Silica anti-blocking agent and method for its preparation

Abstract

The application relates to the field of silica preparation, and particularly discloses a silica anti-caking agent and a preparation method thereof. A preparation method of a silica anti-caking agent comprises the following steps: adding a dispersing agent into a water glass solution, then stirring and introducing carbon dioxide into the water glass solution at a temperature of 50-90 DEG C, the introduction rate being 150-180 mL / min, the reaction being continued until the pH in the system is reduced to 10-10.5, the carbon dioxide introduction rate being adjusted to 250-280 mL / min, the reaction being continued until the pH in the system is reduced to 8.5-9, the reaction being stopped, the solid substance being filtered, washed, dried, and the silica anti-caking agent with a specific surface area of 346-392 m<2> / g and an oil absorption value of 291-330 mL / 100g being obtained, which can reduce the rest angle of powder substances by more than 43% through test detection, and has very excellent anti-caking capacity. 2 / g, and an oil absorption value of 291-330 mL / 100g, which can reduce the rest angle of powder substances by more than 43% through test detection, and has very excellent anti-caking capacity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silica preparation, and particularly relates to a silica anti-caking agent and a preparation method thereof. BACKGROUND

[0002] Silica has many unique physical properties. Its porous structure and high specific surface area can adsorb moisture and prevent the adhesion of particulate substances, and can solve the caking of products caused by moisture absorption and pressure. At the same time, silica has certain chemical inertness, is safe and non-toxic, and is stable in chemical properties in the pH range of 4-10, and does not participate in the oxidation and hydrolysis reactions of food or drugs. Therefore, silica is often used as an anti-caking agent for powder substances, and has a wide application in table salt, milk powder, instant coffee and animal youngling feed.

[0003] Silica used as an anti-caking agent needs to have a low particle size, a large specific surface area and a suitable oil absorption value, so that the preparation process is required to be higher. At present, the methods for preparing silica include a gas phase method and a precipitation method. The silica prepared by the gas phase method has high purity and structural stability, but it is difficult to control the particle size, the equipment used is relatively precise, and the reaction needs to be completed in a 1500-2000℃ plasma flame, so that the production cost is too high. The silica prepared by the precipitation method has a high specific surface area and high process flexibility, but the preparation process cannot be evenly contacted with the solution during the addition of inorganic acid, which can cause the pH value of the local solution to decrease sharply during the reaction process, so that the local silica gel particles grow rapidly and agglomerate, resulting in that the silica anti-caking agent produced is seriously aggregated. Therefore, how to prepare silica anti-caking agent with suitable particle size, specific surface area and oil absorption value has become a big problem. SUMMARY

[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 application provides a preparation method of a silica anti-caking agent, comprising the following steps: adding a dispersant into a water glass solution, and then introducing carbon dioxide into the water glass solution under stirring at a temperature of 50-90℃, the introduction rate being 150-180 mL / min, the reaction being continued until the pH in the system is reduced to 10-10.5, the introduction rate of carbon dioxide is adjusted to 250-280 mL / min, and the reaction is continued until the pH in the system is reduced to 8.5-9, the reaction is stopped, the solid material is filtered, washed, and dried to obtain the silica anti-caking agent; the dispersant comprises 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, and the acrylic compound is one or more of methacrylic acid, N-isopropyl acrylamide, dimethylaminoethyl methacrylate, and 2-acrylamide-2-methylpropanesulfonic acid.

[0006] By adopting the above technical solution, the application uses the carbonation method to prepare the silica anti-caking agent, accurately controls the introduction rate of carbon dioxide under a specific temperature condition, and combines the dispersant with a specific ratio, so as to effectively inhibit the sharp change of the local pH value in the reaction process, thereby avoiding the abnormal growth and agglomeration of the silica gel particles. In addition, the synergistic effect of PEG-6000 and the hyperdispersant in the used dispersant further improves the structural stability of the product, so that the finally prepared silica anti-caking agent has excellent anti-caking performance and can better meet the moisture-proof needs of powder substances such as food and medicine. The hyperdispersant of the application is prepared by reacting n-butyl methacrylate and an acrylic compound, has good space stabilization effect, has multiple anchoring sites, reduces the particle agglomeration degree in the system in a multi-point adsorption manner, and improves the uniformity of the particle size distribution of the final product.

