Industry challenges
Paper and board must balance strength, light weight, filler retention, surface smoothness and cost. Higher filler ratios weaken fibre bonding, while lower basis weight risks poor tensile, burst and ply-bond strength. Too much nanomaterial slows drainage and raises drying energy.
What nanocellulose does
CNF enters the gaps between pulp fibres and increases the hydrogen-bonding area, forming a fine network that raises dry strength, density and filler retention. CNC suits surface coating, functional coatings or low-dosage nano-reinforcement. Nanocellulose can also serve as the bio-based skeleton of later barrier and functional layers.
Recommended grade
Recommended: hydroxyl CNF or carboxylated CNF.
Why: paper reinforcement relies on a long-fibre network and bridging between fibres, so CNF is more direct than short rod-like CNC. Hydroxyl CNF suits general pulp reinforcement; test C-CNF first when better dispersion, interfacial action or further functionalisation is wanted.
Alternatives
For surface densification, transparent coatings or composite functions consider CNC; for natural colour, hydrophobic components or specific interfacial properties evaluate lignin-containing CNF. Run a charge-matching test before using strongly anionic C-CNF in a highly cationic wet end.
Trial suggestions
On oven-dry pulp, set a blank plus 0.25%, 0.5%, 1.0% and 2.0%. Dilute and disperse the CNF before mixing it thoroughly with the stock, and do not change the retention system drastically in the first round. Test tensile, burst, tear, ply bond, filler retention, drainage time and formation.
Common issues
- Much slower drainage: reduce the CNF dosage or optimise retention and drainage aids.
- Worse formation: check how the CNF is mixed into the stock.
- No strength gain: check fibre dispersion, pulp type and drying conditions.
- Flocculation: watch charge density, salts and the order in which cationic additives are added.
Note
These suggestions are for nanocellulose material selection and preliminary trials only, not fixed formulations, final process parameters or regulatory conclusions. Results depend on product type, surface groups, solids content, dispersion state, dosing method, and on the system's pH, ionic strength, resin/polymer/protein type, pigments, fillers and other additives. Run a blank and a dosage gradient to confirm the grade and process conditions for your own system. For food, cosmetic, medical and food-contact uses, confirm regulations, purity, testing and market access separately for the target market.
