Carbon black: Characteristics
From N100 to N900: decoding tyre-grade black
What this tab covers The physical and chemical properties that set its grade, price and uses, with the commercial grades and the standards that define them.Carbon black grades are defined by particle size (surface area), structure (how particles aggregate) and surface chemistry. These set reinforcement, wear and rolling resistance in tyres, and jetness and conductivity in specialty uses. ASTM D1765 names rubber grades from N100 (finest, treads) to N900 (coarsest, thermal).
Properties that matter commercially
| Property | Value / specification | Why it matters | Source |
|---|---|---|---|
| Surface area (iodine number or nitrogen surface area) | about 10-150 m2/g for rubber grades (indicative) | finer particles reinforce more but raise heat build-up | ASTM D1765 (indicative) |
| Structure (oil absorption number) | about 40-130 ml/100 g (indicative) | higher structure increases stiffness and conductivity | ASTM D1765 (indicative) |
| Ash and sulphur | below about 1% ash (indicative) | impurities affect rubber properties; rCB has 10-20% ash (indicative) | indicative |
Commercial grades
- Hard (tread) grades N100-N300
- Soft (carcass) grades N500-N700
- Thermal black N990
- Specialty pigment blacks for inks and coatings
- Conductive and battery grades, acetylene black
- Recovered carbon black