Calcium carbonate filler particles, process for their preparation and use

Abstract

The application relates to the technical field of filler particles, and particularly discloses calcium carbonate filler particles, a preparation method and application thereof, wherein the average particle diameter of the calcium carbonate filler particles is between 0.5 and 5 microns, the particle diameter distribution span is less than 1.0, the specific surface area is 22-26 m2 / g, the particle surface is grafted with organic functional groups, and the grafting rate reaches 10%-15%. The organic functional groups are hydroxyl groups; a synergistic process of pulse ultrasonic cavitation, micro-fluidic classification and low-temperature plasma grafting is adopted for the first time, the performance and application adaptability of the calcium carbonate filler are significantly improved, the pulse ultrasonic cavitation technology has a frequency of 1.0-1.5 MHz and a power density of 400-600 W / L, can crush the coarse gypsium powder with a particle diameter of 80-120 microns into nanoscale particles with a particle diameter of 0.6-1.0 microns, and the particle diameter distribution span can be controlled within 0.5-0.7, which is reduced by more than 40% compared with the traditional ball milling method.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of filler particles, in particular to calcium carbonate filler particles and a preparation method and application thereof. BACKGROUND

[0002] As an important inorganic filler, calcium carbonate is widely used in plastics, coatings, rubber, papermaking and many other industries. The particles on the market have the problems of wide particle size distribution and poor controllability. The particle size of the calcium carbonate particles prepared by the conventional grinding method on the market is usually in the micron level, and the particle size distribution span is usually greater than 1.5, which leads to uneven dispersion of the filler in the polymer matrix and affects the mechanical properties of the composite material.

[0003] In addition, the particles on the market also have the problems of high process energy consumption and difficult classification. The traditional ball milling method for preparing nano calcium carbonate consumes a large amount of electric energy, and it is difficult to obtain particles with narrow distribution by centrifugal classification.

[0004] In addition, the particles on the market also have the problems of high process energy consumption and difficult classification. The traditional ball milling method for preparing nano calcium carbonate consumes a large amount of electric energy, and it is difficult to obtain particles with narrow distribution by centrifugal classification. SUMMARY

[0005] The purpose of the present application is to provide calcium carbonate filler particles and a preparation method and application thereof. The calcium carbonate filler particles prepared by the present application are superior to the traditional method in particle size control, surface modification and process efficiency through the synergistic process of pulse ultrasonic cavitation, microfluidic classification and low-temperature plasma grafting, especially in the high filling amount scene, and can still maintain excellent performance, providing an innovative solution for the application of calcium carbonate filler in high-end materials.

[0006] To achieve the above purpose, the present application provides the following technical scheme:

[0007] In a first aspect, the average particle size of the calcium carbonate filler particles is between 0.5 and 5 microns, the particle size distribution span is less than 1.0, the specific surface area is 22 m 2 / g to 26 m 2 / g, and the particle surface is grafted with an organic functional group with a grafting rate of 10% to 15%.

[0008] Preferably, the organic functional group is a hydroxyl group.

[0009] The calcium carbonate filler particle preparation method is as follows:

[0010] S1: Nanocrystallization by pulse ultrasonic cavitation:

[0011] The raw material is chalk rock, which is crushed into 80-120 μm coarse powder by high-pressure water jet;

[0012] Treatment: immerse the coarse powder in 0.05-0.15 mol / L ammonium citrate solution, adjust the pH value to 4-6, and heat to 40-60°C, shake for 20-40 minutes to increase the surface reaction activity;

[0013] Crushing: Using a pulsed high-frequency ultrasonic reactor, the coarse powder is mixed with 0.3-0.7% polyacrylate ammonium dispersant to form a 20-30% solid content slurry, and CO2 is introduced to saturation to increase the cavitation effect; a calcium carbonate slurry with a particle size of 0.6-1.0 μm and a span of 0.5-0.7 is obtained;

[0014] S2: Microfluidic chip grading, using PDMS microfluidic chip, the main channel width is 150-250μm, with a built-in array branch channel, combined with electroosmotic flow control valve;

[0015] The ultrasonically treated slurry was injected into the main channel at a flow rate of 0.3-0.7 mL / min. Under an electric field of 15-25 V / mm, three-stage separation was achieved based on the particle size-charge mobility difference:

[0016] Large particles, 1.2 to 1.4 μm, are discharged from wide channels, 40 to 60 μm;

