Friction type silicon dioxide with low specific surface area and low pore volume for toothpaste and preparation method of friction type silicon dioxide

Abstract

The invention belongs to the technical field of silicon dioxide. The invention particularly relates to low-specific-surface-area and low-pore-volume friction type silicon dioxide for toothpaste and a preparation method of the friction type silicon dioxide. The friction type silicon dioxide provided by the invention has the specific surface area of less than 2.79 m < 2 > / g and the pore volume of less than 0.4 cm < 3 > / g, has the advantages of high stability, better essence permeability, high dispersing performance, high cleaning property, good fluorine compatibility and the like, is suitable for being applied to toothpaste, and is particularly suitable for being applied to export toothpaste. The silicon dioxide preparation method provided by the invention has the advantages of simple and stable process, easily controlled conditions, low cost and the like, and is easier for industrial production, popularization and application.

Description

Technical Field

[0001] The present invention belongs to the technical field of silica. More specifically, it relates to a friction-type silica for toothpaste with a low specific surface area and a low pore volume, and a preparation method thereof. Background Art

[0002] Silica is a high-quality toothpaste abrasive that has developed rapidly in recent years. It has the advantages of good cleaning effect, strong polishing effect, good fluorine compatibility, good chemical stability, etc., and is widely used. The market space for silica used in toothpaste is broad. The Chinese toothpaste industry also has a large share in exports. According to relevant foreign regulations, silica used in toothpaste shall not contain nanomaterials. In the relevant regulations, it is defined that when 50% or more of the particles in the size distribution based on the number of solid particles satisfy that one or more external dimensions of these particles are in the size range of 1 nm to 100 nm, then the solid particle is regarded as a nanomaterial. However, a material with a volume specific surface area less than 6 m 2 / cm 3 should not be regarded as a nanomaterial. The particle size of silica used in toothpaste is usually characterized by the weight median diameter D50. During the formation of silica, new small particles are continuously generated and grown. The particles generated later have a small particle size, and some small particles will be produced after the silica product is broken, and the particle size range can reach 1 nm to 100 nm. The number of these particles with a particle size less than 100 nm cannot be accurately characterized, and it is impossible to accurately judge whether it is a nanomaterial according to the above definition. The density of silica is 2.15 g / cm 3 , so the requirement of "volume specific surface area less than 6 m 2 / cm 3 " can be converted into "the specific surface area of silica is less than 2.79 m 2 / g". Therefore, in order to ensure that the produced silica can meet the above requirements, it is necessary to develop silica with a specific surface area less than 2.79 m 2 / g to make it meet the requirement of a volume ratio less than 6 m 2 / cm 3 .

[0003] The specific surface area (BET) of silica is 1000 times the ratio of 4 times the pore volume to the pore diameter. Therefore, the reduction of the specific surface area can be achieved by two ways: reducing the pore volume or increasing the pore diameter. At present, the pore volume of existing silica is basically 0.4 cm 3Above / g, and there is little attention paid to the low pore volume in the reports; it is mostly involved in the pore volume in the production of silica for other fields rather than toothpaste, and mostly pursues a large pore volume to improve its adsorption performance. However, for silica used in toothpaste, it is better to choose the way of reducing the pore volume. Toothpaste does not require the adsorption performance of silica, nor its reactivity. Instead, it is necessary for it to remain inert and act as an abrasive quietly, so that it has a higher compatibility with other ingredients in toothpaste. When the pore volume of silica is small, the internal pores are relatively few, the active sites provided are few, and the ability to adsorb and load other substances is weak. The ability to adsorb essence is weak, so the volatility of essence is better, which can reduce the cost of toothpaste (essence is the most expensive raw material in the toothpaste formula). Moreover, silica with a low pore volume is more dense, and the corresponding dispersion performance and cleaning performance will be better. Therefore, when pursuing a low specific surface area of silica for toothpaste, it is more advantageous to reduce the pore volume as much as possible. For silica with a low specific surface area, to prepare silica with a pore volume less than 0.4 cm 3 / g, more precise control of the pore structure and pore size is required, which is of high difficulty and it is difficult to achieve both a low specific surface area and a low pore volume at the same time. Moreover, due to the inherent microscopic structure characteristics of silica, it is relatively difficult to form more pores, and it is difficult to reduce the pore volume. There is a lack of means to precisely control the formation of pores in the existing technology. Therefore, the existing solutions generally achieve the reduction of the specific surface area of silica by increasing the pore diameter.

[0004] The specific surface area of the existing silica is usually relatively high. The low specific surface area silica prepared in Patent CN201810273705 has a specific surface area range of 30.3 - 38.7 m 2 / g, and the specific surface area still cannot meet the non-nano requirements described above. The silica prepared in Patent US12145852B2 has a specific surface area range of 0.1 - 3.4 m 2 / g, but it does not give the pore volume and pore diameter data. The silica prepared in this patent is mainly used for semiconductor packaging materials.

[0005] Therefore, exploring and developing abrasive silica for toothpaste with a specific surface area less than 2.79 m 2 / g and a pore volume less than 0.4 cm 3 / g has important value for the raw materials of silica for toothpaste and the export of the toothpaste industry in our country. Summary of the Invention

[0006] The present invention aims to develop abrasive silica for toothpaste with a specific surface area less than 2.79 m 2 / g and a pore volume less than 0.4 cm 3 / g.

[0007] The purpose of the present invention is to provide an abrasive silica for toothpaste with a low specific surface area and a low pore volume.

