Silica anti-caking agent and preparation method thereof

Abstract

The invention relates to the field of silicon dioxide preparation, and particularly discloses a silicon dioxide anti-caking agent and a preparation method thereof. The preparation method of the silicon dioxide anti-caking agent comprises the following steps: adding a dispersing agent into a water glass solution, then introducing carbon dioxide into the water glass solution while stirring at the temperature of 50-90 DEG C at the introduction rate of 150-180mL / min, reacting until the pH value in the system is reduced to 10-10.5, adjusting the introduction rate of the carbon dioxide to 250-280mL / min, filtering, washing and drying to obtain the silicon dioxide anti-caking agent. The preparation method comprises the following steps: adding the silicon dioxide into a reaction kettle, reacting until the pH value in a system is reduced to 8.5-9, stopping the reaction, filtering to obtain a solid substance, washing and drying to obtain the silicon dioxide anti-caking agent with the specific surface area of 346-392 m < 2 > / g and the oil absorption value of 291-330 mL / 100g, and the silicon dioxide anti-caking agent can reduce the repose angle of a powdery substance by 43% or above through test detection and has very excellent anti-caking capability.

Description

Technical Field

[0001] The present application relates to the technical field of silicon dioxide preparation, and in particular to a silicon dioxide anti-caking agent and a preparation method thereof. Background Art

[0002] Silica possesses many unique physical properties. Its porous structure and high surface area allow it to absorb moisture and prevent particles from clumping, effectively preventing products from caking due to moisture absorption and pressure. It is also chemically inert, safe, and non-toxic. Its chemical properties are stable within a pH range of 4-10, and it does not participate in oxidation or hydrolysis reactions in foods or pharmaceuticals. Therefore, silica is often used as an anti-caking agent for powdered substances, and is widely used in salt, milk powder, instant coffee, and animal feed.

[0003] Silica used as an anti-caking agent needs to have a low particle size, a large specific surface area, and an appropriate oil absorption value, so its preparation process has higher requirements. Currently, the methods for preparing silica include vapor phase method and precipitation method. Among them, silica produced by vapor phase method has high purity and structural stability, but its particle size is difficult to control, the equipment used is relatively sophisticated, and the reaction needs to be completed in a plasma flame at 1500-2000℃, which makes the production cost too high. Although silica produced by precipitation method has a high specific surface area and high process flexibility, this preparation process cannot be in balanced contact with the solution during the addition of inorganic acid, which will cause the pH value of the local solution to drop sharply during the reaction, causing the local silica gel particles to grow rapidly and agglomerate, resulting in serious agglomeration of the produced silica anti-caking agent. Therefore, how to prepare silica anti-caking agent with suitable particle size, specific surface area and oil absorption value has become a major problem. Summary of the Invention

[0004] In order to solve the above technical problems, the present application provides a silica anti-caking agent and a preparation method thereof.

[0005] In a first aspect, the present application provides a method for preparing a silica anti-caking agent, comprising the following steps: adding a dispersant to a water glass solution, then introducing carbon dioxide into the water glass solution while stirring at a temperature of 50-90°C, at a rate of 150-180 mL / min, reacting until the pH in the system drops to 10-10.5, adjusting the carbon dioxide introduction rate to 250-280 mL / min, reacting again until the pH in the system drops to 8.5-9, stopping the reaction, filtering the solid matter, washing, and drying to obtain a silica anti-caking agent; the dispersant comprises PEG-6000 and a hyperdispersant in a weight ratio of 1:(3-7), the hyperdispersant being prepared by reacting n-butyl methacrylate and an acrylic compound, the acrylic compound being one or more of methacrylic acid, N-isopropylacrylamide, dimethylaminoethyl methacrylate, and 2-acrylamide-2-methylpropanesulfonic acid.

[0006] By adopting the above technical solution, the present application utilizes carbonization method to prepare silica anti-caking agent, accurately controls the introduction rate of carbon dioxide under specific temperature conditions, and combines with a specific ratio of dispersant to effectively suppress the drastic change of local pH value during the reaction process, thereby avoiding the abnormal growth and agglomeration of silica gel particles. In addition, the synergistic effect of PEG-6000 and hyperdispersant in the dispersant used further improves the structural stability of the product, so that the silica anti-caking agent finally obtained has excellent anti-caking performance, which can better meet the moisture-proof requirements of powdered substances such as food and medicine. The hyperdispersant of the present application is prepared by the reaction of n-butyl methacrylate and acrylic acid compounds, has good spatial stabilization effect, has multiple anchoring sites, uses multi-point adsorption to reduce the degree of particle agglomeration in the system, and improves the uniformity of particle size distribution of the final product.

