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In the toothpaste industry, CMC acts as a binder, preventing separation of solid and liquid components, imparting appropriate viscoelasticity and shape to the paste, enabling it to form ribbons with good structure that adhere to toothbrushes without collapsing or thinning. Toothpaste-grade CMC must maintain uniformity and flowability while providing water retention and thickening properties, and meeting filling speed requirements—low viscosity during filling and higher viscosity after storage. These performance requirements are closely related to CMC’s viscosity, degree of substitution (DS), and salt resistance.

CMC viscosity significantly influences thickening performance:

• Too low thickening: Poor ribbon formation, paste collapses easily after extrusion.

• Too high thickening: Difficult to extrude, paste becomes rough.

Important note: There is no strict linear relationship between CMC viscosity and toothpaste consistency. The same or similar viscosity CMC may yield different toothpaste consistencies; sometimes higher viscosity CMC produces lower consistency. This is because toothpaste consistency reflects comprehensive CMC properties, including rheological characteristics and substitution uniformity. Selection must consider both paste characteristics and manufacturing requirements.

Toothpaste-grade CMC typically has DS in the range of 0.65–1.25:

• DS directly affects CMC thixotropy. Higher DS leads to lower thixotropy (due to reduced insoluble crystalline regions).

• Thixotropy affects thickening: Lower DS provides better thickening; higher DS results in poorer thickening.

Substitution uniformity is equally critical:

• Non-uniform substitution: Poor water retention, short thickening duration, easy hydrolysis, reduced stability.

• Uniform substitution: Less free fiber, higher solution clarity, smooth and glossy paste.

• However, excessively uniform substitution: Low thixotropy, insufficient post-storage swelling, low consistency, poor ribbon formation.

Salt resistance of CMC is measured by Salt Viscosity Ratio (SVR) :

• Higher SVR indicates better stability (typically achieved with uniformly etherified CMC).

• Toothpaste often contains various salt-type electrolyte drugs, which can affect paste stability. When producing such toothpastes, CMC with good salt resistance is required.

The application performance of CMC in toothpaste reflects the synergy of multiple properties, which interact and influence each other. Selection should:

1. Prioritize based on paste characteristics (salt content, target consistency, ribbon formation requirements).

2. Balance viscosity, DS, substitution uniformity, salt resistance, and other indicators.

3. Validate through actual toothpaste manufacturing trials to select the CMC grade that best matches overall performance needs.

SIDLEYCHEM offers a full range of toothpaste-grade Sodium Carboxymethyl Cellulose (CMC) products, with customizable viscosity, DS, and salt resistance specifications to ensure smooth, glossy paste, good ribbon formation, and storage stability. Our technical team can assist with formulation testing and selection optimization to help produce high-quality toothpaste.