[0008] Another object of the present invention is to provide a method for preparing the friction-type silica for toothpaste with a low specific surface area and a low pore volume.

[0009] The above object of the present invention is achieved by the following technical solutions:

[0010] The present invention provides a friction-type silica for toothpaste with a low specific surface area and a low pore volume, which meets the following indicators:

[0011] (1) Specific surface area: 0.01 - 2.79 m 2 / g,

[0012] (2) Pore volume: 0.00004 - 0.3 cm 3 / g;

[0013] (3) Pore diameter: 5 - 26 nm;

[0014] (4) D50 median particle size: 1 - 25 μm.

[0015] Furthermore, the friction-type silica for toothpaste with a low specific surface area and a low pore volume has the following performance indicators:

[0016] (5) Fluorine compatibility: 75% - 99%,

[0017] (6) Copper sheet wear value: 6 - 25 mg per 10,000 revolutions,

[0018] (7) RDA value: 180 - 360;

[0019] (8) PCR value: 80 - 160;

[0020] (9) Apparent density: 0.02 - 1.5 g / ml;

[0021] (10) Oil absorption value: 10 - 125 g / 100 g.

[0022] Preferably, the friction-type silica for toothpaste with a low specific surface area and a low pore volume meets the following indicators:

[0023] (1) Specific surface area: 0.01 - 2.79 m 2 / g,

[0024] (2) Pore volume: 0.00004 - 0.1 cm 3 / g;

[0025] (3) Pore diameter: 15 - 26 nm;

[0026] (4) D50 median particle size: 1 - 20 μm.

[0027] Furthermore, the friction-type silica for toothpaste with a low specific surface area and a low pore volume has the following performance indicators:

[0028] (5) Fluoride compatibility: 80%-99%,

[0029] (6) Copper sheet wear value: 10-20 mg per 10,000 revolutions,

[0030] (7) RDA value: 180-260;

[0031] (8) PCR value: 100-160;

[0032] (9) Apparent density: 0.3-1.5 g / ml;

[0033] (10) Oil absorption value: 10-60 g / 100 g.

[0034] More preferably, the friction-type silica for toothpaste with a low specific surface area and a low pore volume meets the following indicators:

[0035] (1) Specific surface area: 0.1-2.5 m 2 / g,

[0036] (2) Pore volume: 0.00004-0.02 cm 3 / g;

[0037] (3) Pore diameter: 15-26 nm;

[0038] (4) D50 median particle size: 1-16 μm.

[0039] Furthermore, the friction-type silica for toothpaste with a low specific surface area and a low pore volume has the following performance indicators:

[0040] (5) Fluoride compatibility: 90%-99%,

[0041] (6) Copper sheet wear value: 10-20 mg per 10,000 revolutions,

[0042] (7) RDA value: 200-250;

[0043] (8) PCR value: 100-160;

[0044] (9) Apparent density: 0.5-1.0 g / ml;

[0045] (10) Oil absorption value: 10-60 g / 100 g.

[0046] The friction-type silica provided by the present invention has a specific surface area of less than 2.79 m 2 / g and a pore volume of less than 0.4 cm 3 / g, with advantages such as high stability, better fragrance permeability, high dispersion performance, high cleanliness, and good fluorine compatibility. It is suitable for use in toothpaste and complies with relevant foreign regulations, making it suitable for use in exported toothpaste.

[0047] Therefore, the present invention also provides the use of the low specific surface area and low pore volume abrasive silica for toothpaste in the preparation of oral abrasives, cleaning aids, or toothpaste.

[0048] Furthermore, the present invention also provides an oral composition containing the above-mentioned low specific surface area and low pore volume abrasive silica for toothpaste, and an orally acceptable carrier.

[0049] Optionally, in the oral composition, the content of silica is 0.5 - 90.0% by mass ratio.

[0050] Preferably, in the oral composition, the content of silica is 1.0 - 80.0% by mass ratio.

[0051] In the oral composition, the silica exists as the only abrasive in the oral composition.

[0052] In the oral composition, the silica exists as an abrasive and / or a cleaning aid.

[0053] As an optional specific embodiment, the composition is toothpaste.

[0054] The present invention has also explored and optimized the preparation method of the above-mentioned low specific surface area and low pore volume abrasive silica for toothpaste, and developed a method for preparing the low specific surface area and low pore volume abrasive silica for toothpaste based on the precipitation method. The precipitation method process is simpler, more stable, the conditions are easy to control, and it is more suitable for industrial production.

[0055] Specifically, the present invention provides a method for preparing the above-mentioned low specific surface area and low pore volume abrasive silica for toothpaste, comprising the following steps:

[0056] 1) Add a sodium sulfate solution to a reaction vessel (such as a reaction kettle).

[0057] 2) Add a sodium silicate solution and stir evenly until the pH of the solution is 7 - 14.

[0058] 3) Heat up to a solution temperature of 60 - 97°C; and maintain the reaction temperature, stir at a speed of 200 - 600 revolutions per minute, and simultaneously slowly add the sodium silicate solution and the sulfuric acid solution. The flow rate of the sodium silicate solution is 5 - 30m 3 / h, and maintain the pH within the range of 7 - 10 by adjusting the flow rate of the sulfuric acid solution.

