Silica as a toothpaste additive and its production process

Abstract

This application relates to the technical field of toothpaste additives, and specifically discloses silica as a toothpaste additive and its production process. The production process first mixes quartz sand and soda ash, reacts them at 1400 - 1600 °C for 4 - 6 h to obtain a molten material, cools it to obtain a solid, uses steam at 100 - 150 °C, pressurizes it to 0.4 - 1 MPa, and sprays and dissolves the solid to obtain an aqueous sodium silicate solution; heats the aqueous sodium silicate solution to maintain it at 70 - 100 °C, then adds pentasodium aminotris(methylenephosphonic acid), after mixing evenly, adds acid and water under stirring conditions to make the final pH of the solution reach 2 - 4. After white precipitate is generated and no longer precipitates, filter to obtain the precipitate, wash the precipitate, then spray-dry the precipitate to obtain a white powder, and finally bake the white powder at a temperature of 150 - 200 °C to completely decompose the small amount of undecomposed silicic acid in the white powder into silica, obtaining silica powder with high purity, good homogeneity, high dispersibility and not easy to agglomerate.

Description

Technical Field

[0001] The present application relates to the technical field of toothpaste additives, and more specifically, to a silica as a toothpaste additive and its production process. Background Art

[0002] The main components of general toothpaste include abrasives, humectants, thickeners, surfactants, flavoring agents, and therapeutic drugs. Among them, the function of the abrasive is to rub the tooth surface to remove dirt, and the representative components are silica, calcium hydrogen phosphate, calcium carbonate, etc. The function of the thickener is to bond other components to form a toothpaste with a stable form, and the representative components are silica, sodium carboxymethyl cellulose, carbomer, etc.

[0003] The particle diameter of silica for toothpaste should be between 5 and 45 μm. If the particle diameter is too large, there will be an obvious sand feeling during brushing. The toothpaste paste made of an abrasive with a suitable particle size has a smooth and delicate appearance and a comfortable feeling of friction on the oral cavity and gums during brushing. If the particle size is too fine (such as less than 1 μm), the toothpaste will show a phenomenon of coarsening during storage. This is because during the long-term storage of the toothpaste, the too-fine abrasive undergoes flocculation due to Brownian motion.

[0004] Some silica for toothpaste on the market has problems such as too large or too small particle diameter, poor uniformity, and easy caking. Summary of the Invention

[0005] In order to improve the problems of too large or too small particle diameter, poor uniformity, and easy caking of some silica for toothpaste on the market, the present application proposes a silica as a toothpaste additive and its production process.

[0006] In the first aspect, the present application proposes a production process of silica as a toothpaste additive and adopts the following technical solutions.

[0007] A production process of silica as a toothpaste additive, the production process comprising:

[0008] Mix quartz sand and soda ash, react at 1400 - 1600 °C for 4 - 6 h to obtain a molten material, cool to obtain a solid, use steam at 100 - 150 °C, pressurize to 0.4 - 1 MPa, spray and dissolve the solid to obtain an aqueous sodium silicate solution; heat the aqueous sodium silicate solution to keep it at 70 - 100 °C, then add pentasodium aminotris(methylenephosphonic acid), after mixing evenly, add acid and water under stirring conditions to make the final pH of the solution reach 2 - 4. After white precipitate is generated and no longer precipitates, filter to obtain the precipitate, wash the precipitate, then spray-dry the precipitate to obtain a white powder, and finally bake the white powder at a temperature of 150 - 200 °C to obtain the silica.

