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Recycling and new tyres

By David Shaw

There has been a lot of discussion about the use of recycled materials in new tyres. I see four key challenges for those who want to supply recycled materials – and especially recycled tyre materials into the new tyre industry.David-Shaw300

First is the technology of the recycling process and the recycled materials. Second is the scale. Third is the issue of input materials and how they affect the output. Fourth, but by no means least, is the issue of price and cost-down.

These are structural issues and affect all attempts to use recycled materials in new tyres.

Let me explain those four objections in more detail.

In terms of technology, I’ve seen a series of attempts to use recyclate over the years. One common success factor – or more particularly a common factor in failure – is the presence or otherwise of detailed understanding of the rubber industry within the recycler.

In every single case where the recycling venture has been successful, the recycler has had full access to detailed, extensive understanding of the rubber industry. I have never seen a venture succeed where that knowledge was absent.

Anyone selling a virgin material into the rubber or tyre industry has to go through a series of increasingly technical presentations to demonstrate how the new material will perform in comparison with the established ingredients. Recycled materials are no different. If a recycler tries to sell the new material without the knowledge and understanding necessary to do the research and present the results in a way familiar to the rubber community, they are doomed to failure.

Second is the scale. A billion tyres made each year consume around 15 million tonnes of rubber polymer. Replacing even 1 per cent of that requires a production capacity of 150 kt/year. Most recyclers are set up to handle perhaps 1000 tonnes a year. They need to think big, invest big and to set up global networks which can produce identical materials for delivery to tyre factories in Qingdao, South Carolina and Hungary.

Third is the fact that tyres vary in their composition around the world. OE car tyres in North America use a lot of silica in the tread, but replacement tyres tend to use carbon black. A whole tyre uses up to ten different compounds. These might be based on natural rubber, polybutadiene, SBR or halobutyl, or blends of two or more of these. Not all of these materials are compatible with one another.

As tyre makers struggle to achieve good label grades, variability in the input materials has become a major issue for tire makers. Greater variability means greater spread in the final properties and this could mean that the tire label has to be downgraded, in order to take account of the statistical variability due to the input materials.

Cost factor

The fourth issue is cost. We need to be clear about this. No tyre company is going to use recycled materials just because they are less damaging to the environment. That decision will be driven by cost-down.

In the rubber reclaim business there is a rule of thumb which suggests that reclaimed rubber becomes economically viable when it sells for half the price of the same weight of natural rubber, or less.

Any business model which relies on costly re-processing technologies that drive the price significantly above this nominal thresh-hold is likely to result in disappointment.

Today the interest among tyre makers to use recycled materials has never been higher. However, the technical demands on those materials have also become more stringent.

Reclaim is commonly used in tyre manufacture, and not just in India. Every premium tyre maker (with a single exception) has a specification for reclaim and the option to use up to 5 per cent in certain specific compounds. Some permit up to 10 per cent.

As reclaim companies move toward high tensile specifications; become more selective about the input materials and more aware of the impact of their process on carbon chain length, I can see the use of reclaim increasing. It’s a known technology and delivers a cost-effective result for mid- to low- specification tyres.

However – and especially in the Western world, the use of reclaim depends on the price of rubber; especially the price of natural rubber. As NR has dropped below $2/kg in July 2014, reclaim is has become less economically attractive, but many experts forecast a rise in NR prices before the end of 2014. That might encourage tyre makers to re-discover the benefits of reclaimed rubber.

Tyre makers are now beginning to use granulated and reprocessed materials in retreads. As they build up experience in the benefits and drawbacks, then I expect this technology to move into new tyres, but that will be a slow process.

The most likely route will be to grind the granulated material into very fine powders.

The question is whether those powders will undergo some kind of post-processing. That might be some kind of de-vulcanisation or surface processing. While I believe this has to be the long-term goal, I also think it is a very long-term objective because the costs of destroying the tyre and then grinding it into ultra-fine particles are already high. Adding another process to improve the interaction with virgin compound will be uneconomic, until the price of NR rises significantly.

. David Shaw is Head of UK-based Tire Industry Research and author of Sustainability In Tire Industry 2014 Report

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