[0059] 4) When the volume ratio of the sodium silicate solution to the sodium sulfate solution in step 1) is (1.5 - 2):1 (at this time, the reaction time is about 10000 - 30000 s), stop adding the sodium silicate solution; continue to add the sulfuric acid solution until the pH of the solution reaches 4 - 7, and then stop adding the sulfuric acid solution;

[0060] 5) Continue stirring and aging at a constant temperature for 10 - 60 min to obtain a silica slurry;

[0061] 6) The silica slurry is filtered, washed, dried, and pulverized to obtain the finished product;

[0062] Among them, the mass percentage concentration of the sodium sulfate solution is 6 - 20%;

[0063] The concentration of the sodium silicate solution is 1 - 2.5 mol / L;

[0064] The concentration of the sulfuric acid solution is 1 - 2 mol / L.

[0065] Preferably, the mass percentage concentration of the sodium sulfate solution is 8 - 20%.

[0066] Preferably, the concentration of the sodium silicate solution is 1.5 - 2.5 mol / L.

[0067] Preferably, the pH of the solution in steps 2) and 3) is 7 - 12.

[0068] Preferably, the flow rate of the sodium silicate solution in step 3) is 5 - 7 m 3 / h.

[0069] Preferably, the flow rate of the sulfuric acid solution in step 3) is recommended to be adjusted within the range of 10 - 12 m 3 / h.

[0070] Preferably, the stirring speed in step 3) is 200 - 400 revolutions per minute.

[0071] Specifically, the present invention provides another method for preparing the friction-type silica for toothpaste with low specific surface area and low pore volume, including the following steps:

[0072] 1) Put the sodium sulfate solution and the sodium silicate solution into a reaction vessel (such as a reaction kettle), and heat up to 90 - 95 °C;

[0073] 2) Stir at a rotation speed of 200 - 600 revolutions per minute, add the sulfuric acid solution to the reaction vessel (such as a reaction kettle), and adjust the pH during the process to 7.0 - 7.5;

[0074] 3) While slowly adding the above-mentioned sodium silicate solution and sulfuric acid solution (adding acid and alkali simultaneously), the adding speed of the sodium silicate solution is 5 - 20 m 3 / h; and the pH of the solution is maintained at 7.0 - 7.5 by adjusting the flow rate of the sulfuric acid solution;

[0075] Under the condition that the pH of the process is slightly neutral, the mobility of the grown silica particles is poor, which can reduce the collision between particles. The acid-base neutralization rate in the reaction system is high, and the crystal grains grow rapidly. Due to the high activity at the ends of the sol bonds and the low aggregation density, the active groups are easy to approach each other, thus promoting the growth of the bonds and forming a linear chain structure, which is beneficial to the formation of dense particles and reduces the specific surface area of the particles;

[0076] 4) When the sodium silicate solution is added until the volume ratio of the sodium silicate solution to the sodium sulfate solution in step 1) is (3 - 8):1, stop adding the sodium silicate solution; continue to add the sulfuric acid solution until the pH of the solution is 4 - 7, and then stop adding the sulfuric acid solution;

[0077] 5) Continue stirring and keep aging for 30 min to obtain a silica slurry;

[0078] 6) The silica slurry is filtered through a diaphragm to recover the sodium sulfate solution; then it is washed, spray-dried, and crushed by a jet mill to obtain silica with a low specific surface area and a low pore volume;

[0079] Among them, the mass percentage concentration of the sodium sulfate solution is 6 - 20%;

[0080] The concentration of the sodium silicate solution is 1 - 2.5 mol / L;

[0081] The concentration of the sulfuric acid solution is 1 - 2 mol / L.

[0082] Preferably, in step 1), the volume ratio of the sodium sulfate solution to the sodium silicate solution is 1:(0.05 - 0.2).

[0083] More preferably, in step 1), the volume ratio of the sodium sulfate solution to the sodium silicate solution is 1:0.1.

[0084] Preferably, in step 2), the flow rate of the sulfuric acid solution is 5 - 10 m 3 / h.

[0085] More preferably, in step 2), the flow rate of the sulfuric acid solution is 5 m 3 / h.

[0086] Preferably, in step 4), when the sodium silicate solution is added until the volume ratio of the sodium silicate solution to the sodium sulfate solution in step 1) is 5:1, stop adding the sodium silicate solution.

[0087] Preferably, in step 3), the flow rate of the sulfuric acid solution is recommended to be adjusted within the range of 10 - 12 m 3 / h.

[0088] The preparation method of the present invention uses sodium silicate, sulfuric acid, and sodium sulfate as reaction raw materials, and prepares friction-type silica with a low specific surface area and low pore volume through a reaction. In the preparation method of the present invention, a precipitation method reaction is adopted. A high-concentration sodium sulfate solution is added as a reaction assistant at the beginning of the reaction. By dropping the sodium silicate solution, the reaction system is made weakly alkaline, and the reaction is carried out at 60-97 °C, so that the particles of the initial silica particles have a denser structure, thereby reducing the specific surface area and low pore volume of the silica. Then, an acid-base co-dropping feeding method is adopted to keep the pH value of the reaction process weakly alkaline, avoid gel formation, and ensure the low specific surface area and low pore volume of the finished product. At the end of the reaction, the pH value at the titration end point is adjusted to 4.0-7.0 with acid, and the silica is aged for 10-60 min under the conditions of this acidic system and heat preservation to make the structure of the silica stable.

[0089] The friction-type silica prepared according to the above method has an extremely low specific surface area and pore volume. The specific specific surface area is 0.01-2.79 m 2 / g, and the pore volume is 0.0006-0.3 cm 3 / g. Moreover, the fluorine compatibility of this friction-type silica is 90%-96%. This friction-type silica has the advantages of high stability, better fragrance permeability, high dispersion performance, high cleanliness, and good fluorine compatibility, is suitable for use in toothpaste, and meets the requirements of relevant foreign regulations. And the method is simple, with low temperature and low cost.

