Dolomite-based anti-caking agent as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of preparation of anti-blocking agents, and discloses a dolomite-based anti-blocking agent as well as a preparation method and application thereof. The preparation method comprises the following steps: modifying wollastonite powder and a first modifier solution to obtain modified wollastonite powder; modifying calcium carbonate powder and a second modifier solution to obtain modified calcium carbonate powder; and mixing dolomite powder, brucite powder, modified wollastonite powder and modified calcium carbonate powder to obtain the dolomite-based anti-caking agent. The dolomite-based anti-blocking agent is prepared by compounding four powders of dolomite, brucite, wollastonite and light calcium carbonate according to a reasonable filler compounding ratio and surface modification treatment, and the dolomite-based anti-blocking agent is applied to redispersible latex powder, so that compared with a traditional anti-blocking agent, the anti-blocking agent has the advantages that the anti-blocking effect is good, and the anti-blocking effect is good. The indexes such as anti-caking performance, blanking and low ash content of the product can be effectively considered, and the market requirements are met.

Description

Technical Field

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

[0002] Redispersible latex powder is a water-soluble redispersible powder, which is divided into ethylene / vinyl acetate copolymer, vinyl acetate / versatate copolymer, acrylic copolymer, etc. The redispersible latex powder adhesive prepared by spray drying uses polyvinyl alcohol as a protective colloid and can be quickly redispersed into an emulsion after contact with water. Due to the high bonding ability and unique properties of redispersible latex powder, it is widely used in construction putty, mortar, waterproof coatings, tile adhesives and other fields.

[0003] However, redispersible latex powders are susceptible to extrusion during transportation and storage, leading to clumping of the latex powder. This prevents it from being fully redispersed and achieving the desired performance in downstream applications. Therefore, anti-caking agents are added during production to effectively mitigate the potential clumping of latex powders during transportation and storage. Currently, the main anti-caking agents used are mineral fillers such as calcium carbonate, kaolin, silica fume, and talc. However, if the amount of these mineral filler anti-caking agents added is too low, the anti-caking performance will be insignificant, and product dispensing may also be problematic. If the amount added is too high, the ash content of the finished latex powder may exceed the standard, failing to meet industry standards.

[0004] Therefore, a dolomite-based anti-caking agent with excellent anti-caking performance and low ash content, as well as its preparation method and application are of great significance. Summary of the Invention

[0005] In view of this, the present invention provides a dolomite-based anti-caking agent and a preparation method and application thereof, the purpose of which is to solve the problems of poor anti-caking performance, difficult feeding, high ash content, etc. of existing anti-caking agents.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a method for preparing a dolomite-based anti-caking agent, comprising the following steps: 1) Modifying wollastonite powder with a first modifier solution to obtain modified wollastonite powder; 2) Modifying the calcium carbonate powder with a second modifier solution to obtain modified calcium carbonate powder; 3) mixing dolomite powder, brucite powder, modified wollastonite powder and modified calcium carbonate powder to obtain a dolomite-based anti-caking agent; There is no order of precedence for step 1) and step 2).

[0007] Preferably, in step 1), the first modifier solution comprises a first modifier and water, and the mass ratio of the first modifier to water is 2 to 4:1; The first modifier is a co-hydrolyzed oligomer of alkylsilane and aminosilane and polyethylene glycol, and the mass ratio of the co-hydrolyzed oligomer of alkylsilane and aminosilane to polyethylene glycol is 3-4:1.

[0008] Preferably, in step 1), the D50 of the wollastonite powder is 9-10 μm; The mass ratio of wollastonite powder to the first modifier is 1000:3~5.

[0009] Preferably, in step 2), the second modifier solution includes a second modifier and water, and the mass ratio of the second modifier to water is 2 to 4:1; The second modifier is bistriethanolamine diisopropyl titanate and bis(acetylacetonate) diisopropyl titanate, and the mass ratio of bistriethanolamine diisopropyl titanate to bis(acetylacetonate) diisopropyl titanate is 1:2-3.

