Sodium carboxymethyl cellulose (CMC) plays the following main roles in paint:
1. Thickening
- Sodium carboxymethyl cellulose can increase the viscosity of the paint, making it less likely to flow, and helps the paint maintain a stable thickness and uniformity during construction. For example, when applying wall paint, the appropriate viscosity can ensure that the paint can be evenly attached to the wall without sagging or uneven thickness, thereby achieving a better coating effect.
- The fluidity of the paint can be controlled, making it easier to operate and apply. For some areas that require special coating effects, such as corners, complex decorative lines, etc., the thickened paint can better stay in these areas and improve the accuracy and quality of construction.
2. Dispersion and stabilization
- It can make solid particles such as pigments and fillers evenly dispersed in the paint system to prevent particle aggregation and precipitation. For example, in colored paints, the uniform dispersion of pigments is crucial for color consistency and stability. Sodium carboxymethyl cellulose, through its special molecular structure and charge characteristics, is adsorbed on the surface of particles, forming steric hindrance and electrostatic repulsion, thereby maintaining the dispersed state of the particles.
- It helps to improve the storage stability of the coating and extend the shelf life of the coating. During long-term storage, the dispersed and stable coating will not show stratification, agglomeration and other phenomena, and always maintain good performance.
3, water retention effect
- After the coating is applied, sodium carboxymethyl cellulose can help the coating retain a certain amount of moisture and slow down the volatilization rate of moisture. This is very important for the drying process of the coating and the formation of the coating film. Appropriate water retention can give the various components in the coating enough time to undergo chemical reactions and physical cross-linking, thereby forming a uniform and dense coating film.
- The water retention effect can also reduce coating defects caused by too fast evaporation of water, such as cracking and blistering. Especially when applied in a dry climate or a well-ventilated environment, the water retention effect of sodium carboxymethyl cellulose is more significant.
4, bonding effect
- Sodium carboxymethyl cellulose can enhance the bonding between the various components in the coating and between the coating and the substrate. During the film formation process, it can form chemical bonds or physical adsorption with pigments, fillers and substrate surfaces, thereby improving the adhesion and durability of the film.
- For some porous or rough substrates, such as cement mortar walls, wood, etc., good bonding can ensure that the paint can be firmly attached to the substrate and is not easy to fall off.