[0090] In addition, the present invention has also explored the calcination process, and calcination can also form silica with a relatively low pore volume and specific surface area. However, compared with the improved preparation method provided above in the present invention, although calcination can also form a relatively low pore volume and specific surface area, the requirements for the calcination temperature and time are relatively strict. If not controlled well, it is easy to generate extra pores, and strict control of conditions is required to prepare silica that meets the requirements of low specific surface area and low pore volume. Moreover, the calcination method is relatively prone to unevenness and instability, and the cost is also relatively high, and the energy consumption is relatively high. Therefore, the industrial applicability of the calcination process is inferior to the improved precipitation method preparation process provided above in the present invention.

[0091] The present invention has the following beneficial effects:

[0092] The friction-type silica of the present invention has the following advantages:

[0093] (1) Low specific surface area: The BET specific surface area is less than 2.79 m 2 / g. Toothpaste prepared with silica having a low specific surface area has relatively high stability. Moreover, silica with a low specific surface area less than 2.79 m 2 / g can meet the definition of non-nano materials and belongs to non-nano materials. Compared with the existing friction-type silica, it has a broader prospect.

[0094] (2) Low pore volume: It has the advantages of weak ability to adsorb flavor essence, better flavor essence permeability, and reduction of toothpaste cost. Moreover, the silica with low pore volume is denser, and the corresponding dispersion performance and cleaning performance will be better.

[0095] (3) Good fluorine compatibility: The fluorine compatibility range is 75%-99%.

[0096] (4) The preparation method of the friction-type silica for toothpaste with low specific surface area and low pore volume provided by the present invention has the advantages of simple and stable process, easy control of conditions, low cost, and being more suitable for industrial production, popularization and application. Description of the Drawings

[0097] Figure 1 It is the scanning electron micrograph of the silica in Example 1.

[0098] Figure 2 It is the scanning electron micrograph of the silica in Example 5.

[0099] Figure 3 It is the scanning electron micrograph of the silica in Comparative Example 4.

[0100] Figure 4 It is the scanning electron micrograph of the silica in Comparative Example 7. Detailed Embodiments

[0101] The following further illustrates the present invention in conjunction with the drawings of the specification and specific embodiments, but the embodiments do not impose any form of limitation on the present invention.

[0102] Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the technical field.

[0103] Unless otherwise specified, the reagents and materials used in the following embodiments are all commercially available.

[0104] The test methods for detecting the indexes of silica particles in the present invention are as follows:

[0105] 1. Method for measuring the oil absorption value of powder:

[0106] The test method for the oil absorption value of powder refers to ASTM-D281.

[0107] 2. Method for measuring the BET specific surface area of powder:

[0108] According to the instruction manual, a JW-BK112 type static nitrogen adsorption instrument is used to test the specific surface area, pore volume and pore diameter.

[0109] 3. Method for measuring the fluorine compatibility of powder

[0110] (1) Weigh: For the friction type, weigh 7.00 g or for the thickening type, weigh 2.00 g (usually weigh 2 portions for parallel testing) into a plastic bottle, and slowly add 30.00 g of NaF (1624 ppm stock solution). Seal it (to prevent liquid volatilization) to completely wet SiO 2 , and vibrate it, place it on a rotary rack at 60 °C, rotate and heat for 1 h, cool it, centrifuge it at 15000 rpm for 15 min, and take the supernatant.

[0111] (Note: If there is no rotary rack, place the sample bottle in an oven maintained at 60 °C for heating, and often shake it by hand. Use a No. 4 rotor, use 5-ml centrifuge tubes, for one sample, load 2 centrifuge tubes, for 2 samples, load a total of 4 centrifuge tubes)

[0112] (2) Accurately weigh 2.00 g of the supernatant, and then weigh 9 times (18 g) of the EDTA / THAM buffer solution into a plastic bottle for testing.

[0113] (3) Replace with a reference electrode and an F ion electrode, adjust to mv in pH / mv, and the temperature is at room temperature. First, wash it with distilled water until it is above 370 mv (washed in advance).

[0114] (4) Dry the washed glass electrode. First, measure the low standard solution (10%), record it after the number stabilizes, wash the glass electrode with distilled water, then measure the high standard solution (90%), record it. After measuring the standard solutions, rinse and dry it, then measure the sample to be tested, wait for the reading to stabilize, and record the data.

[0115] (5) Calculate

[0116] y1 = ax1 + b

[0117] y2 = ax2 + b

[0118] y1 is the concentration of the high standard solution at 90%, y2 is the concentration of the low standard solution at 10%, x1 is the reading of the high standard solution, and x2 is the reading of the low standard solution. Calculate the values of a and b

[0119] y = ax + b, where x is the reading of the sample to be tested and y is the fluorine compatibility of the sample to be tested.

[0120] 4. PCR test method

[0121] PCR (film cleanliness) is carried out with reference to GB / T 43576-2023 "Laboratory Test Method for the Effect of Oral Care Products Toothpaste on Removing Exogenous Stains".

[0122] 5. RDA test method

[0123] The Radioactive Dentin Abrasion (RDA) value is determined by Annex B of ISO 11609:2010(E) of the International Organization for Standardization. This test is repeated at least three times, and the average value is calculated to obtain the average RDA.

