Highly reinforcing and highly dispersible silica, process for its preparation and use

Abstract

The application provides high-reinforcing and high-dispersing silicon dioxide as well as a preparation method and application thereof. The preparation method comprises the following steps: mixing a water glass solution and sulfuric acid to obtain a first reaction solution; adding sulfuric acid to the first reaction solution at a first dropping speed, and adding the water glass solution at the same time to obtain a second reaction solution; adding sulfuric acid to the second reaction solution at a second dropping speed, and adding the water glass solution at the same time to obtain a third reaction solution; adding sulfuric acid to the third reaction solution at a third dropping speed, and adding the water glass solution at the same time to obtain a fourth reaction solution; and adjusting the pH of the fourth reaction solution to obtain a precipitated silicon dioxide suspension. The application realizes high-reinforcing performance of the precipitated silicon dioxide, and also has excellent dispersing performance by optimizing the preparation process and regulating the material structure, so as to meet the demand of the market for high-performance materials.

Description

Technical Field

[0001] This invention belongs to the field of silica preparation technology, and relates to a method for preparing precipitated silica in a segmented manner, particularly to a highly reinforced and highly dispersed silica, its preparation method and application. Background Technology

[0002] Precipitated silica is an important material with wide applications in many fields. As an important reinforcing material for tire rubber, it can reduce tire rolling resistance, improve tire anti-skid ability, and also help reinforce tire rubber to give it better mechanical properties.

[0003] CN104291342A discloses a method for preparing precipitated silica and its uses. The method involves reacting water glass with concentrated sulfuric acid to obtain a suspension of precipitated silica. This suspension is then subjected to pressure filtration, washing, slurrying, and drying. The resulting precipitated silica is in the form of spherical microbeads and granular silica. The BET specific surface area of ​​the silica is 185-235 m² / g. 2 / g, CTAB is 165-205m 2 / g, pH value 5.5-7.5, pore volume 1.65-2.25cm³ 3 / g, with an ultrasonic particle size D50 of 6-10μm. The precipitated silica can be used in tire rubber, but its specific surface area is relatively small.

[0004] CN102414127A discloses a microporous precipitated silica, wherein the CTAB surface area of ​​the obtained microporous precipitated silica is 50-300 m². 3 / g, BET / CTAB ratio ≥1.3, and relative width γ of pore size distribution ≤3.5. The preparation method of the precipitated silica includes: establishing an alkali metal silicate with an AZ alkalinity of 5-40 and a temperature of 20-100℃ in a reaction vessel; mixing the alkali metal silicate and an acidifying agent until the pH value is 9-9.7; further adjusting the pH value to 2.5-5; and after solid-liquid separation and drying, microporous precipitated silica is obtained. However, the resulting microporous silica has poor dispersion properties and cannot improve the reinforcing properties of tire rubber.

[0005] The reinforcing properties of precipitated silica are significantly affected by its particle size. Generally, smaller particle sizes result in better reinforcing properties, but smaller particle sizes also lead to difficulties in dispersing silica in rubber matrices. Therefore, how to prepare silica products with excellent reinforcing properties and good dispersibility is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a highly reinforcing and highly dispersed silica, its preparation method and application. By optimizing the preparation process and controlling the material structure, the invention achieves both high reinforcing performance and excellent dispersion performance of precipitated silica, thus meeting the market demand for high-performance materials.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing highly reinforced and highly dispersed silica, the method comprising the following steps:

[0009] (1) Mix water glass solution with sulfuric acid to obtain the first reaction solution;

[0010] (2) Add sulfuric acid to the first reaction solution in step (1) at a first drop rate, and simultaneously add water glass solution to obtain a second reaction solution;

[0011] (3) Add sulfuric acid to the second reaction solution in step (2) at a second drop rate, while simultaneously adding water glass solution to obtain the third reaction solution;

[0012] (4) Add sulfuric acid to the third reaction solution described in step (3) at a third dropping rate, and simultaneously add water glass solution to obtain the fourth reaction solution;

[0013] (5) Adjust the pH of the fourth reaction solution in step (4) to obtain a precipitated silica suspension.

[0014] The preparation method provided by this invention optimizes the preparation process and coordinates the parameters in the subsequent stages of the system, including temperature, pH, water glass concentration, dropping rate, and dropping time, to achieve the goal of reducing product particle size and improving its reinforcing properties while ensuring good dispersibility.

