Low Refractive Index, High Transparency, and Abrasive Type Silica, Preparation Method and Application Thereof

Abstract

An abrasive type silica with low refractive index and high transparency, a preparation method and an application thereof are disclosed. The preparation method of the present invention includes the following steps: S1, a sodium sulfate solution is added into a reaction tank, the solution is heated to 80-95 C., a sodium silicate solution and a sulfuric acid solution are added at the same time while stirring, the dropping rate of the sodium silicate solution is controlled at 13-15 m.sup.3/h, the dropping rate of the sulfuric acid solution is controlled to ensure that the pH value of the reaction process is 3.0-4.5, and stirring is continued for 10-15 min after the adding is finished; and S2, the formed silica is filter pressed, washed, spray-dried and airflow crushed to prepare the abrasive type silica with low refractive index and high transparency.

Claims

1. A method of preparing an abrasive type silica with a low refractive index and a high transparency, comprising the following steps: S1, adding 11-13 m.sup.3 sodium sulfate solution to a reaction kettle, heating the sodium sulfate solution to 80-95 C., stirring and titrated with 8.5-12 m.sup.3 sodium silicate solution and a sulfuric acid solution to obtain a mixed solution, controlling a dropping rate of the sodium silicate solution as 13-15 m .sup.3 /h, controlling a dropping rate of the sulfuric acid solution to ensure that a pH value of a reaction process is 3.0-4.5, stirring the mixed solution for 10-15 min after an addition of the sodium silicate solution and an addition of the sulfuric acid solution were completed to obtain a silica; S2, filtering, washing the silica to obtain a washed silica, spray-drying, and jet-milling the washed silica to obtain the abrasive type silica with the low refractive index and the high transparency; a modulus of the sodium silicate solution is 2.5-3.0, a concentration of the sodium silicate solution 1.5-3.0.

2. The method of claim 1, wherein a mass concentration of the sodium sulfate solution is 6.5-8.5%.

3. The method of claim 1, wherein a concentration of the sulfate acid solution is 4.5-5.0.

4. The method of claim 1, wherein a salinity of the washed silica is 1.8-2%.

5. An abrasive type silica with a low refractive index and a high transparency prepared by the method of claim 1.

6. Toothpaste, comprising the abrasive type silica with the low refractive index and the high transparency of claim 5.

7. The abrasive type silica with the low refractive index and the high transparency of claim 5, wherein a mass concentration of the sodium sulfate solution is 6.5-8.5%.

8. The abrasive type silica with the low refractive index and the high transparency of claim 5, wherein a concentration of the sulfuric acid solution is 4.0-5.0 M.

9. The abrasive type silica with the low refractive index and the high transparency of claim 5, wherein a salinity of the washed silica is 1.8-2%.

Description

DETAILED DESCRIPTION

[0025] The present invention is described in detail below with reference to some specific embodiments, herein, schematic embodiments and illustrations are used for explaining the present invention, but are not intended to limit the present invention.

Embodiment I

[0026] Abrasive type silica with low refractive index and high transparency of the present invention and preparation method thereof.

[0027] S1, 11 m.sup.3 sodium sulfate solution having a mass concentration of 6.5% was added to the reaction tank, the reaction tank was heated to 80 C., stirring at the stirring rate of 40 Hz, 8.5 m.sup.3 sodium silicate solution with a concentration of 1.5 M and a modulus of 2.5, and sulfuric acid solution with a concentration of 4.0 M were dropped into the reaction tank at the same time, the dropping rate of sodium silicate solution was controlled at 13 m.sup.3 /h, and the dropping rate of sulfuric acid solution was controlled to ensure the pH value was 3.0 during the reaction, stirring was continued for 10 min after the addition was completed;

[0028] S2, the silica obtained in S1 was filtered, and washed, and the washed silica was spray-dried, and jet milled to obtain abrasive type silica with low refractive index and high transparency. Wherein, the salinity of the washed silica was 1.8%.

Embodiment II

[0029] Abrasive type silica with low refractive index and high transparency of the present invention and preparation method thereof.