[0010] Preferably, in step 2), the mass ratio of calcium carbonate powder to the second modifier is 1000:5-7.

[0011] Preferably, in step 1) and step 2), the speed of modification is independently 800-1000 rpm, the temperature of modification is independently 80-90° C., and the time of modification is independently 20-30 min.

[0012] Preferably, in step 3), the mass ratio of dolomite powder, brucite powder, modified wollastonite powder and modified calcium carbonate powder is 9-11:1-3:1-2:1.

[0013] Preferably, in step 3), mixing comprises hot mixing and cold mixing performed sequentially; The heat mixing temperature is 40-50°C, the heat mixing speed is 1000-1200 rpm, and the heat mixing time is 40-60 min; The rotation speed of the cold mixing is 200-300 rpm, and the cold mixing time is 10-20 minutes.

[0014] The present invention also provides a dolomite-based anti-caking agent prepared by the method for preparing the dolomite-based anti-caking agent.

[0015] The present invention also provides use of the dolomite-based anti-caking agent in redispersible latex powder.

[0016] It can be seen from the above technical solutions that compared with the prior art, the present invention has the following beneficial effects: The present invention adopts four powders of dolomite, brucite, wollastonite and light calcium carbonate for compounding, and prepares a dolomite-based anti-caking agent through reasonable filler compounding ratio and surface modification treatment. The dolomite-based anti-caking agent is applied to redispersible latex powder. Compared with traditional anti-caking agents, the anti-caking performance, material handling and low ash content of the product can be effectively taken into account, thus meeting market demand.

[0017] The present invention uses dolomite as the main component of the anti-caking agent and utilizes the advantage of dense particles of dolomite powder to improve the feeding performance of latex powder. At the same time, since the decomposition temperature of magnesium carbonate in dolomite is lower than that of calcium carbonate, and the ash content of magnesium oxide is lower than that of calcium oxide, it is beneficial to reduce the ash content of the finished latex powder. By adding flaky brucite powder and needle-shaped wollastonite powder with a high aspect ratio, excellent dimensional stabilization effect is provided to improve the anti-caking performance. The spindle-shaped light calcium carbonate provides sufficient porosity to reduce the agglomeration between latex powder particles, thereby further improving the anti-caking performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0019] Figure 1 The figure is a schematic diagram of the process flow of the preparation method of the dolomite-based anti-caking agent of the present invention. DETAILED DESCRIPTION

[0020] The present invention provides a method for preparing a dolomite-based anti-caking agent, comprising the following steps: 1) Modifying wollastonite powder with a first modifier solution to obtain modified wollastonite powder; 2) Modifying the calcium carbonate powder with a second modifier solution to obtain modified calcium carbonate powder; 3) mixing dolomite powder, brucite powder, modified wollastonite powder and modified calcium carbonate powder to obtain a dolomite-based anti-caking agent; There is no order of precedence for step 1) and step 2).

[0021] In the present invention, dolomite powder is obtained by sequentially grinding and classifying dolomite ore; the magnesium oxide content of the dolomite ore is preferably greater than 19wt%, more preferably greater than 22wt%, and more preferably greater than 24wt%; the grinding is preferably performed by a ring roller mill, and the classification is preferably air flow classification; the D50 of the dolomite powder is preferably 7-7.5μm, more preferably 7.1-7.4μm, and more preferably 7.2-7.3μm, and the D97 of the dolomite powder is preferably 14.5-15.5μm, more preferably 14.7-15.2μm, and more preferably 14.8-15μm.

[0022] In the present invention, the dolomite powder particles are dense, which is beneficial to the feeding of latex powder when used as an anti-caking agent. At the same time, since the decomposition temperature of magnesium carbonate in dolomite is lower than that of calcium carbonate, and the ash content of magnesium oxide is lower than that of calcium oxide, it is beneficial to reduce the ash content of the finished latex powder.