[0007] In summary, the preparation method of this application is a whole scheme, and the steps and parameters are coordinated with each other, and finally a specific surface area of 346-392m 2 / g, and the silica anti-caking agent with an oil absorption value of 291-330mL / 100g has been tested and found to be able to reduce the angle of repose of powdered materials by more than 43%, and control the change in the angle of repose within 14% in 6 months, and has excellent anti-caking ability.

[0008] Preferably, the modulus of the water glass is 3.3.

[0009] By adopting the above technical solution, the present application controls the modulus of water glass to 3.3, effectively regulating the particle size and structural properties of the silica anti-caking agent. Specifically, the selection of this modulus helps to form more uniform silica gel particles during the subsequent reaction process, reducing the occurrence of agglomeration, thereby producing a silica anti-caking agent with a narrower particle size distribution and a more moderate oil absorption value. This makes the final anti-caking agent exhibit better performance in absorbing water and preventing powdered materials from agglomerating.

[0010] Preferably, the concentration of the water glass solution is 5-8 wt %.

[0011] By adopting the above technical solution, the present application controls the concentration of the water glass solution within the range of 5-8wt%, which can ensure that the concentration of silicate ions in the reaction system is moderate, avoid the agglomeration phenomenon caused by excessively high concentration leading to excessively fast local reactions, and prevent the reaction efficiency from being reduced and resources from being wasted due to too low a concentration. Combined with other reaction parameters strictly controlled by the present application, this concentration range helps to prepare a silica anti-caking agent with uniform particle size, high specific surface area and suitable oil absorption value, thereby effectively improving its anti-caking performance.

[0012] Preferably, the added amount of the dispersant is 1.8-2 wt% of the amount of water glass used.

[0013] By adopting the above technical solution, the present application controls the amount of dispersant added within the range of 1.8-2wt% of the water glass dosage, thereby achieving a better dispersion effect of the water glass solution during the preparation process, thereby effectively avoiding the agglomeration of the silica particles. Combined with the overall solution, this amount of addition synergistically acts with the water glass solution, the carbon dioxide introduction rate, and the reaction conditions to ensure that the resulting silica anti-caking agent has a relatively suitable oil absorption value, thereby improving its performance as an anti-caking agent and effectively preventing powdered substances from agglomerating due to moisture absorption.

[0014] Preferably, the temperature is 70°C.

[0015] By adopting the above-mentioned technical solution, the present application controls the reaction temperature to 70°C, which can further optimize the reaction conditions and make the reaction between the water glass solution and carbon dioxide more stable, thereby effectively inhibiting the abnormal growth and agglomeration of silica gel particles. This temperature condition helps to form a silica anti-caking agent with uniform particle size distribution and moderate specific surface area, further improving its adsorption performance and anti-caking effect.

[0016] Preferably, before the pH in the system drops to 10-10.5, the carbon dioxide introduction rate is 175 mL / min; after the pH in the system drops to 10-10.5, the carbon dioxide introduction rate is 270 mL / min.

[0017] By adopting this technical solution, the carbon dioxide injection rate can be precisely controlled during the reaction, effectively adjusting the gradient of the system's pH change. Before the pH drops to 10-10.5, a lower injection rate helps maintain a slow decrease in the system's pH, preventing abnormal growth of silica gel particles caused by drastic pH changes in localized solutions. After the pH drops to 10-10.5, increasing the injection rate can accelerate the reaction process while ensuring a more uniform distribution of the resulting silica gel particles, thereby producing a silica anti-caking agent with an appropriate particle size and significantly reduced agglomeration.

[0018] Preferably, the dispersant comprises PEG-6000 and a hyperdispersant in a weight ratio of 1:4.

