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Adhesion of millable PU to general purpose rubber

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Polyurethanes are known for their outstanding abrasion resistance and strength properties, properties that are important for applications such as conveyor belting for mining, footwear and other applications.

Millable polyurethanes are often used for these applications, but their relatively high cost can be a disadvantage vs. general purpose rubbers like SBR and NR, which are more commonly used. Co-vulcanizing a thin layer of the millable polyurethane over a general purpose rubber gives a highly abrasion-resistant layer, resulting in improved performance and lower total cost compared to an all-polyurethane compound.

Bonding of these dissimilar polymer types has been difficult in the past, but the inclusion of a minor proportion of a polybutadiene-based thermoplastic polyurethane to either or both components has been found to result in excellent adhesion.