A method for producing high specific surface area and high dispersion white carbon black

Abstract

The application relates to the technical field of white carbon black, and discloses a production method of high-specific-surface-area and high-dispersion white carbon black, which comprises the following steps: S1, adding acid liquid to a 30%-40% mass sodium silicate solution to adjust the pH to 6-7 for first reaction, aging, and obtaining a mixture A; S2, adding a 20%-30% mass sodium silicate solution to the mixture A, then adding acid liquid to adjust the pH to 7.5-8.5 for second reaction, and obtaining a mixture B; and S3, adding the remaining mass sodium silicate solution to the mixture B, then adding acid liquid to adjust the pH to 3.5-4.5 for third reaction, and post-treatment, and obtaining white carbon black. Through the technical scheme, the problem of low specific surface area of the white carbon black in the related art is solved.

Description

Technical Field

[0001] This invention relates to the field of silica technology, specifically to a method for producing high specific surface area and highly dispersed silica. Background Technology

[0002] Silica, as an important inorganic chemical product, has excellent properties such as high temperature resistance and electrical insulation. It is widely used in the light industry and chemical industry, especially as a reinforcing filler in the rubber industry.

[0003] Silica production methods include gas-phase and precipitation methods. The gas-phase method is relatively complex, with drawbacks such as high cost and demanding equipment requirements, resulting in a relatively high price for the produced silica and limiting its widespread application. In contrast, the precipitation method offers advantages such as low cost and simple operation, making it popular across various industries. However, improper setting of reaction conditions and other parameters during the precipitation reaction can hinder the increase of the silica's specific surface area, often making it difficult to achieve a specific surface area of ​​over 200 m² / g, thus limiting further applications of silica.

[0004] Therefore, there is a need for a method to produce silica with a high specific surface area. Summary of the Invention

[0005] This invention proposes a method for producing high specific surface area and highly dispersed silica, which solves the problem of low specific surface area of ​​silica in related technologies.

[0006] The technical solution of the present invention is as follows: This invention proposes a method for producing high specific surface area and highly dispersed silica, comprising the following steps: S1. Add acid to a 30%~40% sodium silicate solution to adjust the pH to 6~7 for the first reaction, then age to obtain mixture A; S2. After adding 20% ​​to 30% by mass of sodium silicate solution to the mixture A, acid solution is added to adjust the pH to 7.5 to 8.5 for a second reaction to obtain mixture B; S3. After adding the remaining mass of sodium silicate solution to the mixture B, add acid to adjust the pH to 3.5~4.5 for a third reaction, followed by post-treatment to obtain silica.

[0007] As a further technical solution, the temperature of the first reaction is 70~90℃, for example, it can be 70℃, 74℃, 76℃, 78℃, 80℃, 86℃, 90℃, etc., preferably 70℃, 80℃, 90℃, and more preferably 80℃.

[0008] As a further technical solution, the time for the first reaction is 10-15 minutes, for example, 10 minutes, 11 minutes, 13 minutes, 14 minutes, 15 minutes, etc., preferably 10 minutes, 12 minutes, 15 minutes, and more preferably 12 minutes.

[0009] As a further technical solution, the stirring speed of the first reaction is 120~170 rpm, for example, it can be 120 rpm, 135 rpm, 145 rpm, 150 rpm, 170 rpm, etc., preferably 120 rpm, 150 rpm, 170 rpm, more preferably 150 rpm.

[0010] As a further technical solution, the aging time is 15-25 minutes.

[0011] As a further technical solution, the temperature of the second reaction is 70~95℃, for example, it can be 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, etc., preferably 70℃, 75℃, 80℃, 95℃.

[0012] As a further technical solution, the time for the second reaction is 10-15 minutes, for example, 10 minutes, 12 minutes, 14 minutes, 15 minutes, etc., preferably 10 minutes, 14 minutes, 15 minutes.

[0013] As a further technical solution, the stirring speed of the second reaction is 120~170 rpm, for example, it can be 120 rpm, 125 rpm, 130 rpm, 140 rpm, 150 rpm, 170 rpm, etc.

[0014] As a further technical solution, the temperature of the third reaction is 80~95℃, for example, it can be 80℃, 82℃, 85℃, 90℃, 92℃, 95℃, etc., preferably 80℃, 90℃, 95℃, more preferably 90℃.