[0124] 6. The copper loss test method refers to the hard particle test of JSJ-C-109

[0125] First, confirm that the hard particle tester can be powered on, and then turn off the power to continue with the next operation.

[0126] Take 2 copper sheets, clean them with distilled water, dry them with a hair dryer, place them in a desiccator for 15 minutes, then put on gloves and take out the copper sheets. Weigh the weights m1 and m2 of the two copper sheets before wear (the unit is mg). After weighing, place the two copper sheets in the trough of the hard particle tester and fix them.

[0127] Accurately weigh 20.0 g of silica or friction particle sample, disperse it evenly in 120.0 g of sorbitol solution, and transfer the obtained slurry to the trough of the hard particle tester.

[0128] Turn on the hard particle tester and make the friction head continuously rub the copper sheet 10000 times in the test slurry.

[0129] After the rubbing is completed, first turn off the power, then take out the copper sheet, rinse the copper sheet with tap water, then rinse the copper sheet twice with distilled water, finally dry it with a hair dryer, place it in a desiccator for 15 minutes, then put on gloves, take out the copper sheet, and weigh its weights m1 and m2 after wear (the unit is mg).

[0130] The difference in weight of the two copper sheets before and after is the wear value Δm of the copper loss 1 , and Δm 2 (The unit is mg, and take its average value as the final result. The deviation of the parallel experiment results shall not exceed 20%).

[0131] Example 1 Preparation of silica by precipitation method

[0132] (I) Raw materials:

[0133] Sodium sulfate solution: Prepare a sodium sulfate solution with a mass percentage concentration of 12.0%.

[0134] Sodium silicate solution: Use solid sodium silicate with a modulus of 3.3 - 3.45. After high-temperature liquefaction, add water to adjust it to a sodium silicate solution with a concentration of 2.0 mol / L.

[0135] Sulfuric acid solution: Prepare a sulfuric acid solution with a concentration of 1.3 mol / L.

[0136] (II) Preparation of silica, the steps are as follows:

[0137] 1) Add 17.5 m of sodium sulfate solution to the reaction kettle 3 ;

[0138] 2) Add sodium silicate solution to adjust the pH of the solution to 8.5;

[0139] 3) Heat up to a solution temperature of 80 °C and maintain the reaction temperature. Stir at a speed of 400 revolutions per minute, and at the same time slowly add the above-mentioned sodium silicate solution and sulfuric acid solution (add acid and alkali simultaneously). The addition rate (flow rate) of the sodium silicate solution is 5 m 3 / h; and maintain the pH of the solution at 8.5 by adjusting the flow rate of the sulfuric acid solution;

[0140] 4) When 35 m of the sodium silicate solution is added 3 (at this time, the reaction time is about 25200 s), stop adding the sodium silicate solution; continue to add the sulfuric acid solution until the pH of the solution reaches 4.5, then stop adding the sulfuric acid solution;

[0141] 5) Continue to stir and age at a constant temperature for 30 min to obtain a silica slurry;

[0142] 6) The silica slurry is filtered through a diaphragm to recover the sodium sulfate solution; then it is washed, spray-dried, and crushed by a jet mill to obtain friction-type silica with a low specific surface area and low pore volume.

[0143] Example 2 Preparation of silica by precipitation method

[0144] Compared with Example 1, the difference in this example is only that: the mass percentage concentration of the sodium sulfate solution is 17%.

[0145] Example 3 Preparation of silica by precipitation method

[0146] Compared with Example 1, the difference in this example is only that: the concentration of the sodium silicate solution is 1.3 mol / L.

[0147] Example 4 Preparation of silica by precipitation method

[0148] Compared with Example 1, the difference in this example is only that: the pH of the solution in steps 2) to 3) is maintained at 7.5.

[0149] Example 5 Preparation of silica by precipitation method

[0150] Compared with Example 1, the difference in this example is only that: the reaction temperature in step 3) is maintained at 95 °C.

[0151] Example 6 Preparation of silica by precipitation method

[0152] Compared with Example 1, the difference in this example is only that: the stirring speed in step 3) is 600 revolutions per minute.

[0153] Example 7 Preparation of silica by precipitation method

[0154] Compared with Example 1, the difference in this example is only that: the concentration of the sulfuric acid solution is 1.8 mol / L.

[0155] Example 8 Preparation of silica by precipitation method

[0156] Compared with Example 1, the difference in this example is only that: in step 3), the flow rate of the sodium silicate solution is 7 m 3 / h. The sulfuric acid concentration is still 1.3 mol / L. Under the condition that the alkali flow rate remains unchanged, the pH is maintained at 8.5 by adjusting the flow rate of the sulfuric acid solution.

[0157] Example 9 Preparation of silica by precipitation method

[0158] Compared with Example 1, the difference in this example is only that: in step 4), the addition amount of the sodium silicate solution is 28 m 3 .

[0159] Example 10 Preparation of silica by precipitation method

[0160] Compared with Example 1, the difference in this example is only that: in step 5), the heat preservation and aging time is 50 min.

[0161] Comparative Example 1

[0162] Compared with Example 1, the difference in this comparative example is only that: the mass percentage concentration of the sodium sulfate solution is 5%.

[0163] Comparative Example 2

[0164] Compared with Example 1, the difference in this comparative example is only that: the concentration of the sodium silicate solution is 0.8 mol / L.

[0165] Comparative Example 3

[0166] Compared with Example 1, the difference in this comparative example is only that: the pH of the solution in steps 2) to 3) is maintained at 6.5.