[0007] In summary, the preparation method of the application as a whole scheme, the steps and parameters cooperate with each other, and the finally prepared silica anti-caking agent has a specific surface area of 346-392 m 2 / g and an oil absorption value of 291-330 mL / 100g, which can reduce the rest angle of the powder substance by more than 43% and control the 6-month rest angle change to be within 14%, and has very excellent anti-caking ability.

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

[0009] By adopting the technical scheme, the modulus of the water glass is controlled to be 3.3, and the particle size and structural characteristics of the silica anti-blocking agent can be effectively controlled. Specifically, the selection of the modulus helps to form more uniform silica gel particles in the subsequent reaction process, and reduces the occurrence of agglomeration, so that the silica anti-blocking agent with a narrower particle size distribution and a more moderate oil absorption value is prepared. This makes the finally prepared anti-blocking agent exhibit more excellent performance in adsorbing moisture and preventing powder substances from blocking.

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

[0011] By adopting the technical scheme, the concentration of the water glass solution is controlled to be in 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 too high concentration and too low concentration, and prevent the reaction efficiency from being reduced and resources from being wasted. Combined with other reaction parameters strictly controlled by the application, the concentration range helps to prepare a silica anti-blocking agent with uniform particle size, high specific surface area and suitable oil absorption value, thereby effectively improving the anti-blocking performance.

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

[0013] By adopting the technical scheme, the addition amount of the dispersant is controlled to be in the range of 1.8-2wt% of the amount of the water glass, so that the dispersion effect of the water glass solution in the preparation process is better, thereby effectively avoiding the agglomeration of silica particles. Combined with the overall scheme, the addition amount, the water glass solution, the carbon dioxide introduction rate and the reaction conditions synergistically ensure that the finally prepared silica anti-blocking agent has a suitable oil absorption value, thereby improving its performance as an anti-blocking agent and effectively preventing powder substances from blocking due to moisture absorption.

[0014] Preferably, the temperature is 70℃.

[0015] By adopting the technical scheme, the reaction temperature is controlled to be 70℃, which can further optimize the reaction conditions, so that the reaction of the water glass solution and the carbon dioxide is more stable, thereby effectively inhibiting the abnormal growth and agglomeration of silica gel particles. The temperature condition helps to form a silica anti-blocking agent with uniform particle size distribution and moderate specific surface area, thereby further improving its adsorption performance and anti-blocking effect.

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

[0017] By adopting the technical scheme, the carbon dioxide feeding rate can be accurately controlled in the reaction process, so as to effectively adjust the gradient of the pH value change of the system. Before the pH value decreases to 10-10.5, the lower feeding rate helps to maintain the slow decrease of the pH value of the system, so as to avoid the abnormal growth of the silica gel particles caused by the sharp change of the pH value of the local solution; after the pH value decreases to 10-10.5, the feeding rate is increased, so as to accelerate the reaction process, and ensure that the generated silica gel particles are more uniformly distributed, and then the silica anti-settling agent with appropriate particle size and significantly reduced agglomeration is prepared.

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

[0019] By adopting the technical scheme, the growth behavior of the silica gel particles in the reaction process can be effectively improved, the specific surface area is promoted, and the serious agglomeration is prevented, so that the silica particles with more uniform particle size are obtained.

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

[0021] By adopting the technical scheme, the silica anti-settling agent prepared has more appropriate particle size, specific surface area and oil absorption value, and the molar ratio of N-isopropyl acrylamide and 2-acrylamide-2-methylpropanesulfonic acid is 4:(1-3), which can effectively regulate the performance of the hyperdispersant, so as to improve the dispersion effect and avoid the excessive agglomeration of the silica gel particles in the reaction process. This makes the finally prepared silica anti-settling agent have more uniform particle size distribution, and significantly improves the use effect as an anti-settling agent.