[0015] As a further technical solution, the time for the third reaction is 20 to 40 minutes, for example, it can be 20 minutes, 24 minutes, 30 minutes, 34 minutes, 40 minutes, etc., preferably 20 minutes, 30 minutes, or 40 minutes, and more preferably 30 minutes.

[0016] As a further technical solution, the stirring speed of the third reaction is 120~170 rpm, for example, it can be 120 rpm, 130 rpm, 135 rpm, 140 rpm, 145 rpm, 155 rpm, 165 rpm, 170 rpm, etc.

[0017] As a further technical solution, the temperature of the first reaction is higher than the temperature of the second reaction.

[0018] In this invention, during the preparation of silica, the temperature of the first reaction is adjusted to be higher than that of the second reaction, based on the first reaction temperature being 70~90℃ and the second reaction temperature being 70~95℃. This allows the molecules to move smoothly during the reaction, which is beneficial for forming smaller primary particles and increasing the specific surface area of ​​the final silica.

[0019] As a further technical solution, the stirring speed of the second reaction is less than the stirring speed of the third reaction.

[0020] In this invention, during the preparation of silica, the stirring speed of the second reaction is lower than that of the third reaction, so that the sodium silicate solution and sulfuric acid solution are fully mixed and reacted, promoting the uniform formation of precipitate and obtaining silica particles with uniform distribution and high specific surface area. This avoids the problem of uneven mixing of raw materials and insufficient reaction caused by excessively slow stirring speed, which leads to a decrease in the specific surface area of ​​silica.

[0021] As a further technical solution, the stirring speed of the second reaction is 130~140 rpm, and the stirring speed of the third reaction is 145~155 rpm.

[0022] In this invention, during the preparation of silica, especially when the stirring speed for the second reaction is 130-140 rpm and the stirring speed for the third reaction is 145-155 rpm, the specific surface area of ​​the silica obtained can reach 270 m². 2 / g or more.

[0023] The structure and properties of silica vary depending on the reaction temperature and stirring speed during its preparation. Therefore, by controlling the stirring speed and reaction temperature within the range specified in this invention, on the one hand, the reactants can be fully contacted, improving the uniformity of the reaction, reducing side reactions, and preventing the agglomeration of particles. On the other hand, this facilitates the preparation of silica with a high specific surface area, thereby affecting its adsorption and dispersion properties, broadening the application range of silica in rubber and other fields, and ensuring that silica performs optimally during application.

[0024] As a further technical solution, the post-processing includes filtration, washing, and drying in sequence.

[0025] In the preparation of silica, post-treatment can separate the silica produced by the reaction from the reaction mixture and remove a large number of soluble impurities and solvents, thereby improving the purity and stability of silica and facilitating its subsequent processing and application in various fields.

[0026] As a further technical solution, in steps S1, S2 and S3, the acid solution independently includes a sulfuric acid solution.

[0027] As a further technical solution, in steps S1, S2 and S3, the mass fraction of the sodium silicate solution is independently 10%~15%; The mass fraction of each acid solution is independently 20% to 25%.

[0028] As a further technical solution, dinonylphenol is added during the third reaction.

[0029] As a further technical solution, the mass of the dinonylphenol is 5% to 8% of the mass of the sodium silicate solution in steps S1 to S3.

[0030] Because of its high specific surface area, silica easily adsorbs moisture, resulting in an abundance of surface hydroxyl groups. This leads to silica agglomeration, affecting its further application. Existing technologies often use organosiloxanes (such as hexamethyldisiloxane) or long-chain alkanol activators (such as dodecyl alcohol) to treat silica to improve its dispersibility. However, the improvement in dispersibility is limited, and silica still suffers from large particle size due to easy agglomeration. Therefore, in this invention, dinonylphenol is used to treat silica during production. Compared with existing technologies, the particle size D50 of silica treated with dinonylphenol can be reduced to below 2μm, greatly improving the agglomeration problem. Furthermore, the silica produced by this invention has excellent dispersibility and a high specific surface area.

