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Sodium Carboxymethyl Cellulose (CMC) is widely used in the paper industry because it plays a “customized” key role in meeting the specific requirements of different paper types. It enhances paper strength, improves formation uniformity and printability, while optimizing production efficiency and reducing costs. This article systematically reviews CMC applications in various paper grades and key technical considerations.

1.1 Printing Paper

• Coated Paper/Art Paper: As a coating thickener and stabilizer, it increases coating strength, improves adhesion and gloss, reduces printing dusting, and imparts excellent gloss and printability.

• Offset Paper: Mainly used for surface sizing. Forms a strong film on the paper surface, solving linting and dusting issues during high-speed printing, while improving ink absorption uniformity for clear printing and vibrant colors.

1.2 Packaging Paperboard (Linerboard, etc.)

• Enhances hydrogen bonding between fibers, significantly improving ring crush strength, burst strength, and stiffness, increasing box load-bearing capacity.

• Improves wet strength, extending packaging service life.

• Increases interlayer bonding, reducing defects like delamination and blistering.

1.3 Tissue Paper

• Wet-End Strengthening Agent: Tissue paper is typically unsized, pursuing softness and water absorption. Adding very low doses of high-DS CMC can appropriately improve dry/wet strength without affecting softness, preventing holes during use.

1.4 Specialty and Functional Paper

• Cigarette Paper: Regulates paper permeability for stable combustion; enhances stiffness and flexibility for cigarette processing, while preventing breakage during smoking.

• Filter Paper: Enhances wet strength to prevent paper breakage when filtering liquids, ensuring smooth filtration process; affects fiber bonding to indirectly regulate permeability.

• High-Precision Industrial Paper: Used as wet-end additive and surface treatment agent to enhance fiber bonding and durability; prevents dimensional changes in specialty papers like banknote paper due to humidity variations.

1. Viscosity Selection: High-DS, medium-high viscosity CMC suitable for surface sizing and coating for better water retention; medium-low viscosity CMC suitable for wet-end addition.

2. pH Compatibility: pH during CMC addition should be controlled within appropriate ranges for different applications.

3. Charge Balance: CMC is anionic; attention should be paid to system charge balance to avoid flocculation or reduced effectiveness.

Notes:

1. Different viscosity and purity grades can be produced according to customer requirements;

2. Granulated products require special specification.