Sodium carboxymethylcellulose (CMC) is an anionic cellulose ether. Its appearance is white or slightly yellow flocculent fiber powder or white powder, odorless, tasteless, and non-toxic; it is easily soluble in cold or hot water and forms a certain viscosity. transparent solution. The solution is neutral or slightly alkaline, insoluble in ethanol, ether, isopropanol, acetone and other organic solvents, but soluble in 60% ethanol or acetone solution. It is hygroscopic and stable to light and heat. The viscosity decreases with the increase of temperature. The solution is stable at pH 2-10. When the pH is lower than 2, solids are precipitated. When the pH is higher than 10, the viscosity decreases. The discoloration temperature is 227°C, the carbonization temperature is 252°C, and the surface tension of 2% aqueous solution is 71mn/n.
chemical properties
It is obtained by treating cellulose with carboxymethyl substituents, treating cellulose with sodium hydroxide to form alkali cellulose, and then reacting with monochloroacetic acid. The glucose unit that constitutes cellulose has three hydroxyl groups that can be replaced, so products with different degrees of replacement can be obtained. On average, 1mmol of carboxymethyl group per 1g of dry weight is insoluble in water and dilute acid, but can be swelled and used for ion exchange chromatography. Carboxymethyl pKa is about 4 in pure water and about 3.5 in 0.5mol/L NaCl. It is a weakly acidic cation exchanger and is usually used for the separation of neutral and basic proteins at pH>4. More than 40% of the hydroxyl groups are replaced by carboxymethyl groups, which can be dissolved in water to form a stable high-viscosity colloidal solution.
The main purpose
Carboxymethylcellulose (CMC) is a non-toxic, odorless white flocculent powder with stable performance and is easily soluble in water. Its aqueous solution is a neutral or alkaline transparent viscous liquid, soluble in other water-soluble glues and resins, and insoluble in organic solvents such as ethanol. CMC can be used as a binder, thickener, suspending agent, emulsifier, dispersant, stabilizer, sizing agent, etc.
Sodium carboxymethyl cellulose (CMC) is the product with the largest output, the widest range of uses and the most convenient use among cellulose ethers, commonly known as “industrial monosodium glutamate”.
1. Used in oil and natural gas drilling, well digging and other projects
① CMC-containing mud can make the well wall form a thin and firm filter cake with low permeability, reducing water loss.
② After adding CMC to the mud, the drilling rig can get a low initial shear force, so that the mud can easily release the gas wrapped in it, and at the same time, the debris can be quickly discarded in the mud pit.
③ Drilling mud, like other suspensions and dispersions, has a certain shelf life. Adding CMC can make it stable and prolong the shelf life.
④ CMC-containing mud is rarely affected by mold, so it is not necessary to maintain a high pH value and use preservatives.
⑤ Contains CMC as a treatment agent for drilling mud flushing fluid, which can resist the pollution of various soluble salts.
⑥ CMC-containing mud has good stability and can reduce water loss even if the temperature is above 150°C.
CMC with high viscosity and high degree of substitution is suitable for mud with low density, and CMC with low viscosity and high degree of substitution is suitable for mud with high density. The choice of CMC should be determined according to different conditions such as mud type, region, and well depth.
2. Used in textile, printing and dyeing industries. In the textile industry, CMC is used as a sizing agent for light yarn sizing of cotton, silk wool, chemical fiber, blended and other strong materials;
3. Used in paper industry CMC can be used as paper smoothing agent and sizing agent in paper industry. Adding 0.1% to 0.3% of CMC in the pulp can increase the tensile strength of the paper by 40% to 50%, increase the crack resistance by 50%, and increase the kneading property by 4 to 5 times.
4. CMC can be used as a dirt adsorbent when added to synthetic detergents; daily chemicals such as toothpaste industry CMC glycerol aqueous solution is used as toothpaste gum base; pharmaceutical industry is used as a thickener and emulsifier; CMC aqueous solution is used as a float after thickening Mining and so on.
5. It can be used as adhesive, plasticizer, suspending agent of glaze, color fixing agent, etc. in the ceramic industry.
6. Used in construction to improve water retention and strength
7. Used in the food industry. The food industry uses CMC with a high degree of replacement as a thickener for ice cream, canned food, instant noodles, and a foam stabilizer for beer. For thickeners, binders or conformal agents.
8. The pharmaceutical industry chooses CMC with appropriate viscosity as the binder, disintegrating agent of tablets, and suspending agent of suspensions, etc.