[0030] S1, 13 m.sup.3 sodium sulfate solution having a mass concentration of 8.5% was added to the reaction tank, the reaction tank is heated to 95 C., stirring at the stirring rate of 60 Hz, 12 m.sup.3 sodium silicate solution with a concentration of 3.0 M and a modulus of 2.6, and sulfuric acid solution with a concentration of 5.0 M were dropped into the reaction tank at the same time, the dropping rate of sodium silicate solution was controlled at 15 m.sup.3 /h, and the dropping rate of sulfuric acid solution was controlled to ensure the pH value was 4.5 during the reaction, stirring was continued for 15 min after the addition was completed;

[0031] S2, the silica obtained in S1 was filtered, and washed, and the washed silica was spray-dried, and jet milled to obtain abrasive type silica with low refractive index and high transparency. Wherein, the salinity of the washed silica was 2.0%.

Embodiment III

[0032] Abrasive type silica with low refractive index and high transparency of the present invention and preparation method thereof.

[0033] S1, 12 m.sup.3 sodium sulfate solution having a mass concentration of 7.0% was added to the reaction tank, the reaction tank is heated to 85 C., stirring at the stirring rate of 50 Hz, 10 m.sup.3 sodium silicate solution with a concentration of 2.0 M and a modulus of 2.8, and sulfuric acid solution with a concentration of 4.5 M were dropped into the reaction tank at the same time, the dropping rate of sodium silicate solution was controlled at 14 m.sup.3 /h, and the dropping rate of sulfuric acid solution was controlled to ensure the pH value was 4.0 during the reaction, stirring was continued for 10 min after the addition was completed;

[0034] S2, the silica obtained in S1 was filtered, and washed, and the washed silica was spray-dried, and jet milled to obtain abrasive type silica with low refractive index and high transparency. Wherein, the salinity of the washed silica was 1.8%.

Embodiment IV

[0035] Abrasive type silica with low refractive index and high transparency of the present invention and its preparation method:

[0036] S1, 13 m.sup.3 sodium sulfate solution having a mass concentration of 8.0% was added to the reaction tank, the reaction tank is heated to 80 C., stirring at the stirring rate of 60 Hz, 12 m.sup.3 sodium silicate solution with a concentration of 1.5 M and a modulus of 3.0, and sulfuric acid solution with a concentration of 5.0 M were dropped into the reaction tank at the same time, the dropping rate of sodium silicate solution was controlled at 14 m.sup.3 /h, and the dropping rate of sulfuric acid solution was controlled to ensure the pH value was 4.0 during the reaction, stirring was continued for 10 min after the addition was completed;

[0037] S2, the silica obtained in S1 was filtered, and washed, and the washed silica was spray-dried, and jet milled to obtain abrasive type silica with low refractive index and high transparency. Wherein, the salinity of the washed silica was 1.9%.

Embodiment V

[0038] Abrasive type silica with low refractive index and high transparency of the present invention and preparation method thereof.

[0039] S1, 12 m.sup.3 sodium sulfate solution having a mass concentration of 6.5% was added to the reaction tank, the reaction tank is heated to 90 C., stirring at the stirring rate of 40 Hz, 11 m.sup.3 sodium silicate solution with a concentration of 3.0 M and a modulus of 2.8, and sulfuric acid solution with a concentration of 4.0 M were dropped into the tank at the same time, the dropping rate of sodium silicate solution was controlled at 15 m.sup.3 /h, and the dropping rate of sulfuric acid solution was controlled to ensure the pH value was 3.5 during the reaction, stirring was continued for 15 min after the addition was completed;

[0040] S2, the silica obtained in S1 was filtered, and washed, and the washed silica was spray-dried, and jet milled to obtain abrasive type silica with low refractive index and high transparency. Wherein, the salinity of washed silica was 2.0%.

Embodiment VI

[0041] The application of the abrasive type silica with low refractive index and high transparency of this invention in toothpaste.

