Sodium carboxymethyl cellulose (also known as: sodium carboxymethyl cellulose, carboxymethyl cellulose, CMC, Carboxymethyl, Cellulose Sodium, Sodium salt of Caboxy Methyl Cellulose) is the most widely used and the largest amount used in the world today types of cellulose.

CMC-Na for short, is a cellulose derivative with a glucose polymerization degree of 100-2000, and a relative molecular mass of 242.16. White fibrous or granular powder. Odorless, tasteless, tasteless, hygroscopic, insoluble in organic solvents.

Basic properties

1. Molecular structure of sodium carboxymethylcellulose (CMC)

It was first produced by Germany in 1918, and it was patented in 1921 and appeared in the world. Commercial production has since been achieved in Europe. At that time, it was only crude product, used as colloid and binder. From 1936 to 1941, the industrial application research of sodium carboxymethyl cellulose was quite active, and several inspiring patents were invented. During World War II, Germany used sodium carboxymethylcellulose in synthetic detergents. Hercules made sodium carboxymethylcellulose for the first time in the United States in 1943, and produced refined sodium carboxymethylcellulose in 1946, which was recognized as a safe food additive. my country began to adopt it in the 1970s, and it was widely used in the 1990s. It is the most widely used and the largest amount of cellulose in the world today.

Structural formula: C6H7O2 (OH) 2OCH2COONa Molecular formula: C8H11O7Na

This product is the sodium salt of cellulose carboxymethyl ether, an anionic fiber

2. Appearance of sodium carboxymethyl cellulose (CMC)

This product is the sodium salt of cellulose carboxymethyl ether, an anionic cellulose ether, white or milky white fibrous powder or granule, density 0.5-0.7 g/cm3, almost odorless, tasteless, hygroscopic. It is easy to disperse in water to form a transparent colloidal solution, and is insoluble in organic solvents such as ethanol [1]. The pH of 1% aqueous solution is 6.5-8.5, when the pH>10 or <5, the viscosity of the mucilage decreases significantly, and the performance is the best when the pH=7. Stable to heat, the viscosity rises rapidly below 20°C, and changes slowly at 45°C. Long-term heating above 80°C can denature the colloid and significantly reduce the viscosity and performance. It is easily soluble in water, and the solution is transparent; it is very stable in alkaline solution, but it is easily hydrolyzed when it encounters acid, and it will precipitate when the pH value is 2-3, and it will also react with polyvalent metal salts.

The main purpose

It is used as a thickener in the food industry, as a drug carrier in the pharmaceutical industry, and as a binder and anti-redeposition agent in the daily chemical industry. In the printing and dyeing industry, it is used as a protective colloid for sizing agents and printing pastes. In petrochemical industry, it can be used as a component of oil recovery fracturing fluid. [2]

Incompatibility

Sodium carboxymethylcellulose is incompatible with strong acid solutions, soluble iron salts, and some other metals such as aluminum, mercury, and zinc. When the pH is less than 2, and when mixed with 95% ethanol, precipitation will occur.

Sodium carboxymethyl cellulose can form co-agglomerates with gelatin and pectin, and can also form complexes with collagen, which can precipitate certain positively charged proteins.

craft

CMC is usually an anionic polymer compound prepared by reacting natural cellulose with caustic alkali and monochloroacetic acid, with a molecular weight of 6400 (±1 000). The main by-products are sodium chloride and sodium glycolate. CMC belongs to natural cellulose modification. The Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) have officially called it “modified cellulose”.

The main indicators to measure the quality of CMC are degree of substitution (DS) and purity. Generally, the properties of CMC are different if the DS is different; the higher the degree of substitution, the stronger the solubility, and the better the transparency and stability of the solution. According to reports, the transparency of CMC is better when the degree of substitution is 0.7-1.2, and the viscosity of its aqueous solution is the largest when the pH value is 6-9. In order to ensure its quality, in addition to the choice of etherification agent, some factors that affect the degree of substitution and purity must also be considered, such as the relationship between the amount of alkali and etherification agent, etherification time, water content in the system, temperature, pH value, solution Concentration and salt etc.

