Application of Carboxymethyl Cellulose CMC

Carboxymethyl Cellulose (CMC) is an important cellulose ether. It is an anionic soluble polymer compound made from natural cellulose through chemical modification reaction. It is a white or slightly yellow fibrous or granular powder, odorless, tasteless, non-toxic, with good water solubility, colloidal dispersibility, film-forming property, water retention and chemical stability. Therefore, it is widely used in many fields such as industry, food, and medicine.

1. Basic properties of CMC

CMC is a product made by reacting chloroacetic acid with alkali cellulose under alkaline conditions based on natural cellulose. Carboxylmethyl groups (-CH2COOH) are introduced into its molecular structure, which makes cellulose soluble and surface active. The solubility, viscosity, degree of substitution (DS, referring to the number of carboxylmethyl groups substituted on each anhydrous glucose unit) and other properties of CMC depend on the reaction conditions during its manufacturing process.

Generally, the degree of substitution of CMC is between 0.4 and 1.2. When the DS value is greater than 0.6, CMC can be completely dissolved in water. Its aqueous solution is neutral to weakly alkaline, can form a transparent, uniform colloidal solution, and has good rheological and thermal stability. CMC is hygroscopic, but not easily decomposed by bacteria, and its chemical properties are relatively stable.

2. Main application areas of CMC

2.1. Food industry
CMC is mainly used as a thickener, stabilizer, water retainer, film former and emulsifier in the food industry. For example:
Adding CMC to ice cream can prevent ice crystal formation and improve taste;
Increasing water retention in bread and pastries and extending the shelf life;
It plays a role in stabilizing suspended matter and preventing precipitation in juice and dairy products;
It is used as a dietary fiber substitute for low-calorie foods to help control calorie intake.
CMC is an edible food additive that meets the food safety standards of many countries.

2.2. Pharmaceutical Industry
CMC is widely used as a binder, sustained-release material, thickener and suspending agent for tablets in the pharmaceutical industry:
Sodium CMC can be used as artificial tears in eye drops;
It plays a thickening and film-forming role in oral care products (such as toothpaste);
It is used to prepare sustained-release drugs to improve the controlled-release performance of drugs;
It provides good adhesion and moisturizing properties in topical ointments and gels.

2.3. Daily Chemical Industry
In shampoo, laundry detergent, skin care products and other products, CMC can provide good thickening, emulsification stability and water retention, making the product texture more delicate and more comfortable to use. For example:
In laundry detergent, it prevents dirt from re-depositing;
In skin care products, it is used as a moisturizer to improve the touch of the skin;
In toothpaste, it improves the foam structure and taste.

2.4. Petroleum Industry
CMC is an important drilling fluid additive in oil drilling. It can effectively adjust the viscosity and thixotropy of drilling fluid, and play a role in stabilizing the well wall, preventing well collapse, and carrying out drilling cuttings. Its advantages include:
It still has good stability under high temperature and high pressure conditions;
It is not easy to be degraded by microorganisms and is suitable for long-term drilling operations;
It can effectively reduce water loss and improve drilling efficiency.

2.5. Textile and papermaking industry
CMC is used as a slurry in the textile industry to improve the sizing performance of fabrics; in the papermaking industry, it is used as a surface sizing agent, reinforcing agent and dispersant:
Enhance the dry and wet strength of paper;
Improve the smoothness and ink absorption performance of paper;
Improve the uniform distribution of pigments and fillers.

2.6. Ceramics and building materials
In the ceramic industry, CMC is used as an adhesive and plasticizer to enhance the plasticity and dry strength of the embryo; in the construction field, it is used as a thickener and water-retaining agent for dry mortar and wall putty to improve the construction performance and the overall adhesion of the material.

3. Advantages and development trends of CMC

CMC has become one of the world’s largest and most widely used cellulose ethers with its natural source, safety, environmental protection and excellent performance. With the increasing attention paid to green chemistry and renewable resources, the application prospects of CMC are very broad.

The research and development of CMC will focus more on the following directions:
Improve the functional diversity of products, such as developing CMC derivatives with antibacterial and conductive functions;
Optimize production processes to reduce environmental load and costs;
Improve adaptability to safety standards of specific industries (such as food and medicine);
Develop new degradable and renewable materials to expand applications in high value-added fields such as biomedicine and environmentally friendly materials.

As a high-performance, multifunctional, green and environmentally friendly material, carboxymethyl cellulose plays an irreplaceable role in all walks of life. With the advancement of technology and the growth of application demand, the market prospects of CMC will be broader, and it is expected to play a greater role in new materials, new energy, biomedicine and other fields.