[0019] By adopting the above technical solution, the growth behavior of silica gel particles during the reaction process can be effectively improved, the specific surface area can be increased, and serious agglomeration can be prevented, thereby obtaining silica particles with more uniform particle size.

[0020] Preferably, the acrylic compound is N-isopropylacrylamide and 2-acrylamide-2-methylpropanesulfonic acid in a molar ratio of 4:(1-3).

[0021] By adopting the above technical solution, the silica anti-caking agent prepared has a more suitable particle size, specific surface area and oil absorption value. The application selects N-isopropylacrylamide and 2-acrylamide-2-methylpropanesulfonic acid in a molar ratio of 4:(1-3) as acrylic acid compounds, which can effectively regulate the performance of the hyperdispersant, thereby improving the dispersion effect and avoiding excessive agglomeration of silica gel particles during the reaction process. This makes the particle size distribution of the final silica anti-caking agent more uniform, significantly improving its use as an anti-caking agent.

[0022] In the second aspect, the present application provides a silica anti-caking agent prepared by the above preparation method, with a specific surface area of 346-392m 2 / g, and the oil absorption value is 291-330mL / 100g.

[0023] By adopting the above technical solution, the silica anti-caking agent prepared in the present application has a high specific surface area and a suitable oil absorption value. Specifically, by controlling the reaction conditions of the water glass solution, including temperature, stirring and the staged introduction rate of carbon dioxide, the problem of silica gel particle agglomeration caused by a sharp change in local pH value is effectively avoided, thereby obtaining silica particles with uniform particle size distribution. At the same time, the addition of a dispersant with a specific proportion and composition further suppresses the particle agglomeration phenomenon, ensuring the high specific surface area characteristics of the final product. In addition, the precise regulation of various parameters during the preparation process enables the oil absorption value of the silica anti-caking agent to be within an ideal range, so that when it is used as an anti-caking agent, it can fully play the role of absorbing moisture and preventing powdered substances from agglomerating, meeting the application needs in the fields of food, medicine, etc.

[0024] In a third aspect, the present application provides an application of a silica anti-caking agent, wherein the amount of the silica anti-caking agent is 0.07-0.08 wt % of the total amount of the powdered material.

[0025] By adopting the above technical solution, the amount of the silica anti-caking agent of the present application is precisely controlled to 0.07-0.08wt% of the total amount of the powder material, which can ensure the anti-caking effect while avoiding the cost increase and possible negative effects caused by excessive use. The silica anti-caking agent within this dosage range can effectively absorb moisture and prevent the powder material from agglomerating due to moisture absorption and pressure. At the same time, due to its high specific surface area and suitable oil absorption value, it can be evenly dispersed in the powder, improving the powder fluidity without affecting the other physical and chemical properties of the powder.

[0026] In summary, this application has the following beneficial technical effects: 1. The preparation method of the present application effectively inhibits the agglomeration of silica gel particles by adding a dispersant in a specific ratio to a water glass solution and controlling the carbon dioxide introduction rate and the reaction pH. The carbon dioxide introduction rate is regulated in stages to ensure a steady decrease in the pH value of the reaction system and avoid abnormal particle growth caused by drastic changes in local pH values. The result is a silica anti-caking agent with a high specific surface area, uniform particle size distribution, and suitable oil absorption. 2. The silica anti-caking agent prepared in this application has a high specific surface area and a suitable oil absorption value, with a specific surface area of 346-392m 2 / g, oil absorption value is 291-330mL / 100g 3. The dosage of the silica anti-caking agent of the present application is precisely controlled at 0.07-0.08wt% of the total amount of the powder material, which can ensure the anti-caking effect while avoiding the cost increase and possible negative effects caused by excessive use, effectively adsorb moisture and prevent powder materials from agglomerating due to moisture absorption and pressure. At the same time, due to its high specific surface area and appropriate oil absorption value, it can be evenly dispersed in the powder, improving the powder fluidity without affecting other physical and chemical properties of the powder. DETAILED DESCRIPTION

[0027] Material Source Unless otherwise specified, the raw materials used in this application are all commercially available products, specifically: n-Butyl methacrylate, CAS number 97-88-1; Methacrylic acid, CAS number 79-41-4; N-isopropylacrylamide, CAS number 2210-25-5; Dimethylaminoethyl methacrylate, CAS number 2867-47-2; 2-Acrylamido-2-methylpropanesulfonic acid, CAS number 15214-89-8; Stearic methacrylate, CAS number 32360-05-7; 2-Ethylhexyl methacrylate, CAS number 28675-80-1; Ethyl methacrylate, CAS number 97-63-2; PEG-6000, CAS number 25322-68-3; Water glass, modulus is 3.3; Carbon dioxide, 99.9% pure; Non-dairy creamer was purchased from Shaanxi Chenming Biotechnology Co., Ltd., with a moisture content of ≤5g / 100g.

