Views: 1 Author: Site Editor Publish Time: 2022-01-22 Origin: Site
Carboxymethyl cellulose (also known as CMC and sodium carboxymethyl cellulose) can be described as an anionic water-soluble polymer, produced from natural cellulose through etherification, replacing the hydroxyl group with the carboxymethyl group on the cellulose Chain carboxymethyl cellulose is used as a binder, thickener, suspending agent and filler in various applications.
The main chemical reactions of CMC are the alkalization reaction of cellulose and alkali to form alkali cellulose and the etherification reaction of alkali cellulose and monochloroacetic acid.
Step 1: Alkalization: [C6H7O2(OH) 3]n + nNaOH→[C6H7O2(OH) 2ONa ]n + nH2O
Step 2: Etherification: [C6H7O2(OH) 2ONa ]n + nClCH2COONa →[C6H7O2(OH) 2OCH2COONa ]n + nNaCl
The cellulose derivative with carboxymethyl substituent is prepared by treating cellulose with sodium hydroxide to form alkali cellulose, and then reacting with monochloroacetic acid. The glucose unit constituting cellulose has 3 hydroxyl groups that can be replaced, so products with different degrees of replacement can be obtained. On average, 1mmol of carboxymethyl is introduced per 1g of dry weight. It is insoluble in water and dilute acid, but can swell and be used for ion exchange chromatography. The pKa of carboxymethyl 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 separation of neutral and basic proteins at pH 4 or higher. Those with more than 40% of the hydroxyl groups replaced by carboxymethyl can be dissolved in water to form a stable high-viscosity colloidal solution.
Product characteristics of detergent grade CMC
After being added to the detergent, the consistency is high, transparent, and does not return to thin;
It can effectively thicken and stabilize the composition of liquid detergent;
Adding washing powder and liquid detergent can prevent the dirt that has been washed from settling on the fabric again. Adding 0.5-2% to synthetic detergent can achieve satisfactory results;
CMC uses in Detergent Industry,Mainly focus on the emulsification and protective colloid properties of CMC. The anion produced during the washing process can simultaneously make the surface of the washing and the dirt particles negatively charged, so that the dirt particles have phase separation in the water phase and have the same effect on the surface of the solid wash. Repellency, prevents dirt from re-depositing on the laundry, can maintain whiteness of white fabrics, and bright colors of colored fabrics.
Function of CMC in detergent
1. Thickening, dispersing and emulsifying, it can absorb the oily stains around the spots to wrap the oily stains, so that the oily stains are suspended and dispersed in the water, and form a hydrophilic film on the surface of the washed items, thereby preventing the oily stains from directly contacting the washed items .
2. High degree of substitution and uniformity, good transparency;
3. Good dispersibility in water and good resorption resistance;
Super high viscosity and good stability.