The role of carbon black dispersant
Carbon black (carbon black) is a filler and colorant widely used in rubber, plastic, coating, ink and other industries, but
its particles are small and have high surface energy, which makes it easy to agglomerate, resulting in uneven dispersion
in the matrix and affecting the performance of the material. The main role of carbon black dispersant is to improve the
dispersibility of carbon black particles in the medium through physical or chemical effects, including the following aspects:
1. Reduce surface tension and improve wettability
Mechanism of action: The surface of carbon black is usually hydrophobic and has poor compatibility with polar matrices
(such as water-based coatings and resins). Dispersants adsorb on the surface of carbon black to reduce its surface tension
and enhance wettability with the matrix.
Effect: Promote the uniform dispersion of carbon black particles in the medium and reduce agglomeration.
2. Provide steric hindrance or electrostatic repulsion
Steric hindrance: Polymer dispersants (such as polymer type) form an adsorption layer on the surface of carbon black, preventing
particles from approaching through physical barriers to avoid agglomeration.
Electrostatic repulsion: Ionic dispersants charge the surface of carbon black particles and maintain the distance between particles
through electrostatic repulsion.
Effect: Stabilize the dispersion system and prevent sedimentation or flocculation.
3. Enhance the binding force between carbon black and the matrix
Mechanism of action: Dispersants may contain functional groups compatible with the matrix (such as resin, rubber), and enhance the
binding of carbon black to the matrix through chemical bonds or physical adsorption.
Effect: Improve the mechanical properties (such as strength, wear resistance), conductivity or optical properties (such as blackness, hiding
power) of the material.
4. Reduce the viscosity of the system and improve processing performance
Mechanism of action: Uniformly dispersed carbon black particles reduce the friction between particles and reduce the viscosity of the system.
Effect: Improve the fluidity of the material and facilitate processing (such as extrusion, injection molding, coating).
5. Improve the stability of product performance
Mechanism of action: Dispersants stabilize the dispersion state of carbon black to prevent reagglomeration during storage or use.
Effect: Extend the service life of the product and maintain performance consistency.
Basis for selection of dispersant
Carbon black type: Different carbon blacks (such as furnace carbon black and channel carbon black) have different surface properties and
particle sizes, so a matching dispersant needs to be selected.
Matrix properties: The dispersant needs to be compatible with the matrix (such as water-based, solvent-based, thermoplastic resin).
Application requirements: Select a suitable dispersant according to product performance requirements (such as conductivity, tinting strength,
and weather resistance).
Advantages in practical applications
Rubber industry: Improve the dispersibility of carbon black in rubber, enhance the reinforcement effect, and improve the wear resistance and tear
resistance of vulcanized rubber.
Coatings and inks: Improve blackness and hiding power, reduce color difference, and improve leveling and gloss.
Plastic industry: Improve the conductivity of conductive plastics and improve antistatic properties.
Summary
Carbon black dispersants significantly improve the dispersibility of carbon black in the matrix by reducing surface tension, providing steric
hindrance or electrostatic repulsion, and enhancing bonding strength, thereby improving the performance and processing efficiency of the
material.
Selecting a suitable dispersant is the key to optimizing the application effect of carbon black.