[0023] In the present invention, the brucite powder is obtained by sequentially grinding and classifying brucite concentrate; the magnesium oxide content of the brucite concentrate is preferably greater than 63wt%, more preferably greater than 65wt%, and more preferably greater than 69wt%; the diameter-to-thickness ratio is preferably greater than 30:1, more preferably greater than 35:1, and more preferably greater than 38:1; the grinding is preferably performed by a ring roller mill, and the classification is preferably air flow classification; the D50 of the brucite powder is preferably 5.5-6.5μm, more preferably 5.7-6.4μm, and more preferably 6-6.2μm; the D97 of the brucite powder is preferably 26-28μm, more preferably 26.5-27.5μm, and more preferably 27-27.2μm.

[0024] In the present invention, the brucite powder with a heterogeneous flaky structure has good dimensional stability, can generate sufficient gaps between the rubber powder particles, reduce the agglomeration of the rubber powder particles, and effectively improve the anti-caking performance. At the same time, since the decomposition temperature of brucite is relatively low, it helps to reduce the ash content of the product.

[0025] In the present invention, in step 1), the first modifier solution preferably includes a first modifier and water, and the mass ratio of the first modifier to water is preferably 2-4:1, more preferably 2.5-3.5:1, and more preferably 3-3.2:1; The first modifier is preferably a co-hydrolyzed oligomer of alkylsilane and aminosilane and polyethylene glycol, and the mass ratio of the co-hydrolyzed oligomer of alkylsilane and aminosilane to polyethylene glycol is preferably 3-4:1, more preferably 3.2-3.8:1, and more preferably 3.5-3.6:1.

[0026] In the present invention, in step 1), the D50 of the wollastonite powder is preferably 9-10 μm, more preferably 9.2-9.8 μm, and more preferably 9.4-9.5 μm; The mass ratio of wollastonite powder to the first modifier is preferably 1000:3-5, more preferably 1000:3.5-4.5, and even more preferably 1000:4-4.2.

[0027] In the present invention, wollastonite powder is obtained by grinding and classifying wollastonite concentrate through a jet mill; the silicon dioxide content of the wollastonite concentrate is preferably >51wt%, more preferably >53wt%, and more preferably >55wt%, and the aspect ratio is preferably >15:1, more preferably >17:1, and more preferably >20:1.

[0028] In the present invention, wollastonite with a high aspect ratio has a significant dimensional stability effect, and is compounded with flaky brucite powder to increase the porosity and further improve the anti-caking effect of the product.

[0029] In the present invention, in step 2), the second modifier solution preferably includes a second modifier and water, and the mass ratio of the second modifier to water is preferably 2-4:1, more preferably 2.5-3.5:1, and more preferably 3-3.2:1; The second modifier is preferably bistriethanolamine diisopropyl titanate and bis(acetylacetonate) diisopropyl titanate, and the mass ratio of bistriethanolamine diisopropyl titanate to bis(acetylacetonate) diisopropyl titanate is preferably 1:2-3, more preferably 1:2.2-2.8, and more preferably 1:2.4-2.6.

[0030] In the present invention, in step 2), the mass ratio of calcium carbonate powder to the second modifier is preferably 1000:5-7, more preferably 1000:5.5-6.5, and even more preferably 1000:6-6.2.

[0031] In the present invention, the calcium carbonate powder is preferably light calcium carbonate powder, and the oil absorption of the light calcium carbonate powder is preferably 60-70 mL / 100 g, more preferably 62-68 mL / 100 g, and more preferably 64-66 mL / 100 g. The sedimentation volume of the light calcium carbonate powder is preferably >3 mL / g, more preferably >3.2 mL / g, and more preferably >3.8 mL / g.

[0032] In the present invention, the crystal morphology of the calcium carbonate powder is spindle-shaped light calcium carbonate, which has the advantages of fluffy particles and low apparent specific gravity. As an anti-caking auxiliary additive, it can further improve the anti-caking performance.