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

[0023] By adopting the technical scheme, the silica anti-caking agent prepared by the 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 the temperature, stirring, and the staged carbon dioxide feeding rate, the problem of particle agglomeration of silica gel caused by the sharp change of local pH value is effectively avoided, so that silica particles with uniform particle size distribution are obtained. At the same time, by adding dispersants with specific proportions and compositions, the particle agglomeration phenomenon is further inhibited, and the high specific surface area characteristics of the final product are ensured. In addition, the accurate regulation of various parameters during preparation makes the oil absorption value of the silica anti-caking agent in the ideal range, so that it can fully play the role of adsorbing moisture and preventing the caking of powder materials when used as an anti-caking agent, and meet the application requirements in the fields of food, medicine, etc.

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

[0025] By adopting the above technical scheme, the amount of the silica anti-caking agent of the application is accurately controlled to be 0.07-0.08wt% of the total amount of the powder material, which can ensure the anti-caking effect while avoiding the increase in cost and possible negative effects caused by excessive use. The silica anti-caking agent in the amount range can effectively adsorb moisture and prevent the caking of powder materials due to moisture absorption and pressure, and at the same time, due to its high specific surface area and suitable oil absorption value, it can be uniformly dispersed in the powder to improve the flowability of the powder without affecting other physical and chemical properties of the powder.

[0026] In summary, the application has the following beneficial technical effects:

[0027] 1. The preparation method of the application effectively inhibits the agglomeration of silica gel particles by adding dispersants with specific proportions in the water glass solution and controlling the feeding rate of carbon dioxide and the change of reaction pH value. By adopting the method of staged regulation of the carbon dioxide feeding rate, the pH value of the reaction system is ensured to decrease smoothly, and the abnormal growth of particles caused by the sharp change of local pH value is avoided, so that the silica anti-caking agent with a high specific surface area, uniform particle size distribution, and suitable oil absorption value is finally obtained;

[0028] 2. The silica anti-caking agent prepared by the application has a high specific surface area and a suitable oil absorption value, and the specific surface area is 346-392m 2 / g, and the oil absorption value is 291-330mL / 100g

[0029] 3. The amount of silica anti-caking agent used in the present application is precisely controlled at 0.07-0.08wt% of the total amount of powder material, which can ensure the anti-caking effect while avoiding the cost increase and possible negative effects caused by excessive use, effectively adsorbing moisture and preventing the powder material from caking due to moisture absorption and pressure, and at the same time, due to its high specific surface area and suitable oil absorption value, it can be uniformly dispersed in the powder, improving the flowability of the powder without affecting other physical and chemical properties of the powder. DETAILED DESCRIPTION

[0030] Material sources

[0031] The raw materials used in the present application are all commercially available products, except for special instructions, which are as follows:

[0032] n-Butyl methacrylate, CAS number 97-88-1;

[0033] Methacrylic acid, CAS number 79-41-4;

[0034] N-Isopropyl acrylamide, CAS number 2210-25-5;

[0035] Dimethylaminoethyl methacrylate, CAS number 2867-47-2;

[0036] 2-Acrylamido-2-methylpropanesulfonic acid, CAS number 15214-89-8;

[0037] Methyl methacrylate stearate, CAS number 32360-05-7;

[0038] Isocetyl methacrylate, CAS number 28675-80-1;

[0039] Ethyl methacrylate, CAS number 97-63-2;

[0040] PEG-6000, CAS number 25322-68-3;

[0041] Water glass, modulus 3.3;

[0042] Carbon dioxide, purity 99.9%;

[0043] Plant fat powder, purchased from Shaanxi Chenming Biotechnology Co., Ltd., moisture content ≤5g / 100g.

