Polyester Carbon Black Viscosity Reducer and Dispersant Usage Guide: Enhancing Blackness and Smoother Processing
In industries such as rubber, plastics, and coatings, carbon black serves as a crucial reinforcing filler and colorant, and
its dispersion effect directly impacts product performance. However, carbon black particles, due to their high surface
energy and tendency to agglomerate, often lead to soaring system viscosity and processing difficulties. Polyester
carbon black viscosity reducers and dispersants address this problem through physicochemical action. The following
sections cover their working principle, usage methods, and precautions.
I. Working Principle: A Two-Pronged Approach to Solving the Problem
Polyester dispersants function through a dual mechanism of "physical isolation + chemical adsorption":
Reducing Surface Tension: Dispersant molecules adsorb onto the carbon black surface, forming a hydrophilic or
oleophilic layer, weakening the attraction between particles and reducing agglomeration.
Stereohindrance Effect: Polymer chains unfold on the carbon black surface, forming a three-dimensional barrier that
prevents particles from approaching, maintaining dispersion stability.
Adjusting System Viscosity: Some dispersants are compatible with the matrix, reducing internal friction and significantly
improving the flowability of the mixture.
II. Usage Methods: Precise Control is Key
Pre-dispersion Treatment: Premix the dispersant and carbon black at a ratio of 10%-20% (the specific ratio needs to be
adjusted according to the product instructions). Disperse initially using high-speed stirring or grinding equipment to form a
uniform slurry. This step avoids excessively high local concentrations caused by direct addition.
Step-by-Step Addition Method:First, add a portion of the dispersant to the matrix (such as rubber or resin), stirring until
completely dissolved. Then, gradually add the carbon black, mixing thoroughly after each addition, and finally replenish the
remaining dispersant. This method avoids carbon black instantly adsorbing too much dispersant, leading to ineffectiveness.
Viscosity Monitoring Method:In the laboratory or pilot-scale testing stage, a "dispersant dosage-system viscosity curve"
can be plotted: add the dispersant dropwise to the carbon black slurry, record the viscosity change, and the lowest point
corresponds to the optimal dosage. Fine-tuning is required in actual production based on process conditions.
III. Precautions: Details Determine Success
Type Matching: Select the dispersant according to the matrix properties: use anionic or nonionic dispersants for aqueous
systems, and cationic or composite dispersants for oily systems. For example, polyester dispersants work better in polar solvents.
Dosage Control: Excessive addition may cause over-dispersion, leading to re-aggregation of carbon black particles or thickening
of the system. It is recommended to determine the optimal dosage through small-scale testing, typically 5%-15% of the carbon
black mass.
Process Optimization:
Temperature: High temperatures can accelerate dispersant adsorption, but it is necessary to avoid exceeding its
decomposition temperature (generally not exceeding 80℃).
Shear Force: High-shear equipment (such as a three-roll mill) can improve dispersion efficiency, but localized overheating
must be prevented.
pH Value: Some dispersants are sensitive to acidity and alkalinity; the system pH should be maintained between 6 and 8.
Storage and Compatibility: Dispersants should be stored in a sealed container in a cool, dry place, avoiding mixing with
strong oxidizing or reducing agents. Long-term storage may affect the effect due to precipitation or stratification;
thorough stirring is required before use.
IV. Application Scenarios: From Laboratory to Production Line
Rubber Industry: Improves the dispersibility of carbon black in rubber, reduces the Mooney viscosity of rubber
compounds, and improves tire wear resistance.
In the coatings industry: It prevents the sedimentation of high-pigment carbon black, improves the storage stability of
color pastes, and results in a uniform gloss of the paint film.
In plastics processing: It reduces the impact of carbon black on melt flowability, preventing flow marks on the surface of
injection molded parts.
By scientifically selecting the type of dispersant, precisely controlling the dosage, and optimizing process conditions,
polyester carbon black viscosity-reducing dispersants can significantly improve material performance, helping to reduce
costs and increase efficiency in industrial production. In practical applications, adjustments should be made flexibly
based on specific formulations and equipment conditions. It is recommended to conduct small-scale trials before
large-scale application.
