Home > Knowledge > Content
PPT Hydrophilic Silica for Abrasive
Feb 11, 2019

                                          PPT Hydrophilic Silica for Abrasive

Abrasives are solid ingredients in toothpaste that can work together with toothbrushes to erase dental scales on the surface of teeth and reduce foreign substances such as dental stains, dental plaque and dental calculi. Abrasives are the main raw materials of toothpaste, which generally account for 20%-50% of the formula. The most important role in toothpaste is to remove the scales and alleviate the calculi. 

Silica Abrasive


Abrasives should have proper hardness and friction value, uniform particle size, white appearance, no odor, comfortable taste, safety, non-toxicity, low solubility and chemical stability, and do not react with other components in toothpaste. 

1. Hardness is a mechanical property of a material, indicating its ability to resist the indentation and indentation of other materials into its surface. Brushing teeth is to use the pressure of the toothbrush to make the abrasive press into the scales, plaques and calculi to break up the dirt. However, the hardness of the abrasive should not be too hard, so as not to damage the enamel, so the choice of abrasive must be free of super-hard particles. If the Mohr hardness of enamel is 6 degrees, the hardness of the abrasive should be lower than 5 degrees of Mohr hardness. 

2. The solubility product of abrasives should be small. 

Abrasives are required to be insoluble in water or slightly soluble in water, which is an important index to maintain the chemical stability of toothpaste. The solubility product of precipitated silica (xSiO 2 H 2) friction agent is 15.6 10 - 13. 

3. Selection of Particle Size of Abrasive 

The diameter of abrasive particles used in toothpaste should be between 5 and 40 microns, the particle size is too large, and there is obvious sand feeling when brushing teeth; the toothpaste body made of suitable abrasive particles has smooth and delicate appearance and comfortable feeling to the mouth and gums when brushing teeth; if the particle size is too fine (such as less than 1 micron), there will be coarsening phenomenon in toothpaste rack test, because toothpaste is too fine in long-term storage rack test. Flocculation occurs due to Brownian motion. The particle size of our precipitated silica is between 3 micron to 250 micron.

4. The frictional value of abrasives should be moderately controlled. 

Apart from keeping teeth clean, toothpaste can remove easily adhered scales, calculi and stains, it should not have excessive friction. Therefore, it is necessary to measure and control the friction value of the abrasives in order to clean the teeth without damaging them. Dentin friction value (RDA) is usually used to express dentin friction value. Because of the difficulty of RDA testing, copper wear value is also used to replace it. Friction value of commonly used abrasives. The RDA value of abrasives should not exceed 250. The relative friction value of precipitated silica (xSiO 2 H 2) is 280 RDA, 110 ~ 160, and the wear coefficient is 0.003. 

In all,PPT silica is an good choice for toothpaste abrasive.