[0028] The present application is further described in detail below with reference to preparation examples, embodiments and comparative examples.

[0029] Preparation Example 1.1 The preparation method of the hyperdispersant comprises the following steps: 1 mol of n-butyl methacrylate, 1 mol of acrylic compound (methacrylic acid and N-isopropylacrylamide in a molar ratio of 1:1) and 0.002 mol of azobisisobutyronitrile were dissolved in 1 L of tetrahydrofuran and then transferred to an argon-purged reaction apparatus equipped with a diaphragm. Three freeze-thaw cycles were performed and the reaction was carried out at 60°C for 16 hours. The reaction solution was then added dropwise to an appropriate amount of methanol for precipitation and collected by centrifugation. The supernatant was poured off and dissolved with chloroform, followed by precipitation with methanol. The above operation was repeated three times to obtain a pure product. Finally, the product was dried in a vacuum oven at 70°C for 24 hours to obtain a hyperdispersant.

[0030] Preparation Example 1.2 The preparation method of the hyperdispersant comprises the following steps: 1 mol of n-butyl methacrylate, 1 mol of an acrylic compound (methacrylic acid and dimethylaminoethyl methacrylate in a molar ratio of 1:1) and 0.002 mol of azobisisobutyronitrile were dissolved in 1 L of tetrahydrofuran, then transferred to an argon-purged reaction apparatus equipped with a diaphragm, subjected to three freeze-thaw cycles, and reacted at 60°C for 16 hours. The reaction solution was then added dropwise to an appropriate amount of methanol for precipitation and collected by centrifugation. The supernatant was poured off and dissolved with chloroform, followed by precipitation with methanol. The above operation was repeated three times to obtain a pure product. Finally, the product was dried in a vacuum oven at 70°C for 24 hours to obtain a hyperdispersant.

[0031] Preparation Example 1.3 The preparation method of the hyperdispersant comprises the following steps: 1 mol of n-butyl methacrylate, 1 mol of acrylic acid compound (methacrylic acid and 2-acrylamide-2-methylpropanesulfonic acid in a molar ratio of 1:1) and 0.002 mol of azobisisobutyronitrile were dissolved in 1 L of tetrahydrofuran and then transferred to an argon-purged reaction apparatus equipped with a diaphragm. Three freeze-thaw cycles were performed and the reaction was carried out at 60°C for 16 hours. The reaction solution was then added dropwise to an appropriate amount of methanol for precipitation and collected by centrifugation. The supernatant was poured off and dissolved with chloroform, followed by precipitation with methanol. The above operation was repeated three times to obtain a pure product. Finally, the product was dried in a vacuum oven at 70°C for 24 hours to obtain a hyperdispersant.

[0032] Preparation Example 1.4 The preparation method of the hyperdispersant comprises the following steps: 1 mol of n-butyl methacrylate, 1 mol of acrylic compound (N-isopropylacrylamide and dimethylaminoethyl methacrylate in a molar ratio of 1:1) and 0.002 mol of azobisisobutyronitrile were dissolved in 1 L of tetrahydrofuran, then transferred to an argon-purged reaction apparatus equipped with a diaphragm, subjected to three freeze-thaw cycles, and reacted at 60°C for 16 hours. The reaction solution was then added dropwise to an appropriate amount of methanol for precipitation and collected by centrifugation. The supernatant was poured off and dissolved with chloroform, followed by precipitation with methanol. The above operation was repeated three times to obtain a pure product. Finally, the product was dried in a vacuum oven at 70°C for 24 hours to obtain a hyperdispersant.