[0031] The working principle and beneficial effects of this invention are as follows: In this invention, the production method of high specific surface area and high dispersion silica involves first reacting 30% to 40% by mass of sodium silicate solution with acid, then adding 20% ​​to 30% by mass of sodium silicate solution for a second reaction, and finally adding the remaining sodium silicate solution for a third reaction. The silica produced by this three-step reaction has a higher specific surface area. Attached Figure Description

[0032] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0033] Figure 1 This is a particle size distribution diagram of the silica prepared in Example 10 of the present invention.

[0034] Figure 2 This is a particle size distribution diagram of the silica prepared in Example 11 of the present invention. Detailed Implementation

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] Example 1 A method for producing high specific surface area and highly dispersed silica includes the following steps: S1. Add sulfuric acid solution to a 30% sodium silicate solution to adjust the pH to 6. Mix the solution at 70°C and 120 rpm for 15 min, then age for 25 min to obtain mixture A. S2. After adding 30% sodium silicate solution to mixture A, add sulfuric acid solution to adjust the pH to 7.5. Mix at 75℃ and 120 rpm for 15 min to obtain mixture B. S3. After adding the remaining sodium silicate solution to mixture B, add sulfuric acid solution to adjust the pH to 3.5. Mix at 80℃ and 120 rpm for 40 min, filter, rinse the filter cake with distilled water until the pH reaches 6.5, and dry the filter cake in an oven at 110℃ for 20 h to obtain silica. The mass fraction of sodium silicate solution is 20%, and the mass fraction of sulfuric acid solution is 12%.

[0037] Example 2 A method for producing high specific surface area and highly dispersed silica includes the following steps: S1. Add sulfuric acid solution to a 40% sodium silicate solution to adjust the pH to 7. Mix at 90℃ and 170 rpm for 10 min, then age for 15 min to obtain mixture A. S2. After adding 20% ​​sodium silicate solution to mixture A, add sulfuric acid solution to adjust the pH to 8.5. Mix at 95℃ and 170 rpm for 10 min to obtain mixture B. S3. After adding the remaining sodium silicate solution to mixture B, add sulfuric acid solution to adjust the pH to 4.5. Mix at 95℃ and 170 rpm for 20 min, filter, rinse the filter cake with distilled water until the pH reaches 7, and dry the filter cake in an oven at 110℃ for 20 h to obtain silica. The mass fraction of sodium silicate solution is 25%, and the mass fraction of sulfuric acid solution is 15%.

[0038] Example 3 A method for producing high specific surface area and highly dispersed silica includes the following steps: S1. Add sulfuric acid solution to a 35% sodium silicate solution to adjust the pH to 6.5. Mix at 80℃ and 150 rpm for 12 min, then age for 20 min to obtain mixture A. S2. After adding 25% sodium silicate solution to mixture A, sulfuric acid solution is added to adjust the pH to 8. The mixture is then mixed at 80℃ and 125 rpm for 14 min to obtain mixture B. S3. After adding the remaining mass of sodium silicate solution to mixture B, add sulfuric acid solution to adjust the pH to 4. Mix at 90℃ and 125 rpm for 30 min, filter, rinse the filter cake with distilled water until the pH reaches 7, and dry the filter cake in an oven at 110℃ for 20 h to obtain silica. The mass fraction of sodium silicate solution is 22% and the mass fraction of sulfuric acid solution is 14 wt%.

[0039] Example 4 The only difference between this embodiment and Embodiment 3 is that the temperature in step S1 is 70°C.

[0040] Example 5 The only difference between this embodiment and Embodiment 3 is that the temperature in step S2 is 70°C.

[0041] Example 6 The only difference between this embodiment and embodiment 5 is that the stirring speed in step S3 is 165 rpm.

[0042] Example 7 The only difference between this embodiment and embodiment 5 is that the stirring speed in step S3 is 145 rpm.

[0043] Example 8 The only difference between this embodiment and embodiment 5 is that the stirring speed in step S3 is 155 rpm.

[0044] Example 9 The only difference between this embodiment and embodiment 8 is that the stirring speed in step S2 is 150 rpm.

[0045] Example 10 The only difference between this embodiment and embodiment 8 is that the stirring speed in step S2 is 130 rpm.

[0046] Example 11 The only difference between this embodiment and embodiment 8 is that the stirring speed in step S2 is 140 rpm.

