Compounds AG, in collaboration with Hefner GmbH & Co. KG has developed a sustainable, "green" roller compound for the first time. The proportion of renewable raw materials in the compound - mainly natural rubber and a wood-based functionalized filler (see Figure 1) - is almost 60%.
The company Hefner GmbH & Co. KG has produced the first prototypes of transport rollers from this mixture (see Fig. 2), which are currently being put through their paces in the wood processing industry. So far, all test results are very promising and suggest that they will be ready for the market in the course of 2023. The first examples of these rollers, manufactured based on sustainable and CO2-negative mixtures, were presented to a broad trade audience at the BAU trade fair in Munich in April 2023.
The starting point of the joint research project of Compounds AG and Hefner GmbH & Co. KG was the question of the extent to which traditional compound ingredients can be replaced by sustainable and environmentally friendly substances and what influence these substitutions have on the properties of the compound, the vulcanizate and the final article.
The aim here was to develop compounds for rollers based on bio-based, sustainable raw materials, with a negative carbon footprint with comparable technical properties to existing rollers made from synthetic raw materials.
The result of the joint research work is the realization that, with the right choice of compound components and with the right mixing method, compounds with a negative CO2 footprint can be produced from the combination of natural rubber with wood-based fillers, with mechanical properties that match the requirement profile of existing rollers.
That this has been achieved is shown by an exemplary comparison of some mechanical and dynamic-mechanical data of a standard compound with the data of the new sustainable compound A4442 produced by Compounds AG (see Table 1), which can be used as standard for transport rollers.
| Methode | Referenz | A4442 | |
|---|---|---|---|
| σ Bruch [MPA] | DIN 53504 - S2 | 7 | 8 |
| ε Bruch[%] | DIN 53504 - S2 | 694 | 441 |
| DVR 70°C/24h/25% | DIN ISO 815-1 Typ B | 52 | 28 |
| Härte [ShA] | DIN ISO 7619-1 | 40 | 46 |
| Rückprall [%] | DIN 53512 | 62 | 60 |
| Weiterreissen [N/mm] | DIN ISO 34-1 A | 3.4 | 4.5 |
A comparison of the values shows that the mechanical properties of the new sustainable compound A4442 are almost identical to the values of the standard compound. Since the tear resistance of compound A4442 is about 20% higher than the corresponding value of the conventional reference compound, slight advantages can be expected in the mechanical stability and service life of the components manufactured from this compound.
In addition, the use of the wood-based fillers can reduce the density of the sustainable, bio-based compound by up to 15%. This results in a significant weight reduction of the entire roll.
Thus, on the one hand, the CO2 footprint is significantly reduced through the use of sustainable raw materials in the manufacture of the rolls. Furthermore, the energy costs of the rolls in operation are reduced due to the lower weight, and the slightly better mechanical properties mean that a longer service life can be expected.
