Application of Precipitated Silica as a Thickener in Toothpaste
Precipitated silica is widely used as a thickening agent in toothpaste to provide excellent pseudoplasticity and thixotropy to the paste. This is mainly due to the three-dimensional network structure of the silica particles, which can be highly dispersed in aqueous solutions, converting a large quantity of free water into bound water within the network structure. When this network structure is subjected to external force, it can quickly transform into a low-viscosity suspension. However, the surface hydroxyl groups of the particles can enable them to reform into a homogeneous plastic state with increasing viscosity when the external force is removed.
During the production and use of toothpaste, the excellent pseudoplasticity and thixotropy of the paste allows it to withstand mechanical processing, preventing the components from being damaged. The reduction in viscosity of the paste during the flow process also helps to minimize the frictional force during filling, thereby improving production efficiency. After stopping, the apparent viscosity of the paste gradually increases, resulting in a fuller shape of the tube and stronger adhesion of the squeezed toothpaste. Moreover, the high surface area of precipitated silica allows for strong adsorption of fragrance, leading to a more gentle and long-lasting aroma, as well as an improvement in the gloss of the paste and a finer texture in the mouth.
Toothpaste containing precipitated silica is a tasteless, odorless, white powder with good stability, fluoride compatibility, and adjustable friction value. The refractive index of the powder is close to that of wetting agents, making it suitable for making transparent toothpaste. It also has good compatibility with fragrances and various surfactants, facilitating fragrance release and foam dispersion. This application of precipitated silica in toothpaste is only one of the many benefits of this versatile substance, which has a wide range of applications in various industries.