[0167] Comparative Example 4

[0168] Compared with Example 1, the difference in this comparative example is only that: the stirring speed in step 3) is 800 revolutions per minute.

[0169] Comparative Example 5

[0170] Compared with Example 1, the difference in this comparative example is only that: the reaction temperature in step 3) is maintained at 50 °C.

[0171] Comparative Example 6

[0172] Compared with Example 1, the difference in this comparative example is only that: the concentration of the sulfuric acid solution is 3 mol / L.

[0173] Comparative Example 7

[0174] Compared with Example 1, the difference in this comparative example is only that: in step 3), the flow rate of the sodium silicate solution is 35 m 3 / h. The sulfuric acid concentration is still 1.3 mol / L. With the alkali flow rate remaining unchanged, the pH is maintained at 8.5 by adjusting the flow rate of the sulfuric acid solution.

[0175] Comparative Example 8

[0176] Compared with Example 1, the difference in this comparative example is only that: in step 4), the addition amount of the sodium silicate solution is 40 m 3 .

[0177] Comparative Example 9

[0178] Compared with Example 1, the difference in this comparative example is only that: in step 4), the final pH of the solution is 3.0.

[0179] Comparative Example 10

[0180] Compared with Example 1, the difference in this comparative example is only that: in step 5), the heat preservation and aging time is 2 min.

[0181] Performance detection of the silica prepared in Examples 1-10 and Comparative Examples 1-10

[0182] The performance of the silica in Examples 1-11 and Comparative Examples 1-10 was detected, and the detection results are shown in Table 1 below:

[0183] The fluorine compatibility of the silica in Examples 1-10 of the present invention is all between 90% and 96%, the specific surface area < 2.79 m 2 / g, which can meet the requirements for non-nano materials in relevant foreign regulations. At the same time, the pore volume is between 0.0006 and 0.02 cm 3 / g, and it has excellent fragrance permeability. Moreover, the dispersibility and cleaning performance are excellent.

[0184] While the specific surface area of Comparative Examples 1-10 > 2.79 m 2 / g, which cannot meet the requirements for non-nano materials; the pore volume is significantly higher than that of each example; the fluorine compatibility is also significantly lower than that of each example.

[0185] Table 1 Performance detection results of the silica in Examples 1-10 and Comparative Examples 1-10

[0186]

[0187]

[0188] Example 11 Preparation of low specific surface area and low pore volume silica by post-treatment of precipitation method

[0189] The precipitated silica obtained in Comparative Example 7 was subjected to high-temperature calcination treatment: samples were prepared, the temperature of the muffle furnace was set to 800 °C, and high-temperature calcination was carried out for 6 h. After high-temperature calcination, the internal pores of the silica collapsed, the pore volume decreased, and the specific surface area decreased accordingly.

[0190] Example 12 Preparation of low specific surface area and low pore volume silica by post-treatment of the precipitation method

[0191] Compared with Example 11, the difference in this example is only that: the temperature of the muffle furnace was set to 900 °C, and high-temperature calcination was carried out for 3 h. After high-temperature calcination, the internal pores of the silica collapsed, the pore volume decreased, and the specific surface area decreased accordingly.

[0192] Example 13 Preparation of low specific surface area and low pore volume silica by post-treatment of the precipitation method

[0193] Compared with Example 11, the difference in this example is only that: the temperature of the muffle furnace was set to 1000 °C, and high-temperature calcination was carried out for 2 h. After high-temperature calcination, the internal pores of the silica collapsed, the pore volume decreased, and the specific surface area decreased accordingly.

[0194] Comparative Example 11

[0195] Compared with Example 11, the difference in this comparative example is only that: the temperature of the muffle furnace was set to 500 °C, and high-temperature calcination was carried out for 2 h.

[0196] Comparative Example 12

[0197] Compared with Example 11, the difference in this comparative example is only that: the temperature of the muffle furnace was set to 600 °C, and high-temperature calcination was carried out for 4 h.

[0198] Comparative Example 13

[0199] Compared with Example 11, the difference in this comparative example is only that: the temperature of the muffle furnace was set to 800 °C, and high-temperature calcination was carried out for 4 h.

[0200] Performance detection of silica prepared in Examples 11-13 and Comparative Examples 11-13

[0201] The fluorine compatibility of the silica in Examples 11-13 of the present invention is all above 90%, the specific surface area < 2.79 m 2 / g, which can meet the requirements for non-nano materials in relevant foreign regulations. At the same time, the pore volume is 0.0006 - 0.02 cm 3 / g, and it has excellent fragrance permeability. Moreover, the dispersibility and cleaning performance are excellent.

[0202] However, the specific surface area of Comparative Examples 11-13 > 2.79 m 2 / g, which cannot meet the requirements for non-nano materials; the pore volume is significantly higher than that of each example; the fluorine compatibility is also significantly lower than that of each example.