[0009] By adopting the above technical solution, in the kiln, quartz sand (SiO 2 ) and soda ash (Na 2 CO 3 ) can be mixed and reacted at 1400 - 1600 °C for 4 - 6 h to obtain molten sodium silicate. The sodium silicate obtained by reacting at this temperature has less impurity content. After cooling, the sodium silicate becomes solid, which can be loaded into a rotary spherical digester and dissolved with high-temperature steam at 100 - 150 °C under a pressure of 0.4 - 1 MPa to form a colorless, transparent and viscous liquid, namely sodium silicate aqueous solution. Heat the sodium silicate aqueous solution to 70 - 100 °C, then add pentasodium aminotrimethylene phosphonate, mix evenly, and add acid and water under stirring conditions to make the final pH of the solution reach 2 - 4. The acid can be sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, etc. Among them, sodium silicate reacts with the acid to form silicic acid, and the aqueous solution is heated and maintained at 70 - 100 °C to maintain the stability of the reaction rate. Pentasodium aminotrimethylene phosphonate is easily soluble in water. On the one hand, it can form hydrogen bonds with silicic acid to hinder the excessive aggregation of silicic acid. On the other hand, because the molecular chain of pentasodium aminotrimethylene phosphonate is short and three-dimensional, the wrapping of silicic acid is moderate, and the diameter of the microparticles aggregated by silicic acid is appropriate, neither too large nor too small. On the third hand, pentasodium aminotrimethylene phosphonate can also increase the density of the aqueous solution and reduce the interfacial tension between silicic acid microparticles and water, which is beneficial to the dispersion of microparticles, so that the silicic acid microparticles are suspended in the aqueous solution, preventing the silicic acid particles from settling and aggregating too quickly, and making the silicic acid microparticles disperse evenly. After adding the acid, the white precipitate is silicic acid. At this time, pentasodium aminotrimethylene phosphonate and silicic acid are completely desorbed, and the desorption efficiency is high. Silicic acid decomposes into silicon dioxide by heating, and the precipitated silicon dioxide microparticles are of uniform size, high purity and good whiteness. When the final pH of the solution reaches 2 - 4, it can not only react with the excessive soda ash, but also hinder the ionization of silicic acid, and the ionization equilibrium shifts to the molecular state. Silicic acid molecules are easy to decompose by heating to precipitate silicon dioxide. If the pH is too low, the solubility of silicic acid is high and it is not easy to precipitate silicon dioxide. If the pH is too high, the ionization equilibrium shifts to the ionic state and it is also not easy to precipitate silicon dioxide. After the white precipitate no longer precipitates, it indicates that silicic acid / silicon dioxide no longer precipitates. After filtration, washing and spray drying, a white powder is obtained. The white powder is baked at a temperature of 150 - 200 °C to completely decompose the small amount of undecomposed silicic acid in the white powder into silicon dioxide, obtaining a silicon dioxide powder with high purity, good homogeneity, high dispersibility and not easy to agglomerate.

[0010] Optionally, the mass ratio of the soda ash to the quartz sand is 1:(1.5 - 3.5).

[0011] By adopting the above technical solution, soda ash and quartz sand react at 1400 - 1600 °C for 4 - 6 h to obtain molten sodium silicate, with the molecular formula of Na 2 O·nSiO 2, according to the ratio of soda ash and quartz sand input, it can be known that the modulus n is 1.5 to 3.5. If n is too large, the sodium silicate formed is not easily soluble in water, which is not conducive to being dissolved by water vapor, and it also affects the subsequent reaction with acid and the particle size concentration of the generated silicon dioxide. If n is too small, the consumption of soda ash increases.

[0012] Optionally, the mass ratio of the soda ash to the quartz sand is 1:3.

[0013] By adopting the above technical solution, the generated sodium silicate has high purity, high efficiency of being dissolved by high-temperature water vapor, and relatively small consumption of soda ash.

[0014] Optionally, the mass ratio of the quartz sand to the pentasodium aminotris(methylenephosphonic acid) is 1:(0.01 - 0.03).

[0015] By adopting the above technical solution, when the quartz sand first reacts with soda ash to form sodium silicate, and during the process of sodium silicate reacting with acid to form silicic acid, a hydrogen bond is formed between the pentasodium aminotris(methylenephosphonic acid) and silicic acid, which hinders the excessive aggregation of silicic acid, and controls the size of the silicic acid aggregated particles within the range of 23 - 45 μm, so that when the silicon dioxide is applied in toothpaste, it has good grinding effect and thickening effect.

[0016] Optionally, the mass ratio of the quartz sand to the pentasodium aminotris(methylenephosphonic acid) is 1:0.02.

[0017] By adopting the above technical solution, when the quartz sand first reacts with soda ash to form sodium silicate, and during the process of sodium silicate reacting with acid to form silicic acid, a hydrogen bond is formed between the pentasodium aminotris(methylenephosphonic acid) and silicic acid, which hinders the excessive aggregation of silicic acid, and significantly increases the proportion of the silicic acid aggregated particles within the range of 33 - 38 μm, with high particle size uniformity and not easy to agglomerate, so that when the silicon dioxide is applied in toothpaste, it has better grinding effect and thickening effect.

[0018] Optionally, acid and water are added under the stirring condition, and the final pH of the aqueous solution is adjusted to 2.8 - 3.2.