[0042] The abrasive type silica with low refractive index and high transparency of the embodiment I-V were applied to toothpaste and toothpastes 1-5 were prepared respectively. The specific formulation of the toothpastes was as follows (% by mass): abrasive type silica was 18%, silica thickener type was 3%, sorbitol was 55%, polyethylene glycol was 4%, carboxymethyl cellulose was 0.6%, carrageenan was 0.4%, saccharin was 0.2%, sodium benzoate was 0.2%, flavor was 1%, sodium dodecyl sulfate was 2%, and water was 15.6%.

[0043] The toothpaste was detected according to the toothpaste standard GB8372, the paste was smooth with exquisite appearance, and crystal clear, transparency was high, pH value was 7.5, consistency was 12 mm, the results of main testing index meet the requirements of the toothpaste standard.

[0044] Wherein, the perspective degree of the toothpastes is shown in the following table:

TABLE-US-00001 Transparency Toothpastes 1.0 mm 0.5 mm 0.1 mm 0.05 mm 0.01 mm 1 Clearly Clearly Clearly Clearly Visible visible visible visible visible 2 Clearly Clearly Clearly Clearly Visible visible visible visible visible 3 Clearly Clearly Clearly Clearly Visible visible visible visible visible 4 Clearly Clearly Clearly Clearly Visible visible visible visible visible 5 Clearly Clearly Clearly Clearly Visible visible visible visible visible

COMPARATIVE EXAMPLE I

[0045] As compared with the embodiment III, the present comparative example differs only in that: a sodium silicate solution has a modulus of 2.0.

COMPARATIVE EXAMPLE II

[0046] As compared with the embodiment III, the present comparative example differs only in that: a sodium silicate solution has a modulus of 3.3.

COMPARATIVE EXAMPLE III

[0047] As compared with the embodiment III, the present comparative example differs only in that: pH value of the reaction procedure is controlled at 2.5.

COMPARATIVE EXAMPLE IV

[0048] As compared with the embodiment III, the present comparative example differs only in that: pH value of the reaction process is controlled at 5.0.

COMPARATIVE EXAMPLE V

[0049] As compared with the embodiment III, the present comparative example differs only in that: the reaction temperature is controlled at 70 C.

COMPARATIVE EXAMPLE VI

[0050] As compared with the embodiment III, the present comparative example differs only that: the reaction temperature is controlled at 100 C.

[0051] Test Case I

[0052] Performance test of the abrasive type silica with low refractive index and high transparency of the present invention.

[0053] Transparency, amount of water absorption and oil absorption, and apparent density of the silica prepared by the embodiments 1-5 and comparative examples 1-6 were detected in a refractive index range of 1.430-1.460, the results are shown in Table 1.

TABLE-US-00002 TABLE 1 The detection results of each silica Water Oil Light transmittance/ absorption absorption Apparent Transparency (%) amount amount density Item 1.430 1.435 1.438 1.440 1.443 1.450 mL/20 g mL/100 g g/mL Embodiment I 74.1 82.3 92.0 97.5 97.1 91.0 22.0 130 0.30 Embodiment 70.4 80.0 91.2 91.7 95.0 90.4 16.0 90 0.50 II Embodiment 77.5 86.2 94.4 97.5 97.8 92.0 18.5 105 0.39 III Embodiment 71.9 80.7 91.5 94.4 95.8 89.5 17.8 98 0.45 IV Embodiment V 72.3 80.2 91.5 94.7 95.4 88.6 19.0 108 0.37 Comparative 59.4 63.0 86.0 90.7 91.1 70.4 19.1 108 0.37 Example I Comparative 72.4 76.9 80.5 92.5 90.1 80.9 18.0 100 0.4 Example II Comparative 87.4 89.0 92.3 94.6 97.5 95.5 30.0 162 0.28 Example III Comparative 64.1 77.3 84.0 89.3 91.4 84.3 18.5 105 0.39 Example IV Comparative 73.0 85.5 87.9 90.8 91.2 90.4 29.3 150 0.27 Example V Comparative 77.0 82.1 92.2 95.3 89.0 87.6 16.8 94 0.48 Example VI

[0054] As can be seen from Table 1:

[0055] (1) the transparency of the silica of embodiments 1-5 in refractive index range of 1.430-1.440 can reach more than 90%, and is higher than 95% in the refractive index range of 1.440-1.460, having high transparency in the low refractive index. Meanwhile, water absorption of the silica of the present invention is 16-22 ml/20 g, oil absorption is 90-130 ml/100 g, and apparent density is equal to or more than 0. 3 g/mL, meeting the standard requirements of abrasive type silica, and it has good abrasive properties, suitable for use in toothpaste.