[0015] The principle of the silica preparation process of this invention is as follows: During the preparation of the first reaction solution (base solution), an acid-base precipitation reaction generates a small amount of initial silica precipitates. In the secondary precipitation, as water glass solution (sodium silicate) and sulfuric acid are added dropwise simultaneously, the reaction pH remains unchanged, i.e., H... +With a constant concentration, the increased volume of the reaction solution and the gradually decreasing dropping rate, combined with the gradually decreasing dropping rate in subsequent precipitation, result in a slow initial particle formation rate and low concentration of silica. This significantly reduces the probability of collisions between particles, making collisions less likely. Furthermore, the slower silica particle formation rate, lower than the silica condensation rate, leads to smaller initial particle sizes. This results in a larger specific surface area for the silica prepared after multiple precipitation processes. The reduced collisions also decrease hydrogen bonding between silica particles, with most particles bound by van der Waals forces, allowing for easier dispersion of silica particles within the rubber matrix.

[0016] As a preferred technical solution of the present invention, the concentration of the water glass solution in steps (1), (2), (3) and (4) is 10 to 30 wt%, for example, it can be 12 wt%, 15 wt%, 17 wt%, 19 wt%, 20 wt%, 22 wt%, 25 wt%, 27 wt% or 29 wt%, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0017] Preferably, the concentration of sulfuric acid in steps (1), (2), (3) and (4) is 5 to 25 wt%, for example, it can be 7 wt%, 9 wt%, 10 wt%, 12 wt%, 15 wt%, 17 wt%, 19 wt%, 20 wt%, 22 wt% or 24 wt%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0018] As a preferred technical solution of the present invention, the mixing temperature in step (1) is 60 to 85°C, for example, it can be 62°C, 65°C, 67°C, 69°C, 70°C, 72°C, 75°C, 77°C, 79°C, 80°C, 82°C or 84°C, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] In this invention, during the mixing process described in step (1), the mixing temperature can be maintained by introducing water vapor at a certain temperature. The mixing process described in step (1) involves adding sulfuric acid to a water glass solution.

[0020] Preferably, the pH of the first reaction solution in step (1) is 9.0 to 10.5, for example, it can be 9.2, 9.4, 9.5, 9.7, 9.9, 10.0, 10.1, 10.3 or 10.4, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0021] As a preferred technical solution of the present invention, when adding dropwise in steps (2), (3) and (4), the temperature of the reaction system is controlled to be 60-85℃, for example, 62℃, 65℃, 67℃, 69℃, 70℃, 72℃, 75℃, 77℃, 79℃, 80℃, 82℃ or 84℃, etc., but not limited to the listed values, other unlisted values ​​within the range are also applicable.

[0022] Preferably, in step (2), the first dropping acceleration is 0.6-1 m / s. 3 / h, for example, could be 0.65m 3 / h, 0.7m 3 / h, 0.75m 3 / h, 0.8m 3 / h, 0.85m 3 / h, 0.9m 3 / h or 0.95m 3 / h, etc., but not limited to the listed values; other unlisted values ​​within the range also apply.

[0023] Preferably, the dropping rate of the water glass solution is controlled to maintain the pH of the reaction process in step (2) at 9.0 to 10.5, for example, it can be 9.2, 9.4, 9.5, 9.7, 9.9, 10.0, 10.1, 10.3 or 10.4, etc., but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] Preferably, the dripping time in step (2) is 20 to 50 minutes, for example, it can be 22 minutes, 25 minutes, 27 minutes, 30 minutes, 32 minutes, 35 minutes, 37 minutes, 40 minutes, 42 minutes, 45 minutes, 47 minutes or 49 minutes, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0025] Preferably, the pH of the second reaction solution in step (2) is 9.0 to 10.5, for example, it can be 9.2, 9.4, 9.5, 9.7, 9.9, 10.0, 10.1, 10.3 or 10.4, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] As a preferred technical solution of the present invention, the second dropping speed in step (3) is 0.6 to 0.8 times the first dropping speed in step (2), for example, it can be 0.62 times, 0.64 times, 0.65 times, 0.67 times, 0.69 times, 0.7 times, 0.72 times, 0.74 times, 0.75 times, 0.77 times or 0.79 times, etc., but is not limited to the listed values. Other unlisted values ​​within the value range are also applicable.

[0027] Preferably, the dropping rate of the water glass solution is controlled to maintain the pH of the reaction process in step (3) at 8.0 to 9.0, for example, it can be 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8 or 8.9, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] Preferably, the dripping time in step (3) is 20 to 50 minutes, for example, it can be 22 minutes, 25 minutes, 27 minutes, 30 minutes, 32 minutes, 35 minutes, 37 minutes, 40 minutes, 42 minutes, 45 minutes, 47 minutes or 49 minutes, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0029] Preferably, the pH of the third reaction solution in step (3) is 8.0 to 9.0, for example, it can be 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8 or 8.9, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0030] As a preferred technical solution of the present invention, the third dropping acceleration in step (4) is 0.4 to 0.6 times the second dropping acceleration in step (3), for example, it can be 0.42 times, 0.44 times, 0.45 times, 0.47 times, 0.49 times, 0.5 times, 0.52 times, 0.54 times, 0.55 times, 0.57 times or 0.59 times, etc., but is not limited to the listed values. Other unlisted values ​​within the value range are also applicable.