[0019] By adopting the above technical solution, silicic acid basically exists in the molecular state in the solution and is extremely easy to decompose into silicon dioxide by heat, obtaining highly dispersed silicon dioxide particles, most of the particle sizes are within the uniform range of 23 - 45 μm, and the proportion within the range of 33 - 38 μm can reach more than 30%.

[0020] Optionally, after mixing the quartz sand and the soda ash, they are reacted at 1550 - 1560 °C for 4.8 - 5.2 h to obtain the molten material.

[0021] By adopting the above technical solution, within this temperature range, the sodium silicate generated from the reaction of quartz sand and soda ash has high purity, correspondingly improving the purity of the subsequent-produced silicon dioxide, which can reach over 98%.

[0022] Optionally, the volume of the sodium silicate aqueous solution is V, and the flow rate of adding acid is V / (20 - 40) per minute. During the acid addition process, the stirring speed is maintained at 200 - 300 revolutions per minute.

[0023] By adopting the above technical solution, controlling the acid addition speed and the stirring speed improves the dispersibility and particle size uniformity of the generated silicic acid.

[0024] Optionally, heat the sodium silicate aqueous solution to 84 - 86 °C, then add pentasodium aminotris(methylenephosphonic acid), and after mixing evenly, add acid and water under stirring conditions.

[0025] By adopting the above technical solution, at this temperature, pentasodium aminotris(methylenephosphonic acid) has strong activity and a large hydrogen bond effect with silicic acid, making the particle size of silicic acid suitable and the dispersion uniform.

[0026] In a second aspect, the present application also proposes a silicon dioxide as a toothpaste additive, and the following technical solution is adopted.

[0027] A silicon dioxide as a toothpaste additive, which is prepared according to the above production process.

[0028] By adopting the above technical solution, a silicon dioxide with suitable particle size, good uniformity, not easy to agglomerate, and suitable for use as both a toothpaste abrasive and a thickener is prepared.

[0029] In summary, a silicon dioxide as a toothpaste additive and its production process of the present application have the following beneficial effects:

[0030] By controlling the reaction temperature at 1400 - 1600 °C, quartz sand (SiO 2 ) and soda ash (Na 2 CO 3 ) react to obtain molten sodium silicate, and the sodium silicate obtained by reacting at this temperature has less impurity content.

[0031] Using high-temperature steam at 100 - 150 °C and pressurizing to 0.4 - 1 MPa, solid sodium silicate can be efficiently dissolved to form a colorless, transparent, viscous liquid, namely sodium silicate aqueous solution.

[0032] Heat the aqueous sodium silicate solution and maintain it at 70 - 100°C, then add pentasodium aminotris(methylenephosphonic acid). After mixing evenly, add acid and water under stirring conditions. The reaction between sodium silicate and acid generates silicic acid. Among them, heating the aqueous solution to 70 - 100°C maintains the stability of the reaction rate. Pentasodium aminotris(methylenephosphonic acid) can, on the one hand, form hydrogen bonds with silicic acid, hindering the excessive aggregation of silicic acid. On the other hand, due to the relatively short and three-dimensional molecular chain of pentasodium aminotris(methylenephosphonic acid), the encapsulation of silicic acid is moderate, and the diameter of the microparticles formed by the aggregation of silicic acid is appropriate, neither too large nor too small. On the third hand, the density of pentasodium aminotris(methylenephosphonic acid) is greater than 1.4 g / cm 3 , and it can also moderately increase the density of the aqueous solution, reduce the interfacial tension between silicic acid microparticles and water, facilitate the dispersion of microparticles, make the silicic acid microparticles suspended in the aqueous solution, prevent the silicic acid particles from settling and aggregating too quickly, and make the silicic acid microparticles evenly dispersed. Silicic acid decomposes upon heating to form silicon dioxide, and the precipitated silicon dioxide microparticles are uniform in size, high in purity, and good in whiteness.

[0033] Add acid, and the reaction between sodium silicate and acid generates silicic acid. Control the final pH of the solution to reach 2 - 4, which can not only react with the excess soda ash but also hinder the ionization of silicic acid, shifting the ionization equilibrium towards the molecular state. Silicic acid molecules are prone to decompose upon heating to precipitate silicon dioxide. If the pH is too low, the solubility of silicic acid is high and it is not easy to precipitate silicon dioxide. If the pH is too high, the ionization equilibrium shifts towards the ionic state and it is also not easy to precipitate silicon dioxide.