[0017] Target particles are 0.8-1.2 μm and collected from the middle channel at 25-35 μm;

[0018] Ultrafine particles 0.4-0.6 μm, recovered from narrow channels 8-12 μm;

[0019] Obtain a narrow distribution slurry with a particle size of 0.6-0.8 μm ± 0.1-0.2 μm and a span of 0.4-0.5;

[0020] S3: Low-temperature plasma grafting: spray-dry the narrow-distribution slurry into microparticles with a water content of 2-4%, and place them in a radio frequency plasma reaction chamber. Then, introduce argon gas and treat it at a vacuum of 80-120 Pa and a power of 150-250 W for 3-7 minutes. The collision of high-energy plasma electrons with argon gas achieves argon ionization, water vapor cracking, and isolation surface activation.

[0021] Azobisisobutyronitrile is prepared into a 5% by mass solution with anhydrous ethanol, and the solution is introduced into the reaction chamber at a volume ratio of 1:8 to 1:12 with gaseous acrylic acid monomer at a rate of 1 to 3% by mass of the acrylic acid monomer.

[0022] Liquid acrylic acid is vaporized in a stainless steel vaporizer, and its jacket is heated to 80-90°C. The pressure difference between the vaporizer unit and the reaction chamber is controlled by a buffer tank + back pressure valve to be ≤20Pa; the temperature is raised to 50-70°C; the reaction is carried out for 1-3 hours; and 2,2'-dicyano-2-propyl free radicals are added to the β-position of the double bond of acrylic acid to initiate chain polymerization.

[0023] The active hydrogen atoms generated by the plasma react with the polyacrylic acid free radical chains to introduce hydroxyl groups, and the remaining free radicals are terminated by argon ion collisions. The temperature is raised to 100-120°C, and 0.1-0.5% p-toluenesulfonic acid is added. The hydroxyl-containing polyacrylic acid chains dehydrate and condense with the hydroxyl groups on the particle surface to form ether bonds for covalent grafting. The reaction lasts for 20-40 minutes, resulting in a grafting rate of 10-15% and a specific surface area of ​​22-26 m 2 / g of calcium carbonate filler particles.

[0024] Preferably, the pulsed high-frequency ultrasonic reactor in S1 has a frequency of 1.0-1.5 MHz, a power density of 400-600 W / L, and is treated in a 4-6 s on / 1-3 s off pulse mode for 1.5-2.5 hours, with a temperature controlled at 35-45°C.

[0025] Preferably, the frequency of the radio frequency plasma reaction chamber in S3 is 13.56 MHz, and the flow rate of the argon gas is 40 to 60 sccm.

[0026] Preferably, the equipment for spray drying in S3 is equipped with a hot air filter assembly and uses a polytetrafluoroethylene filter element with a pore size of ≤1 μm.

[0027] Preferably, the calcium carbonate filler particles are used as reinforcing fillers in polymer materials such as polyethylene, polypropylene or polyvinyl chloride.

[0028] Preferably, the calcium carbonate filler particles are used as functional fillers in water-based paints or solvent-based paints, and the addition amount is 15 to 40% of the total mass of the paint.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. This invention, for the first time, significantly improves the performance and application adaptability of calcium carbonate fillers through the synergistic process of pulsed ultrasonic cavitation, microfluidic classification, and low-temperature plasma grafting. Pulsed ultrasonic cavitation technology, with a frequency of 1.0-1.5 MHz and a power density of 400-600 W / L, can crush coarse chalk powder of 80-120 μm to the nanoscale of 0.6-1.0 μm, controlling the particle size distribution span to 0.5-0.7, which is more than 40% lower than that of traditional ball milling. Furthermore, the microfluidic chip classification technology further reduces the target particle span to 0.4-0.5, and the ultrafine particle recovery rate is increased to over 50%, meeting the demand for narrow distribution fillers in high-end materials.

[0031] 2. The application adopts the advantages of low-temperature plasma grafting, activates the surface of the particles in the radio frequency plasma reaction cavity, and the grafting rate can reach 10-15%, which is several times higher than that of the traditional liquid phase method, and the reaction time is shortened to within thirty minutes. The grafted hydroxyl functional groups significantly improve the interfacial compatibility of the particles and the organic matrix by forming hydrogen bonds and physical entanglement with the polypropylene matrix. With 15% addition of polypropylene as the matrix, the test shows that compared with unmodified calcium carbonate, the interfacial bonding strength is improved by 30-50%, the tensile strength of the composite material is improved by 20-40%, and the elongation at break is improved by 15-25%.