[0031] Preferably, the dropping rate of the water glass solution is controlled to maintain the pH of the reaction process in step (4) at 7.0 to 8.0, for example, it can be 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8 or 7.9, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0032] Preferably, the dripping time in step (4) is 20 to 50 minutes, for example, it can be 22 minutes, 25 minutes, 27 minutes, 30 minutes, 32 minutes, 35 minutes, 37 minutes, 40 minutes, 42 minutes, 45 minutes, 47 minutes or 49 minutes, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0033] Preferably, the pH of the fourth reaction solution in step (4) is 7.0 to 8.0, for example, it can be 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8 or 7.9, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0034] As a preferred technical solution of the present invention, the adjustment in step (5) is to adjust the pH to 4.0 to 6.0, for example, it can be 4.1, 4.3, 4.5, 4.7, 4.9, 5, 5.2, 5.4, 5.6, 5.8 or 5.9, etc., but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0035] Preferably, the adjustment in step (5) is made using sulfuric acid, and the dropping rate of the sulfuric acid is 0.45 to 0.55 times the first dropping rate in step (2), for example, it can be 0.46 times, 0.47 times, 0.48 times, 0.49 times, 0.5 times, 0.51 times, 0.52 times, 0.53 times or 0.54 times, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] Preferably, after obtaining the precipitated silica suspension in step (5), the process further includes: sequentially performing pressure filtration, washing, slurrying and drying on the precipitated silica suspension to obtain highly reinforced and highly dispersed silica.

[0037] In this invention, the pressure filtration, washing, slurrying and drying are conventional operations and are not specifically limited here.

[0038] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0039] (1) Mix water glass solution and sulfuric acid at a temperature of 60-85℃ to obtain a first reaction solution with a pH of 9.0-10.5;

[0040] (2) Add sulfuric acid to the first reaction solution in step (1) at a first drop rate, and add water glass solution at the same time to obtain a second reaction solution with a pH of 9.0 to 10.5;

[0041] The first drop acceleration is 0.6-1m. 3 / h; control the dropping rate of the water glass solution to maintain the pH of the reaction process in step (2) at 9.0 to 10.5; the dropping time is 20 to 50 min;

[0042] (3) Add sulfuric acid to the second reaction solution in step (2) at a second dropping rate, while adding water glass solution to obtain a third reaction solution with a pH of 8.0 to 9.0;

[0043] The second dropping rate is 0.6 to 0.8 times the first dropping rate in step (2); the dropping rate of the water glass solution is controlled to maintain the pH of the reaction process in step (3) at 8.0 to 9.0; the dropping time is 20 to 50 minutes.

[0044] (4) Add sulfuric acid to the third reaction solution described in step (3) at a third dropping rate, and add water glass solution at the same time to obtain a fourth reaction solution with a pH of 7.0 to 8.0;

[0045] The third dropping rate is 0.4 to 0.6 times the second dropping rate in step (3); the dropping rate of the water glass solution is controlled to maintain the pH of the reaction process in step (4) at 7.0 to 8.0; the dropping time is 20 to 50 minutes.

[0046] (5) Use sulfuric acid to adjust the pH of the fourth reaction solution in step (4) to 4.0-6.0 to obtain a precipitated silica suspension;

[0047] The dropping rate of the sulfuric acid is 0.45 to 0.55 times the first dropping rate in step (2);

[0048] (6) The precipitated silica suspension described in step (5) is subjected to pressure filtration, washing, slurrying and drying in sequence to obtain highly reinforced and highly dispersed silica;

[0049] In step (1), step (2), step (3) and step (4), the concentration of the water glass solution is 10 to 30 wt%.

[0050] The concentration of sulfuric acid in steps (1), (2), (3) and (4) is 5-25 wt%.

[0051] During the dropwise addition in steps (2), (3) and (4), the temperature of the reaction system is controlled to be 60–85°C.

[0052] In a second aspect, the present invention provides a highly reinforced and highly dispersed silica, wherein the highly reinforced and highly dispersed silica is prepared by the preparation method described in the first aspect.

[0053] Preferably, the BET specific surface area of ​​the highly reinforced and highly dispersed silica is ≥300 m². 2 / g, for example, could be 302m 2 / g、305m 2 / g、307m 2 / g、310m 2 / g、315m 2 / g、320m 2 / g、330m 2 / g or 340m2 / g, etc., but not limited to the listed values; other unlisted values ​​within the range also apply.

