Table of Contents
As with many of today’s chemical products and applications, the demand for environmentally friendly solutions continues to grow and develop. Industrial and protective coatings are no exception. One of the more recent significant technical advances to meet this demand is the introduction of 100% solids coatings.
Coatings companies have devoted extensive resources to developing a portfolio of epoxies, polyureas, urethanes, and other hybrid formulations to satisfy this need. These coatings are formulated without any solvents or water, thus containing no volatile organic compounds (VOCs). As a result, 100% solids coatings continue to provide superior protection while addressing the performance and regulatory requirements of the more traditional coating formulations. As might be expected, this coating technology change is also accompanied by a change in the equipment required to process these materials.
100% Solids Coatings Overview
As previously referenced, 100% solids coatings are formulated without any solvents or water. They are two components (in some cases, multi-component), consisting of a resin and a hardener. Upon mixing, the components transition from a liquid mixture into a solid, durable layer. Due to the absence of the solvent or water carrier, no evaporation occurs during the cure and all the components contribute to the final film.
The materials are engineered for high-performance applications such as flooring, tank linings, wastewater treatment plants, and other environments that require a tough, resilient surface. The coatings provide a durable, resistant barrier against corrosion, abrasion, and chemical exposure, which is critical in demanding industries such as oil and gas, marine, and infrastructure. They provide for smooth, seamless finishes and are self-leveling, in some cases. In addition, the formulations can be pigmented or clear, based on requirements.
These coatings are high in viscosity, which contributes to their ability to build thick films with fewer coats, thus reducing labor and material costs. As a result of their high viscosity, specialized equipment (which will be discussed later in this article) is required for application.
Advantages of 100% Solids Coatings
The advantages of 100% solids coatings include reduced life cycle costs, quick cure (and return to service), environmental and safety benefits, and improvements in performance and physical properties.
Reduced Life Cycle Costs
When considering the total life cycle of an asset, the use of 100% solids coatings typically provides a lower maintenance and replacement cost because of their superior durability, toughness, and longevity. Since there is no solvent base, the coating does not shrink during cure, resulting in a thicker, more durable film that assists in maintaining the coating integrity and protection consistency.
One application of a 100% solids coating can provide a dry film thickness, which would require multiple coats in solvent-based formulations. The resulting thickness enhances chemical-, abrasion-, and impact-resistance properties. Analysis indicates that these coatings can last significantly longer than lower solids-based formulations; in some cases, they offer 20-30 years of protection under normal circumstances.
The cost reduction in labor, equipment, and mobilization when eliminating the need for multiple coats (as required in traditional systems) can be substantial, especially in large projects. Additionally, the lack of shrinkage attributable to these products makes them more suitable for the repair of damaged surfaces, as well as the filling of cracks and voids without the use of additional fillers. The initial investment may be higher when considering 100% solids coating systems, but the reduced need for re-coating and repairs often makes them more cost effective over the life of the asset.
Quick Cure and Return to Service
Most 100% solids formulations, especially polyureas and fast-set epoxies, cure within minutes (or a few hours). Advantages of these reduced cure times are especially valuable and evident in infrastructure and asset applications, where downtime directly affects serviceability and lost revenue.
Environmental/Health and Safety Benefits
Many traditional coating systems contain solvents, which release VOCs into the atmosphere when applied and contribute to pollution, poor air quality, and potential health risks to applicators who are not properly educated and protected. The 100% solids products offer an environmentally friendly, worker-safe solution, especially in confined spaces such as tank lining or shop applications.
The elimination of evaporation helps minimize the footprint of paint operations, as well as the costs involved. With the absence of solvents, the 100% solids formulations also reduce the risk of fire and explosion, along with the exposure of applicators, workers, and occupants.
Performance and Physical Property Improvements
Coatings with 100% solids typically offer improved properties related to chemical, abrasion, and impact resistance. The coating thickness is typically more consistent and predicable because the entire volume remains as the protective coating, thus allowing for a reduction of the number of required coats to achieve the required level of protection. Since they are solvent-free, they shrink minimally during curing.
Excellent adhesion is another attribute typical of these systems. A variety of substrates, including steel, concrete, wood, and other materials are all serviceable with these systems. 100% solids coatings can also be formulated for specific needs, such as UV light resistance or antimicrobial settings.
As a result of their low permeability, these systems are viable solutions for waterproofing, marine, and water/wastewater applications. Their chemical resistance to acids, oils, and solvents makes them an especially excellent choice for lining and flooring applications. Aesthetically, the systems offer high-gloss finishes, which, in certain low-light application areas, can provide improved reflectivity and reduce the need for additional lighting.