[0047] Example 12 A method for producing high specific surface area and highly dispersed silica includes the following steps: S1. Add sulfuric acid solution to a 35% sodium silicate solution to adjust the pH to 6.5. Mix at 80℃ and 150 rpm for 12 min, then age for 20 min to obtain mixture A. S2. After adding 25% sodium silicate solution to mixture A, sulfuric acid solution is added to adjust the pH to 8. The mixture is then mixed at 70°C and 140 rpm for 14 min to obtain mixture B. S3. Add the remaining sodium silicate solution and dinonylphenol to mixture B, then add sulfuric acid solution to adjust the pH to 4. Mix at 90℃ and 155 rpm for 30 min, filter, rinse the filter cake with distilled water until the pH reaches 7, and dry the filter cake in an oven at 110℃ for 20 h to obtain silica. The mass fraction of sodium silicate solution is 22%, the mass fraction of sulfuric acid solution is 14 wt%, the mass of dinonylphenol is 5% of the total mass of sodium silicate solution in steps S1 to S3, and the dinonylphenol is 2,3-dinonylphenol.

[0048] Example 13 The only difference between this embodiment and Embodiment 12 is that the mass of dinonylphenol is 8% of the total mass of sodium silicate solution in steps S1 to S3.

[0049] Example 14 The only difference between this embodiment and Embodiment 12 is that dinonylphenol is replaced with hexamethyldisiloxane.

[0050] Example 15 The only difference between this embodiment and Embodiment 12 is that nonylphenol is replaced with 1-dodecanool.

[0051] Example 16 A method for producing high specific surface area and highly dispersed silica includes the following steps: S1. Add sulfuric acid solution to a 40% sodium silicate solution to adjust the pH to 6. Mix at 70°C and 120 rpm for 15 min, then age for 25 min to obtain mixture A. S2. After adding 20% ​​sodium silicate solution to mixture A, add sulfuric acid solution to adjust the pH to 7.5. Mix at 75℃ and 120 rpm for 15 min to obtain mixture B. S3. After adding the remaining sodium silicate solution to mixture B, add sulfuric acid solution to adjust the pH to 3.5. Mix at 80℃ and 120 rpm for 40 min, filter, rinse the filter cake with distilled water until the pH reaches 6.5, and dry the filter cake in an oven at 110℃ for 20 h to obtain silica. The mass fraction of sodium silicate solution is 20%, and the mass fraction of sulfuric acid solution is 12%.

[0052] Comparative Example 1 A method for producing high specific surface area and highly dispersed silica includes the following steps: S1. Add sulfuric acid solution to a 35% sodium silicate solution to adjust the pH to 6.5. Mix at 80℃ and 150 rpm for 12 min, then age for 20 min to obtain mixture A. S2. After adding the remaining mass of sodium silicate solution to mixture A, sulfuric acid solution is added to adjust the pH to 4. The mixture is stirred at 125 rpm at 90°C for 30 min, filtered, and the filter cake is washed with distilled water until the pH reaches 7. The filter cake is then placed in an oven at 110°C and dried for 20 h to obtain silica. The mass fraction of sodium silicate solution is 22%, and the mass fraction of sulfuric acid solution is 14 wt%.

[0053] Comparative Example 2 A method for producing high specific surface area and highly dispersed silica includes the following steps: S1. Add sulfuric acid solution to a 20% sodium silicate solution to adjust the pH to 6. Mix at 70°C and 120 rpm for 15 min, then age for 25 min to obtain mixture A. S2. After adding 40% sodium silicate solution to mixture A, add sulfuric acid solution to adjust the pH to 7.5. Mix at 75℃ and 120 rpm for 15 min to obtain mixture B. S3. After adding the remaining sodium silicate solution to mixture B, add sulfuric acid solution to adjust the pH to 3.5. Mix at 80℃ and 120 rpm for 40 min, filter, rinse the filter cake with distilled water until the pH reaches 6.5, and dry the filter cake in an oven at 110℃ for 20 h to obtain silica. The mass fraction of sodium silicate solution is 20%, and the mass fraction of sulfuric acid solution is 12%.

