CARBOXYMETHYL CELLULOSE

CARBOXYMETHYL CELLULOSE

Carboxymethyl Cellulose (CMC), commonly referred to as “glaze binder” in the ceramic industry, is an organic polymer derived from natural cellulose. CMC is an essential additive that functions as a binder, thickener, and stabilizer.

Its most important role is to improve the workability of the glaze slurry and enhance the mechanical strength of ceramics in the dry (green body) state.

1. Classification and Composition

   •   Chemical formula: [C₆H₇O₂(OH)₂OCH₂COONa]ₙ (Sodium Carboxymethyl Cellulose)

   •   Source: Derived from natural cellulose (wood pulp, plant fibers)

   •   Main composition: An organic polymer in which carboxymethyl groups (–CH₂–COOH) are attached to the cellulose backbone

   •   Classification: CMC is classified by viscosity (low, medium, high) and degree of substitution (DS), which determine its solubility and rheological (binding) properties

2. Technical Specification

Parameters	Characters
Appearance	Fine powder, white, light yellow, or yellow-brown.
Solubility	Rapidly soluble in both cold and hot water, forming a high-viscosity colloidal solution.
Characteristic properties	Anionic nature; forms a network (gel) structure through hydrogen bonding and Van der Waals forces.
Firing loss	Exhibits clean burn-out, leaving negligible ash (carbon residue) after firing and does not affect the color of the glaze or ceramic body.

3. Applications in Ceramics & Industry

A. Ceramic Applications

Glaze:

• Improves adhesion: Enhances bonding between glaze and ceramic body, reducing flaking and cracking
• Suspension stability: Prevents settling, ensures uniform dispersion of raw materials and pigments
• Viscosity control: Provides smooth application, improves surface finish, and reduces pinholes

Green Body:

• Enhances plasticity: Improves shaping and forming process
• Increases green strength: Reduces breakage during handling and transportation (2–3 times higher)

B. Other Industrial Applications

• Oil Drilling: Used in drilling fluids to control viscosity, reduce fluid loss, and stabilize wellbore walls
• Food & Cosmetics: Acts as a thickener, stabilizer, and gelling agent
• Paper Industry: Improves dry and wet strength of paper