status quo

In order to solve the shortage of raw materials (refined cotton made of cotton linters), in recent years, some scientific research units in my country have cooperated with enterprises to comprehensively utilize rice straw, ground cotton (waste cotton), and bean curd dregs to produce CMC successfully. The production cost is greatly reduced, which opens up a new source of raw materials for CMC industrial production and realizes the comprehensive utilization of resources. On the one hand, the production cost is reduced, and on the other hand, CMC is developing towards higher precision. The research and development of CMC mainly focuses on the transformation of existing production technology and the innovation of manufacturing process, as well as new CMC products with unique properties, such as the “solvent-slurry method” [3] process that has been successfully developed abroad and has been widely used. A new type of modified CMC with high stability is produced. Due to the higher degree of substitution and the more uniform distribution of substituents, it can be used in a wider range of industrial production fields and complex use environments to meet higher process requirements. Internationally, this new type of modified CMC is also called “polyanionic cellulose (PAC, Poly anionic cellulose)”.

safety

High security, ADI does not need regulations, and national standards have been formulated [4] .

application

This product has the functions of binding, thickening, strengthening, emulsifying, water retention and suspension.

Application of CMC in food

FAO and WHO have approved the use of pure CMC in food. It was approved after very strict biological and toxicological research and tests. The safe intake (ADI) of the international standard is 25mg/(kg·d) , that is about 1.5 g/d per person. It has been reported that some people did not have any toxic reaction when the intake reached 10 kg. CMC is not only a good emulsification stabilizer and thickener in food applications, but also has excellent freezing and melting stability, and can improve the flavor of the product and prolong the storage time. The amount used in soy milk, ice cream, ice cream, jelly, beverages, and cans is about 1% to 1.5%. CMC can also form a stable emulsified dispersion with vinegar, soy sauce, vegetable oil, fruit juice, gravy, vegetable juice, etc., and the dosage is 0.2% to 0.5%. Especially, it has excellent emulsifying performance for animal and vegetable oils, proteins and aqueous solutions, enabling it to form a homogeneous emulsion with stable performance. Because of its safety and reliability, its dosage is not limited by the national food hygiene standard ADI. CMC has been continuously developed in the food field, and research on the application of sodium carboxymethylcellulose in wine production has also been carried out.

The use of CMC in medicine

In the pharmaceutical industry, it can be used as an emulsion stabilizer for injections, a binder and a film-forming agent for tablets. Some people have proved that CMC is a safe and reliable anticancer drug carrier through basic and animal experiments. Using CMC as the membrane material, the modified dosage form of the traditional Chinese medicine Yangyin Shengji Powder, Yangyin Shengji Membrane, can be used for dermabrasion operation wounds and traumatic wounds. Animal model studies have shown that the film prevents wound infection and has no significant difference from gauze dressings. In terms of controlling wound tissue fluid exudation and rapid wound healing, this film is significantly better than gauze dressings, and has the effect of reducing postoperative edema and wound irritation. The film preparation made of polyvinyl alcohol: sodium carboxymethyl cellulose: polycarboxyethylene at a ratio of 3:6:1 is the best prescription, and the adhesion and release rate are both increased. The adhesion of the preparation, the residence time of the preparation in the oral cavity and the efficacy of the medicine in the preparation are all significantly improved. Bupivacaine is a powerful local anesthetic, but it can sometimes produce serious cardiovascular side effects when poisoned. Therefore, while bupivacaine is widely used clinically, research on the prevention and treatment of its toxic reactions has always been paid more attention. Pharmacological studies have shown that CIVIC as a sustained-release substance formulated with bupivacaine solution can significantly reduce the side effects of the drug. In PRK surgery, the use of low-concentration tetracaine and non-steroidal anti-inflammatory drugs combined with CMC can significantly relieve postoperative pain. Prevention of postoperative peritoneal adhesions and reduction of intestinal obstruction are one of the most concerned issues in clinical surgery. Studies have shown that CMC is significantly better than sodium hyaluronate in reducing the degree of postoperative peritoneal adhesions, and can be used as an effective method to prevent the occurrence of peritoneal adhesions. CMC is used in catheter hepatic arterial infusion of anti-cancer drugs for the treatment of liver cancer, which can significantly prolong the residence time of anti-cancer drugs in tumors, enhance the anti-tumor power, and improve the therapeutic effect. In animal medicine, CMC also has a wide range of uses. It has been reported [5] that intraperitoneal instillation of 1% CMC solution to ewes has a significant effect on preventing dystocia and abdominal adhesions after reproductive tract surgery in livestock.