[0033] Preparation Example 1.5 The preparation method of the hyperdispersant comprises the following steps: 1 mol of n-butyl methacrylate, 1 mol of acrylic compound (N-isopropylacrylamide and 2-acrylamide-2-methylpropanesulfonic acid in a molar ratio of 1:1) and 0.002 mol of azobisisobutyronitrile were dissolved in 1 L of tetrahydrofuran, then transferred to an argon-purged reaction apparatus equipped with a diaphragm, subjected to three freeze-thaw cycles, and reacted at 60°C for 16 hours. The reaction solution was then added dropwise to an appropriate amount of methanol for precipitation and collected by centrifugation. The supernatant was poured off and dissolved with chloroform, followed by precipitation with methanol. The above operation was repeated three times to obtain a pure product. Finally, the product was dried in a vacuum oven at 70°C for 24 hours to obtain a hyperdispersant.

[0034] Preparation Example 1.6 The preparation method of the hyperdispersant comprises the following steps: 1 mol of n-butyl methacrylate, 1 mol of an acrylic compound (dimethylaminoethyl methacrylate and 2-acrylamide-2-methylpropanesulfonic acid in a molar ratio of 1:1) and 0.002 mol of azobisisobutyronitrile were dissolved in 1 L of tetrahydrofuran, then transferred to an argon-purged reaction apparatus equipped with a diaphragm, subjected to three freeze-thaw cycles, and reacted at 60°C for 16 hours. The reaction solution was then added dropwise to an appropriate amount of methanol for precipitation and collected by centrifugation. The supernatant was poured off and dissolved with chloroform, followed by precipitation with methanol. The above operation was repeated three times to obtain a pure product. Finally, the product was dried in a vacuum oven at 70°C for 24 hours to obtain a hyperdispersant.

[0035] Preparation Example 2.1 The preparation method of the hyperdispersant is different from that of Preparation Example 1.5 in that the molar ratio of N-isopropylacrylamide and 2-acrylamide-2-methylpropanesulfonic acid is 4:1, and the rest is the same as that of Preparation Example 1.5.

[0036] Preparation Example 2.2 The preparation method of the hyperdispersant is different from that of Preparation Example 1.5 in that the molar ratio of N-isopropylacrylamide and 2-acrylamide-2-methylpropanesulfonic acid is 4:3, and the rest is the same as Preparation Example 1.5.

[0037] Preparation Example 2.3 The preparation method of the hyperdispersant is different from that of Preparation Example 1.5 in that the molar ratio of N-isopropylacrylamide and 2-acrylamide-2-methylpropanesulfonic acid is 1:4, and the rest is the same as Preparation Example 1.5.

[0038] Comparative Preparation Example 1.1 The preparation method of the hyperdispersant is the same as that of Preparation Example 1.1 except that n-butyl methacrylate is replaced with stearic methacrylate. The rest is the same as that of Preparation Example 1.1.

[0039] Comparative Preparation Example 1.2 The preparation method of the hyperdispersant is the same as that of Preparation Example 1.1 except that n-butyl methacrylate is replaced with isooctyl methacrylate. The rest is the same as that of Preparation Example 1.1.

[0040] Comparative Preparation Example 1.3 The preparation method of the hyperdispersant is the same as that of Preparation Example 1.1 except that n-butyl methacrylate is replaced by ethyl methacrylate. The rest is the same as that of Preparation Example 1.1.

[0041] Example 1.1 A method for preparing a silicon dioxide anti-caking agent comprises the following steps: 10 g of dispersant (1.25 g of PEG-6000 and 8.75 g of the hyperdispersant prepared in Preparation Example 1.1) was added to 10 L of a 5 wt % water glass solution, and then carbon dioxide was introduced into the water glass solution while stirring at 90° C. at a rate of 150 mL / min. The reaction was continued until the pH in the system dropped to 10.5. The carbon dioxide introduction rate was adjusted to 250 mL / min, and the reaction was continued until the pH in the system dropped to 9. The reaction was stopped, and the solid matter was filtered, washed, and dried to obtain a silica anti-caking agent.