[0054] Preferably, the CTAB specific surface area of ​​the highly reinforced and highly dispersed silica is ≥200 m². 2 / g, for example, could be 202m 2 / g、205m 2 / g、207m 2 / g、210m 2 / g、215m 2 / g、220m 2 / g、230m 2 / g or 240m 2 / g, etc., but not limited to the listed values; other unlisted values ​​within the range also apply.

[0055] Preferably, the difference between the BET specific surface area and the CTAB specific surface area of ​​the highly reinforced and highly dispersed silica is 70–130 m². 2 / g, for example, could be 75m 2 / g、80m 2 / g、85m 2 / g、90m 2 / g、95m 2 / g, 100m 2 / g, 105m 2 / g、110m 2 / g、115m 2 / g、120m 2 / g or 125m 2 / g, etc., but not limited to the listed values; other unlisted values ​​within the range also apply.

[0056] Preferably, the primary particle size of the highly reinforced and highly dispersed silica is 8–20 nm, for example, it can be 9 nm, 10 nm, 12 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm or 19 nm, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0057] Thirdly, the present invention provides an application of the highly reinforcing and highly dispersed silica described in the second aspect, wherein the highly reinforcing and highly dispersed silica is used in tire rubber.

[0058] Preferably, the dispersion of the highly reinforcing and highly dispersed silica in tire rubber is >9.0, for example, it can be 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.9 or 10.0, etc., but is not limited to the listed values, other unlisted values ​​within the range are also applicable.

[0059] Preferably, the highly reinforcing and highly dispersed silica is used in tire rubber, and the tensile strength of the tire rubber is >20MPa and the elongation at break is >500%.

[0060] In this invention, the tensile strength of the tire rubber is >20MPa, for example, it can be 22MPa, 24MPa, 25MPa, 27MPa, 29MPa or 30MPa, etc., and the elongation at break is >500%, for example, it can be 520%, 540%, 550%, 570%, 590% or 600%, etc., but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0061] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0062] Compared with the prior art, the present invention has the following beneficial effects:

[0063] (1) The preparation method provided by the present invention effectively improves the specific surface area of ​​precipitated silica, reduces the primary particle size of the product, and improves the dispersion performance of high-reinforced silica products by optimizing the preparation process and controlling the material structure.

[0064] (2) When the silica prepared by this invention is applied to tire rubber, the dispersion is >9.0, the tensile strength is >20MPa, and the elongation at break is >500%. While achieving high reinforcing performance of precipitated silica, it also has excellent dispersion performance, meeting the market demand for high-performance materials. Detailed Implementation

[0065] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0066] Example 1

[0067] This embodiment provides a method for preparing highly reinforced and highly dispersed silica, the method comprising the following steps:

[0068] (1) A water glass solution and sulfuric acid were mixed at a temperature of 85°C to obtain a first reaction solution with a pH of 10.5;

[0069] (2) Add sulfuric acid to the first reaction solution in step (1) at a first drop rate, and add water glass solution at the same time to obtain a second reaction solution with a pH of 10.5;

[0070] The first drop acceleration is 0.8 m. 3 / h; control the dropping rate of the water glass solution to maintain the pH of the reaction process in step (2) at 10.5; the dropping time is 20 min;

[0071] (3) Add sulfuric acid to the second reaction solution in step (2) at a second drop rate, and add water glass solution at the same time to obtain a third reaction solution with a pH of 9.0;

[0072] The second dropping rate is 0.8 times the first dropping rate in step (2); the dropping rate of the water glass solution is controlled to maintain the pH at 9.0 during the reaction process in step (3); the dropping time is 20 min;

[0073] (4) Add sulfuric acid to the third reaction solution described in step (3) at a third dropping rate, and add water glass solution at the same time to obtain a fourth reaction solution with a pH of 8.0;

[0074] The third dropping rate is 0.6 times the second dropping rate in step (3); the dropping rate of the water glass solution is controlled to maintain the pH at 8.0 during the reaction process in step (4); the dropping time is 20 min;

[0075] (5) Use sulfuric acid to adjust the pH of the fourth reaction solution in step (4) to 6.0 to obtain a precipitated silica suspension;

[0076] The dropping rate of the sulfuric acid is 0.5 times the first dropping rate in step (2);

[0077] (6) The precipitated silica suspension described in step (5) is subjected to pressure filtration, washing, slurrying and drying in sequence to obtain highly reinforced and highly dispersed silica;

[0078] In step (1), step (2), step (3) and step (4), the concentration of the water glass solution is 10 wt%.

[0079] The concentration of sulfuric acid in steps (1), (2), (3) and (4) is 5 wt%.

[0080] During the dropwise addition in steps (2), (3) and (4), the temperature of the reaction system is controlled at 85°C.