CMC in other industrial applications

In detergents, CMC can be used as an anti-soil redeposition agent, especially for hydrophobic synthetic fiber fabrics, which is significantly better than carboxymethyl fiber.

CMC can be used to protect oil wells as a mud stabilizer and water retention agent in oil drilling. The dosage for each oil well is 2.3t for shallow wells and 5.6t for deep wells;

In the textile industry, it is used as a sizing agent, a thickener for printing and dyeing paste, textile printing and stiffening finishing. When used as a sizing agent, it can improve solubility and viscosity, and is easy to desizing; as a stiffening agent, its dosage is above 95%; when used as a sizing agent, the strength and flexibility of the size film are significantly improved; with regenerated silk fibroin The composite membrane composed of carboxymethyl cellulose is used as the matrix for immobilizing glucose oxidase, and the glucose oxidase and ferrocene carboxylate are immobilized, and the glucose biosensor made has higher sensitivity and stability. Studies have shown that when the silica gel homogenate is prepared with a CMC solution with a concentration of about 1% (w/v), the chromatographic performance of the prepared thin-layer plate is the best. At the same time, the thin-layer plate coated under optimized conditions has Appropriate layer strength, suitable for various sampling techniques, easy to operate. CMC has adhesion to most fibers and can improve the bonding between fibers. The stability of its viscosity can ensure the uniformity of sizing, thereby improving the efficiency of weaving. It can also be used as a finishing agent for textiles, especially for permanent anti-wrinkle finishing, which brings durable changes to fabrics.

CMC can be used as an anti-sedimentation agent, emulsifier, dispersant, leveling agent, and adhesive for coatings. It can make the solid content of the coating evenly distributed in the solvent, so that the coating does not delaminate for a long time. It is also widely used in paints. .

When CMC is used as a flocculant, it is more effective than sodium gluconate in removing calcium ions. When used as a cation exchange, its exchange capacity can reach 1.6 ml/g.

CMC is used as a paper sizing agent in the paper industry, which can significantly improve the dry strength and wet strength of paper, as well as oil resistance, ink absorption and water resistance.

CMC is used as a hydrosol in cosmetics and as a thickener in toothpaste, and its dosage is about 5%.

CMC can be used as flocculant, chelating agent, emulsifier, thickener, water retaining agent, sizing agent, film-forming material, etc., and is also widely used in electronics, pesticides, leather, plastics, printing, ceramics, toothpaste, daily chemicals and other fields , and because of its excellent performance and wide range of uses, it is constantly opening up new application fields, and the market prospect is extremely broad.

Precautions

(1) The compatibility of this product with strong acid, strong alkali, and heavy metal ions (such as aluminum, zinc, mercury, silver, iron, etc.) is contraindicated.

(2) The allowable intake of this product is 0-25mg/kg·d.

Instructions

Mix CMC directly with water to make a pasty glue for later use. When configuring CMC glue, first add a certain amount of clean water into the batching tank with a stirring device, and when the stirring device is turned on, slowly and evenly sprinkle CMC into the batching tank, stirring continuously, so that the CMC Fully integrated with water, CMC can fully dissolve. When dissolving CMC, the reason why it should be evenly sprinkled and stirred continuously is to “prevent the problems of agglomeration, agglomeration, and reduce the amount of CMC dissolved when CMC meets water”, and to increase the dissolution rate of CMC. The time for stirring is not the same as the time for CMC to completely dissolve. They are two concepts. Generally speaking, the time for stirring is much shorter than the time for CMC to completely dissolve. The time required for the two depends on the specific situation.

The basis for determining the stirring time is: when the CMC is uniformly dispersed in the water and there are no obvious large lumps, the stirring can be stopped, allowing the CMC and water to penetrate and fuse with each other in a standing state.

The basis for determining the time required for CMC to completely dissolve is as follows:

(1) CMC and water are completely bonded, and there is no solid-liquid separation between the two;

(2) The mixed paste is in a uniform state, and the surface is flat and smooth;

(3) The color of the mixed paste is close to colorless and transparent, and there are no granular objects in the paste. From the time when CMC is put into the batching tank and mixed with water to the time when CMC is completely dissolved, the required time is between 10 and 20 hours.