[0033] In the present invention, the fluidity of light calcium carbonate is improved through modification treatment, thereby avoiding the influence of the light calcium carbonate particles on the discharge of the product due to the characteristics of the light calcium carbonate particles being fluffy and having a large oil absorption capacity.

[0034] In the present invention, in step 1) and step 2), the modification speed is independently preferably 800-1000 rpm, more preferably 850-950 rpm, and more preferably 880-900 rpm; the modification temperature is independently preferably 80-90° C., more preferably 82-88° C., and more preferably 85-86° C.; and the modification time is independently preferably 20-30 min, more preferably 22-28 min, and more preferably 25-26 min.

[0035] In the present invention, in step 3), the mass ratio of dolomite powder, brucite powder, modified wollastonite powder and modified calcium carbonate powder is preferably 9-11:1-3:1-2:1, more preferably 9.5-10.5:1.5-2.5:1.2-1.8:1, and more preferably 9.8-10:2-2.2:1.5-1.7:1.

[0036] In the present invention, in step 3), mixing comprises hot mixing and cold mixing performed sequentially; The heat mixing temperature is preferably 40-50°C, more preferably 42-48°C, more preferably 43-46°C, the heat mixing speed is preferably 1000-1200 rpm, more preferably 1050-1180 rpm, more preferably 1100-1150 rpm, and the heat mixing time is preferably 40-60 min, more preferably 45-55 min, more preferably 48-52 min; The cold mixing speed is preferably 200-300 rpm, more preferably 220-280 rpm, more preferably 240-260 rpm, and the cold mixing time is preferably 10-20 min, more preferably 12-18 min, more preferably 14-16 min.

[0037] In the present invention, the mixing in step 3) is preferably performed by first mixing the dolomite powder, brucite powder and modified wollastonite powder, and then adding the modified calcium carbonate powder for secondary mixing; In the primary mixing and the secondary mixing, the mixing temperature is independently preferably 0-50° C., more preferably 42-48° C., more preferably 43-46° C., the mixing speed is independently preferably 1000-1200 rpm, more preferably 1050-1180 rpm, more preferably 1100-1150 rpm, and the mixing time is independently preferably 20-30 min, more preferably 22-28 min, more preferably 24-26 min.

[0038] In the present invention, in step 3), after cold mixing, collection, screening, testing and packaging are carried out in sequence; The sieving is preferably performed through a 200 mesh sieve.

[0039] The present invention also provides a dolomite-based anti-caking agent prepared by the method for preparing the dolomite-based anti-caking agent.

[0040] The present invention also provides use of the dolomite-based anti-caking agent in redispersible latex powder.

[0041] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0042] In the present invention, the emulsion is a styrene acrylic emulsion, 998A, purchased from Badful Group Co., Ltd.; white carbon black is purchased from Evonik Specialty Chemicals (Shanghai) Co., Ltd., model M-5; heavy calcium carbonate is produced from Lianzhou Guangyuan Calcium Carbonate Co., Ltd., model CC-800, metakaolin is purchased from Jiaozuo Yukun Mining Co., Ltd.; silicon micropowder is purchased from Lianzhou Guangyuan Calcium Carbonate Co., Ltd., model GS-800.

