Carboxymethyl Cellulose (CMC)

Product Characteristics

1. Appearance

• Industrial Grade: White or slightly yellow fibrous powder or granules, odorless and tasteless
• Food Grade/Pharmaceutical Grade: Pure white powder, higher purity, fewer impurities
• Product form can be made into coarse granules, fine powder, or high-purity refined products according to the application.

2. Core Structural Features

The molecular structure of CMC involves introducing -CH₂COONa (carboxymethyl) substituents at the C2, C3, and C6 positions of the cellulose glucose unit. The key indicator is the degree of substitution (DS), which is the average number of hydroxyl groups substituted on each glucose unit:

• Low degree of substitution (DS < 0.4): Insoluble in water, only swells
• Medium degree of substitution (DS 0.4–1.2): Soluble in cold water, most common
• High degree of substitution (DS > 1.2): Better solubility, enhanced salt tolerance

Physicochemical Properties

1. Solubility

• Cold Water/Hot Water Easily soluble, forms a transparent or translucent colloidal solution
• Organic Solvents (Ethanol, Ether, Acetone, etc.) Insoluble
• High Concentration Electrolyte Solutions Partially precipitates or gels (depending on DS value)

2. Solution Characteristics

• High viscosity: The viscosity of a 1% aqueous solution can range from tens to tens of thousands of mPa·s, depending on molecular weight and concentration
• Pseudoplasticity/shear thinning: Viscosity decreases upon stirring or shearing, recovers upon standing
• Film-forming properties: Forms a flexible, transparent film after the solution dries.
• Strong water retention: Absorbs and retains a large amount of water.

3. Chemical stability

• pH stability: Relatively stable in the pH range of 5–10; precipitates in strong acids (pH < 3); viscosity decreases in strong alkalis.
• Thermal stability: Stable at normal operating temperatures; prolonged exposure to high temperatures (>80°C) leads to a decrease in viscosity.
• Biodegradability: Slowly degraded by specific microorganisms, making it an environmentally friendly material.
• Compatibility: Compatible with most water-soluble colloids, surfactants, and preservatives.

4. Other important properties

• Emulsification stabilization: Reduces oil-water interfacial tension and prevents stratification.
• Suspension stabilization: Ensures uniform dispersion of solid particles and prevents sedimentation.
• Thickening effect: Significantly increases system viscosity.
• Adhesive properties: Can be used as an adhesive.
• Non-toxic and non-irritating: Food-grade and pharmaceutical-grade products have high safety.

Product Classification

Classification by application area

• Food grade (FH) ≥99.5% Food Additives
• Pharmaceutical Grade ≥99.8% Pharmaceutical Excipients, Sustained-Release Materials
• Toothpaste Grade ≥99% Toothpaste Thickeners
• Petroleum Grade ≥95% Drilling Fluids, Fracturing Fluids
• Textile Printing and Dyeing Grade ≥90% Sizing Agents, Printing Pastes
• Paper Grade ≥90% Surface Sizing, Coating
• Ceramic Grade ≥85% Body Reinforcement, Glaze Suspension
• Detergent Grade ≥65% Anti-Redeposition Agents
• Construction Grade ≥80% Putty, Mortar Thickeners

Classification by Viscosity

• Low Viscosity: 2% Solution Viscosity < 50 mPa·s
• Medium Viscosity: 2% Solution Viscosity 50–5000 mPa·s
• High Viscosity: 2% Solution Viscosity > 5000 mPa·s

Main Uses (by Industry)

1. Food Industry ⭐ CMC It is an internationally recognized food additive (E466) with extremely wide applications:

• Beverages: Stabilizes suspended fruit particles, preventing sedimentation and stratification (e.g., juice, plant protein drinks)
• Dairy Products: Stabilizes the structure of yogurt and ice cream, preventing whey separation
• Baking: Improves dough workability, maintains bread softness, and extends shelf life
• Condiments: Thickens and stabilizes ketchup and salad dressing
• Candy/Jelly: Controls crystallization and improves texture
• Low-calorie Foods: Provides a fat-like texture as a fat substitute