[0032] 3. The energy consumption of the pulse ultrasonic treatment of the application is reduced by 40-50% compared with the traditional ball milling method, and no organic solvent is used to avoid chemical pollution. The water-based slurry is used for grading, and no organic reagent consumption is needed for centrifugal separation. The grading precision exceeds that of the traditional centrifugal method, and the large particles can be directly reused, and the raw material utilization rate is improved to more than 95%.

[0033] 4. The application as a reinforcing filler added to polyvinyl chloride can reduce the thermal expansion coefficient of the composite material while maintaining high light transmittance. The addition of functionalized calcium carbonate in water-based paint can improve the hiding power and scrub resistance of the coating, and the surface hydroxyl group forms hydrogen bonds with the resin to improve the leveling property and anti-settling stability.

[0034] 5. The ultrasonic reactor, microfluidic chip and plasma cavity of the application all use standardized industrial components, which can be adapted to existing filler production lines with low modification cost. Through the technical innovation of "nanofication-functionalization-energy saving", the performance bottleneck of traditional calcium carbonate filler is broken, and an efficient and green filler solution is provided for high-end composite materials, environmentally friendly coatings and other fields. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, not all. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the application.

[0036] It should be noted that the raw materials used in the following experiments are all commercially available.

[0037] Calcium carbonate filler particles, the average particle size of the calcium carbonate filler particles is between 0.5-5 μm, the particle size distribution span is less than 1.0, the specific surface area is 22-26 m 2 / g, the particle surface is grafted with organic functional groups, and the grafting rate reaches 10-15%, the organic functional groups are hydroxyl groups.

[0038] Example One

[0039] S1: Pulse ultrasonic cavitation nanometerization:

[0040] Raw material, chalk rock, 80 μm coarse powder by high pressure water jet crushing, processing, coarse powder immersed in 0.05 mol / L ammonium citrate solution, adjust pH to 4, and heated to 40℃, oscillation 20 min, improve surface reactivity;

[0041] Crushing, using pulse high frequency ultrasonic reactor, coarse powder mixed with 0.3% polyacrylamide dispersant into 20% solid content slurry, saturated with CO2 to increase cavitation effect; at this time, the pulse high frequency ultrasonic reactor, frequency 1.0 MHz, power density 400 W / L, pulse mode 4 s on / 1 s off, treated at 35℃ for 1.5 h, obtained calcium carbonate slurry with average particle size 0.6 μm, span 0.5.

[0042] S2: In the microfluidic chip grading experiment, the microfluidic chip of PDMS material was used, the width of the main channel was set to 150 μm, and the width of the branch channel was gradually decreased according to the gradient of 40-60 μm, 25-35 μm and 8-12 μm. In the experiment, the slurry was injected into the main channel at a flow rate of 0.3 mL / min, and separated under the action of an electric field of 15 V / mm. Finally, the target particles located in the middle channel 25-35 μm were collected, and the particle size of these particles was 0.6 μm±0.1 μm, and the particle size span was 0.4.

[0043] S3: Low temperature plasma grafting, spray drying the graded slurry to a water content of 2%, placed in a radio frequency plasma reaction chamber, frequency 13.56 MHz, then 40 sccm argon gas was introduced, treated at 80 Pa vacuum, 150 W power for 3 min.

[0044] Plasma high energy electrons are used to realize water vapor cracking to generate active hydrogen atoms.

[0045] Azobisisobutyronitrile was prepared into a 5% solution with anhydrous ethanol, and the amount was 1% of the mass of the acrylic monomer. After the acrylic monomer was gasified, it was introduced into the reaction chamber according to the volume ratio of 1:8. The acrylic acid was gasified by the gasification tank, and the pressure difference of the buffer tank was controlled to be less than or equal to 20 Pa. The temperature was raised to 50℃, and the reaction was carried out for 1 h. The temperature was raised to 100℃, and 0.1% p-toluenesulfonic acid was added, and the reaction was carried out for 20 min. The grafting rate of the obtained calcium carbonate filler particles was 10%, and the specific surface area was 22 m2 / g. The role is to add to polyethylene as a reinforcing filler.

