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Finding a Better Way to Test for VOCs

Fri, 05/05/2006 - 8:19am
Charles Bartish, director of product safety and regulatory affairs, Air Products & Chemicals Inc.
Charles Bartish heads task force to analyze impact of regulations on thermosets By Lisa Arrigo Charles M. Bartish is an expert on safety and regulatory issues, which makes him the ideal chairman for the Thermoset Resin Formulators Association’s task force on VOCs. The task force has been commissioned to analyze VOC regulations and determine how those regulations are affecting the overall use and distribution of the thermoset industry’s products. Bartish, who has a bachelor’s degree in chemistry and a doctorate in inorganic chemistry, has spent the last 30 years of his career at Air Products & Chemicals Inc., a worldwide supplier of industrial gases and equipment, specialty and intermediate chemicals and environmental and energy systems headquartered in Allentown, PA. His current assignment is serving as the director of product safety and regulatory affairs. Under his leadership, the Thermoset Resin Formulators Association’s task force is hoping to work with regulatory agencies to exclude benzyl alcohol in VOC calculations and to establish an appropriate VOC testing method for thermoset resins. EPA’s Test Method 24, which is made up of various ASTM test methods, is widely used to determine the amount of VOCs in products but does not include a specific test for thermosets. Q: Why are regulations that restrict VOCs, or volatile organic compounds, gaining more attention now? A: The federal Clean Air Act set strict emissions standards for VOCs. The definition of VOCs varies from state to state, but most states generally follow EPA guidelines, exemptions and test methods. In 2002, the California Air Resource Board established VOC standards for a variety of coatings and consumer products. In 2005, the Ozone Transport Commission, which regulates Northeastern states, adopted strict rules patterned after California’s. These rules reduce the acceptable level of VOCs in many coatings and consumer products. Formulators must provide environmentally friendly new products with reduced VOC content to sell in these regions. Q: How are VOC regulations influencing the use and distribution of thermosets? A: The new state regulations restrict sale of products with VOC content exceeding regulatory limits. Product formulators must identify new components that meet both regulations and demanding performance targets. The formulator must consider all characteristics of products, components and application conditions to develop effective, efficient and economical products. The challenge is to meet the letter of the law and introduce products acceptable in the market. Q: What are examples of thermoset applications that VOC regulations affect? A: One good example is thermoset flooring systems. These formulated epoxy systems provide floors needing a waterproof, impact-, wear- and chemical-resistant surface. Epoxy systems are often used for applications where resistance to severe chemical exposures and secondary containment are important. The flooring products are designed to cure at ambient temperatures to facilitate application over a wide range of substrates, surfaces and environmental conditions. Many of the most effective flooring systems include benzyl alcohol, which enhances resin compatibility and improves film formation and appearance. Q: Why should regulatory agencies exclude benzyl alcohol in VOC calculations? A: Tests to characterize VOC content were designed for products intended to be applied as aerosols or cured with heat. Such conditions facilitate all volatile components to evaporate. Benzyl alcohol in flooring systems behaves much differently. Floor coatings are applied with brushes, trowels or rollers and cure over several days under ambient conditions. A high-boiling — bp 203°C — low-vapor pressure liquid, benzyl alcohol does not completely evaporate upon cure. Like a plasticizer, most benzyl alcohol remains in the final floor coating, contributing to desirable properties of the floor coating. Q: Why is EPA’s Test Method 24 unsuitable for thermosets? A: EPA Test Method 24 — EPA24 — which incorporates ASTM D2369 protocol to determine VOC content of coatings, requires a test sample be heated to 110°C for at least one hour. In addition, sample cure time allowed prior to heating is only one hour at ambient temperature, whereas in practice ambient cure thermosets are allowed to cure for two to seven days before being placed in service. Although EPA24 protocol may be useful for materials applied as aerosols or heat cured, its conditions are inappropriate to characterize ambient cure thermosets. Q: What’s a better test method for thermosets? A: A better test method would take into account the chemical or physical behavior of every component. It would exclude non-volatile components. For example, solids, resins and pigments are already excluded from the calculation. In waterborne formulations, water is excluded from the VOC calculation, even though water volatilizes during EPA24. In Rule 354, provision is made for excluding reactive diluents from VOC calculations, even though the reactive diluent otherwise meets the definition of VOC. Precedent exists to modify VOC methods to handle exceptions. Our objective is to present the technically sound case to exclude benzyl alcohol from VOC calculations.
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