Industrial, Commercial, and Residential Applications
Systems formulated with 100% solids have utility in a variety of applications as a result of their excellent properties, environmental footprint, and health and safety attributes. Some of the various applications include:
- Marine and offshore structures — Oil platforms, ships and seaworthy vessels, bridges, docks, and any other applications that require resistance to saltwater, mechanical wear, or UV
- Pipelines and tank linings — Applications requiring superior chemical and/or corrosion resistance, such as pipelines, water and wastewater tanks, and chemical storage and transfer tanks
- Industrial, commercial, and residential buildings — Shop, warehouse, manufacturing, garage, and basement floors where abrasion and chemical resistance are required; parking garages and applications where a resilient finish and a seamless surface are of value; containment areas where hazardous materials may be stored
- Aerospace and automotive — Specialized applications like automotive detailing, which require good hydrophobicity, scratch and mar resistance, and excellent appearance; aerospace applications with harsh environments that require tough, durable surfaces
Equipment and Application Considerations
As a consequence of their high level of solids, pot-life, rapid cure, and sensitivity to temperature and humidity, 100% solids systems can present challenges in both mixing and application if the correct equipment and processing procedures are not considered. For example, in most cases, heated equipment is required to reduce viscosity and improve material flow.
Material pot-life necessitates precise metering and timing with 100% solids coatings, and the single-component spray equipment used with traditional systems is inadequate. Instead, plural-component or airless spray equipment is required for precise mixing and delivery.
Selecting the right equipment is critical to achieving optimal results. Plural-component equipment is designed and engineered to process two or more components separately until the point of application to avoid clogging the lines and ruining the equipment. Airless spray equipment systems deliver high-pressure atomization of the material without the need for compressed air. Key considerations for each are highlighted below.
Plural-Component Spray Equipment
- Metering and mixing — Utilize pumps to precisely meter and mix components at the proper ratio to ensure correct reaction profiles and cure
- High pressure — Plural-component systems generate the necessary high pressure (up to ~7,000 psi) to atomize the viscous materials for application to the substrate
- Accuracy — Control systems are either automated or manual, providing operators the ability to vary and monitor flow rates and spray patterns
- Temperature — Temperature control in the pumps and hoses is integrated into the system to maintain optimal viscosity and to prevent premature curing or clogging of the machinery, all while allowing for atomization and even coverage on large surface areas
- Mixers and spray guns — Static mixers are used to combine the resin and the hardener to ensure a homogeneous mixture prior to atomization and application; selected based on the material properties, guns and tips provide for a controlled and even spray pattern, desired film thickness, and surface finish
- Equipment suppliers — Leading suppliers of plural-component systems include Graco, WIWA, Madewell, and Binks. These systems, which are necessary for polyurethane, epoxy, and polyurea systems, are portable for ease of use in the field.
Airless Spray Equipment
- High pressure — High-pressure pumps generate pressures of 2,000-7,000 psi for efficient application of the highly viscous coatings through small orifices, creating a fine spray
- Versatility — Airless equipment can handle a wide range of coating and substrate types, and they are most notably used in marine, industrial, and commercial applications; spray guns and tips are specific to the material viscosity and recommended flow characteristics
- Uniform coverage — 100% solids systems can be applied efficiently and economically (depending on the coating system) in atomized form, allowing for even coverage on large surfaces
- Equipment suppliers — Major suppliers of airless equipment systems for metering these systems include Graco, Madewell, Sames, WIWA, and Binks
Whether plural-component or airless, all spray equipment requires regular, preventive maintenance to prevent wear, leakage, blockages, and temperature fluctuations. Cleaning and inspection of the equipment is necessary after each daily use; pumps, hoses, guns, and spray tips should be cleaned with the appropriate agents. Seals, filters, and mixing components need to be checked for wear and failure, while temperature and pressure gauges and equipment should be inspected for proper calibration.
As with traditional coating systems, successful application and performance are dependent on the following:
- Equipment calibration — All equipment should be checked and verified to ensure that it is operating to manufacturing recommendations; all ratios, temperature and pressure settings, spray guns, and tips should be selected in accordance with the coating supplier’s specifications
- Operator training — Plural-component systems are somewhat more complex than traditional spray equipment; operators should be trained and certified in the safety and use of the equipment to ensure favorable results and maximum safety
- Environmental elements — To the extent possible, temperature and humidity should be controlled to eliminate blistering and poor cure
- Surface preparation — The need for a clean and adequate surface profile to ensure proper adhesion and coating performance cannot be over-emphasized
- Quality assurance — Upon application, the surface area should be inspected for uniformity, dry film thickness, and adhesion
Reap Long-Term Benefits
Coating systems formulated with 100% solids offer a variety of benefits in industrial, commercial, and residential applications. In addition to the obvious environmental and health benefits due to the absence of VOCs, these systems exhibit excellent chemical, abrasion, and impact resistance — all with great adhesion.
The unique nature of 100% solids coatings systems does require specialized equipment and some additional considerations during processing and handling. While the initial investment may be higher, the long-term cost effectiveness of these systems pays dividends over the life of the asset.
To learn more, reach out to the author at bworms@chemquest.com.
Read in CoatingsPro.