Recommendations for the use of high surface carbon black dispersants

Recommendations for the use of high surface carbon black dispersants

High surface carbon black dispersants are key additives used to improve the dispersion performance of carbon black in the medium. Their effective use is crucial to product performance (such as uniformity, gloss and conductivity of coatings, inks, and plastics). The following provides professional suggestions from three dimensions: formulation design, application process, and common problem solving:

I. Formulation design stage

Compatibility of dispersants and carbon black

Preferably select dispersants with strong anchoring groups (such as carboxylates and sulfonates) that can form chemical bonds with the active sites on the surface of carbon black

For high-structure carbon black (such as N990), it is recommended to use high molecular weight dispersants (molecular weight>10000), whose steric hindrance effect can effectively prevent reaggregation

Test the compatibility of dispersants with system solvents, and recommend the use of dispersants with HLB values of 8-14 for polar systems

Dispersant dosage optimization

The basic dosage is recommended to be 30-80% of the mass of carbon black, and the specific optimal addition amount needs to be determined by Zeta potential test

Use the "step addition method": first add 50% dispersant to pre-wet the carbon black , the rest is gradually added during the grinding stage

II. Application process control

Pre-dispersion process

It is recommended to use a high-speed agitator (3000-5000rpm) for pre-dispersion, and the time is controlled within 15-30 minutes

Temperature control: water-based system ≤60℃, solvent-based system ≤80℃, to prevent dispersant degradation

Grinding process

It is recommended to use a bead mill (0.3-0.8mm zirconium beads) for dispersion

The filling rate of the grinding media is maintained at 60-75%, and the linear speed is controlled at 8-12m/s

Grinding three elements control: temperature <60℃, viscosity <500cps, and the number of cycles is 3-5 times

III. Solutions to common problems

Floating color and flowery problems

Check the compatibility of the dispersant and the resin, and it is recommended to use a grafted dispersant

Adjust the pH value to 7.5-9.0 (water-based System)

Add 0.2-0.5% anti-settling agent (such as organic bentonite)

Insufficient gloss

Check the dispersed particle size, it is recommended that D50 < 150nm

Optimize the amount of dispersant, excessive dispersant may cause gloss reduction

Add 0.1-0.3% leveling agent

Storage stability issues

Check the synergistic effect of dispersant and anti-settling agent

Add 0.1-0.3% fungicide to prevent microbial degradation

Storage temperature is controlled at 5-35℃

IV. Performance verification method

Dispersion stability test

Use centrifugal acceleration test (3000rpm/30min) to observe the sedimentation rate

Measure the viscosity change rate after 30 days of storage (should be <15%)

Dispersed particle size analysis

Use laser particle size analyzer to detect D50 and D90 values

Observe TEM electron microscope photos to confirm the dispersion state

Performance Comparative test

Compare the gloss (60° angle), hiding power, conductivity and other key indicators of the product before and after addition

V. Application precautions

Compatibility of dispersant with other additives in the system

Avoid direct contact with strong acid/alkaline substances

Add 30 minutes after defoaming agent

Safety operation specifications

Wear protective equipment, dispersant may be irritating to the skin

Store in a cool and dry place, away from fire