[0043] Example 1

[0044] Dolomite ore with a magnesium oxide content of 25 wt% was used as raw material, and was ground by a ring roller mill and then air-classified to obtain dolomite powder with a D50 of 7.37 μm and a D97 of 14.92 μm. Brucite concentrate with a magnesium oxide content of 70 wt% was used as raw material, and grinding and air classification were carried out in a ring roller mill to obtain brucite powder with a D50 of 5.92 μm and a D97 of 27.17 μm. Wollastonite concentrate with a silicon dioxide content of 52 wt% was used as raw material and ground and classified using a jet mill to obtain wollastonite powder with a D50 of 9.52 μm. A first modifier (alkylsilane and aminosilane co-hydrolyzed oligomer and polyethylene glycol in a mass ratio of 3:1) and water in a mass ratio of 2:1 were mixed to obtain a first modifier solution. Wollastonite powder was conveyed to a No. 1 high-speed mixer via a spiral reamer. The first modifier solution (wollastonite powder to first modifier in a mass ratio of 1000:3) was added to the front section of the spiral reamer conveying system. The speed of the No. 1 high-speed mixer was set to 800 rpm, and modification was carried out at 80°C for 20 minutes to obtain modified wollastonite powder. A second modifier (bistriethanolamine diisopropyl titanate and bis(acetylacetonato) diisopropyl titanate in a mass ratio of 1:2) and water were mixed in a mass ratio of 2:1 to obtain a second modifier solution. Spindle-shaped light calcium carbonate (oil absorption of 64 mL / 100 g and sedimentation volume of 3.1 mL / g) was conveyed to a No. 2 high-pressure mixer via a spiral reamer. The second modifier solution (the mass ratio of light calcium carbonate to the second modifier was 1000:5) was added to the front section of the spiral reamer conveying system. The speed of the No. 2 high-pressure mixer was set to 800 rpm, and the mixture was modified at 80°C for 20 minutes to obtain a modified light calcium carbonate powder. Dolomite powder, brucite powder and modified wollastonite powder are placed in a No. 3 high-speed mixer at a mass ratio of 9:1:1, and mixed at a speed of 1000 rpm and 40°C for 20 minutes. Then, modified light calcium carbonate powder (the mass ratio of dolomite powder to modified light calcium carbonate powder is 9:1) is added to the No. 3 high-speed mixer, and mixed at a speed of 1000 rpm and 40°C for 20 minutes to obtain a composite powder. The obtained composite powder is placed in a horizontal mixer and cold mixed at a speed of 200 rpm for 10 minutes, and then passed through a 200-mesh sieve to obtain a dolomite-based anti-caking agent.

[0045] Example 2

[0046] Dolomite ore with a magnesium oxide content of 25 wt% was used as raw material, and was ground by a ring roller mill and then air-classified to obtain dolomite powder with a D50 of 7.26 μm and a D97 of 14.76 μm. Brucite concentrate with a magnesium oxide content of 70 wt% was used as raw material, and grinding and air classification were carried out in a ring roller mill to obtain brucite powder with a D50 of 6.04 μm and a D97 of 27.42 μm. Wollastonite concentrate with a silicon dioxide content of 52 wt% was used as raw material and ground and classified using a jet mill to obtain wollastonite powder with a D50 of 9.48 μm. A first modifier (alkylsilane and aminosilane co-hydrolyzed oligomer and polyethylene glycol in a mass ratio of 4:1) and water in a mass ratio of 3:1 were mixed to obtain a first modifier solution. Wollastonite powder was conveyed to a No. 1 high-speed mixer via a spiral reamer. The first modifier solution (wollastonite powder to first modifier in a mass ratio of 1000:4) was added to the front section of the spiral reamer conveying system. The speed of the No. 1 high-speed mixer was set to 900 rpm, and the mixture was modified at 85°C for 25 minutes to obtain modified wollastonite powder. A second modifier (bistriethanolamine diisopropyl titanate and bis(acetylacetonato) diisopropyl titanate in a mass ratio of 1:3) and water were mixed in a mass ratio of 3:1 to obtain a second modifier solution. Spindle-shaped light calcium carbonate (oil absorption of 66 mL / 100 g and sedimentation volume of 3.2 mL / g) was conveyed to a No. 2 high-pressure mixer via a spiral reamer. The second modifier solution (the mass ratio of light calcium carbonate to the second modifier was 1000:6) was added to the front section of the spiral reamer conveying system. The speed of the No. 2 high-pressure mixer was set to 900 rpm, and the mixture was modified at 85°C for 25 minutes to obtain a modified light calcium carbonate powder. Dolomite powder, brucite powder and modified wollastonite powder are placed in a No. 3 high-speed mixer at a mass ratio of 10:2:2, and mixed at a speed of 1100 rpm and 45°C for 25 minutes. Then, modified light calcium carbonate powder (the mass ratio of dolomite powder to modified light calcium carbonate powder is 10:1) is added to the No. 3 high-speed mixer and mixed at a speed of 1100 rpm and 45°C for 25 minutes to obtain a composite powder; the obtained composite powder is placed in a horizontal mixer and cold mixed at a speed of 260 rpm for 15 minutes, and then passed through a 200-mesh sieve to obtain a dolomite-based anti-caking agent.