[0044] The present application is further described in detail below in combination with preparation examples, examples and comparative examples.

[0045] Preparation example 1.1

[0046] The preparation method of the hyperdispersant includes the following steps:

[0047] 1 mol of n-butyl methacrylate, 1 mol of acrylic acid 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. The solution was then transferred to an argon-purified reaction apparatus equipped with a diaphragm and subjected to three freeze-thaw cycles. The reaction was carried out at 60 °C for 16 h. Subsequently, the reaction solution was added dropwise to an appropriate amount of methanol to precipitate the product, which was then collected by centrifugation. The supernatant was discarded, and the product was dissolved in chloroform. Then, it was precipitated 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 h to obtain a superdispersant.

[0048] Preparation Example 1.2

[0049] The preparation method of the superdispersant includes the following steps:

[0050] 1 mol of n-butyl methacrylate, 1 mol of acrylic acid 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. The solution was then transferred to an argon-purified reaction apparatus equipped with a diaphragm and subjected to three freeze-thaw cycles. The reaction was carried out at 60 °C for 16 h. Subsequently, the reaction solution was added dropwise to an appropriate amount of methanol to precipitate the product, which was then collected by centrifugation. The supernatant was discarded, and the product was dissolved in chloroform. Then, it was precipitated 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 h to obtain a superdispersant.

[0051] Preparation Example 1.3

[0052] The preparation method of the superdispersant includes the following steps:

[0053] 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-purified reaction apparatus equipped with a diaphragm. Three freeze-thaw cycles were performed, and the reaction was carried out at 60 °C for 16 h. Subsequently, the reaction solution was added dropwise to an appropriate amount of methanol to precipitate the product, and centrifuged to collect the product. The supernatant was discarded, and the product was dissolved in chloroform. Then, it was precipitated with methanol. The above operation was repeated 3 times to obtain a pure product. Finally, the product was dried in a vacuum oven at 70 °C for 24 h to obtain a superdispersant.

[0054] Preparation Example 1.4

[0055] The preparation method of the superdispersant includes the following steps:

[0056] 1 mol of n-butyl methacrylate, 1 mol of acrylic acid 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, and then transferred to an argon-purified reaction apparatus equipped with a diaphragm. Three freeze-thaw cycles were performed, and the reaction was carried out at 60 °C for 16 h. Subsequently, the reaction solution was added dropwise to an appropriate amount of methanol to precipitate the product, and centrifuged to collect the product. The supernatant was discarded, and the product was dissolved in chloroform, followed by precipitation with methanol. The above operation was repeated 3 times to obtain a pure product. Finally, the product was dried in a vacuum oven at 70 °C for 24 h to obtain a superdispersant.

[0057] Preparation Example 1.5

[0058] The preparation method of the superdispersant includes the following steps:

[0059] 1 mol of n-butyl methacrylate, 1 mol of acrylic acid compounds (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, and then transferred to an argon-purified reaction apparatus equipped with a diaphragm. Three freeze-thaw cycles were performed, and the reaction was carried out at 60 °C for 16 h. Subsequently, the reaction solution was added dropwise to an appropriate amount of methanol to precipitate the product, and centrifuged to collect the product. The supernatant was discarded, and the product was dissolved in chloroform, followed by precipitation with methanol. The above operation was repeated 3 times to obtain a pure product. Finally, the product was dried in a vacuum oven at 70 °C for 24 h to obtain a superdispersant.

[0060] Preparation Example 1.6

[0061] The preparation method of the superdispersant includes the following steps:

[0062] 1 mol of n-butyl methacrylate, 1 mol of acrylic acid 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, and then transferred to an argon-purified reaction apparatus equipped with a diaphragm. Three freeze-thaw cycles were performed, and the reaction was carried out at 60 °C for 16 h. Subsequently, the reaction solution was added dropwise to an appropriate amount of methanol to precipitate the product, and centrifuged to collect the product. The supernatant was discarded, and the product was dissolved in chloroform, followed by precipitation with methanol. The above operation was repeated 3 times to obtain a pure product. Finally, the product was dried in a vacuum oven at 70 °C for 24 h to obtain a superdispersant.