[0081] Example 2

[0082] This embodiment provides a method for preparing highly reinforced and highly dispersed silica, the method comprising the following steps:

[0083] (1) A water glass solution and sulfuric acid were mixed at a temperature of 60°C to obtain a first reaction solution with a pH of 9.0;

[0084] (2) Add sulfuric acid to the first reaction solution in step (1) at a first drop rate, and add water glass solution at the same time to obtain a second reaction solution with pH 9.0;

[0085] The first drop acceleration is 0.6 m. 3 / h; control the dropping rate of the water glass solution to maintain the pH of the reaction process in step (2) at 9.0; the dropping time is 50 min;

[0086] (3) Add sulfuric acid to the second reaction solution in step (2) at a second drop rate, and add water glass solution at the same time to obtain a third reaction solution with a pH of 8.0;

[0087] The second dropping rate is 0.6 times the first dropping rate in step (2); the dropping rate of the water glass solution is controlled to maintain the pH at 8.0 during the reaction process in step (3); the dropping time is 50 min;

[0088] (4) Add sulfuric acid to the third reaction solution described in step (3) at a third dropping rate, and add water glass solution at the same time to obtain a fourth reaction solution with a pH of 7.0;

[0089] The third dropping rate is 0.6 times the second dropping rate in step (3); the dropping rate of the water glass solution is controlled to maintain the pH at 7.0 during the reaction process in step (4); the dropping time is 50 min;

[0090] (5) Use sulfuric acid to adjust the pH of the fourth reaction solution in step (4) to 4.0 to obtain a precipitated silica suspension;

[0091] The dropping rate of the sulfuric acid is 0.5 times the first dropping rate in step (2);

[0092] (6) The precipitated silica suspension described in step (5) is subjected to pressure filtration, washing, slurrying and drying in sequence to obtain highly reinforced and highly dispersed silica;

[0093] In step (1), step (2), step (3) and step (4), the concentration of the water glass solution is 30 wt%.

[0094] The concentration of sulfuric acid in steps (1), (2), (3) and (4) is 25 wt%.

[0095] During the dropwise addition in steps (2), (3) and (4), the temperature of the reaction system is controlled at 60°C.

[0096] Example 3

[0097] This embodiment provides a method for preparing highly reinforced and highly dispersed silica, the method comprising the following steps:

[0098] (1) A water glass solution and sulfuric acid were mixed at a temperature of 70°C to obtain a first reaction solution with a pH of 10.0;

[0099] (2) Add sulfuric acid to the first reaction solution in step (1) at a first drop rate, and add water glass solution at the same time to obtain a second reaction solution with a pH of 10.0;

[0100] The first drop acceleration is 1.0 m. 3 / h; control the dropping rate of the water glass solution to maintain the pH of the reaction process in step (2) at 10.0; the dropping time is 30 min;

[0101] (3) Add sulfuric acid to the second reaction solution in step (2) at a second drop rate, and add water glass solution at the same time to obtain a third reaction solution with a pH of 8.5;

[0102] The second dropping rate is 0.7 times the first dropping rate in step (2); the dropping rate of the water glass solution is controlled to maintain the pH at 8.5 during the reaction process in step (3); the dropping time is 30 min;

[0103] (4) Add sulfuric acid to the third reaction solution described in step (3) at a third dropping rate, and add water glass solution at the same time to obtain a fourth reaction solution with a pH of 7.5;

[0104] The third dropping rate is 0.5 times the second dropping rate in step (3); the dropping rate of the water glass solution is controlled to maintain the pH at 7.5 during the reaction process in step (4); the dropping time is 30 min;

[0105] (5) Use sulfuric acid to adjust the pH of the fourth reaction solution in step (4) to 5.0 to obtain a precipitated silica suspension;

[0106] The dropping rate of the sulfuric acid is 0.5 times the first dropping rate in step (2);

[0107] (6) The precipitated silica suspension described in step (5) is subjected to pressure filtration, washing, slurrying and drying in sequence to obtain highly reinforced and highly dispersed silica;

[0108] In step (1), step (2), step (3) and step (4), the concentration of the water glass solution is 15 wt%.

[0109] The concentration of sulfuric acid in steps (1), (2), (3) and (4) is 10 wt%.

[0110] During the dropwise addition in steps (2), (3) and (4), the temperature of the reaction system is controlled at 70°C.

[0111] Example 4

[0112] This embodiment provides a method for preparing highly reinforced and highly dispersed silica, except that in step (2), the first dropping rate is 0.4 m. 3 Except for / h, all other conditions are the same as in Example 3.

[0113] Example 5

[0114] This embodiment provides a method for preparing highly reinforced and highly dispersed silica, except that in step (2), the first dropping rate is 1.4 m. 3 Except for / h, all other conditions are the same as in Example 3.

