Carboxymethyl Cellulose (CMC), also known as sodium carboxymethyl cellulose (Na-CMC), is a water-soluble cellulose ether derivative. It is made from natural cellulose (such as cotton linters, wood pulp, etc.) through alkalization and etherification reactions. The introduction of carboxymethyl (-CH₂-COOH) groups into the molecular chain gives it excellent thickening, suspension, emulsification, film-forming and water-retaining properties.
CMC is a white or slightly yellow powder, odorless and tasteless, easily soluble in water to form a transparent or slightly turbid viscous solution, but insoluble in organic solvents (such as ethanol, acetone, etc.). Its solution is weakly alkaline (pH 7~9), with good thermal stability (stable below 80°C), salt resistance and biocompatibility.
Main raw materials
Cellulose sources: cotton linter, wood pulp, bamboo pulp, etc.
Chemical reagents: sodium hydroxide (NaOH), chloroacetic acid (ClCH₂COOH), ethanol (solvent), etc.
Production process
Alkalization reaction: Cellulose reacts with NaOH to form alkali cellulose.
Cell-OH + NaOH → Cell-ONa + H₂O
Cell-OH + NaOH → Cell-ONa + H₂O
01
Etherification reaction: Alkali cellulose reacts with chloroacetic acid to introduce carboxymethyl groups.
Cell-ONa + ClCH₂COOH → Cell-O-CH₂-COONa + NaCl
Cell-ONa + ClCH₂COOH → Cell-O-CH₂-COONa + NaCl
02
Neutralization and purification: adjust pH to neutral and remove by-products
03
Drying and crushing: Get the CMC powder product.
04
Key factors affecting performance
Degree of substitution (DS): determines the solubility and viscosity of CMC.
Degree of polymerization (DP): affects the molecular weight and solution viscosity of CMC.
Purity: affects the application scope of CMC (e.g. food and pharmaceutical grades require high purity).
Application Areas
Food industry
Thickening and stabilizing agent: used in ice cream, yogurt, sauces, beverages, etc. to prevent stratification and precipitation.
Water-binding agent: retains moisture in baked goods (such as bread and cakes) to extend shelf life.
Low-calorie food: used as dietary fiber in weight loss foods and meal replacement products.
Medicine and cosmetics
Drug excipients: used as tablet adhesives, sustained-release agents (such as stomach medicine, capsules).
Medical dressings: used for wound dressings, artificial tears (such as eye drops).
Cosmetics: used in toothpaste, shampoo, lotion, etc., to provide thickening and stabilization effects.
Petroleum and drilling industry
Drilling fluid additives: increase mud viscosity and prevent well wall collapse.
Fracturing fluid thickener: used in hydraulic fracturing technology in shale gas extraction.
Detergents and daily chemicals
Laundry detergent/detergent: Enhances the ability to remove dirt and prevents dirt from re-depositing.
Toothpaste: As a thickener, it improves the stability of the paste.
Papermaking and Textiles
Papermaking enhancer: improves paper strength and water resistance.
Textile printing and dyeing: as a thickener for pulp and printing paste.
Environmental protection and construction
Sewage treatment: as a flocculant, it helps the suspended matter settle.
Cement additive: improves the water retention and fluidity of concrete.
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