[0063] Preparation Example 2.1

[0064] The preparation method of the superdispersant differs from that of Preparation Example 1.5 in that the molar ratio of N-isopropylacrylamide and 2-acrylamide-2-methylpropanesulfonic acid is 4:1, while the rest are the same as in Preparation Example 1.5.

[0065] Preparation Example 2.2

[0066] The preparation method of the hyperdispersant is different from that of Preparation Example 1.5 in that the molar ratio of N-isopropyl acrylamide and 2-acrylamido-2-methylpropanesulfonic acid is 4:3, and the rest is the same as that of Preparation Example 1.5.

[0067] Preparation Example 2.3

[0068] The preparation method of the hyperdispersant is different from that of Preparation Example 1.5 in that the molar ratio of N-isopropyl acrylamide and 2-acrylamido-2-methylpropanesulfonic acid is 1:4, and the rest is the same as that of Preparation Example 1.5.

[0069] Comparative Preparation Example 1.1

[0070] The preparation method of the hyperdispersant is different from that of Preparation Example 1.1 in that n-butyl methacrylate is replaced by stearyl methacrylate, and the rest is the same as that of Preparation Example 1.1.

[0071] Comparative Preparation Example 1.2

[0072] The preparation method of the hyperdispersant is different from that of Preparation Example 1.1 in that n-butyl methacrylate is replaced by isooctyl methacrylate, and the rest is the same as that of Preparation Example 1.1.

[0073] Comparative Preparation Example 1.3

[0074] The preparation method of the hyperdispersant is different from that of Preparation Example 1.1 in that n-butyl methacrylate is replaced by ethyl methacrylate, and the rest is the same as that of Preparation Example 1.1.

[0075] Example 1.1

[0076] A preparation method of a silica anti-caking agent, comprising the following steps:

[0077] Into a 10L water glass solution with a concentration of 5wt%, 10g dispersant (1.25g PEG-6000 and 8.75g hyperdispersant prepared in Preparation Example 1.1) was added, and then carbon dioxide was introduced into the water glass solution under the condition of a temperature of 90℃ while stirring, and the introduction rate was 150mL / min. The reaction was continued until the pH in the system was reduced to 10.5, the carbon dioxide introduction rate was adjusted to 250mL / min, and the reaction was continued until the pH in the system was reduced to 9. The reaction was stopped, and the solid material was filtered, washed, and dried to obtain a silica anti-caking agent.

[0078] Example 1.2

[0079] A preparation method of a silica anti-caking agent, comprising the following steps:

[0080] To 10 L of 8 wt% water glass solution, 14.4 g dispersant (3.6 g PEG-6000 and 10.8 g of the hyperdispersant prepared in Preparation Example 1.2) was added, then carbon dioxide was bubbled into the water glass solution at a temperature of 50 °C while stirring, the rate of carbon dioxide bubbling was 180 mL / min, the reaction was continued until the pH of the system was reduced to 10, the rate of carbon dioxide bubbling was adjusted to 280 mL / min, and the reaction was continued until the pH of the system was reduced to 8.5, the reaction was stopped, the solid material was filtered, washed, and dried to obtain a silica anti-caking agent.

[0081] Examples 1.3-1.6

[0082] A method for preparing a silica anti-caking agent, which is different 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.

[0083] Examples 2.1-2.3

[0084] A method for preparing a silica anti-caking agent, which is different 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.

[0085] Example 3.1

[0086] A method for preparing a silica anti-caking agent, which is different from Example 1.1 in that the amount of PEG-6000 is 2 g, and the amount of the hyperdispersant prepared in Preparation Example 1.1 is 8 g, and the rest is the same as Example 1.1.