[0203] Table 2 Performance test results of silica in Examples 11-13 and Comparative Examples 11-13

[0204]

[0205] Example 14 Preparation of silica with low specific surface area and low pore volume by two-step reaction

[0206] 1) Charge 6 m of 10% sodium sulfate solution by mass percentage concentration and 0.6 m of 1.5 mol / L sodium silicate solution into the reaction kettle and heat up to 90-95 °C; 3 and 0.6 m of 1.5 mol / L sodium silicate solution 3 , and heat up to 90-95 °C;

[0207] 2) Stir at a speed of 400 revolutions per minute, add 1.5 mol / L sulfuric acid solution into the reaction kettle at a flow rate of 5 m 3 / h, and adjust the pH during the process to 7.0-7.5;

[0208] 3) Slowly add the above-mentioned sodium silicate solution and sulfuric acid solution simultaneously (add acid and alkali dropwise at the same time), the adding speed of the sodium silicate solution is 5 m 3 / h; and keep the pH of the solution at 7.0-7.5 by adjusting the flow rate of the sulfuric acid solution;

[0209] Under the condition that the pH of the process is slightly neutral, the mobility of the grown silica particles is poor, which can reduce the collision between particles. The acid-base neutralization rate in the reaction system is relatively high, and the crystal grains grow rapidly. Since the end of the sol bond has high activity and low aggregation density, the active groups are easy to approach each other, thus promoting the growth of the bond and forming a linear chain structure, which is beneficial to the formation of dense particles and reduces the specific surface area of the particles;

[0210] 4) When the sodium silicate solution is added to 30 m 3 (at this time, the reaction time is about 21600 s), stop adding the sodium silicate solution; continue to add the sulfuric acid solution until the pH of the solution reaches 4.5, and then stop adding the sulfuric acid solution;

[0211] 5) Continue to stir and age at a constant temperature for 30 min to obtain a silica slurry;

[0212] 6) The silica slurry is filtered through a diaphragm to recover the sodium sulfate solution; then it is washed, spray-dried, and crushed by a jet mill to obtain silica with low specific surface area and low pore volume.

[0213] Example 15 Preparation of silica with low specific surface area and low pore volume by two-step reaction

[0214] Compared with Example 14, the difference in this example is only that the reaction speed is adjusted to 600 revolutions per minute.

[0215] Comparative Example 14

[0216] Compared with Example 14, the difference in this comparative example is only that the process pH is adjusted to 6.0 - 6.5.

[0217] Comparative Example 15

[0218] Compared with Example 14, the difference in this comparative example is only that: in step 3), the flow rate of the sodium silicate solution is 40 m 3 / h.

[0219] Performance detection of the silica prepared in Examples 14 - 15 and Comparative Examples 14 - 15

[0220] The fluorine compatibility of the silica in Examples 14 - 15 is above 90%, the specific surface area < 2.79 m 2 / g, which can meet the requirements for non - nano materials in relevant foreign regulations. At the same time, the pore volume is 0.0008 - 0.0009 cm 3 / g, and it has excellent fragrance permeability. Moreover, the dispersibility and cleaning performance are excellent.

[0221] However, the specific surface area of the silica in Comparative Examples 14 - 15 > 2.79 m 2 / g, which cannot meet the requirements for non - nano materials; the pore volume is significantly higher than that of each example; the fluorine compatibility is also lower than that of each example.

[0222] Table 3 Performance detection results of the silica in Examples 14 - 15 and Comparative Examples 14 - 15

[0223]

[0224] Example 16 Preparation of silica with low specific surface area and low pore volume by two - step post - treatment

[0225] The precipitated silica prepared in Comparative Example 15 was subjected to high - temperature calcination treatment: prepare the sample, set the temperature of the muffle furnace to 800 °C, and calcine at high temperature for 3 h. After high - temperature calcination, the internal pores of the silica collapsed, the pore volume decreased, and the specific surface area decreased accordingly.

[0226] Example 17 Preparation of silica with low specific surface area and low pore volume by two - step post - treatment

[0227] The precipitated silica prepared in Comparative Example 15 was subjected to high - temperature calcination treatment: prepare the sample, set the temperature of the muffle furnace to 800 °C, and calcine at high temperature for 2 h. After high - temperature calcination, the internal pores of the silica collapsed, the pore volume decreased, and the specific surface area decreased accordingly.

[0228] Comparative Example 16 Preparation of silica with low specific surface area and low pore volume by two - step post - treatment

[0229] The precipitated silica obtained in Comparative Example 15 was subjected to high-temperature calcination treatment: Samples were prepared, and the temperature of the muffle furnace was set at 500 °C, and high-temperature calcination was carried out for 3 h.

[0230] Comparative Example 17 Preparation of silica with low specific surface area and low pore volume by two-step post-treatment

[0231] The precipitated silica obtained in Comparative Example 15 was subjected to high-temperature calcination treatment: Samples were prepared, and the temperature of the muffle furnace was set at 500 °C, and high-temperature calcination was carried out for 5 h.

[0232] The fluorine compatibility of the silica in Examples 16-17 was above 90%, and the specific surface area was <2.79 m 2 / g, which could meet the requirements for non-nano materials in relevant foreign regulations. At the same time, the pore volume was 0.0005 - 0.0006 cm 3 / g, with excellent fragrance permeability, and excellent dispersibility and cleaning performance.

[0233] However, the specific surface area of the silica in Comparative Examples 16-17 was >2.79 m 2 / g, which could not meet the requirements for non-nano materials; the pore volume was significantly higher than that of each example; and the fluorine compatibility was also lower than that of each example.

[0234] Table 4 Performance test results of silica in Examples 16-17 and Comparative Examples 16-17

[0235]

[0236]

[0237] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A low specific surface area and low pore volume abrasive silica for toothpaste, characterized in that: That: (1) Specific surface area: 0.01-2.79m 2 / g, (2) Pore volume: 0.00004-0.3cm 3 / g; (3) Pore diameter: 5-26 nm; (4) D50 median particle size: 1-25 μm.