[0034] The white powder obtained by spray drying is finally baked at a temperature of 150 - 200°C, so that the small amount of undecomposed silicic acid in the white powder is completely decomposed into silicon dioxide, obtaining silicon dioxide powder with high purity, good homogeneity, high dispersibility and not easy to agglomerate. Specific embodiments

[0035] Some embodiments of the silicon dioxide used as a toothpaste additive and its production process of the present application are specifically described below. The masses of the following materials have been converted into relative mass fractions for description.

[0036] Example 1

[0037] Mix 3 parts of quartz sand and 1 part of soda ash, react at 1555 °C for 5 h to obtain molten sodium silicate, cool to obtain solid sodium silicate, use steam at 125 °C, pressurize to 0.4 MPa, spray and dissolve the sodium silicate to obtain an aqueous sodium silicate solution with a volume of V; heat the aqueous sodium silicate solution to 85 °C, then add 0.02 parts of pentasodium aminotris(methylenephosphonic acid), after mixing evenly, add sulfuric acid and water under stirring conditions, the flow rate of sulfuric acid added is V / 30 per minute, during the addition of sulfuric acid, keep the stirring speed at 250 rpm, control the amount of sulfuric acid added so that the final pH of the solution reaches 3, after white precipitate is generated and no longer precipitates, filter to obtain the precipitate, wash the precipitate, then spray-dry the precipitate to obtain a white powder, and finally bake the white powder at 150 °C to obtain the silica.

[0038] Example 2

[0039] The only difference between this example and Example 1 is that 3.5 parts of quartz sand are added, and steam at 125 °C is also used, pressurize to 1 MPa, spray and dissolve the solid, and the dissolution time is 16% higher than that in Example 1 under the same conditions. After dissolution, an aqueous sodium silicate solution is obtained, and finally silica is prepared.

[0040] Example 3

[0041] The only difference between this example and Example 1 is that 0.01 part of pentasodium aminotris(methylenephosphonic acid) is added, and finally silica is prepared.

[0042] Example 4

[0043] The only difference between this example and Example 1 is that 0.03 part of pentasodium aminotris(methylenephosphonic acid) is added, and finally silica is prepared.

[0044] Example 5

[0045] The only difference between this example and Example 1 is that the amount of sulfuric acid added is controlled so that the final pH of the solution reaches 2, and finally silica is prepared.

[0046] Example 6

[0047] The only difference between this example and Example 1 is that the amount of sulfuric acid added is controlled so that the final pH of the solution reaches 4, and finally silica is prepared.

[0048] Example 7

[0049] The only difference between this example and Example 1 is that after mixing quartz sand and soda ash, react at 1400 °C for 5 h to obtain molten sodium silicate, and finally silica is prepared.

[0050] Example 8

[0051] The only difference between this example and Example 1 is that quartz sand and soda ash are mixed and reacted at 1600 °C for 5 h to obtain molten sodium silicate, and finally silicon dioxide is prepared.

[0052] Example 9

[0053] The only difference between this example and Example 1 is that the aqueous sodium silicate solution is heated and maintained at 70 °C, and then pentasodium aminotris(methylenephosphonic acid) is added, and finally silicon dioxide is prepared.

[0054] Comparative Example 1

[0055] The only difference between this comparative example and Example 1 is that pentasodium aminotris(methylenephosphonic acid) is not added, and finally silicon dioxide is prepared.

[0056] Comparative Example 2

[0057] The only difference between this comparative example and Example 1 is that 0.02 parts of sodium dodecylbenzenesulfonate are added, and finally silicon dioxide is prepared.

[0058] Comparative Example 3

[0059] The only difference between this comparative example and Example 1 is that 0.02 parts of sodium dodecylsulfonate are added, and finally silicon dioxide is prepared.

[0060] Comparative Example 4

[0061] The only difference between this comparative example and Example 1 is that the amount of sulfuric acid added is controlled so that the final pH of the solution reaches 1, and finally silicon dioxide is prepared.

[0062] Comparative Example 5

[0063] The only difference between this comparative example and Example 1 is that the amount of sulfuric acid added is controlled so that the final pH of the solution reaches 5, and finally silicon dioxide is prepared.

[0064] Comparative Example 6

[0065] The only difference between this comparative example and Example 1 is that quartz sand and soda ash are mixed and reacted at 1300 °C for 5 h to obtain molten sodium silicate, and finally silicon dioxide is prepared.

