Method for preparing stannous fluoride by sing hydrofluoric acid

Abstract

A method for preparing stannous fluoride by sing hydrofluoric acid. The method uses hydrofluoric acid and stannous oxide as raw materials, and includes the following steps: (1) first adding hydrofluoric acid into a reactor, staring to stir, then adding a tin granular package in the equivalent of 8-12 wt% of the theoretical amount of stannous oxide, then adding the theoretical amount of stannous oxide into hydrofluoric acid at a speed of 15-25g / min, after material addition, continuing the reaction for 15-30 min, and after the reaction, removing the tin granular package; and from the addition of stannous oxide to the end of the reaction, introducing nitrogen into hydrofluoric acid, wherein the flow is controlled that no liquid spills; and (2) heating to 75-95 DEG C, maintaining the temperature, stirring for concentrating, and conducting vacuum drying to obtain a finished product. The stannous fluoride prepared by the method provided by the invention has low cost, high product yield and high purity.

Description

technical field [0001] The invention relates to a method for preparing stannous fluoride with hydrofluoric acid, in particular to a method for preparing stannous fluoride with hydrofluoric acid and stannous oxide as raw materials. Background technique [0002] Stannous fluoride is mainly used in toothpaste, mouthwash, brazing flux and pharmaceutical additives, and is most widely used in toothpaste and mouthwash. The surface hardness and wear resistance of teeth treated with an appropriate amount of stannous fluoride are increased, which can effectively prevent gingivitis and dental plaque. [0003] At present, the method for preparing stannous fluoride reported mainly contains three kinds: [0004] (1) In US3172724A (disclosure date: March 09, 1965), stannous fluoride was prepared by reacting at 63-80°C with elemental tin flakes and hydrofluoric acid with a mass concentration of 20-30%. Though this method can obtain stannous fluoride product, the purity of product is not h...

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Problems solved by technology

[0004] (1) In US3172724A (disclosure date: March 09, 1965), stannous fluoride was prepared by reacting at 63-80°C with elemental tin flakes and hydrofluoric acid with a mass concentration of 20-30%. Though this method can obtain stannous fluoride product, the purity of product is not high, and productive rate is low;

[0005] (2) In the 1982 Czech patent document No. 231928, stannous fluoride was obtained by direct ion exchange with stannous chloride and sodium fluoride. This method is simple to operate, but the residual sodium fluoride in the product is difficult to remove, and the residual Sodium fluoride reduces the use effect and efficiency of stannous fluoride;

[0006] (3) In CN1141884A (published on February 05, 1997), tin protofluoride was prepared by substitution reaction with elemental tin powder and copper fluoride. This method is easy to operate and the obtained product has high purity, but requires the The mesh number is high, and the prices of high mesh tin powder and copper fluoride are quite expensive, which makes the cost of this method too high and has little economic significance