[0054] Comparative Example 3 A method for producing high specific surface area and highly dispersed silica includes the following steps: S1. Add sulfuric acid solution to a 50% sodium silicate solution to adjust the pH to 6. Mix at 70°C and 120 rpm for 15 min, then age for 25 min to obtain mixture A. S2. After adding 10% sodium silicate solution to mixture A, add sulfuric acid solution to adjust the pH to 7.5. Mix at 75℃ and 120 rpm for 15 min to obtain mixture B. S3. After adding the remaining sodium silicate solution to mixture B, add sulfuric acid solution to adjust the pH to 3.5. Mix at 80℃ and 120 rpm for 40 min, filter, rinse the filter cake with distilled water until the pH reaches 6.5, and dry the filter cake in an oven at 110℃ for 20 h to obtain silica. The mass fraction of sodium silicate solution is 20%, and the mass fraction of sulfuric acid solution is 12%.

[0055] Experimental Example 1 The CTAB specific surface area of ​​the silica prepared in Examples 1-11, Example 16 and Comparative Examples 1-3 was tested according to the standard GB / T 23656-2016 "Determination of Specific Surface Area of ​​Precipitated Hydrated Silica in Rubber Compounds - CTAB Method". The results are shown in Table 1 below.

[0056] Table 1 Specific surface area test results

[0057] Compared with Comparative Examples 1-3, the silica prepared in Examples 1-11 and Example 16 has a higher specific surface area, indicating that the method of preparing silica in three steps of the present invention and the control of the amount of sodium silicate solution added in each step can improve the specific surface area of ​​silica. Furthermore, by adjusting the reaction conditions such as reaction temperature and stirring speed during the production process, the specific surface area of ​​silica is further improved.

[0058] Experimental Example 2 The dispersibility of the silica prepared in Examples 10-15 was tested: silica was mixed with water for 5 minutes to obtain a mixture. The average particle size of the silica particles in the aqueous phase was measured using a wet laser particle size analyzer (HELOS-SUCELL). The average particle size was the particle size of the cumulative distribution of 50%, denoted as D50. The smaller the particle size D50, the better the dispersibility of the silica. The test results are shown in Table 2 below.

[0059] Table 2 Dispersion Test Results

[0060] The particle size distribution diagram of the silica prepared in Example 10 is shown below. Figure 1As shown, the particle size distribution diagram of the silica prepared in Example 11 is as follows. Figure 2 As shown.

[0061] Compared with Examples 10-11 and Examples 14-15, the silica prepared in Examples 12-13 has a smaller particle size D50, indicating that the treatment of silica with dinonylphenol improves the dispersibility of silica and reduces the agglomeration of silica particles.

[0062] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for producing high specific surface area and highly dispersed silica, characterized in that, Includes the following steps: S1. Add acid to a 30%~40% sodium silicate solution to adjust the pH to 6~7 for the first reaction, then age to obtain mixture A; S2. After adding 20% ​​to 30% by mass of sodium silicate solution to the mixture A, acid solution is added to adjust the pH to 7.5 to 8.5 for a second reaction to obtain mixture B; S3. After adding the remaining mass of sodium silicate solution to the mixture B, add acid to adjust the pH to 3.5~4.5 for a third reaction, followed by post-treatment to obtain silica. The temperature of the first reaction is 80~90℃, the time is 10~15min, and the stirring speed is 120~170rpm; The second reaction was carried out at a temperature of 70-80℃ for 10-15 minutes and a stirring speed of 130-140 rpm. The temperature of the third reaction is 80~95℃, the time is 20~40min, and the stirring speed is 145~155rpm; The temperature of the first reaction is greater than the temperature of the second reaction; Dinonylphenol is added during the third reaction; the mass of the dinonylphenol is 5% to 8% of the total mass of the sodium silicate solution in steps S1 to S3.

2. The method for producing high specific surface area highly dispersed silica according to claim 1, characterized in that, The aging time is 15-25 minutes.

3. The method for producing high specific surface area highly dispersed silica according to claim 1, characterized in that, The post-processing includes filtration, washing, and drying in sequence.

4. The method for producing high specific surface area highly dispersed silica according to claim 1, characterized in that, In steps S1, S2 and S3, the acid solution each independently includes a sulfuric acid solution.

5. The method for producing high specific surface area highly dispersed silica according to claim 1, characterized in that, In steps S1, S2, and S3, the mass fraction of the sodium silicate solution is independently 10% to 15%. The mass fraction of each acid solution is independently 20% to 25%.

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