used to apply polyureas. They should only be applied by professionals using professional-grade equipment. The materials used for the polyureas are transferred to the application machines via transfer pumps. The machine that applies the polyurea coating has two portioning pumps—one for the amine resin and the other for the isocyanate. The pumps heat the materials and deliver them to the spraying apparatus in a 1:1 ratio. The materials are not mixed until they reach the sprayer.
The portioning machine that supplies the pumps can work pneumatically, electrically, or electric-hydraulically. Pneumatic machines are the most affordable, while electric-hydraulic offer the best performance.
Because lifting the machine itself is not usually practical, the machine is attached to two heated hoses. The optimum application temperature for polyurea is 140 to 160 °F, so the heated hoses make sure the base materials that have been pre-heated in the machine maintain their temperature until application is completed with a spray gun.
Spray guns usually work with impingement mixing technology. Since the materials begin to react as soon as they come in contact with each other, the spray gun must empty all of the base materials that enter the gun. If this doesn’t happen, they will react and create a solid within the gun, making it impossible to use. For this reason, sprayers have a purge function to ensure that they are emptied completely. The purge function may be mechanical, or use air or a solvent.
There are several types of auxiliary equipment that may be used on job sites. A mobile generator is necessary for running all of the machines. Large capacity air compressors are also used to power machines that run on compressed air. Often, mobile spray rigs are used on job sites for polyurea application, because they combine several necessary components into one system.