“There are still many challenges with the use of recycled rubber, but I think we are living in an exciting time. We have a lot of possibilities and there is definitely a growing momentum towards using recycled content,” said Max Craipeau of Greencore Resources Ltd, Chairman of the BIR Tyres & Rubber Committee, in his concluding comments at the session during the latest BIR convention. 

Whereas most previous meetings of the Committee had focused on end-of-life tyre casings, the latest provided a fascinating insight into the recycling of various other forms of rubber scrap.

For instance, India-based GRP Ltd’s Joint Managing Director Harsh Gandhi outlined his company’s annual production of some 25,000 tonnes of reclaim from butyl inner tubes - around three-quarters of which is sold back to the tyre sector for use in inner tubes and tyre linings where incorporation rates in compounds can be as high as 12-15%. Other leading applications include sound and vibration damping.

Gandhi estimated global butyl reclaim production at 200,000 tonnes per year, with South Korea and China joining India as the largest producers. Martin von Wolfersdorff, Director of Wolfersdorff Consulting in Germany, acknowledged that butyl reclaim volumes in Europe were far lower than those in Asia despite the fact that this “very pure stream” provided “opportunities to recycle rather than downcycle”.

Since 2004, meanwhile, Malaysia-based Bridge Fields Resources has been converting a wide variety of rubber scraps into high-quality gum, with major feedstocks including latex gloves. Company CEO Asmipudin Mohd Ali Jinnah explained that this was also a pure stream with a single polymer structure, therefore delivering “manoeuvrability” in terms of product options, which include shoes, rubber bands, castor wheels and retread tyre applications. “Some manufacturers are willing to pay more if they can put it on their labels as ‘recycled’,” he noted.

Such strong application stories were important for the development of rubber recycling, according to Von Wolfersdorff. “When it gets to the technical performance of recycled materials, there is still really a stigma,” he lamented. “This is something our industry has to work against by showing good performing examples.”

Gandhi believed any increase in the uptake of reclaim would depend largely on the application and polymer type “because they all have different dynamics”. At the same time, however, he called for greater recognition of the role of reclaim in improved process safety and reduced energy consumption.  

The meeting also addressed the main technologies for recycling rubber, namely ambient and cryogenic micronization and reclaim/devulcanization. In Gandhi’s view, many companies preferred reclaim to micronized rubber powder because of the former’s more elastomeric state. “I think reclaim is here to stay longer because it is more active while crumb rubber is more inert,” he contended.

“In the end,” said Von Wolfersdorff, “it’s all about application performance and how much (recycled content) you can put in without loss of properties.”