Classification of silica for toothpaste
May 27, 2022
Classification of silica for toothpaste
There are two kinds of silica in toothpaste: high structure and low structure. The production process is divided according to the water content of the filter cake, that is, the water content of the wet cake. More than 70% of the water content of the wet cake is high structure product, that is, thickening type, and less than 70% is low structure product, that is, friction type. (Note: the water combined with the silica in the filter cake is called structural water.) At present, silicon dioxide is mainly divided into friction type, transparent friction type, general type (comprehensive type, mixed type), thickening type and ultra-fine type.
1. friction silica
This kind of silicon dioxide is a low structure product, and the moisture content of its wet cake is less than 70%, generally about 60%. The water absorption is small, generally 15 ~ 30ml / 20g, the oil absorption value is 110 ~ 130ml / 100g, and the specific surface area is generally 170 ~ 220m2 / g. The refractive index (n) is 1.430 ~ 1.460, and the copper consumption is 8 ~ 10mg. This kind of product has good dispersion and suspension performance, compact particles and strong friction. The toothpaste made of it as friction agent has fine paste, smooth taste and good stability without damaging teeth. It has achieved satisfactory results in improving the tissue structure and appearance of the paste. The transparent toothpaste is often used to thicken the teeth, but the transparency is not high enough.
2. friction transparent type:
The water absorption is generally 25 ~ 40ml / 20g, the refractive index (n) is 1.430 ~ 1.460, the copper consumption is 5 ~ 8mg, and the light transmittance is better than that of the friction type, but the specific thickening is poor. This kind of product has high friction force and good light transmittance. It is made into transparent toothpaste with strong tooth cleaning force and good paste transparency. It can be used as a single thickener without grinding.
3. general purpose:
The water absorption is 30 ~ 38ml/20g, the refractive index (n) is 1.430 ~ 1.460, and the copper consumption is 3 ~ 5mg. The product has a certain friction force, and the light transmittance is better than the friction type, but slightly worse than the friction transparent type. Generally, a certain amount of friction transparent precipitated silica is compounded to enhance the tooth cleaning ability and transparency of the toothpaste. Because the price is relatively low, it can also be compounded with calcium carbonate toothpaste to reduce the abrasion of calcium carbonate toothpaste and make the paste more delicate.
This kind of silica is a high structure product, and the moisture content of its wet cake is more than 70%. The water absorption is 38 ~ 45ml / 20g, the oil absorption value is more than 300ml / 100g, the specific surface area is generally 300m2 / 100g, the refractive index (n) is 1.430 ~ 1.460, and the light transmittance is high, generally more than 90%. It has good compatibility, extremely fine particle size and superior water force. Its structural feature is that silane alcohol genes are cross-linked to form a three-dimensional skeleton structure. Therefore, the silica aqueous dispersion has a certain consistency and good thixotropy. When it is used in common toothpastes together with inorganic gel, it can reduce the dosage of some thickeners, improve the striping and dispersity of the paste, and play a positive role in improving the stability of the paste. The transparent toothpaste made by using it alone has good transparency. However, due to almost no friction force, the tooth surface turns yellow due to too low cleaning force over time. Therefore, it is often used in combination with friction type.
5. ultra fine type:
The water absorption is 40 ~ 50ml/20g, the light transmittance is very high, generally greater than 95%, and the refractive index (n) is 1.430 ~ 1.460. The thickening effect of this product is very good. The transparent toothpaste made of it alone has good transparency and can be like water, but it is often combined with the transparent friction type with high RDA value because it has almost no friction force. It is used to make high-grade transparent toothpaste.