[0115] Example 6

[0116] This embodiment provides a method for preparing highly reinforced and highly dispersed silica. Except for step (2), in which the dropping rate of the water glass solution is controlled to maintain the pH of the reaction process in step (2) at 8.0, all other conditions are the same as in Example 3.

[0117] Example 7

[0118] This embodiment provides a method for preparing highly reinforced and highly dispersed silica. Except that the second dropping rate in step (3) is 0.5 times the first dropping rate in step (2), all other conditions are the same as in embodiment 3.

[0119] Example 8

[0120] This embodiment provides a method for preparing highly reinforced and highly dispersed silica. Except that the second dropping rate in step (3) is 0.9 times the first dropping rate in step (2), all other conditions are the same as in embodiment 3.

[0121] Example 9

[0122] This embodiment provides a method for preparing highly reinforced and highly dispersed silica. Except for step (3), in which the dropping rate of the water glass solution is controlled to maintain the pH of the reaction process in step (3) at 7.0, all other conditions are the same as in Example 3.

[0123] Example 10

[0124] This embodiment provides a method for preparing highly reinforced and highly dispersed silica. Except for step (3), in which the dropping rate of the water glass solution is controlled to maintain the pH of the reaction process in step (3) at 10.0, all other conditions are the same as in Example 3.

[0125] Example 11

[0126] This embodiment provides a method for preparing highly reinforced and highly dispersed silica. Except that the third drop acceleration in step (4) is 0.3 times the second drop acceleration in step (3), all other conditions are the same as in embodiment 3.

[0127] Example 12

[0128] This embodiment provides a method for preparing highly reinforced and highly dispersed silica. Except that the third drop acceleration in step (4) is 0.7 times the second drop acceleration in step (3), all other conditions are the same as in embodiment 3.

[0129] Example 13

[0130] This embodiment provides a method for preparing highly reinforced and highly dispersed silica. Except for step (4), in which the dropping rate of the water glass solution is controlled to maintain the pH of the reaction process in step (4) at 6.0, all other conditions are the same as in Example 3.

[0131] Example 14

[0132] This embodiment provides a method for preparing highly reinforced and highly dispersed silica. Except for step (4), in which the dropping rate of the water glass solution is controlled to maintain the pH of the reaction process in step (4) at 9.0, all other conditions are the same as in Example 3.

[0133] Example 15

[0134] This embodiment provides a method for preparing highly reinforced and highly dispersed silica. Except for the dropping time of 10 min in steps (2), (3) and (4), all other conditions are the same as in Example 3.

[0135] Example 16

[0136] This embodiment provides a method for preparing highly reinforced and highly dispersed silica. Except for the dropping time of 60 min in steps (2), (3) and (4), all other conditions are the same as in Example 3.

[0137] Comparative Example 1

[0138] This comparative example provides a method for preparing highly reinforced and highly dispersed silica. Except for the second drop acceleration being the same as the first drop acceleration, all other conditions are the same as in Example 3.

[0139] Comparative Example 2

[0140] This comparative example provides a method for preparing highly reinforced and highly dispersed silica. Except for the third drop acceleration and the second drop acceleration being the same, all other conditions are the same as in Example 3.

[0141] Comparative Example 3

[0142] This comparative example provides a method for preparing highly reinforced and highly dispersed silica, the method comprising the following steps:

[0143] (1) A 15 wt% water glass solution and a 10 wt% sulfuric acid solution were mixed at a temperature of 70 °C to obtain a reaction base solution with a pH of 10.

[0144] (2) Add water glass solution with a concentration of 15wt% and sulfuric acid with a concentration of 10wt% to the reaction base solution in step (1) at the same time. The temperature of the addition is 70℃ and the time is 90min. Keep the pH at 10 during the addition process and keep the pH value of the base solution constant during the addition process to obtain a mixed reaction solution.

[0145] (3) Use sulfuric acid to adjust the pH of the mixed reaction solution in step (2) to 5.0 to obtain a precipitated silica suspension;

[0146] (4) The precipitated silica suspension described in step (3) is subjected to pressure filtration, washing, slurrying and drying in sequence to obtain highly reinforced and highly dispersed silica.

[0147] The silica prepared in the above examples and comparative examples was subjected to performance characterization and application testing. Specifically, the BET specific surface area of ​​silica was determined according to GB / T19587-2017; the CTAB specific surface area of ​​silica was determined according to GB / T23656-2016; the primary particle size of silica was tested using transmission electron microscopy; silica was made into rubber, and the silica dispersion was tested according to GB / T6030-2006; tensile strength and elongation at break were determined according to GB / T528-2009, the determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber.

[0148] The test results of the above embodiments and comparative examples are shown in Table 1.