[0046] Example Two

[0047] S1: Pulse ultrasonic cavitation nanometerization:

[0048] The raw material, chalk rock, is broken into 100 μm coarse powder by high-pressure water jet, treated, the coarse powder is immersed in 0.1 mol / L ammonium citrate solution, the pH value is adjusted to 5, and the temperature is raised to 50°C, and oscillated for 30 min to improve the surface reactivity; the coarse powder is mixed with 0.5% polyacrylammonium dispersant to form a slurry with a solid content of 25%, and CO2 is introduced until saturation, to increase the cavitation effect; at this time, the pulse high-frequency ultrasonic reactor has a frequency of 1.25 MHz, a power density of 500 W / L, and a pulse mode of 5 s on / 2 s off, and the slurry is treated at 40°C for 2 h to obtain a calcium carbonate slurry with an average particle size of 0.7 μm and a span of 0.6.

[0049] S2: In the microfluidic chip grading experiment, the slurry is injected into the main channel at a flow rate of 0.5 mL / min, and the width is 200 μm, and the separation is carried out under the action of an electric field of 20 V / mm, finally, the target particles located in the middle channel 25-35 μm are collected, the particle size of these particles is 0.7 μm±0.15 μm, and the particle size span is 0.45.

[0050] S3: Low-temperature plasma grafting, the graded slurry is spray dried to a water content of 3%, placed in a radio frequency plasma reaction chamber, then 50 sccm of argon is introduced, treated at 100 Pa vacuum, 200 W power for 5 min;

[0051] Azo-diisobutyronitrile is prepared into a 5% solution with anhydrous ethanol, and is added at 2% of the mass of the acrylic monomer, and the gaseous acrylic monomer after 85°C is introduced into the reaction chamber at a volume ratio of 1:10; the temperature is raised to 60°C, and the reaction is carried out for 1 h to initiate polymerization. After the active hydrogen atom is hydroxylated, the temperature is raised to 110°C, 0.3% p-toluenesulfonic acid is added, and ether bond grafting reaction is carried out for 30 min to obtain calcium carbonate filler particles with a grafting rate of 12.5% and a specific surface area of 24 m2 / g, which are added to polypropylene, and the elongation at break is increased by 15% when the addition amount is 20%.

[0052] Example Three

[0053] S1: Pulse ultrasonic cavitation nanocrystallization:

[0054] The raw material, chalk rock, is broken into 120 μm coarse powder by high-pressure water jet, treated, the coarse powder is immersed in 0.15 mol / L ammonium citrate solution, the pH value is adjusted to 6, and the temperature is raised to 60°C, and oscillated for 40 min to improve the surface reactivity;

[0055] Crushing, using a pulsed high-frequency ultrasonic reactor, the coarse powder was mixed with 0.7% ammonium polyacrylate dispersant into a 30% solid content slurry, and CO2 was introduced to saturation to increase the cavitation effect; at this time, the pulsed high-frequency ultrasonic reactor, frequency 1.5 MHz, power density 600 W / L, pulse mode 6 s on / 3 s off, was treated at 45°C for 2.5 h to obtain a calcium carbonate slurry with an average particle size of 0.8 μm and a span of 0.7.

[0056] S2: In the microfluidic chip grading experiment, the slurry was injected into the main channel at a flow rate of 0.7 mL / min, and the separation was carried out under the action of an electric field of 25 V / mm. Finally, the target particles located in the middle channel 25-35 μm were collected, and the particle size of these particles was 0.8 μm ± 0.2 μm, and the particle size span was 0.5.

[0057] S3: Low-temperature plasma grafting, the graded slurry was spray dried to a water content of 4%, then 60 sccm of argon was introduced, treated at 120 Pa vacuum, 250 W power for 7 min;

[0058] A 5% solution of azobisisobutyronitrile was prepared with absolute ethanol, and 3% of the mass of the acrylic monomer was added, and the gaseous acrylic monomer after vaporization at 90°C was introduced into the reaction chamber at a volume ratio of 1:12; the temperature was raised to 70°C, and the polymerization was initiated for 3 h. The temperature was raised to 120°C, and 0.5% p-toluenesulfonic acid was added, and the reaction was carried out for 40 min to obtain calcium carbonate filler particles with a grafting rate of 15% and a specific surface area of 26 m2 / g. The functional filler was added to the solvent-based paint, and the amount of addition was 40%, and the scrub resistance was improved by 50%.

