Brown says process can economically restore process scrap

Glossop, Derbyshire - Watson-Brown HSM claims it can process scrap rubber so that it can be re-used in the production process at high volumes. Even up to 100 percent, but more typically at 30 to 50 percent. The company says it has found a way to break cross-link bonds, effectively de-vulcanising process scrap. The resulting material can then be added to virgin compound with no significant degradation in final performance, or change in process characteristics.

The company makes use of theoretical and research work by Bill Watson, former director of Rapra Technology, combined with the engineering expertise of Chris Brown, former director of Francis Shaw.

At present the company is running extensive and lengthy trials with undisclosed customers, but David Brown, director of Watson-Brown says that the process provides significant economic benefits where compound cost is above Euro 10/kg, and often provides benefits for cheaper compounds, especially where either volumes or scrap rates are high.

Although many companies, he said, estimate scrap rates at 3 percent or so, the reality is different. Some companies, he said say they need 10 kg of rubber to make a 7 kg part, but still maintain that their scrap rate is below three percent. He said in these times of increasing raw materials costs and potential shortages, this process can offer significant economic benefits to many companies.

Brown said the Watson-Brown has recently struck a deal with an un-named Chinese company to build the machines needed to recover process scrap. The machines can be made in any size from a few litres capacity up to hundreds of litres for high-volume applications, he said. This means it is possible for companies using small volumes of high-value compounds to take advantage of the process.

Brown said the company mixed a typical tyre tread compound, cured it and then tested it. Afterwards, they re-processed the material at 100 percent recyclate and performed more tests. While elongation at break suffered, the tensile strength, hardness and other properties were unaffected by the re-processing. When oil was added to the re-processed mix, elongation at break was only fractionally lower than the initial material, while all other properties were very similar.

Brown emphasised that this is not merely about re-grinding process scrap and adding it to the mix as a low-value filler. Instead, he said, it is about adding finished compound at the start of processing to save money and reduce wastage with no significant loss in performance or difference in process conditions.

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Website of Watson-Brown HSM