2. Pharmaceutical Industry

• Tablet Binder: Helps form drug powders
• Sustained-release Formulations: Controls drug release rate
• Ointment/Cream Base: Thickens and moisturizes
• Eye Drops/Nasal Drops: Increases residence time
• Capsule Materials: Partially replaces gelatin
• Toothpaste: Acts as a binder and thickener, giving toothpaste good extrudability and stability

3. Oil and Gas Industry

• Drilling Fluids: Reduces filtration loss, forms dense mud cake, and protects the wellbore
• Fracturing fluid: Thickens the sand-carrying fluid, improving fracturing efficiency
• Completion fluid/workover fluid: Adjusts rheology, suspends solid particles
• Tertiary oil recovery: Used as a polymer flooding agent

4. Textile and printing industry

• Warp sizing: Improves yarn strength, reduces weaving breakage
• Printing paste: Uses as a dye carrier, controlling dye penetration
• Fabric finishing: Gives fabrics a soft hand feel

5. Paper industry

• Surface sizing: Improves paper strength, smoothness, and printability
• Coatings: Uses as an adhesive, improving coating performance
• Wet end additives: Enhances inter-fiber bonding

6. Daily chemical/detergent

• Laundry detergent/liquid: Anti-fouling redeposition agent, prevents washed-out dirt from re-adhering to clothing
• Cosmetics: Thickening and stabilizing agent for face creams and lotions
• Shampoo/shower gel: Adjusts viscosity, improves user experience

7. Construction industry

• Putty powder/mortar: Retains water and thickens, improves workability, and prevents cracking
• Tile adhesive: Improves workability and adhesion
• Self-leveling materials: Adjusts rheological properties

8. Ceramic industry

• Body strengthening agent: Improves green body strength and reduces breakage
• Glaze slurry suspending agent: Prevents glaze sedimentation and ensures uniform glazing

9. Battery industry

• Lithium battery electrode: As a binder (often used in conjunction with SBR), it adheres the active material to the current collector

10. Other applications

• Agriculture: Seed coating, pesticide suspending agent
• Welding rod: As an adhesive and slagging agent
• Leather: Tanning aid
• Tobacco: Sheet adhesive

Brief description of production process

The production of CMC mainly involves the following steps:

1. Raw material preparation: Using refined cotton linters or wood pulp as raw materials
2. Alkalization: Cellulose reacts with sodium hydroxide to produce alkali cellulose
3. Etherification: Alkali cellulose reacts with chloroacetic acid (or sodium chloroacetate) to introduce carboxymethyl groups
4. Neutralization/Washing: Neutralize excess alkali with acid, and wash with a water-ethanol mixture to remove byproducts (sodium chloride, sodium glycolate, etc.).
5. Drying/Pulverizing/Sieving: Obtain the finished powder.
6. Packaging: Package according to grade requirements.

Safety and Regulations

• Toxicity: CMC itself is non-toxic, non-carcinogenic, and non-mutagenic.
• ADI (Acceptable Daily Intake): The FAO/WHO Joint Expert Committee stipulates "no special provisions" (i.e., use as needed for production).
• Regulations: Listed in China's GB 2760 "Standards for the Use of Food Additives", the US FDA GRAS list, and the EU E466, etc.
• Precautions: High-purity products are highly safe, but industrial-grade products may contain impurities and cannot be used in food or medicine.

CMC is a high-performance, widely used, safe, and environmentally friendly water-soluble polymer material. Its core value lies in the comprehensive embodiment of multiple functions such as thickening, suspending, emulsifying, water retention, binding, and film formation. From everyday food to high-end pharmaceuticals, from traditional textiles to new energy batteries, CMC plays an indispensable role in modern industry and daily life.