[0087] Example 3.2

[0088] A method for preparing a silica anti-caking agent, which is different from Example 1.1 in that the amount of PEG-6000 is 1.67 g, and the amount of the hyperdispersant prepared in Preparation Example 1.1 is 8.33 g, and the rest is the same as Example 1.1.

[0089] Example 3.3

[0090] A method for preparing a silica anti-caking agent, which is different from Example 1.1 in that the amount of PEG-6000 is 1.25 g, and the amount of the hyperdispersant prepared in Preparation Example 1.1 is 8.75 g, and the rest is the same as Example 1.1.

[0091] Example 4.1

[0092] A method for preparing a silica anti-caking agent, which is different from Example 1.1 in that the temperature is 70 °C, and the rest is the same as Example 1.1.

[0093] Example 4.2

[0094] A preparation method of the silica anti-caking agent, which is different from example 1.1 in that the temperature is 50℃, and the rest is the same as example 1.1.

[0095] Example 5.1

[0096] A preparation method of the silica anti-caking agent, which is different from example 1.1 in that the carbon dioxide input rate is 175mL / min before the pH in the system is reduced to 10.5, and the carbon dioxide input rate is 270mL / min after the pH in the system is reduced to 10.5, and the rest is the same as example 1.1.

[0097] Example 5.2

[0098] A preparation method of the silica anti-caking agent, which is different from example 1.1 in that the carbon dioxide input rate is 165mL / min before the pH in the system is reduced to 10.5, and the carbon dioxide input rate is 260mL / min after the pH in the system is reduced to 10.5, and the rest is the same as example 1.1.

[0099] Comparative example 1.1-1.3

[0100] Different from example 1.1 in that the hyperdispersant prepared in preparation example 1.1 is replaced by the hyperdispersant prepared in comparative preparation example 1.1-1.3 respectively, and the rest is the same as example 1.1.

[0101] Comparative example 2.1

[0102] Different from example 1.1 in that the carbon dioxide input rate is always maintained at 150mL / min until the pH in the system is reduced to 9, and the rest is the same as example 1.1.

[0103] Comparative example 2.2

[0104] Different from example 1.1 in that the carbon dioxide input rate is always maintained at 250mL / min until the pH in the system is reduced to 9, and the rest is the same as example 1.1.

[0105] Comparative example 3.1

[0106] Different from example 1.1 in that the temperature is 40℃, and the rest is the same as example 1.1.

[0107] Comparative example 3.2

[0108] Different from example 1.1 in that the temperature is 90℃, and the rest is the same as example 1.1.

[0109] Application example 1

[0110] Put 0.7 g of the silica anti-caking agent obtained in Example 1.1 into 1 kg of vegetable fat powder, and mix evenly to obtain low-caking vegetable fat powder.

[0111] Application Example 2

[0112] Put 0.8 g of the silica anti-caking agent obtained in Example 1.2 into 1 kg of vegetable fat powder, and mix evenly to obtain low-caking vegetable fat powder.

[0113] Application Example 3-23

[0114] Put 0.7 g of the silica anti-caking agent obtained in Example 1.3-Comparative Example 3.2 into 1 kg of vegetable fat powder, and mix evenly to obtain low-caking vegetable fat powder.

[0115] Performance test

[0116] 1. The silica anti-caking agents obtained in the examples and comparative examples were detected and analyzed, and the specific surface area (m 2 / g) and oil absorption value (mL / 100 g) were recorded;

[0117] 2. According to the description in GB / T 16913-2008, the first-day repose angle of the vegetable fat powder and the repose angle of the low-caking vegetable fat powder obtained in the application examples at the 6th month were determined, and the 6-month repose angle of the vegetable fat powder without adding the silica anti-caking agent was taken as a blank control.

