The most important factor is operator health. With this product group, the emission of isocyanate is reduced to a level that makes it indistinguishable in the air.
At Henkel, we are always thinking about what we can do to improve our customers' experience. A key part of this is improving the experience for operators on our customers' factory floors; helping give them a safer, cleaner environment to work in. This is where Micro Emission technologies have a role to play.
There are, of course, reasons why polyurethane (PUR) hot melts containing diisocyanates are used. Every day, manufacturers benefit from their best-in-class bonding performance on a variety of substrates: easy application, long shelf life and low level of VOCs compared to alternative technologies. However, PUR hot melts containing diisocyanates still carry a sensitisation risk. The exact degree of risk depends on the type of isocyanate and the concentration in which it is found.
Over the years, the industry has made significant progress in reducing the risk from isocyanates. Conventional PUR hot melt adhesives once contained 2–5% of monomeric MDI, which led to them being classified as carcinogenic. Over the years, the residual monomeric MDI could be continuously reduced, resulting in much safer products.
The industry benchmark for these "low-emission" polyurethanes was previously 1% isocyanate content (or to be more precise, "low monomer MDI"). "Low-emission" may sound good, but the risk is still there, and there are associated regulatory requirements, such as specific labelling, training and infrastructure.
However, advancing technologies mean we can push the boundaries even further without compromising on product performance. We are now able to reduce the isocyanate concentration to below 0.1%.
This is the threshold for what's known as a Micro Emission (ME) product. At this level, the product is recognised as safe, meaning no hazardous labelling and no mandatory training for operators. This is why ME technology has taken off since its introduction 18 years ago, and the term has become standard across the market.
The most important factor is operator health. With this product group, the emission of isocyanate is reduced to a level that makes it indistinguishable in the air. This means operators do not need to worry about sensitisation, and manufacturers do not need to go through expensive compliance projects and training, or install new exhaust systems.
It's important to stress that there is no risk to the consumers who buy the furniture, whichever system the manufacturer uses. Once adhesive is fully cured after application, there are no longer any chemical emissions to be concerned about.
From a technical perspective, Micro Emission products function in the same way as traditional PUR materials. They can run on the same line, and key properties such as efficiency and stability are at a comparable level. Customers do not need to worry about loss of performance. In fact, in some cases, either the ME product will be more stable than conventional PUR technology, or it will have fewer cleaning requirements.
The good news is that switching from traditional PUR to Micro Emission is not difficult. Processes and equipment will not need to be changed, since the chemistry is the same: a reactive system.
As with any transition, the best advice is to work with an experienced partner who knows the opportunities and how to deal with any situation that may arise. At Henkel, we have long-term experience with ME technologies as we have been working with them since they were first brought to market. This means we can offer technical service, run process simulations within our own premises to replicate the customer's conditions, and support analysis with tailored training materials. Finally, we constantly keep in touch with regulators and have an entire department purely for dealing with regulatory issues and making sure we support our customers in their transitions.
Our safety journey is certainly not finished yet. We are always striving to improve the safety and prosperity of our customers and our end consumers.
The adhesive industry makes up just a small proportion of all the users of isocyanates, but nevertheless we have a responsibility to look to the future and to champion positive change. Recognising this, Henkel works continuously to improve its portfolio and fulfil customer needs. Health and safety are always a top priority. Within this framework, we will work to ensure that our products are high-performing, best-in-class choices.