[0047] Example 3

[0048] Dolomite ore with a magnesium oxide content of 25 wt% was used as raw material, and was ground by a ring roller mill and then air-classified to obtain dolomite powder with a D50 of 7.14 μm and a D97 of 14.55 μm. Brucite concentrate with a magnesium oxide content of 70 wt% was used as raw material, and grinding and air classification were carried out in a ring roller mill to obtain brucite powder with a D50 of 5.62 μm and a D97 of 26.32 μm. Wollastonite concentrate with a silicon dioxide content of 52 wt% was used as raw material and ground and classified using a jet mill to obtain wollastonite powder with a D50 of 9.76 μm. A first modifier (alkylsilane and aminosilane co-hydrolyzed oligomer and polyethylene glycol in a mass ratio of 4:1) and water were mixed in a mass ratio of 4:1 to obtain a first modifier solution. Wollastonite powder was conveyed to a No. 1 high-speed mixer via a spiral reamer. The first modifier solution (wollastonite powder to first modifier in a mass ratio of 1000:5) was added to the front section of the spiral reamer conveying system. The speed of the No. 1 high-speed mixer was set to 1000 rpm, and modification was carried out at 90°C for 30 minutes to obtain modified wollastonite powder. A second modifier (bistriethanolamine diisopropyl titanate and bis(acetylacetonato) diisopropyl titanate in a mass ratio of 1:3) and water in a mass ratio of 4:1 were mixed to obtain a second modifier solution. Spindle-shaped light calcium carbonate (oil absorption of 68 mL / 100 g and sedimentation volume of 3.3 mL / g) was conveyed to a No. 2 high-pressure mixer via a spiral reamer. The second modifier solution (the mass ratio of light calcium carbonate to the second modifier was 1000:7) was added to the front section of the spiral reamer conveying system. The speed of the No. 2 high-pressure mixer was set to 1000 rpm, and the mixture was modified at 90°C for 30 minutes to obtain a modified light calcium carbonate powder. Dolomite powder, brucite powder and modified wollastonite powder are placed in a No. 3 high-speed mixer at a mass ratio of 11:3:2, and mixed at a speed of 1200 rpm and 50°C for 30 minutes. Then, modified light calcium carbonate powder (the mass ratio of dolomite powder to modified light calcium carbonate powder is 11:1) is added to the No. 3 high-speed mixer and mixed at a speed of 1200 rpm and 50°C for 30 minutes to obtain a composite powder. The obtained composite powder is placed in a horizontal mixer and cold mixed at a speed of 300 rpm for 20 minutes, and then passed through a 200-mesh sieve to obtain a dolomite-based anti-caking agent.

[0049] The whiteness, oil absorption, moisture content and particle size distribution of the dolomite-based anti-caking agents obtained in Examples 1 to 3 were tested respectively. The test results are shown in Table 1.

[0050] Whiteness: tested in accordance with GB / T 23774-2009; Oil absorption: tested in accordance with GB / T 5211.15-2014; Moisture content: tested in accordance with GB / T 6284-2006; Particle size distribution: tested in accordance with GB / T 19077-2016.

[0051] Table 1 Performance test results of dolomite-based anti-caking agents obtained in Examples 1 to 3

[0052] VAE type redispersible latex powder was prepared according to the components and their contents shown in Table 2.