[0066] Comparative Example 7

[0067] The only difference between this comparative example and Example 1 is that the aqueous sodium silicate solution is heated and maintained at 50 °C, and then pentasodium aminotris(methylenephosphonic acid) is added, and finally silicon dioxide is prepared.

[0068] Comparative Example 8

[0069] The only difference between this comparative example and Example 1 is that the flow rate of sulfuric acid added is V / 10 per minute, and finally silicon dioxide is prepared.

[0070] Test Example 1

[0071] The silicon dioxide prepared in Examples 1-9 and Comparative Examples 1-8 was detected, and the detection was carried out in accordance with the "Inspection Standard for Silicon Dioxide for Toothpaste QB / T2346-2007". The test results are shown in Table 1.

[0072] Table 1 Test Results of the Properties of Silicon Dioxide Prepared in Each Example and Comparative Example

[0073]

[0074]

[0075] The particle size detection of the silicon dioxide prepared in each example and comparative example was increased, and a 600-mesh sieve (particle size passing through 23 μm), a 425-mesh sieve (particle size passing through 33 μm), a 400-mesh sieve (particle size passing through 38 μm), and a 325-mesh sieve (particle size passing through 45 μm) were used for testing. The results are shown in Table 2 below.

[0076] Table 2 Particle Size Detection of Silicon Dioxide Prepared in Each Example and Comparative Example

[0077]

[0078]

[0079] As can be seen from Table 1 and Table 2 above, compared with the silicon dioxide prepared in Comparative Examples 1-8, the particle size concentration of Examples 1-9 has been significantly improved. The proportion in the range of 23-45 μm can reach more than 70%, and the proportion in the range of 33-38 μm can reach more than 30%. When the particle diameter of silicon dioxide is 23-45 μm, or even 33-38 μm, it is not easy to agglomerate. When applied to toothpaste, it has good friction properties, is not easy to damage teeth, and has a thickening effect on toothpaste, making the toothpaste have elasticity and shape retention under low shear force.

[0080] Compared with other examples, Example 1 has the best particle size concentration and purity.

[0081] Compared with Example 1, Example 2 increased the amount of quartz sand used, and its particle size concentration decreased to a certain extent.

[0082] In Examples 3 and 4, compared with Example 1, the addition ratio of pentasodium aminotris(methylenephosphonic acid) was adjusted. In Examples 5 and 6, compared with Example 1, the final pH of the solution was adjusted, and the purity and particle size concentration of the silicon dioxide decreased slightly.

[0083] In Example 7, compared with Example 1, the melting reaction temperature of quartz sand and soda ash was reduced to 1400 °C, and the purity of the finally prepared silica was reduced by 1.5%, and the particle size concentration decreased insignificantly.

[0084] In Example 8, compared with Example 1, the melting reaction temperature of quartz sand and soda ash was increased to 1600 °C, and the purity and particle size concentration of the finally prepared silica were comparable to those of Example 1.

[0085] In Example 9, compared with Example 1, the temperature of heating the sodium silicate aqueous solution was reduced from 85 °C to 70 °C, and the purity of the finally prepared silica was reduced by 1.1%, and the particle size concentration also decreased significantly. It can be seen that the reaction temperature has an obvious influence on the reaction of sodium silicate and sulfuric acid and the dispersion effect of sodium nitrilotris(methylenephosphonic acid) pentasodium.

[0086] In Comparative Example 1, compared with Example 1, sodium nitrilotris(methylenephosphonic acid) pentasodium was not added, and finally the particle size range of the prepared silica was dispersed, and the proportions of less than 23 μm and greater than 45 μm were both relatively high.

[0087] In Comparative Example 2, compared with Example 1, sodium dodecylbenzenesulfonate was used instead of sodium nitrilotris(methylenephosphonic acid) pentasodium, and finally the prepared silica had a significantly increased proportion of dry agent loss on ignition at 900 °C. It may be that after sodium dodecylbenzenesulfonate combines with silicic acid, it is not easy to be washed clean, resulting in the influence of residues.

[0088] In Comparative Example 3, compared with Example 1, sodium dodecylsulfonate was used instead of sodium nitrilotris(methylenephosphonic acid) pentasodium, and finally the prepared silica had a significantly increased proportion of dry agent loss on ignition at 900 °C. It may be that after sodium dodecylbenzenesulfonate combines with silicic acid, it is not easy to be washed clean, resulting in the influence of residues.