[0059] Example Four

[0060] S1: Pulsed ultrasonic cavitation nanocrystallization:

[0061] Raw materials, chalk rock was selected, and 100 μm coarse powder was prepared by high-pressure water jet crushing. The coarse powder was immersed in 0.1 mol / L ammonium citrate solution, the pH value was adjusted to 5, and the temperature was raised to 50°C, and the surface reactivity was improved by oscillation for 30 min. Crushing, using a pulsed high-frequency ultrasonic reactor, the coarse powder was mixed with 0.5% ammonium polyacrylate dispersant into a 25% solid content slurry, and CO2 was introduced to saturation to increase the cavitation effect; at this time, the pulsed high-frequency ultrasonic reactor, frequency 1.25 MHz, power density 500 W / L, pulse mode 5 s on / 2 s off, was treated at 40°C for 2 h to obtain a calcium carbonate slurry with an average particle size of 0.7 μm and a span of 0.6.

[0062] S2: In the microfluidic chip classification experiment, the slurry was injected into the main channel at a flow rate of 0.5 mL / min, the width was 200 μm, and the separation was carried out under the action of an electric field of 20 V / mm. The ultrafine particles in the narrow channel were 8-12 μm, the particle size of these particles was 0.5 μm, and the particle size span was 0.4.

[0063] S3: Low-temperature plasma grafting, spray drying the classified slurry to a water content of 3%, then introducing 50 sccm of argon, treating at 100 Pa vacuum and 2000 W power for 5 min;

[0064] A 5% solution of azobisisobutyronitrile was prepared with anhydrous ethanol, added at 2% of the mass of the acrylic monomer, and introduced into the reaction cavity with the gaseous acrylic monomer at 85°C at a volume ratio of 1:10; the temperature was raised to 70°C, and the reaction was carried out for 3 h to initiate polymerization. The temperature was raised to 120°C, and 0.5% p-toluenesulfonic acid was added, and the reaction was carried out for 30 min to obtain calcium carbonate filler particles with a grafting rate of 12.5% and a specific surface area of 24 m2 / g. Its role is to be added as a reinforcing filler to polyethylene to improve the tensile strength by 20%. Added to water-based paint, the addition amount is 15%, the hiding power is improved by 15%, and it is used for high-end wall paint.

[0065] Example Five

[0066] S1: Pulsed ultrasonic cavitation nanocrystallization:

[0067] Raw materials, white chalk rock, 100 μm coarse powder was prepared by high-pressure water jet crushing, treatment, the coarse powder was immersed in 0.1 mol / L ammonium citrate solution, the pH value was adjusted to 5, and the temperature was raised to 50°C, and oscillated for 30 min to improve the surface reactivity; crushing, a pulsed high-frequency ultrasonic reactor was used, the coarse powder was mixed with 0.5% polyacrylamide dispersant to form a 25% solid content slurry, and CO2 was introduced to saturation to increase the cavitation effect; at this time, the pulsed high-frequency ultrasonic reactor, the frequency was 1.25 MHz, the power density was 500 W / L, the pulse mode was 5 s on / 2 s off, and the treatment was carried out at 40°C for 2 h to obtain calcium carbonate slurry with an average particle size of 0.7 μm and a span of 0.6. S2: In the microfluidic chip classification experiment, the slurry was injected into the main channel at a flow rate of 0.5 mL / min, the width was 200 μm, and the separation was carried out under the action of an electric field of 20 V / mm. Finally, the target particles located in the middle channel 25-35 μm were collected, the particle size of these particles was 0.7 μm±0.15 μm, and the particle size span was 0.45.

[0068] S3: Low-temperature plasma grafting, spray drying the classified slurry to a water content of 3%, placed into a radio frequency plasma reaction cavity, the radio frequency plasma reaction cavity frequency was 13.56 MHz, then introduced 60 sccm of argon, treated at 120 Pa vacuum and 250 W power for 7 min;

[0069] The azobisisobutyronitrile is prepared into a 5% solution with anhydrous ethanol, and is introduced into the reaction cavity at a volume ratio of 1:8 with the acrylic monomer after vaporization at 90 DEG C according to 3% of the mass of the acrylic monomer; the temperature is raised to 70 DEG C, and polymerization is initiated by reacting for 3 hours; the temperature is raised to 120 DEG C, and 0.5% of p-toluenesulfonic acid is added, and the reaction is carried out for 40 minutes, so that the calcium carbonate filler particles with a grafting rate of 15% and a specific surface area of 26 m2 / g are obtained.