[0042] Example 1.2 A method for preparing a silicon dioxide anti-caking agent comprises the following steps: 14.4 g of dispersant (3.6 g of PEG-6000 and 10.8 g of the hyperdispersant obtained in Preparation Example 1.2) was added to 10 L of a water glass solution having a concentration of 8 wt %, and then carbon dioxide was introduced into the water glass solution while stirring at a temperature of 50° C. at a rate of 180 mL / min. The mixture was reacted until the pH in the system dropped to 10. The carbon dioxide introduction rate was adjusted to 280 mL / min, and the mixture was reacted until the pH in the system dropped to 8.5. The reaction was stopped, and the solid matter was filtered, washed, and dried to obtain a silica anti-caking agent.

[0043] Examples 1.3-1.6 A method for preparing a silica anti-caking agent, which differs from Example 1.1 in that the hyperdispersant prepared in Preparation Example 1.1 is replaced by the hyperdispersants prepared in Preparation Examples 1.3-1.6 respectively, and the rest is the same as Example 1.1.

[0044] Examples 2.1-2.3 A method for preparing a silica anti-caking agent, which differs from Example 1.5 in that the hyperdispersant prepared in Preparation Example 1.5 is replaced by the hyperdispersants prepared in Preparation Examples 2.1-2.3 respectively, and the rest is the same as Example 1.5.

[0045] Example 3.1 A method for preparing a silica anti-caking agent, which differs from Example 1.1 in that the amount of PEG-6000 used is 2 g, the amount of the hyperdispersant prepared in Preparation Example 1.1 used is 8 g, and the rest is the same as Example 1.1.

[0046] Example 3.2 A method for preparing a silica anti-caking agent, which differs from Example 1.1 in that the amount of PEG-6000 used is 1.67 g, the amount of the hyperdispersant prepared in Preparation Example 1.1 used is 8.33 g, and the rest is the same as Example 1.1.

[0047] Example 3.3 A method for preparing a silica anti-caking agent, which differs from Example 1.1 in that the amount of PEG-6000 used is 1.25 g, the amount of the hyperdispersant prepared in Preparation Example 1.1 used is 8.75 g, and the rest is the same as Example 1.1.

[0048] Example 4.1 A method for preparing a silica anti-caking agent, which differs from Example 1.1 in that the temperature is 70° C., and the rest is the same as Example 1.1.

[0049] Example 4.2 A method for preparing a silica anti-caking agent, which differs from Example 1.1 in that the temperature is 50° C., and the rest is the same as Example 1.1.

[0050] Example 5.1 A method for preparing a silica anti-caking agent, which differs from Example 1.1 in that before the pH in the system drops to 10.5, the carbon dioxide introduction rate is 175 mL / min; after the pH in the system drops to 10.5, the carbon dioxide introduction rate is 270 mL / min; otherwise, the same as Example 1.1.

[0051] Example 5.2 A method for preparing a silica anti-caking agent, which differs from Example 1.1 in that before the pH in the system drops to 10.5, the carbon dioxide introduction rate is 165 mL / min, and after the pH in the system drops to 10.5, the carbon dioxide introduction rate is 260 mL / min. The rest is the same as Example 1.1.

[0052] Comparative Examples 1.1-1.3 The difference from Example 1.1 is that the hyperdispersant prepared in Preparation Example 1.1 is replaced by the hyperdispersants prepared in Comparative Preparation Examples 1.1-1.3 respectively, and the rest is the same as Example 1.1.

[0053] Comparative Example 2.1 The difference from Example 1.1 is that the carbon dioxide introduction rate is always maintained at 150 mL / min until the pH in the system drops to 9. The rest is the same as Example 1.1.

[0054] Comparative Example 2.2 The difference from Example 1.1 is that the carbon dioxide introduction rate is always maintained at 250 mL / min until the pH in the system drops to 9. The rest is the same as Example 1.1.

[0055] Comparative Example 3.1 The difference from Example 1.1 is that the temperature is 40°C, and the rest is the same as Example 1.1.

[0056] Comparative Example 3.2 The difference from Example 1.1 is that the temperature is 90° C., and the rest is the same as Example 1.1.

[0057] Application Example 1 0.7 g of the silicon dioxide anti-caking agent obtained in Example 1.1 was added to 1 kg of non-dairy creamer, and the mixture was mixed evenly to obtain a low-caking non-dairy creamer.

[0058] Application Example 2 0.8 g of the silicon dioxide anti-caking agent obtained in Example 1.2 was added to 1 kg of non-dairy creamer, and the mixture was mixed evenly to obtain a low-caking non-dairy creamer.

