The amount of sodium carboxymethyl cellulose (CMC) added to washing powder is usually 0.5% to 2.0%. The specific amount will vary depending on the formula design, functional positioning and production process of the washing powder. It mainly plays the following roles in washing powder:
1. Anti-redeposition effect: CMC contains a large number of hydrophilic groups such as hydroxyl and carboxyl in its molecular structure, which can form a hydrophilic adsorption film on the surface of the fabric. When the washing powder is dissolved in water, CMC will adsorb on the surface of the washed dirt particles, making the dirt particles negatively charged, thereby increasing the repulsive force between the dirt particles, preventing the dirt from re-depositing on the fabric, effectively preventing the dirt from attaching to the clothes again during the washing process, and maintaining the cleanliness of the clothes. Especially when washing multi-fiber blended clothes or washing multiple times, the anti-redeposition effect is more obvious.
2. Thickening effect: After CMC is dissolved in water, it will form a viscous colloidal solution, which increases the viscosity of the detergent. Appropriate viscosity can keep the detergent on the surface of clothes for a long time, prolong the washing time, and help the active ingredients in the detergent to be evenly distributed and improve the washing effect. In addition, the thickened detergent is easier to control during use, not easy to flow, and convenient to operate.
3. Stabilizing foam effect: It can be adsorbed on the surface of the foam film to form a relatively firm membrane structure, increase the elasticity and toughness of the foam, and thus stabilize the foam. During the washing process, a certain amount of foam is maintained, and the foam can carry dirt and suspend it in the detergent, reducing the chance of dirt redeposition. However, the amount of foam is not the more the better. Modern washing powder will also reasonably control the foam level according to actual needs, and the stabilizing foam effect of CMC can keep the foam within an appropriate range.
4. Improve the molding and fluidity of washing powder: In the production process of washing powder, as an additive, it helps to improve the particle structure of the powder, making it easier to shape the washing powder during the granulation process to form uniform and solid particles. Good molding can prevent the washing powder from caking during storage, and at the same time improve its fluidity, making the washing powder smoother when pouring and using, and convenient for measurement and use.
5. Synergistic effect with other ingredients: CMC has synergistic effect with other ingredients in washing powder, such as surfactants and enzyme preparations. For example, it can interact with surfactants to enhance the surfactants' ability to emulsify and disperse dirt, thereby improving the overall washing effect; when used in conjunction with enzyme preparations, it can provide a relatively stable environment for the enzyme, protect the enzyme's activity, and enable it to better play its role in decomposing dirt.
