Paper bio-dry-strength agents

Paper bio-dry-strength agents are wet-end and surface additives of biological origin — modified starches, carboxymethyl cellulose and other cellulosic polymers, refining enzymes and biopolymer resins — dosed at 0.5–2% on dry fiber to rebuild the hydrogen-bond network that gives paper its tensile, burst and short-span compressive strength. They are the structural answer to two pressures on the industry at once: the collapse of fresh-fiber quality as recycled content rises toward 100% in containerboard and tissue, and the regulatory and brand-driven drive to replace fossil, non-biodegradable polyacrylamide (PAM) dry-strength resins. A well-tuned bio-starch program lifts tensile and short-span compressive strength by 20–40% and lets a mill raise filler or recycled-fiber loading by 5–15 percentage points without losing runnability, while enzymatic refining pre-treatment cuts refining energy by 15–30%.

Key directions of paper bio-dry-strength agents:

1. Cationic & thermally modified starch (Cationic/Thermally Modified Starch): the dominant bio-based DSA, cooked and dosed at the wet end or size press to add 20–40% tensile on recycled liner.
2. Cellulosic polymers & nanocellulose (Cellulosic Polymers/Nanocellulose): CMC, micro- and nano-fibrillated cellulose that form bond-bridges between fibers, raising Scott-bond and surface strength and enabling higher filler loadings.
3. Enzyme-assisted refining & strength (Enzyme-Assisted Refining): cellulase and amylase treatments that cut refining energy 15–30% while preserving fiber length, often layered with a starch program.
4. Biopolymer & biomass-balanced resins (Biopolymer/Biomass-Balanced Resins): chitosan, guar, alginate and biomass-balanced strength resins that displace fossil PAM and are fully compatible with the paper-recycling loop.

Sectoral value chain#

[starch/biomass] ──> [modification] ──> [wet-end dosing] ──> [sheet forming]
                          │                                         │
                  (cook / enzyme)                           (press + dry)
                          │                                         │
                          ▼                                         ▼
[strength-tested paper] <─── [strength development] <───── [recycle loop]

Value chain levels#

Cross-cutting technologies of the sector:

• Jet-cook & on-site starch preparation (Jet-Cook Starch Prep): continuous starch cooking for stable wet-end viscosity.
• Enzymatic refining control (Enzymatic Refining Control): cellulase dosing tuned to freeness targets.
• Real-time wet-end sensors (Real-Time Wet-End Sensors): charge, retention and strength feedback for closed-loop DSA dosing.

The bio-dry-strength stack is built on starch chemistry, enzymatic fiber conditioning and closed-loop wet-end control.

1. Cationic & thermally modified starch (Cationic/Thermally Modified Starch):
   • cooked at 90–95 °C and dosed at 0.5–2% on dry fiber to add 20–40% tensile.
   • case: Roquette STABILYS® A040 thermally modified starch for industrial paper-bioindustry strength.
2. Enzyme-assisted refining & strength (Enzyme-Assisted Refining):
   • cellulase and amylase treatment cuts refining energy 15–30% at target freeness.
   • case: Buckman Smarter Strength layering Ackumen ECHOWISE Pro sensing with targeted enzymes.
3. Biomass-balanced & biopolymer resins (Biomass-Balanced/Biopolymer Resins):
   • biomass-balanced and renewable-carbon strength resins displace fossil PAM.
   • case: Kemira FennoBond™ 777E and biomass-balanced strength additives; Solenis BioBond renewable starch program.