[0149] Table 1

[0150]

[0151]

[0152] As shown in Table 1:

[0153] (1) The preparation method provided by the present invention achieves high reinforcing and high dispersibility of precipitated silica by optimizing the preparation process and controlling the material structure. When the silica is applied to tire rubber, the tensile strength is >20MPa, the elongation at break is >550%, and the dispersion is >9.0.

[0154] (2) Comparing Examples 3 and 4-5, it can be seen that when the sulfuric acid is dropped too slowly in step (2), the growth rate of the primary silica particles is greater than the generation rate, resulting in an increase in the primary silica particle size and a decrease in the specific surface area; when the sulfuric acid is dropped too quickly in step (2), the growth rate of silica is less than the generation rate, causing silica to polymerize and precipitate prematurely through collision before it can grow, resulting in a smaller primary particle size; comparing Examples 3 and 6, it can be seen that when the pH is maintained at 8.0 during the reaction process in step (2), the alkaline concentration in the reaction solution is low in the early stage of the reaction, resulting in a larger primary silica particle size generated in this stage;

[0155] (3) Comparing Examples 3 and 7-8, it can be seen that when the sulfuric acid dripping rate in step (3) is 0.5 times that of the previous stage, the growth rate of primary silica particles is greater than the generation rate due to the slow dripping rate of sulfuric acid, resulting in an increase in the primary silica particle size and a decrease in the specific surface area; when the sulfuric acid dripping rate in step (3) is 0.9 times that of the previous stage, the growth rate of silica is less than the generation rate due to the excessively fast dripping rate of sulfuric acid, resulting in premature polymerization and precipitation of silica through collision before it can grow, leading to a smaller primary particle size.

[0156] (4) Comparing Examples 3 and 9-10, it can be seen that when the pH of the reaction process in step (3) is maintained at 7.0, the primary particle size of silica is larger in this stage due to the low alkali concentration in the reaction solution; when the pH of the reaction process in step (3) is maintained at 10.0, the primary particle size of silica is smaller in this stage due to the high alkali concentration in the reaction solution.

[0157] (5) A comparison of Examples 3 and 15-16 shows that when the subsequent dripping time is too short and the dripping rate of sulfuric acid remains constant, the overall concentration of silica particles in the reaction solution is low. The low concentration cannot provide sufficient raw materials for the growth of primary silica particles. At the same time, the short reaction time results in a large number of primary particles not having enough time to grow, so the size of the primary particles is small and the specific surface area increases. When the subsequent dripping time is too long and the dripping rate of sulfuric acid remains constant, the concentration of silica particles in the reaction solution is high, making it easier for them to collide and bond to grow into larger primary particles, resulting in a significant decrease in specific surface area.

[0158] (6) Comparing Example 3 and Comparative Examples 1-3, it can be seen that when the dropping rate is not gradually reduced or the dropping rate is kept constant throughout the process, the silica particles generated are always small, just like in the initial reaction stage, due to the excessively fast addition of sulfuric acid in the later reaction. This results in poor overall dispersion performance of silica. The purpose of the segmented reaction is to reduce the reaction rate of the second and third stages, so as to provide sufficient time for the growth of silica particles in the later stage, reduce the number of primary particles that cannot grow due to the excessively fast reaction rate, and thus ensure the dispersion performance of the finished product.

[0159] The applicant declares that the detailed structural features of the present invention are illustrated through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components selected in the present invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing highly reinforced and highly dispersed silica, characterized in that, The preparation method includes the following steps: (1) Mix water glass solution with sulfuric acid to obtain the first reaction solution; (2) Add sulfuric acid to the first reaction solution in step (1) at a first drop rate, and add water glass solution at the same time to obtain the second reaction solution; (3) Add sulfuric acid to the second reaction solution in step (2) at a second drop rate, while adding water glass solution to obtain the third reaction solution; (4) Add sulfuric acid to the third reaction solution in step (3) at a third drop rate, and simultaneously add water glass solution to obtain the fourth reaction solution; (5) Adjust the pH of the fourth reaction solution in step (4) to obtain a precipitated silica suspension; Step (2) The first drop acceleration is 0.6-1m. 3 / h; Control the dropping rate of the water glass solution to maintain the pH of the reaction process in step (2) at 9.0~10.5; In step (3), the second drop acceleration is 0.6 to 0.8 times the first drop acceleration in step (2); Control the dropping rate of the water glass solution to maintain the pH of the reaction process in step (3) at 8.0~9.0; The third drop acceleration in step (4) is 0.4 to 0.6 times the second drop acceleration in step (3); Control the dropping rate of the water glass solution to maintain the pH of 7.0~8.0 during the reaction process in step (4).

2. The preparation method according to claim 1, characterized in that, The concentration of the water glass solution in steps (1), (2), (3) and (4) is 10~30wt%.

