This group comprises thermal carbon black and lamp black.
Thermal carbon black, which is delivered in the form of gray-black pellets, has a very low particle surface area and low structure, which allows the use of large quantities of additive relative to base material in mixtures. Using thermal carbon black (N990) results in vulcanizates with low compression set, high elasticity, low permeability to gases, and low viscosity of the compound. Improvements in terms of mechanical properties are less pronounced as the structural reinforcement provided by this type of carbon black is limited. Common applications include foam rubber, gaskets, and windscreen wiper blades. N990 is also the type of carbon black most commonly used in FKM blends.
Lamp black, LUVOMAXX® LB/P, has a low particle surface area and a relatively high structure. The broad range of particle sizes in combination with high structure and low particle surface size means that the rubber blend is easy to process with excellent results, and extruded profiles are characterized by a glossy surface finish. As compared to the very low PAH content of common types of furnace black, the PAH content of LUVOMAXX LB/P is comparable to the channel blacks listed by the FDA in §177.2600.