[0118] Table 1 test results

[0119]

[0120]

[0121] Data analysis:

[0122] As can be seen from Table 1, the specific surface area of the silica anti-caking agents prepared in Examples 1.1-1.6 of the present application is 346-392 m2 / g, the oil absorption value is 291-330 mL / 100 g, the initial repose angle of the vegetable fat powder can be reduced by more than 41.5%, and after being stored for half a year, the repose angle of the vegetable fat powder can still be maintained to be not more than 35°, and the repose angle change rate is also not more than 14%, which proves that the preparation method of the present application as a whole scheme, the steps and parameters cooperate with each other, effectively inhibit the agglomeration phenomenon of the silica gel particles, ensure the stable decrease of the pH value of the reaction system, avoid the abnormal growth of the particles caused by the sharp change of the local pH value, and ultimately obtain the silica anti-caking agent with high specific surface area, uniform particle size distribution and suitable oil absorption value.

[0123] In Examples 2.1-2.3, different hyperdispersants were used, and the results showed that the silica anti-caking agent obtained in Example 2.1 had a more moderate oil absorption value, and at the same time, the static angle of the plant stearin was reduced to 26°, proving that by adjusting the raw materials used in the preparation of the hyperdispersant, the performance of the hyperdispersant can be effectively controlled, thereby improving the dispersion effect, avoiding excessive agglomeration of silica gel particles during the reaction process, and making the particle size distribution of the finally prepared silica anti-caking agent more uniform, significantly improving its use effect as an anti-caking agent.

[0124] In Example 3.1, the weight ratio of PEG-6000 and hyperdispersant was adjusted, and the results showed that the silica anti-caking agent obtained in Example 3.1 had a more moderate oil absorption value, and at the same time, the static angle of the plant stearin was reduced to 29°, proving that by adjusting the weight ratio of the two, the growth behavior of silica gel particles during the reaction process can be effectively improved, promoting the increase of the specific surface area, preventing severe agglomeration, and thereby obtaining silica particles with more uniform particle size.

[0125] In Examples 4.1-4.2, the reaction temperature was adjusted, and the results showed that the silica anti-caking agent obtained in Example 4.1 had a more moderate oil absorption value, and at the same time, the static angle of the plant stearin was reduced to 28°, proving that by controlling the reaction temperature to 70°C, the reaction conditions can be further optimized, making the reaction of water glass solution and carbon dioxide more stable, thereby effectively inhibiting the abnormal growth and agglomeration of silica gel particles, and this temperature condition is helpful 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.

[0126] In Examples 5.1-5.2, the carbon dioxide introduction rate was adjusted, and the results showed that the silica anti-caking agent obtained in Example 5.1 had a more moderate oil absorption value, and at the same time, the static angle of the plant stearin was reduced to 27°, proving that the carbon dioxide introduction rate can be precisely controlled during the reaction process, thereby effectively adjusting the gradient of pH value change in the system, avoiding the abnormal growth of silica gel particles caused by the sharp change of local solution pH, and at the same time, ensuring that the generated silica gel particles are more uniformly distributed, and thereby obtaining a silica anti-caking agent with appropriate particle size and significantly reduced agglomeration.

[0127] In Comparative Examples 1.1-1.3, different hyperdispersants were used, and the results showed that the static angle of the plant stearin was all higher than 35°, and the static angle change rate after 6 months was also not less than 15.38%, proving that the synergistic effect of PEG-6000 and hyperdispersant in the dispersant used by the present application further improves the structural stability of the product, making the finally prepared silica anti-caking agent have excellent anti-caking performance, and better meeting the moisture-proof needs of powder substances such as food and medicine.

[0128] In Comparative Examples 2.1-2.2, the application maintained a uniform rate of carbon dioxide input, and the results showed that the angle of repose of the groundnut kernel was all higher than 35°, and the 6-month angle of repose change rate was not less than 17.14%, proving that the application can achieve precise control of the carbon dioxide input rate during the reaction, thereby effectively adjusting the gradient of the pH value change of the system, avoiding abnormal growth of the silica gel particles due to the sharp change of the local solution pH, while ensuring that the generated silica gel particles are more uniformly distributed, thereby preparing a silica anti-blocking agent with appropriate particle size and significantly reduced agglomeration.