[0059] Application Example 3-23 0.7 g of the silicon dioxide anti-caking agent obtained in Example 1.3-Comparative Example 3.2 was added to 1 kg of non-dairy creamer, and the mixture was mixed evenly to obtain a low-caking non-dairy creamer.

[0060] Performance testing 1. The silicon dioxide anticaking agent obtained in the examples and comparative examples was tested and analyzed, and the specific surface area (m 2 / g) and oil absorption value (mL / 100g); 2. Referring to the records in GB / T 16913-2008, the angle of repose of the non-dairy creamer on the first day and the angle of repose of the low-caking non-dairy creamer obtained in the application example at the sixth month were measured, and the angle of repose of the non-dairy creamer without the addition of silica anti-caking agent at the sixth month was used as a blank control.

[0061] Table 1 Test results Data Analysis: As can be seen from Table 1, the specific surface area of the silica anti-caking agent prepared in Examples 1.1-1.6 of the present application is 346-392 m2 / g, and the oil absorption value is 291-330 mL / 100 g. It can reduce the initial angle of repose of the non-dairy creamer by more than 41.5%. After storage for half a year, the angle of repose of the non-dairy creamer can still be kept at no more than 35°, and the rate of change of the angle of repose is no more than 14%. This proves that the preparation method of the present application is an overall scheme, and the steps and parameters cooperate with each other, which effectively inhibits the agglomeration of silicone gel particles, ensures that the pH value of the reaction system decreases steadily, and avoids abnormal particle growth caused by drastic changes in local pH values, and finally obtains a silica anti-caking agent with high specific surface area, uniform particle size distribution and suitable oil absorption value.

[0062] In Examples 2.1-2.3, the present application replaced different hyperdispersants. The results showed that the silica anti-caking agent obtained in Example 2.1 had a more moderate oil absorption value and was able to reduce the angle of repose of the non-dairy creamer to 26°. This proves that the present application can effectively regulate the performance of the hyperdispersant by adjusting the raw materials used in the preparation of the hyperdispersant, thereby improving the dispersion effect and avoiding excessive agglomeration of silicone gel particles during the reaction process, so that the particle size distribution of the final silica anti-caking agent is more uniform, significantly improving its use effect as an anti-caking agent.

[0063] In Example 3.1, the present application adjusted the dosage ratio of PEG-6000 and hyperdispersant. The results showed that the silica anti-caking agent obtained in Example 3.1 had a more moderate oil absorption value and was able to reduce the angle of repose of the non-dairy creamer to 29°. This proves that the present application can effectively improve the growth behavior of silicone gel particles during the reaction process by adjusting the weight ratio of the two, promote the increase of specific surface area, prevent serious agglomeration, and thus obtain silica particles with more uniform particle size.

[0064] In Examples 4.1-4.2, the present application adjusted the reaction temperature. The results showed that the silica anti-caking agent obtained in Example 4.1 had a more moderate oil absorption value and was able to reduce the angle of repose of the non-dairy creamer to 28°. This proved that the present application controlled the reaction temperature to 70°C, which could further optimize the reaction conditions and make the reaction between the water glass solution and carbon dioxide more stable, thereby effectively inhibiting the abnormal growth and agglomeration of the silicone gel particles. This temperature condition helps to form a silica anti-caking agent with uniform particle size distribution and moderate specific surface area, further improving its adsorption performance and anti-caking effect.

[0065] In Examples 5.1-5.2, the present application adjusted the rate of introduction of carbon dioxide. The results showed that the silica anti-caking agent obtained in Example 5.1 had a more moderate oil absorption value and was able to reduce the angle of repose of the non-dairy creamer to 27°, proving that the present application was able to achieve precise control of the carbon dioxide introduction rate during the reaction process, thereby effectively adjusting the gradient of the pH value change of the system, avoiding abnormal growth of silica gel particles caused by drastic changes in pH in local solutions, and ensuring that the generated silica gel particles were more evenly distributed, thereby obtaining a silica anti-caking agent with suitable particle size and significantly reduced agglomeration.