2. The low specific surface area and low pore volume abrasive silica for toothpaste according to claim 1, characterized in that: That: (1) Specific surface area: 0.01-2.79m 2 / g, (2) Pore volume: 0.00004-0.1cm 3 / g; (3) Pore diameter: 15-26 nm; (4) D50 median particle size: 1-20 μm.

3. The low specific surface area and low pore volume abrasive silica for toothpaste according to claim 2, characterized in that: That: (1) Specific surface area: 0.1-2.5m 2 / g, (2) Pore volume: 0.00004-0.02cm 3 / g; (3) Pore diameter: 15-26 nm; (4) D50 median particle size: 1-16 μm.

4. The low specific surface area and low pore volume abrasive silica for toothpaste according to any one of claims 1 to 3, characterized in that: That: (5) Fluorine compatibility: 75%-99%, (6) Copper sheet wear value: 6-25 mg per 10,000 revolutions, (7) RDA value: 180-360; (8) PCR value: 80-160; (9) Apparent density: 0.02-1.5 g / ml; (10) Oil absorption value: 10-125g / 100g.

5. The low specific surface area and low pore volume abrasive silica for toothpaste according to claim 4, characterized in that: That: (5) Fluorine compatibility: 80%-99%, (6) Copper sheet wear value: 10-20 mg per 10,000 revolutions, (7) RDA value: 180-260; (8) PCR value: 100-160; (9) Apparent density: 0.3-1.5 g / ml; (10) Oil absorption value: 10-60g / 100g.

6. The low specific surface area and low pore volume abrasive silica for toothpaste according to claim 5, characterized in that: That: (5) Fluorine compatibility: 90%-99%, (6) Copper sheet wear value: 10-20 mg per 10,000 revolutions, (7) RDA value: 200-250; (8) PCR value: 100-160; (9) Apparent density: 0.5-1.0 g / ml; (10) Oil absorption value: 10-60g / 100g.

7. Use of the low specific surface area and low pore volume toothpaste-use abrasive silica as claimed in any one of claims 1 to 6 in the preparation of oral abrasives, cleaning aids or toothpaste.

8. An oral composition, characterized in that A toothpaste-use abrasive silica having low specific surface area and low pore volume according to any one of claims 1 to 6, and an orally acceptable carrier.

9. The oral composition according to claim 8, characterized in that The content of silicon dioxide is 0.5-90.0% by mass, and preferably, the content of silicon dioxide is 1.0-80.0% by mass.

10. The oral composition according to claim 8 or 9, characterized in that The silica is present as the only abrasive in the oral composition.

11. The oral composition according to claim 8 or 9, characterized in that: The silica is present as an abrasive and / or cleaning aid.

12. The oral composition according to any one of claims 8 to 11, characterized in that: The composition is a toothpaste.

13. The method for preparing the low specific surface area and low pore volume abrasive silica for toothpaste according to any one of claims 1 to 6, characterized in that: The steps include: 1) adding sodium sulfate solution into a reaction vessel; 2) Add sodium silicate solution and stir evenly until the pH of the solution is 7-14; 3) heating the solution to a temperature of 60-97°C; Maintain the reaction temperature, stir at a speed of 200-600 rpm, and slowly add sodium silicate solution and sulfuric acid solution at a flow rate of 5-30m / min. 3 / h, and the pH is maintained in the range of 7-10 by adjusting the flow rate of sulfuric acid solution; 4) When the volume ratio of the sodium silicate solution added to the sodium silicate solution and the sodium sulfate solution in step 1) is (1.5-2):1, stop adding the sodium silicate solution; continue to add the sulfuric acid solution until the pH of the solution reaches 4-7, then stop adding the sulfuric acid solution; 5) Continue stirring and heat-insulating for 10-60 minutes to obtain a silicon dioxide slurry; 6) The silicon dioxide slurry is filtered, washed, dried and crushed to obtain a finished product; Wherein, the mass percentage concentration of the sodium sulfate solution is 6-20%; The concentration of the sodium silicate solution is 1-2.5 mol / L; The concentration of the sulfuric acid solution is 1-2 mol / L.

14. The method for preparing the low specific surface area and low pore volume abrasive silica for toothpaste according to any one of claims 1 to 6, characterized in that: The steps include: 1) Add sodium sulfate solution and sodium silicate solution into a reaction vessel and heat it to 90-95°C; 2) adding sulfuric acid solution to the reaction vessel while stirring at a speed of 200-600 rpm and adjusting the pH to 7.0-7.5; 3) Slowly add the above sodium silicate solution and sulfuric acid solution at the same time, the sodium silicate solution addition speed is 5-20m 3 / h; and the pH of the solution is maintained at 7.0-7.5 by adjusting the flow rate of the sulfuric acid solution; 4) When the volume ratio of the sodium silicate solution added to the sodium silicate solution and the sodium sulfate solution in step 1) is (3-8):1, stop adding the sodium silicate solution; continue to add the sulfuric acid solution until the pH of the solution is 4-7, then stop adding the sulfuric acid solution; 5) Continue stirring and keep warm for 30 minutes to obtain a silicon dioxide slurry; 6) The silica slurry is filtered, washed, dried and crushed to obtain low specific surface area and low pore volume silica; Wherein, the mass percentage concentration of the sodium sulfate solution is 6-20%; The concentration of the sodium silicate solution is 1-2.5 mol / L; The concentration of the sulfuric acid solution is 1-2 mol / L.

15. The friction-type silica prepared by the method according to claim 14, wherein the specific surface area is 0.01-2.79 m 2 / g, pore volume is 0.0006-0.3cm 3 / g.

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