Issue 10: Understanding Polyurea Hybrid Coatings; What is the mix

Issue 10: Polyurea Hybrid Coatings: Understand the Differences

Sometimes a customer is told that a supplier has a polyurea hybrid and that a hybrid will outperform polyurethane because of the polyurea component of the formula. However, all polyurea hybrid coatings are not created equal.

UV Stable Polyurea School Staircase; Get the Correct Coatings

Most customers take what they are told at face value, without a more in-depth understanding of the issues involved. Customers should ask questions. If the polyurea component is the determining factor that boosts the physical properties, exactly how much of the hybrid product is polyurea coating and how much is polyurethane? One supplier could offer an 80% polyurea coating/20% polyurethane mix to get one level of performance; a second could have a 50%/50% ratio to have a perfectly balanced blend, according to its claims; and a third could use a 99% polyurethane/1% polyurea coating system. While each supplier would be correct in calling their product a Polyurea Hybrid, the customers of each would be purchasing a coating with drastically different performance characteristics.

It’s extremely important to know what you’re buying. Too many coating specifiers are unaware of the subtle differences in these coatings and their properties. Every contractor should either seek out specifiers that understand the key differences between polyurea hybrid coatings or be willing to train the specifiers with whom they work.

Issue: 9 Safer is Always Better

Safer is Always Better

Many safety issues surround polyurea coating handling and application. Appropriate personal protective equipment (PPE) should always be used according to the polyurea coating system and the application equipment used. The safety of applicators, observers, and unknowing passersby is critical, as underscored by OSHA regulations.

The use of PPE cannot, and should not, be the only way to stay safe. The real risk to the polyurea coating spray applicator stems from the actual chemistry itself. These materials are reactive. Even though they can be touted as environmentally friendly once cured, they must be respected and handled with caution during application. Safer formulations should be available to applicators choosing to limit risk exposure while handling and applying the coating.

Methylene Diphenyl Diisocyanate (MDI) adds another facet to the safety issue.  While MDI has a variety of forms, it’s well known that exposure to vapor or small particle MDI can cause sensitization, health-related problems, and death. To date, there have been at least four deaths attributable to MDI overexposure. The federal government issued a report after the causes of the deaths had been investigated. Tragically, the investigation was limited to exploring the circumstances surrounding these deaths and the PPE that should be used in their light, not what can be done to mitigate and reduce these risks from an equipment or application method viewpoint.

Alternative application methods and/or techniques, along with different equipment options, could greatly reduce risks arising from spraying polyurea-type coatings. However, large equipment manufacturers have no incentive to bring attention to such possibilities, since employing safer spraying parameters would include not purchasing or using the equipment they presently offer.

Common sense safety precautions include covering the skin, wearing eye protection, and using a National Institute for Occupational Safety and Health (NIOSH)-approved respirator. When spraying isocyanate-based (MDI or other) material, wear a respirator at all times; and, if spraying in a confined space, a supplied air respirator.

But don’t only consider respiratory protection in assessing the equipment necessary to manage the health risks posed by spraying polyurea types of coating systems. The increased risk of skin contact from spray mist when spraying polyureas, polyurethanes, and polyurea hybrid materials using high pressure spray equipment is also a considerable concern.

Anyone having experienced high pressure spraying, hot spray, is familiar with the mist cloud that forms around the spray area and moves with any air movement. This mist contains reacted, reacting, and unreacted particles of isocyanates, amines, polyols, or other additives included in the original formulation. Therefore, it’s recommended that not only the skin surfaces of the body be fully covered, but also that a full-face respirator be used to protect the eyes and facial skin from the coating mist moving around the sides of protective eye wear or face shields and being deposited onto the skin. A hooded suit, or head sock, may also be worn to protect the heads of those within the spray area.

The link between particle size and potential health risks is not generally discussed in trade publications.  In fact, there is a direct relationship between smaller particle size and a higher likelihood that the particle could pass through, or around, safety equipment and/or be deposited on something that is touched later when the user is not wearing gloves. Exposure to the chemicals can result before, during, or after actual spraying. It’s imperative to consider personal protection during the entire process: arrival, taping or masking out, equipment setup, substrate preparation, test spraying, actual job spraying, unmasking or untaping, clean up, and use.

Since smaller particle sizes are suspended in the air more easily, and are more easily passed through or around safety equipment, larger particle size application equipment should be considered a safer alternative—that is, cold spray and warm spray low-pressure equipment.

Issue 8: UV stable coatings or “what are Aromatic vs. Aliphatic coatings?”

The Importance of Aliphatic Coatings and UV-Stability

In theory, UV-stable products should have very little loss of gloss or color fade over time, even when exposed to sunlight. On the other hand, non-UV-stable products will first lose gloss when exposed to sunlight, then fade and/or yellow, and, eventually, experience polymer breakdown and coating failure. By definition, aliphatic polyurea coating systems are UV-stable, while aromatic polyurea coating systems are not. What seems pure and simple, is neither pure or simple.