[0056] (2) As compared with the embodiment III, Comparative Example I and Comparative Example II respectively decreases and increases the modulus of sodium silicate solution, thereby the transparency of the silica is found to have a significantly reduce.

[0057] (3) As compared with the embodiment III, Comparative Example III reduces the pH value in the reaction process, the transparency of the silica is enhanced, but significant increases of the amount of water absorption and oil absorption are observed, abrasive performance of the silica is reduced, and property thereof is inclined to silica thickener type, which does not meet the standard of abrasive silica; in the Comparative Example IV, the pH value of the reaction process is increased, thus there is a significant reduction in the transparency of the silica.

[0058] (4) As compared with the embodiment III, Comparative Example V reduces the reaction temperature, there is a significant decrease in the transparency of the silica, and the water absorption and oil absorption are significantly increased, the abrasive performance is reduced, which does not meet the standard of abrasive silica; Comparative Example VI enhances the reaction temperature, but the transparency of the silica is not increased, rather reduced.

[0059] Test Case II

[0060] Application effect of the abrasive type silica with low refractive index and high transparency of the present invention in the toothpaste

[0061] Specific toothpaste formulations are shown below in Table 2:

TABLE-US-00003 TABLE 2 Ingredients of Toothpaste Toothpaste Toothpaste Toothpaste toothpaste/% A B C D Abrasive type 18(silica of 18(silica of 18(silica of 18(silica of silica embodiment embodiment embodiment comparative III) III) III) example II) Thickening 3 3 3 3 type silica Sorbitol 59 57 55 55 Polyethylene 4 4 4 4 glycol Carboxymethyl 0.6 0.6 0.6 0.6 cellulose Carrageenan 0.4 0.4 0.4 0.4 Saccharin 0.2 0.2 0.2 0.2 Sodium 0.2 0.2 0.2 0.2 benzoate Essence 1 1 1 1 Sodium lauryl 2 2 2 2 sulfate Water 11.6(liquid 13.6(liquid 15.6(liquid 15.6(liquid phase 1.438) phase 1.435) phase 1.430) phase 1.430)

[0062] The degree of transparency of the above-mentioned toothpastes are detected, results are shown in the following Table 3:

TABLE-US-00004 TABLE 3 Perspective Degree of the Toothpaste Tooth- Transparency paste 2 mm 1.0 mm 0.5 mm 0.1 mm 0.05 mm 0.01 mm Tooth- Clearly Clearly Clearly Clearly Clearly Clearly paste A visible visible visible visible visible visible Tooth- Clearly Clearly Clearly Clearly Clearly Clearly paste B visible visible visible visible visible visible Tooth- Clearly Clearly Clearly Clearly Clearly Visible paste C visible visible visible visible visible Tooth- Visible Visible Fuzzy Very Very Very paste D fuzzy fuzzy fuzzy

[0063] As can be seen in the table above: when silica of the present invention is applied to the toothpaste, the transparent performance of the toothpaste is good, the paste is crystal clear, and the perspective degree is high. Wherein, when applying to toothpaste with a water content of 15.6%, the paste remains clear, increasing the amount of water used in the toothpaste and reducing the amount of humectant by 4%. Thus, when the silica of the present invention is applied to the toothpaste, for toothpaste formulation having high transparency requirement, 4% more of water can be added, and for the semi-transparent toothpaste, it is possible to add 4-10% more of water, thus greatly reducing the production cost of the toothpaste.

[0064] The above embodiments only schematically explain the principle and efficacy of the present invention, rather than limit the invention. Any person familiar with the technology may modify or alter the above embodiments without prejudice to the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by persons of ordinary skill in the art without departing from the spirit and technical thoughts disclosed by the present invention shall still be covered by the claims of the present invention.