3. The preparation method according to claim 1, characterized in that, The concentration of sulfuric acid in steps (1), (2), (3) and (4) is 5-25 wt%.

4. The preparation method according to claim 1, characterized in that, The mixing temperature in step (1) is 60~85℃.

5. The preparation method according to claim 1, characterized in that, Step (1) The pH of the first reaction solution is 9.0~10.

5.

6. The preparation method according to claim 1, characterized in that, During the dropwise addition in steps (2), (3) and (4), the temperature of the reaction system is controlled to be 60~85℃.

7. The preparation method according to claim 1, characterized in that, The dripping time in step (2) is 20~50 min.

8. The preparation method according to claim 1, characterized in that, In step (2), the pH of the second reaction solution is 9.0~10.

5.

9. The preparation method according to claim 1, characterized in that, The dripping time in step (3) is 20~50 min.

10. The preparation method according to claim 1, characterized in that, The pH of the third reaction solution in step (3) is 8.0~9.

0.

11. The preparation method according to claim 1, characterized in that, The dripping time in step (4) is 20~50 min.

12. The preparation method according to claim 1, characterized in that, The pH of the fourth reaction solution in step (4) is 7.0~8.

0.

13. The preparation method according to claim 1, characterized in that, The adjustment in step (5) is to adjust the pH to 4.0~6.

0.

14. The preparation method according to claim 1, characterized in that, The adjustment in step (5) is made by using sulfuric acid, and the dripping rate of the sulfuric acid is 0.45 to 0.55 times the first dripping rate in step (2).

15. The preparation method according to claim 1, characterized in that, After obtaining the precipitated silica suspension in step (5), the process further includes: sequentially performing pressure filtration, washing, slurrying and drying on the precipitated silica suspension to obtain highly reinforced and highly dispersed silica.

16. The preparation method according to claim 1, characterized in that, The preparation method includes the following steps: (1) Mix water glass solution and sulfuric acid at a temperature of 60~85℃ to obtain a first reaction solution with a pH of 9.0~10.5; (2) Add sulfuric acid to the first reaction solution in step (1) at a first drop rate, and add water glass solution at the same time to obtain a second reaction solution with a pH of 9.0~10.5; The first drop acceleration is 0.6-1 m. 3 / h; control the dropping rate of the water glass solution to maintain the pH of the reaction process in step (2) at 9.0~10.5; the dropping time is 20~50min; (3) Add sulfuric acid to the second reaction solution in step (2) at a second drop rate, and add water glass solution at the same time to obtain a third reaction solution with a pH of 8.0~9.0; The second dropping rate is 0.6 to 0.8 times the first dropping rate in step (2); the dropping rate of the water glass solution is controlled to maintain the pH of the reaction process in step (3) at 8.0 to 9.0; the dropping time is 20 to 50 minutes. (4) Add sulfuric acid to the third reaction solution described in step (3) at a third dropping rate, and add water glass solution at the same time to obtain a fourth reaction solution with a pH of 7.0~8.0; The third dropping rate is 0.4 to 0.6 times the second dropping rate in step (3); the dropping rate of the water glass solution is controlled to maintain the pH of the reaction process in step (4) at 7.0 to 8.0; the dropping time is 20 to 50 minutes. (5) Use sulfuric acid to adjust the pH of the fourth reaction solution in step (4) to 4.0~6.0 to obtain a precipitated silica suspension; The sulfuric acid is added at a rate that is 0.45 to 0.55 times the first adding rate in step (2); (6) The precipitated silica suspension described in step (5) is subjected to pressure filtration, washing, slurrying and drying in sequence to obtain highly reinforced and highly dispersed silica; In each of steps (1), (2), (3), and (4), the concentration of the water glass solution is 10-30 wt%. The concentration of sulfuric acid in steps (1), (2), (3), and (4) is 5-25 wt%; During the dropwise addition in steps (2), (3) and (4), the temperature of the reaction system is controlled to be 60~85℃.

17. A highly reinforcing and highly dispersed silica, characterized in that, The highly reinforced and highly dispersed silica is prepared by the preparation method described in any one of claims 1-16.

18. An application of the highly reinforced and highly dispersed silica as described in claim 17, characterized in that, The highly reinforcing and highly dispersed silica is used in tire rubber.

19. The application of the highly reinforced and highly dispersed silica according to claim 18, characterized in that, The high-reinforcing and highly dispersed silica has a dispersion of >9.0 in tire rubber.

20. The application of the highly reinforcing and highly dispersed silica according to claim 18, wherein the highly reinforcing and highly dispersed silica is used in tire rubber, and the tensile strength of the tire rubber is >20MPa and the elongation at break is >500%.

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