[0053] Table 2 Compositions and mass fractions of each group of VAE redispersible latex powder

[0054] The performance tests were performed on the VAE redispersible latex powders obtained from No. 1 to No. 7 in Table 2. The test standards and results are shown in Table 3.

[0055] Table 3 Performance test standards and results of 1#~7# VAE type redispersible latex powder

[0056] Among them, "1t / 180 days" means 1 ton of weight is pressed for 180 days.

[0057] As can be seen from Table 3, the dolomite-based anti-caking agents obtained in Examples 1 to 3 of the present invention are compared with traditional mineral filler anti-caking agents. When added to VAE-type redispersible latex powder, the dolomite-based anti-caking agents obtained in Examples 1 to 3 have better bulk density than traditional anti-caking agents, are more conducive to the feeding of latex powder, and have low ignition residue. The tensile strength, elongation at break and anti-caking performance are all better than those of traditional anti-caking agents. While ensuring performance, the amount of anti-caking agent can be increased, the proportion of white carbon black in the formula can be reduced, and the formula cost can be effectively reduced.

[0058] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a dolomite-based anti-caking agent, characterized in that: The steps include: 1) Modifying wollastonite powder with a first modifier solution to obtain modified wollastonite powder; 2) Modifying the calcium carbonate powder with a second modifier solution to obtain modified calcium carbonate powder; 3) mixing dolomite powder, brucite powder, modified wollastonite powder and modified calcium carbonate powder to obtain a dolomite-based anti-caking agent; There is no order of precedence for step 1) and step 2).

2. The method for preparing a dolomite-based anti-caking agent according to claim 1, wherein In the step 1), the first modifier solution includes a first modifier and water, and the mass ratio of the first modifier to water is 2 to 4:1; The first modifier is a co-hydrolyzed oligomer of alkylsilane and aminosilane and polyethylene glycol, and the mass ratio of the co-hydrolyzed oligomer of alkylsilane and aminosilane to polyethylene glycol is 3-4:

1.

3. The preparation method of a dolomite-based anti-caking agent according to claim 2, wherein In the step 1), the D50 of the wollastonite powder is 9-10 μm; The mass ratio of wollastonite powder to the first modifier is 1000:3~5.

4. The preparation method of a dolomite-based anti-caking agent according to claim 2 or 3, wherein In the step 2), the second modifier solution includes a second modifier and water, and the mass ratio of the second modifier to water is 2 to 4:1; The second modifier is bistriethanolamine diisopropyl titanate and bis(acetylacetonate) diisopropyl titanate, and the mass ratio of bistriethanolamine diisopropyl titanate to bis(acetylacetonate) diisopropyl titanate is 1:2-3.

5. The method for preparing a dolomite-based anti-caking agent according to claim 4, wherein In the step 2), the mass ratio of calcium carbonate powder to the second modifier is 1000:5-7.

6. The method for preparing a dolomite-based anti-caking agent according to claim 1, wherein In the steps 1) and 2), the speed of the modification is independently 800-1000 rpm, the temperature of the modification is independently 80-90° C., and the time of the modification is independently 20-30 min.

7. The method for preparing a dolomite-based anti-caking agent according to claim 6, wherein: In the step 3), the mass ratio of dolomite powder, brucite powder, modified wollastonite powder and modified calcium carbonate powder is 9-11:1-3:1-2:

1.

8. The method for preparing a dolomite-based anti-caking agent according to claim 7, wherein: In step 3), mixing includes hot mixing and cold mixing in sequence; The heat mixing temperature is 40-50°C, the heat mixing speed is 1000-1200 rpm, and the heat mixing time is 40-60 min; The rotation speed of the cold mixing is 200-300 rpm, and the cold mixing time is 10-20 minutes.

9. A dolomite-based anti-caking agent obtained by the preparation method of a dolomite-based anti-caking agent according to any one of claims 1 to 8.

10. Use of the dolomite-based anti-caking agent according to claim 9 in redispersible latex powder.

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