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Design007-Mar2022

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68 DESIGN007 MAGAZINE I MARCH 2022 formance in abundance and top environmen- tal credentials to match, making it a win-win solution. We are also "future-proofing" at the same time; for instance, if the government says to introduce new environmental measures in a couple years' time, then manufacturers are covered. 2. What is the financial impact for a bio-based coating over a traditional chemistry? Currently, many of the supply chains of these new raw materials are developing scale econo- mies, so the raw materials are more expensive than their mature, petroleum-derived alter- natives. erefore, the improvement in per- formance of the bio-based coating material, over a more traditional petrochemical mate- rial, can come at an increased cost. However, as electric vehicles become more commonly adopted and the internal combustion engine (ICE) becomes more economical and less widely used, oil production is likely to slow and become increasingly expensive, so at some point in the near future, the bio-based materi- als are likely to become more economical than oil-based feedstock. 3. Which conformal coatings are the most popular and why? is is a tough question and one we get asked a lot. In general, I would say that acrylic mate- rials and UV-curable materials are amongst the most popular. Acrylic materials remain amongst the most popular class of coating due to their ease of application, rapid drying by solvent evaporation, and ease of re-work— immerse them in solvent, wash with solvent, et voila, no coating remaining. However, acrylic coatings provide less adequate levels of protection in more demanding applications, such as condensation and high environmen- tal impact. Many end users are beginning to realise that they will need to move away from acrylic materials due to both of these factors. Especially prevalent is the requirement of many automotive OEMs to pass a condensa- tion test (e.g. K15-19 from BMW GS95024-3- 1). Even in aerospace applications, there is an increased focus on condensation resistance in coated assemblies due to the rapid environ- mental changes experienced during descent from 40,000 feet to a hot and humid runway, for example. As for UV-cure materials, the rapid nature of the primary UV cure, as well as the polymeri- sation process itself, tend to cause significant amounts of shrinkage, which creates a lot of stress in the coating that is commonly allevi- ated by stress-cracking during thermal cycling. e materials must also contain a secondary curing mechanism to ensure material beneath components, or otherwise shadowed from UV radiation by taller components, develops hardness, and cross-links. is is commonly a moisture-initiated cure reaction and can take weeks, months, or even years to complete, due to the fact that the outside of the material is partly cured from exposure to UV radiation; moisture must permeate through this mem- brane and CO 2 gas produced during this cur- ing process must permeate back out through the same membrane. e benefit of a 2K UV-curable material is that once the two components are mixed, the reaction will proceed to completion in less than 24 hours in these shadowed areas that are not exposed to UV radiation. Also, the addi- tional cure nature of the reaction ensures sig- nificantly less shrinkage and less stress, result- ing in more flexible coatings that can better survive thermal shock. 4. Why did we decide to include bio-content in our conformal coatings and how did we test them? We are very committed to the ISO 14000 obligations. It is an entirely logical and natural progression to look at how we can reduce the carbon footprint of our materials. e only sur- prising factor was the degree of performance

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