1.Product Overview

Dry Strength Agents (DSAs) are a class of water-soluble polymers added during the papermaking process to enhance the mechanical properties of paper and paperboard in their dry state. Unlike wet strength agents that create chemical cross-links, dry strength agents primarily work through physical mechanisms—improving fiber-to-fiber bonding and fines retention—to increase strength without significantly affecting other key paper properties. They are a cost-effective means of boosting strength, allowing for the use of more recycled or weaker fibers, or reducing basis weight while maintaining performance.

2. Application in Papermaking

Addition Point: Typically added to the thick stock (at the fan pump or before) or the thin stock system. Optimal location depends on the chemical and system charge.
Dosage: Common dosage ranges from 0.1% to 1.0% (on dry fiber weight), with starch often at the higher end and synthetic polymers at the lower end of this range.
Retention & System Charge: Performance is highly dependent on proper adsorption and retention. Effectiveness can be diminished by high levels of anionic “trash” (interfering substances) in recycled furnishes. Charge balance management is critical.
Compatibility: Generally compatible with other wet-end additives like retention aids and sizing agents, but addition order and location must be optimized.

3. Typical Applications

Used across a vast range of paper and board grades where enhanced dry strength is economically or functionally critical:
Packaging Grades: Linerboard, corrugating medium, folding cartonboard (to improve crush resistance, stiffness, and puncture).
Tissue & Towel: To allow lower basis weight or improve converting performance.
Fine Papers: Printing/writing papers to improve surface strength (reducing picking) and internal bonding.
Newsprint & Publication Grades: To compensate for the weak mechanical properties of high-yield pulps.
Paperboard & Specialty Papers.