[0066] In comparative examples 1.1-1.3, the present application replaced different hyperdispersants, and the results showed that the angles of repose of the non-dairy creamer were all higher than 35°, and the rate of change of the angle of repose in 6 months was not less than 15.38%, proving that the synergistic effect of PEG-6000 and the hyperdispersant in the dispersant used in the present application further improved the structural stability of the product, so that the final silica anti-caking agent has excellent anti-caking properties, which can better meet the moisture-proof requirements of powdered substances such as food and medicine.

[0067] In comparative examples 2.1-2.2, the present application always maintains a uniform rate for the introduction of carbon dioxide. The results show that the angles of repose of the non-dairy creamer are all higher than 35°, and the rate of change of the angle of repose in 6 months is not less than 17.14%, which proves that the present application can achieve precise control of the rate of carbon dioxide introduction during the reaction process, thereby effectively adjusting the gradient of the pH value change of the system, avoiding the abnormal growth of silicone gel particles caused by the sudden change of pH in the local solution, and ensuring that the generated silicone gel particles are more evenly distributed, thereby obtaining a silica anti-caking agent with suitable particle size and significantly reduced agglomeration.

[0068] In comparative examples 3.1-3.2, the present application adjusted the reaction temperature, and the results showed that the angles of repose of the non-dairy creamer were all higher than 35°, and the rate of change of the angle of repose in 6 months was not less than 17.14%, proving that the present application can further optimize the reaction conditions by controlling the reaction temperature, making the reaction between the water glass solution and carbon dioxide more stable, thereby effectively inhibiting the abnormal growth and agglomeration of the silicone gel particles.

[0069] The embodiments of this specific implementation method are all preferred embodiments of the present application and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A method for preparing a silicon dioxide anticaking agent, characterized in that: The following steps are involved: A dispersant is added to a water glass solution, and then carbon dioxide is introduced into the water glass solution while stirring at a temperature of 50-90° C. at a rate of 150-180 mL / min, and the reaction is continued until the pH in the system decreases to 10-10.

5. The carbon dioxide introduction rate is adjusted to 250-280 mL / min, and the reaction is continued until the pH in the system decreases to 8.5-9. The reaction is stopped, and the solid matter is filtered, washed, and dried to obtain a silica anti-caking agent. The dispersant includes PEG-6000 and a hyperdispersant in a weight ratio of 1:(3-7), The hyperdispersant is prepared by reacting n-butyl methacrylate and an acrylic compound. The acrylic compound is one or more of methacrylic acid, N-isopropylacrylamide, dimethylaminoethyl methacrylate and 2-acrylamide-2-methylpropanesulfonic acid.

2. The preparation method of a silicon dioxide anticaking agent according to claim 1, wherein The modulus of the water glass is 3.

3.

3. The preparation method of a silicon dioxide anticaking agent according to claim 1, wherein The concentration of the water glass solution is 5-8wt%.

4. The preparation method of a silicon dioxide anticaking agent according to claim 1, wherein The amount of the dispersant added is 1.8-2 wt% of the amount of water glass used.

5. The preparation method of a silicon dioxide anticaking agent according to claim 1, wherein The temperature was 70°C.

6. The preparation method of a silicon dioxide anticaking agent according to claim 1, wherein Before the pH in the system dropped to 10-10.5, the carbon dioxide introduction rate was 175 mL / min; after the pH in the system dropped to 10-10.5, the carbon dioxide introduction rate was 270 mL / min.

7. The preparation method of a silicon dioxide anticaking agent according to claim 1, wherein The dispersant includes PEG-6000 and a hyperdispersant in a weight ratio of 1:

4.

8. The preparation method of a silicon dioxide anticaking agent according to claim 1, wherein The acrylic acid compound is N-isopropylacrylamide and 2-acrylamide-2-methylpropanesulfonic acid in a molar ratio of 4:(1-3).

9. A silicon dioxide anticaking agent prepared by the method for preparing the silicon dioxide anticaking agent according to any one of claims 1 to 8, characterized in that: Specific surface area is 346-392m 2 / g, and the oil absorption value is 291-330mL / 100g.

10. An application of a silicon dioxide anticaking agent, characterized in that: The amount of the silicon dioxide anti-caking agent according to claim 9 is 0.07-0.08wt% of the total amount of the powder material.

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