What is carbon black

Carbon black is mainly used to strengthen rubber in tires, but can also work as colorants in plastic, ink and coating applications. The fundamental properties of carbon black determine application performance. These include:

● Particle Size

● Structure(DBP oil absorption)

● Surface Chemistry or Surface Activity

● Physical Form

PARTICLE SIZE

Measured by electron microscopy, for specialty carbon blacks, smaller particle diameter gives rise to higher surface area and tinting strength. High surface area is usually associated with higher jetness, higher conductivity, improved weatherability, and higher viscosity, but also higher viscosity. Typical particle sizes range from around 8 nanometers to 100 nanometers for furnace blacks.

STRUCTURE(DBP oil absorption)

This is a measure of the three-dimensional fusion of carbon black particles to form aggregates, which may contain a large number of particles. The shape and degree of branching of the aggregates is referred to as structure. Structure is measured by DBP(Dibutyl Phthalate) oil absorption.

Highly structured(also high DBP oil absorption) carbon blacks provide higher viscosity, greater electrical conductivity and easier dispersion for specialty carbon blacks. Increasing carbon black structure increases hardness, electrical conductivity, and improves carbon black dispersibility, but increases viscosity.

SURFACE CHEMISTRY OR SURFACE ACTIVITY

This is a function of the manufacturing process and the heat history of a carbon black and generally refers to the oxygen-containing groups present on a carbon black’s surface.

For specialty carbon blacks, oxidized surfaces improve pigment wetting, dispersion and overall performance. The extent of surface oxidation is measured by determining the quantity of the “volatile” component on the carbon black.

PHYSICAL FORM

The physical form (beads or powder) can affect the handling and mixing characteristics. Powder carbon blacks are recommended in low-shear dispersers and on three-roll mills. Bead carbon blacks are recommended for shot mills, ball mills, and other high energy equipment.