[0129] In Comparative Examples 3.1-3.2, the application adjusted the reaction temperature, and the results showed that the angle of repose of the groundnut kernel was all higher than 35°, and the 6-month angle of repose change rate was not less than 17.14%, proving that the application can further optimize the reaction conditions by controlling the reaction temperature, making the reaction of the water glass solution and carbon dioxide more stable, thereby effectively inhibiting the abnormal growth of the silica gel particles and the agglomeration phenomenon.

[0130] The examples of the specific embodiment are the preferred examples of the application, but do not limit the protection scope of the application, so: any equivalent changes made in accordance with the structure, shape, principle of the application should be covered within the protection scope of the application.

Claims

1. A method for preparing a silica anti-blocking agent, characterized by, The method comprises the following steps: The dispersant is added into the water glass solution, and then carbon dioxide is bubbled into the water glass solution at a temperature of 50-90℃ and a rate of 150-180 mL / min, and the reaction is continued until the pH in the system is reduced to 10-10.5, the rate of carbon dioxide bubbling is adjusted to 250-280 mL / min, and the reaction is continued until the pH in the system is reduced to 8.5-9, the reaction is stopped, and the solid substance is obtained by filtration, washing, and drying to obtain the silica anti-caking agent; The dispersant comprises PEG-6000 and a hyperdispersant at a weight ratio of 1: (3-7), The hyperdispersant is prepared by reacting n-butyl methacrylate and an acrylic compound, and the acrylic compound is one or more of methacrylic acid, N-isopropyl acrylamide, dimethylaminoethyl methacrylate, and 2-acrylamide-2-methylpropanesulfonic acid; The preparation method of the hyperdispersant comprises the following steps: 1 mol of n-butyl methacrylate, 1 mol of an acrylic compound, and 0.002 mol of azobisisobutyronitrile are dissolved in 1 L of tetrahydrofuran, and then transferred into an argon-purified reaction device equipped with a diaphragm, subjected to three freeze-thaw cycles, reacted at 60℃ for 16 h, and then precipitated dropwise into an appropriate amount of methanol and collected by centrifugation, and then dissolved in chloroform, precipitated in methanol, and repeated the above operation 3 times to obtain a pure product, and finally dried in a vacuum oven at 70℃ for 24 h to obtain the hyperdispersant.

2. The method of claim 1, wherein the silica anti-blocking agent is prepared by the steps of: The modulus of the water glass is 3.

3.

3. The method for preparing a silica anti-caking agent according to claim 1, characterized in that, The concentration of the water glass solution is 5-8 wt%.

4. The method for preparing a silica anti-caking agent according to claim 1, characterized in that, The amount of the dispersant added is 1.8-2 wt% of the amount of the water glass.

5. The method for preparing a silica anti-caking agent according to claim 1, characterized in that, The temperature is 70℃.

6. The method of claim 1, wherein the silica anti-blocking agent is prepared by the steps of: The rate of carbon dioxide bubbling is 175 mL / min before the pH in the system is reduced to 10-10.5, and the rate of carbon dioxide bubbling is 270 mL / min after the pH in the system is reduced to 10-10.

5.

7. The method for preparing a silica anti-caking agent according to claim 1, characterized in that, The dispersant comprises PEG-6000 and a hyperdispersant at a weight ratio of 1:

4.

8. The method for preparing a silica anti-caking agent according to claim 1, characterized in that, The acrylic compound is N-isopropyl acrylamide and 2-acrylamide-2-methylpropanesulfonic acid at a molar ratio of 4: (1-3).

9. A silica anti-blocking agent produced by the method of producing a silica anti-blocking agent according to any one of claims 1 to 8, characterized by, The specific surface area is 346-392 m 2 / g, and the oil absorption number is 291-330 mL / 100 g.

10. Use of a silica anti-blocking agent, characterized in that, The amount of the silica anti-caking agent is 0.07-0.08 wt% of the total amount of the powder substance.

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