Labels of aliphatic coating products can be deceptive. Although a number of aliphatic systems are truly 100% aliphatic, there are too many aliphatic products out there that are, in fact, blends of aliphatic and aromatic. Some producers will make a blend that is only 51% aliphatic and 49% aromatic and still claim it is an aliphatic product. While there is some argument for this being true, is the customer educated during the purchasing process?

Educate yourself. When purchasing an aliphatic system, ask the producer about the percent of aliphatic materials in their product. Read the product’s Material Safety Data Sheet (MSDS). An aliphatic polyurea coating will contain only IPDI and/or HDI isocyanate (Side A) component. An aromatic polyurea coating uses MDI or TDI isocyanate. Since MDI and TDI are not UV-stable, you should not find either of these components in a truly aliphatic product.

Aromatic Vs Aliphatic Coatings in UV Testing

 

Issue 7: One Size Fits all Fallacy

The One-Size-Fits-Fallacy

Polyurea coatings and polyurea hybrid coatings are generally both high performing and weather tolerant in ambient application conditions of both high and low temperature. Polyurea coating tends to be highly flexible and waterproof–a good, tough, all-around coating. However, substrate (surface) and application conditions, product usage, application options, chemical and atmospheric exposure considerations, and other factors must be considered when selecting both a coating system supplier and a coating system.

Industrial Coatings requirements are different from Residential and Commercial floor coatings

Many suppliers or marketers of polyurea-based systems take a “one-size-fits-all” approach. They offer a strong, waterproof, durable, product you can use for your roof, your fish ponds, your truck bed liner, your deck, your garage floor, or wherever you have a need. While you could use it that way, don’t assume that a specific polyurea coating system is either the best, or even the safest, product for every application.

Exterior Weather and Wear is different from an interior Store Floor

It’s vital to determine the different exposures (how it will be attacked) and service conditions that the coating will experience before selecting a coating system for a job. Depending on its application, some polyurea coating formulas may work well, whereas others may be inappropriate. For example, a fish pond polyurea hybrid coating can be waterproof, durable, tough, and seamless; but, if the formulator does not use a catalyst that either becomes part of the polymer matrix or is benign to fish, the catalyst will leach out of the coating system and kill the fish!
Unfortunately, the polyurea coating market is being overtaken by short-sighted salesmen wanting to make money quickly. The industry is, in large part, lacking the customer service specialists whose primary interests are to match the end-customers’ needs with the best solutions. Look for coating systems specialists that understand that only by solving each customer’s specific need will they create a customer for life.

Food Processing Work Area Coating

Issue 6: 100% Resin Vs Fillers

Resin Versus Fillers

3d Molecular structure  illustration

 

 

 

 

 

 

 

 

 

Many producers of protective coatings claim that the product they are trying to sell a customer is 100% Solids, suggesting that it contains no solvents. However, they may not be forthright about the amount of non-resin components that have been added to it to reduce cost and increase profit. These additives decrease performance, because resins build a coating’s physical properties, while fillers typically only build volume.

In conversations with sales or technical representatives of companies marketing protective coatings, ask them about the use of resin components versus fillers in product formulations.

WB SEALER SYSTEMS, LLC  uses only materials with no fillers

Contact us at 603-353-0432;

 

Issue 5: Surface and Substrate Preparation

Surface and Substrate Preparation

Having the correct Surface Preparation can be the difference between success and failure in Coating adhesion

Polyurea coating has been called a revolutionary chemistry that can be applied down to -35˚ F and withstand water exposure almost immediately. As good as the technology is, however, the truth is that no coating chemistry can make up for an improperly prepared surface. Ask anyone in the industry, and they’ll tell you that most failures are a direct result of poor surface preparation.

In fact, in its infancy, polyurea was promoted as the coating that would cure on any substrate.  But many early polyurea jobs failed because the coating cured without sticking to the substrate.  The result was a catastrophic adhesion failure for the job and a public relations problem for the polyurea industry. The performance properties of a coating system don’t eliminate the need for the user to ensure that the coating system has something structurally sound and clean to which to adhere.

If a surface is contaminated with oil, for example, the oil must be removed. The substrate must not only have a surface or anchor profile to get good mechanical adhesion, but also have a level of cleanliness appropriate to the application and end use. Beware of the salesperson who tries to convince you that the product is tough enough to make up for an inadequately prepared anchor profile.

Also known as surface profile, the anchor profile is the topography of the surface to be coated.  If the anchor profile left by the surface preparation is too smooth, it allows for coating slippage, or creep, when the coating is exposed to lateral pressure. So be sure that there is an appropriate level of roughness for the coating to fill. The level of anchor profile required depends on the coating system used, the choice of primers, and other considerations that the specifier should consider. The graphic visually demonstrates the anchor profile.

Ask questions and get answers that make sense ahead of time to avoid having to backpedal and investigate a job failure later. Polyurea coating technology is coating chemistry. Protect yourself with the facts. At the end of the day, you are the one to whom your customer will either give, or not give, repeat business and referrals. It’s your reputation on the line.

