Paper Making Dispersant: Enhance Fiber Dispersion & Paper Quality

A paper-making dispersant is a chemical additive designed to prevent fiber flocculation and particulate aggregation in aqueous pulp suspensions. In tissue production (toilet paper, napkin, facial tissue), dispersants adsorb on fiber surfaces or colloidal fines, reduce attractive forces between particles, and maintain an even fiber distribution during forming and web consolidation. The immediate benefits are improved formation uniformity, more consistent sheet softness, and the potential for lower dry-strength additive usage due to better fiber contact and bonding efficiency.

We would like to share how paper making dispersant improves fiber dispersion, paper strength, softness, and uniformity for tissue, napkin, and toilet paper production.

Mechanism of action — practical details

Electrostatic and steric stabilization

Most dispersants work by one or both mechanisms:

• Electrostatic repulsion — charged dispersant molecules increase zeta potential and repel similarly charged fibers/fines.
• Steric hindrance — polymer chains protrude from fiber surfaces forming a physical barrier that prevents close approach and flocculation.

Interaction with fines and fillers

Dispersants also stabilize mineral fillers and colloidal fines, keeping them well distributed so they do not cause streaks or local density variations in tissue. That leads to improved caliper control and visual uniformity in light-weight tissue sheets.

Types of dispersants and selection guidance for tissue grades

Choose a dispersant based on pulp type, furnish chemistry, and desired end-sheet properties. Common categories and practical selection notes:

• Anionic dispersants — effective with kraft and neutral/alkaline pulps; good with mineral fillers; may increase drain time slightly.
• Cationic dispersants — better when high anionic charge exists (e.g., high hemicellulose or charged wet-strength agents); can compete with cationic retention aids on the surface of fines or fibers — choose carefully.
• Nonionic/Amphoteric polymers — versatile, lower sensitivity to pH and ionic strength, often preferred for delicate tissue finishes where softness is critical.

Practical dosing and application steps in tissue production

Typical dosing ranges and where to add

Dispersants are effective at low dosage. Typical mill practices for tissue and toilet grades:

Start at the low end and run formation/retention/drainage tests. Adjust gradually — because overdosing can affect drainage and retention negatively.

Compatibility with other additives and process impacts

Common interactions to monitor

• Retention/ drainage aids — dispersants can change the required dose of micro-polymer retention systems; run jar tests to re-balance.
• Wet-strength and dry-strength agents — surface-active dispersants can reduce effective bonding if overdosed; optimize to maintain target tensile strength.
• Surface/creping additives — dispersants that remain on fibers may influence creping adhesion and hence softness; choose low-foaming, low-residue types for high-softness tissue.

Quality control, testing and troubleshooting

Essential lab and mill tests

• Jar formation tests (image analysis) — quantify formation index before/after dispersant.
• Drainage (CSF or dynamic drainage) — detect any adverse slowing of drain time.
• Retention profile (Ash and turbidity) — measure filler retention and fines loss.
• Tensile, softness (hand-feel and instrument), and caliper — ensure end-sheet performance meets spec.

Troubleshooting guide — short practical fixes

• If formation improves but drainage slows: lower dispersant dose or change application point; increase retention aid slightly.
• If tensile strength drops unexpectedly: check for dispersant adsorption on fiber surfaces and reduce dosage or switch to nonionic variant.
• If filler streaks persist: verify mixing in filler slurry tank and raise dispersant concentration in slurry feed.

Implementation checklist for mills

• Run bench-scale jar and drainage trials to find the lowest effective dose;
• Verify compatibility with your retention and strength chemistries using sequential addition jar tests;
• Define control points: headbox turbidity, white water turbidity, and formation index monitoring;
• Document standard operating procedure (SOP) for dosing, sampling, and corrective actions.

Summary — measurable benefits for tissue producers

When selected and dosed properly, dispersants deliver measurable improvements: more uniform paper formation, enhanced softness perception (by improving uniformity and caliper control).