Regulations concerning banned, restricted, and reportable chemicals are in constant flux. When chemicals are prohibited from use, it can create challenges regarding approved rubber compounds. How do we navigate the process of replacing a banned chemical or compound?
Rubber Compounding
Rubber compounds consist of various chemicals, ranging from simple formulations with four ingredients to complex ones with twenty. Each chemical plays a crucial role in the performance of the rubber compound.
Over time, environmental regulations or industry restrictions have led to the restriction of certain chemicals. This has prompted many rubber companies to reformulate their standard compounds to eliminate the banned substances. One example is the replacement of DEHP plasticizer. NBR was commonly formulated with DEHP due to its favorable low-temperature properties and low extraction. However, studies have linked DEHP to cancer or reproductive harm. Consequently, new rubber compounds had to be developed and tested to replace this phthalate plasticizer.
Similar situations arise when companies discontinue products. Base polymers used in rubber compounds are a pertinent example. As companies enhance their processes, address environmental concerns, or improve market positions, they may discontinue the use of certain base polymers. Compounders are then tasked with reformulating and testing new compounds for their customers.
Reformulation Process
Rubber molders adhere to various regulations to ensure that future changes do not impact parts. If regulations change and new lists of chemicals are introduced, customers are notified accordingly. The initial step involves determining the availability timeframe of the chemical. Customers and molders then collaborate to establish a timeline for providing the product while a new compound is formulated, sample parts are molded, and product testing is conducted.
Some antioxidants have been added to the restriction list. Rubber compounders must consider factors such as the type of antioxidant, its staining properties, and chemical composition (amines, acetals, or phenolics). Once the appropriate antioxidant is selected, small compound batches are mixed and tested. The primary consideration is the impact of the new antioxidant on the processing. Some antioxidants may slow down curing, prolonging molding times and reducing daily yields, while others may accelerate curing, affecting scorch times or molding duration. Subsequently, heat aging and compression set tests are typically conducted at multiple temperatures and durations to assess how the compound withstands long-term aging. Additionally, sensitive application extraction testing ensures that the new antioxidant remains intact upon contact with fluids.
Considerations
Maintaining approval for at least two compounds is advisable for critical new projects or even older ones. Having multiple approved compounds helps prevent rushed developments for replacements. If listing multiple compounds poses challenges, establishing a process for approving changes becomes imperative. In many medical applications, making any alterations has become increasingly difficult. Companies must always anticipate the possibility of materials being banned or discontinued, necessitating proactive adjustments.
Do you need help navigating changing chemical and compound regulations? Contact us here!