Issue 4: Significance of Cross-link Density

The Significance of Cross-Link Density    

Cross-link density refers to the way polymer threads are woven together and the density or packing of those threads. The higher the cross-link density, the better the barrier-type properties of a coating system.

An example illustrating the cross-link densities of two different polyurea coating system formulas is chain link fence vs. chain mail armor. Both are made of metal, are woven together, and offer a certain level of protection. If a circus performer were to throw an ax at you, you could feel equally confident of your safety by standing behind either a section of chain link fence or a section of chain mail armor. In both cases, the molecule size of the ax cannot penetrate the cross-link density of your formula. However, if that same circus performer were to throw a razor-sharp 7” balanced knife at you, you would probably not feel the same level of confidence standing behind the fence as you would the armor. Why? Because the cross-link density of the armor doesn’t allow the small molecule knife to pass through. Which would you choose for protection, the chain mail or the chain link fence?

In comparing Polyurea coating systems, cross-link densities are not all the same. Although similar, the end results, and the level of protection offered, can be very different from one formula to another. By design, coatings with no solvents or volatile organic compounds (VOCs) of any kind (listed, exempt, or other) have the capacity of exhibiting the highest cross-link density.

Don’t be deceived or misled. The use of any solvent in a coating system is both a performance and safety concern. Look for materials which are designed for the specific needs of your project

Issue 3: The Truth About claims of No VOC

The Truth About Claims of No VOCs

 

Finished Basement with Glossy finish

 

The original definition of a Volatile Organic Compound (VOC) was any organic compound with a vapor pressure higher than 0.1 millimeter of mercury, allowing it to enter the atmosphere quickly and easily.  VOCs typically lower the viscosity, or thickness, of the coating chemicals and enable the chemicals to be more easily sprayed. Most solvents meet the original definition of a VOC–entering the atmosphere quickly and easily–but not all solvents are VOCs, something not commonly known

An exempt solvent is a solvent compound that by all characteristics is a VOC according to the original definition but has been exempted from the law for some reason.  Unscrupulous coating suppliers can incorporate either non-VOC solvents or even exempt solvents into their formulated products. By definition, they now have a non-VOC product. Some companies will sell a product labeled as Zero VOC that contains non-VOC solvent, but never disclose that information on the label.  Zero VOCs does not mean no solvents, and the product label may not tell the whole story.

By using a non-VOC solvent to disperse the resins, formulators can use much cheaper resin raw materials.  On the other hand, true 100% solids resin materials, while more expensive, have a low enough viscosity to be cold sprayed without the use of any type of recognized solvent.  Beware of the phrases Zero VOCs or No VOCs.  They do not automatically mean solvent-free or no solvents.

Investigate further into whether a coating, in fact, has no solvents, versus only no VOCs, by learning more about some of the solvents defined as “exempt solvents” in the United States.  These include:  Acetone, Methyl Acetate, Volatile methyl siloxanes, Parachlorobenzotrifluoride (PCBTF), Methylene chloride, and a wide range of chlorofluorocarbons.  You may find these listed either on a side panel of the packaging or on the Material Data Safety Sheet (MSDS).  When you request a MSDS from the product manufacturer, it should always be made available to you.  Some manufacturers provide this information on their websites

Issue 2: Solvent Vs. No Solvents

Solvent Vs. No Solvents 

Coatings that contain solvents or water are inherently more porous than coatings that are truly 100% solids.  With solvent or water in a coating system, the formulator must allow for that solvent or water to evaporate through the coating.  By design, the formulator must plan for enough space between the polymer threads of the coating to allow the solvent or water molecules to escape through the coating itself while it is drying or curing.

However, if there is enough space to allow the molecules to pass out, you should be concerned that there is also enough space for those same molecules to come back in. That coating may be unable to stop water or other contaminants from passing through the coating.  The way the polymer threads are woven together and the density or packing of those threads is called cross-link density. The higher the cross-link density, the better the barrier-type properties of a coating system.

When you apply a coating that has 50% solids and 50% water or solvent, you are paying for materials that will not help protect your surface.  This is because the solvents and/or water volatilize, or evaporate, out through the coating surface, leaving you with only half of the coating thickness that you have brushed or sprayed on.  Possessing only half of the thickness in applications that involve abrasion or wearing away of the coating means that you have only half of the protection, or half of the service life, possible with a coating that contains no solvents or water.

One additional benefit of having a 100% solids, no solvent or water coatings is that it can typically be applied at virtually any coating thickness. Additionally, a coating containing any solvent and/or water has significant limitations in its application thickness.  The coating formulator knows that the solvent and/or water must escape the coating film as the coating dries or cures, or it will bubble, blister, and peel.  So, if the applicator paints the coating on too thick and the solvent/water does not get through the coating film before the top of the coating sets up, the coating will fail.  Unfortunately, since coatings wear away through atmospheric abrasion, UV exposure, and other effects at a certain rate per year, a thin coating means that the coating will likely fail earlier than a thicker coating.  This leads to having to apply multiple coats to try to get longer service life.