Natural cellulose is the most widely distributed and abundant polysaccharide in nature. At present, the modification technology of cellulose mainly focuses on etherification and esterification. Carboxymethylation is a kind of etherification technology. Carboxymethyl cellulose (CMC) is obtained by carboxymethylation of cellulose, and its aqueous solution has the functions of thickening, film formation, bonding, moisture retention, colloidal protection, emulsification and suspension, etc. It is widely used in petroleum, food, medicine, textile and paper industry, and is one of the most important cellulose ethers.

Physical property:

Carboxymethyl cellulose (CMC) is an anionic cellulose ether, the appearance is white or slightly yellow flocculent fiber powder or white powder, odorless, tasteless, non-toxic; Soluble in cold water or hot water, forming a transparent solution with a certain viscosity. The solution is neutral or slightly alkaline, insoluble in ethanol, ether, isopropyl alcohol, acetone and other organic solvents, but soluble in ethanol or acetone solution with 60% water content. It is hygroscopic, stable to light and heat, viscosity decreases with the increase of temperature, the solution is stable at pH 2 ~ 10, the pH is lower than 2, there is solid precipitation, the pH value is higher than 10 and the viscosity decreases. The discoloration temperature is 227℃, the carbonization temperature is 252℃, and the surface tension of 2% aqueous solution is 71mn/n.

Chemical property:

It is prepared from cellulose derivatives of carboxymethyl substituents, which are treated with sodium hydroxide to form alkali cellulose, and then reacted with monochloroacetic acid. The glucose unit that makes up cellulose has three replaceable hydroxyl groups, so products with different degrees of replacement can be obtained. When 1mmol carboxymethyl is introduced per 1g dry weight on average, it is insoluble in water and dilute acid, but can swell and be used for ion exchange chromatography. Carboxymethyl pKa, approximately 4 in pure water and 3.5 in 0.5mol/L NaCl, is a weakly acidic cation exchanger, usually used for the separation of neutral and basic proteins at pH > 4. When more than 40% hydroxyl group is carboxymethyl, it can dissolve in water to form a stable colloidal solution with high viscosity.

Applications:

Carboxymethyl cellulose (CMC) is a non-toxic and tasteless white flocculent powder with stable performance and easy to dissolve in water. Its aqueous solution is neutral or alkaline transparent viscous liquid, soluble in other water-soluble adhesives and resins, and insoluble in organic solvents such as ethanol. CMC can be used as binder, thickener, suspension agent, emulsifier, dispersant, stabilizer, sizing agent, etc.

Carboxymethyl cellulose (CMC) is the largest yield of cellulose ether, the most widely used, the most convenient product, commonly known as "industrial MSG".

1, for oil, natural gas drilling, digging and other projects

(1) The slurry containing CMC can make the well wall form a thin and firm filter cake with low permeability, and reduce the water loss.

(2) After CMC is added to the mud, the rig can get a low initial shear force, so that the mud is easy to release the gas wrapped in it, and the debris is quickly abandoned in the mud pit.

(3) Drilling mud, like other suspended dispersions, has a certain existence period, and the addition of CMC can make it stable and extend the existence period.

(4) Slurry containing CMC is rarely affected by mold, so it is not necessary to maintain a high pH value and use preservatives.

(5) Containing CMC as drilling mud washing fluid treatment agent, can resist various soluble salt pollution.

(6) The slurry containing CMC has good stability and can reduce water loss even if the temperature is above 150 ° C.

High viscosity and high substitution CMC is suitable for low density mud, low viscosity and high substitution CMC is suitable for high density mud. The selection of CMC should be determined according to different conditions such as mud type, region and well depth.

2, used in textile, printing and dyeing industry, the textile industry will CMC as a sizing agent, used for cotton, silk, chemical fiber, blended fabrics such as yarn sizing;

3, for the paper industry CMC in the paper industry can be used as paper smoothing agent, sizing agent. The addition of 0.1% to 0.3% CMC in the pulp can enhance the tensile strength of the paper by 40% to 50%, increase the compressive rupture degree by 50%, and increase the kneading property by 4 to 5 times.

4, CMC added to synthetic detergent can be used as dirt adsorbent; Daily chemical such as toothpaste industry CMC glycerol solution is used as the glue base of toothpaste; Used as thickener and emulsifier in pharmaceutical industry; CMC aqueous solution is used for flotation beneficiation after viscosification.

5, used in the ceramic industry can be used as blank adhesive, plasticizer, glaze suspension agent, fixing agent, etc.

6, used in construction, improve water retention and strength

7, used in the food industry, the food industry uses high replacement degree CMC as ice cream, canned, quick cooking noodles thickener, beer foam stabilizer, etc., in the processing of jam, sugar juice, sherbet, dessert, ice cream drinks, etc., as a thickener, binder or shape agent.

8, the pharmaceutical industry chooses appropriate viscosity CMC as the adhesive, disintegrator of tablets, suspension aid, etc 

Dissolution procedure:

CMC is directly mixed with water, prepared into a paste glue liquid, set aside. When configuring the CMC paste, first add a certain amount of clean water into the mixing tank with the mixing device. When the mixing device is turned on, spread the CMC slowly and evenly into the mixing tank and stir continuously, so that the CMC and the water are completely integrated and the CMC can be fully dissolved. When the CMC is dissolved, the reason why it should be evenly dispersed and constantly stirred is to "prevent the occurrence of clumping and caking when the CMC meets the water, reduce the problem of the dissolution amount of the CMC", and improve the dissolution rate of the CMC. The time of stirring and the time of complete melting of CMC is not consistent, it is two concepts, in general, the time of stirring is much shorter than the time required for complete melting of CMC, and the time required for both depends on the specific situation.

The basis for determining the mixing time is: when the CMC is evenly dispersed in water and there is no obvious large clumps, the mixing can be stopped, so that the CMC and the water penetrate and fuse with each other in a static state.

The basis for determining the time required for complete melting of CMC 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 uniform and the surface is smooth;

(3) The color of the mixed paste is close to colorless and transparent, and there is no granular object in the paste. From the time the CMC is put into the mixing tank with water to the complete dissolution of the CMC, the time required is between 10 to 20 hours.