How to specify e-coats more sustainably

The e-coatings industry has undergone a profound shift in recent years. Regardless of where coating solutions are being deployed, whether in automotive applications, white goods, or agricultural, construction and earth-moving equipment, they play a vital role in maintaining optimal performance, by eliminating or substantially mitigating degradation that occurs as a result of harsh operating conditions.

The requirement for high performing e-coats remains as strong as ever, however, increased scrutiny around sustainability issues introduces an additional hurdle for specifiers. Although e-coats have historically been regarded as more environmentally friendly than their powder and liquid counterparts, it is fair to say that they have not always been entirely above reproach from an ecological standpoint. That said, advancements in e-coat technology are continuing to gather pace, allowing job coaters and surface coating professionals to achieve the required level of protection while meeting increasingly stringent sustainability criteria. Performance and sustainability are not mutually exclusive, and in this article, we explore the key considerations that will enable decision makers to strike an effective balance between the two.

Transitioning away from tin-based catalysts

While e-coats have been in use for decades, they have come a long way since the first generation of solutions, which were made using lead catalysts. The environmental and health consequences of lead are well documented, and despite the fact that lead is no longer in use, we are continuing to see some of the same negative impact from catalysts based on tin compounds. These substances are known to have carcinogenic properties and have the potential to cause significant damage to marine life as well as the wider ecosystem.

The ecological drawbacks of using tin-based catalysts are no secret, making it somewhat questionable that they remain in use. The reasons for this are, above all, economic since the initial cost of setting up a new line with a more environmentally friendly choice of material – financially and in terms of lost productivity – can be prohibitive, acting as a barrier to positive change.

For sustainability-minded businesses, however, we would recommend adopting e-coat solutions which use a non-toxic catalyst material such as Bismuth, helping to overcome the environmental consequences associated with the materials.

Compliance with legislation is always an important consideration and while current legislation does not outright prohibit the use of tin-based catalysts, this is likely to change at some point, hence, it is worth fast tracking the transition away from tin-based catalysts before being legally required to do so.

Never underestimate the power of edge protection

In order to yield the maximum sustainability benefit from a product or component, it is vital to prioritise longevity. The better the protective characteristics of an e-coat, the more durable and robust the surface will be over the long term, in theory.

One of the crucial and sometimes overlooked considerations when selecting an e-coat solution is the degree of edge protection it provides. Not all e-coats are created equal in this regard, since the formulation of certain ones makes them more susceptible to shrinkage during the curing process than others.

There is some inevitable variance in e-coat film thickness at different points within a surface, however this is most pronounced on the edges, where thickness of coating is often lower. Because of shrinkage, the level of protection can be lower across surface edges, leaving this point of the surface vulnerable to degradation and premature decline, undermining the overall quality of the product and its appeal within a competitive marketplace.

Selecting an e-coat product with proven edge protection is therefore a positive step towards helping safefuard the longevity of your surface. Understanding how the coating thickness of your e-coat can vary around surface edges when subjected to test conditions provides a useful indication of performance.

Low cure = reduced energy expenditure

The chemistry of your e-coat solution can affect multiple variables, one of which is the required curing temperature. This is determined by the composition of the backbone resin and crosslinker, which must be exposed to high levels of heat to remove blocking agents, at which point a chemical reaction can take place.
Historically, this process has been highly energy intensive, requiring, in some cases, temperatures reaching 180ᵒC. If we think of this in terms of energy requirements and carbon emissions, the true environmental impact becomes clear. Following this logic, e-coat solutions requiring a lower curing temperature, in some cases in the region of 150ᵒC, offer a significant sustainability benefit and can be a great way to increase overall ecological performance. In the context of the mounting cost of energy, opting for a low cure e-coat solution can also yield sizeable cost savings - all while respecting the planet.

Prioritise e-coats based on organic materials

There is a widespread recognition that more must be done to reduce our dependence on crude oil. Not only is this a finite resource, it is also a major contributor to carbon emissions. While crude oil once accounted for a large portion of the make-up of e-coats, this is fortunately no longer the case. Indeed, many manufacturers are now deriving the necessary raw materials from alternative, bio-friendly sources.

While such oils must undergo a higher degree of purification than crude oils, it could be argued that this is a small but necessary price to in the interests of protecting the planet and its resources, and conducting business in a responsible and sustainable manner.