[0089] In Comparative Examples 4 and 5, compared with Example 1, the final pH of the solution was adjusted, which affected the dispersion effect of silicic acid, and the particle size concentration of the silica decreased to a certain extent.

[0090] In Comparative Example 6, compared with Example 1, the melting reaction temperature of quartz sand and soda ash was reduced to 1300 °C, and the purity of the finally prepared silica was reduced by 3.3%, and the particle size concentration also decreased to a certain extent. Too low a temperature is not conducive to removing impurities.

[0091] In Comparative Example 7, compared with Example 1, the temperature of heating the sodium silicate aqueous solution was reduced from 85 °C to 50 °C, and the particle size concentration of the silica decreased significantly. It can be seen that this reaction temperature has a certain influence on the dispersion effect.

[0092] In Comparative Example 8, compared with Example 1, the flow rate of sulfuric acid added was increased from V / 30 to V / 10 per minute, and the particle size concentration of the finally prepared silica decreased to some extent, indicating that too fast a sulfuric acid addition rate has a certain destructive effect on the dispersion of the generated silicic acid.

[0093] In summary, by controlling the melting reaction temperature of quartz sand (SiO 2 ) and soda ash (Na 2 CO 3 ) at 1400 - 1600 °C, the sodium silicate obtained by the reaction has a low impurity content.

[0094] Maintaining the reaction temperature of sodium silicate and sulfuric acid at 70 - 100 °C, controlling the final pH of the solution to reach 2 - 4, and adding pentasodium aminotris(methylenephosphonic acid) during the reaction have a significant effect on the uniform dispersion of the final product silica and the formation of an appropriate particle size. The white powder obtained by spray drying is finally baked at a temperature of 150 - 200 °C, so that a small amount of undecomposed silicic acid in the white powder is completely decomposed into silica, obtaining silica powder with high purity, good homogeneity, high dispersibility and not easy to agglomerate.

[0095] The above is only the preferred embodiment of the present application, and the protection scope of the present application is not limited to the above embodiments. It should be pointed out that for those of ordinary skill in the art of this technology, several improvements and refinements made without departing from the principle of the present application should also be regarded as falling within the protection scope of the present application.

Claims

1. A production process of silica as a toothpaste additive, characterized in that, the production process includes: Mix quartz sand and soda ash, react at 1400 - 1600 °C for 4 - 6 h to obtain a molten material, cool to obtain a solid, use steam at 100 - 150 °C, pressurize to 0.4 - 1 MPa, spray and dissolve the solid to obtain an aqueous sodium silicate solution; heat the aqueous sodium silicate solution to maintain at 70 - 100 °C, then add pentasodium aminotris(methylenephosphonic acid), after mixing evenly, add acid and water under stirring conditions to make the final pH of the solution reach 2 - 4. After white precipitate is generated and no longer precipitates, filter to obtain the precipitate, wash the precipitate, then spray-dry the precipitate to obtain a white powder, and finally bake the white powder at 150 - 200 °C to obtain the silica; the mass ratio of the quartz sand to the pentasodium aminotris(methylenephosphonic acid) is 1:(0.01 - 0.03); the volume of the aqueous sodium silicate solution is V, and the flow rate of adding acid is V / (20 - 40) per minute.

2. The production process of silica as a toothpaste additive according to claim 1, characterized in that, the mass ratio of the soda ash to the quartz sand is 1:(1.5 - 3.5).

3. The production process of silica as a toothpaste additive according to claim 2, characterized in that, the mass ratio of the soda ash to the quartz sand is 1:

3.

4. The production process of silica as a toothpaste additive according to claim 1, characterized in that, the mass ratio of the quartz sand to the pentasodium aminotris(methylenephosphonic acid) is 1:0.

02.

5. The production process of silica as a toothpaste additive according to claim 1, characterized in that, add acid and water under stirring conditions, and adjust the final pH of the aqueous solution to 2.8 - 3.

2.

6. The production process of silica as a toothpaste additive according to claim 1, characterized in that, after mixing the quartz sand and the soda ash, react at 1550 - 1560 °C for 4.8 - 5.2 h to obtain the molten material.

7. The production process of silica as a toothpaste additive according to claim 1, characterized in that, during the process of adding acid, maintain the stirring speed at 200 - 300 revolutions per minute.

8. The production process of silica as a toothpaste additive according to claim 1, characterized in that, heat the aqueous sodium silicate solution to 84 - 86 °C, then add pentasodium aminotris(methylenephosphonic acid), after mixing evenly, add acid and water under stirring conditions.

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