Precipitation Of Silica As Toothpaste Abrasive

Toothpaste is indispensable for people’s daily oral hygiene care. Toothpaste abrasive is an important component of the toothpaste. Consumers who use the crystal transparent toothpastes used silica as abrasive to brush teeth can maintain and improve oral health, and they also enjoy aesthetics through the crystal transparent gel. The usage of silica as abrasive in toothpaste become more and more. However, due to technical and other reasons of confidentiality, there was few reported in the literature about the law for the key rule of the synthesis of silica as toothpaste abrasive.The silica used as toothpaste abrasive should have a relatively high transmittance and low apparent density, and the particle size of silica is between3and15μm. In order to be able to obtain the technical process of toothpaste abrasive agent, this paper carried out a systematic research on the synthesis of silica using sodium silicate and sulphuric acid as raw materialsIn this article, firstly, it was investigated effects of the reaction conditions such as the concentration of sodium silicate in the reactor, reaction temperature and aging time on the properties of silica. And important indexes, such as apparent density and light transmittance, were tested to evaluate the properties of the synthesized substance. It was found that:as the concentration of sodium silicate decreased, the light transmittance was improved and the apparent density became lower; as the temperature dropped, the light transmittance was improved and the apparent density became lower; increasing the aging time had no significant effect on the light transmittance and the apparent density.Secondly, it was choosed two kinds of electrolytes, Na2SO4and NaCl, which were safe to perple’s health. It was focused on the effect of the concentration of Na2SO4and NaCl adding in the reactor liquid to improve light transmittance. Then, the physical and chemical properties of the synthesized substance were characterized by XRD, SEM and FT-IR. It turned out that:the light transmittance of silica synthesized at65℃had negligible influence on the concentration of Na2SO4or NaCl adding in the reactor liquid0.04-0.12mol·L-1; but at85℃, the light transmittance of silica synthesized under Na2SO40.08mol·L-1was97%and the light transmittance of silica synthesized under NaCl0.04-0.12mol·L-1was95%; the synthesized substance was amorphous silica, and the particle size were below15μm; the properties of the silica could meet the standards of QB/T2346-2007and the silica could be used as toothpaste abrasive.On the basis of the above research, it was investigated effects of the the concentration of sulphuric acid adding in the reactor on the properties of silica. Then, the physical and chemical properties of the synthesized substance were characterized by XRD, SEM and FT-IR. It was found that:when it was added no electrolytes in the reactor, the light transmittance of the silica was firstly rose up and then dropped down as the concentration of sulphuric acid increased; the light transmittance appeared a declining trend when it was changed the concentration of sulphuric acid, but this trend would become weaker when adding specific concentration of electrolytes in the reactor; the synthesized substance was amorphous silica; the properties of the silica could meet the standards of QB/T2346-2007and the silica could be used as toothpaste abrasive.