[0070] Meanwhile, the application is also applied to polyvinyl chloride with an addition amount of 30% and solvent-based paint with an addition amount of 30%, and the thermal expansion coefficient is reduced by 18%, and the coating reflectivity is greater than or equal to 90%.

[0071] Comparative Example 1: Unmodified calcium carbonate prepared by a traditional ball milling method, particle size 10 mu m, Span = 1.8, specific surface area 10 m2 / g.

[0072] Comparative Example 2: Modified calcium carbonate prepared by a traditional liquid phase method.

[0073] Preparation step: 1000 g of heavy calcium carbonate powder with a particle size D50 of 2.5 mu m is taken, 15 g of stearic acid, 0.5 g of benzoyl peroxide initiator is added, and then 1667 g of deionized water is added to prepare a slurry with a solid content of 37.5%;

[0074] In a reaction kettle with stirring, the reaction is carried out at 80 DEG C and 300 r / min for 90 min, and then vacuum filtration is carried out after the reaction, and the filter cake is dried at 110 DEG C for 4 h.

[0075] After being slightly crushed by an airflow crusher with a working pressure of 0.6 MPa, the modified calcium carbonate with a grafting rate of 5% and Span = 1.2 is obtained.

[0076] According to the addition amount of 15%, the polypropylene matrix is extruded and injection molded to prepare a sample for performance testing.

[0077] The performance of the composite material is according to GB / T1040.2-2022 and GB / T9266-2009.

[0078] The following are the test data of Examples 1 to 5 and Comparative Examples

[0079]

[0080] As shown in Table 1

[0081] The grafting rate of the embodiment of the application is 10-15%, which is significantly higher than 5% of Comparative Example 2, and the specific surface area of the embodiment is 22-26 m2 / g, which is significantly higher than 10 m2 / g of Comparative Example 1.

[0082] Secondly, in terms of particle size span, the embodiment is 0.4-0.5, which is reduced by more than 50% compared with 1.8 of Comparative Example 1 and 1.2 of Comparative Example 2, which reflects the advantage of narrow distribution.

[0083] In the description of the application, the terms "one embodiment", "an example", "a specific example" and the like refer to specified features, structures, materials, or characteristics that are included in at least one embodiment of the present application. The appearances of these terms in various places in the specification are not necessarily referring to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0084] The preferred embodiments of the application disclosed above are only to help explain the application. The preferred embodiments do not describe all of the details of the application and limit the application to the specific embodiments described. Obviously, many modifications and variations can be made in light of the above teachings. The specific embodiments described are selected to best explain the principles of the application and practical application, to the best of the applicant's knowledge, to enable others skilled in the art to best utilize the application, and to convey the scope of the application to the skilled person. The application is limited only by the claims and their full scope and equivalents.

Claims

1. Calcium carbonate filler particles, characterized in that: The calcium carbonate filler particles are prepared by the following method: S1: Pulsed Ultrasonic Cavitation Nanocrystallization: The raw material is chalk rock, which is crushed into 80-120 μm coarse powder by high-pressure water jet; Treatment: immerse the coarse powder in 0.05-0.15 mol / L ammonium citrate solution, adjust the pH value to 4-6, and heat to 40-60°C, shake for 20-40 minutes to increase the surface reaction activity; Crushing: Using a pulsed high-frequency ultrasonic reactor, the coarse powder is mixed with 0.3-0.7% of ammonium polyacrylate dispersant to form a 20-30% solid content slurry, and CO2 is introduced to saturation to increase the cavitation effect; a calcium carbonate slurry with a particle size of 0.6-1.0 μm and a span of 0.5-0.7 is obtained; S2: Microfluidic chip grading, using PDMS microfluidic chip, the main channel width is 150-250μm, with a built-in array branch channel, combined with electroosmotic flow control valve; The ultrasonically treated slurry was injected into the main channel at a flow rate of 0.3-0.7 mL / min. Under an electric field of 15-25 V / mm, three-level separation was achieved based on the difference in particle size-charge mobility: large particles of 1.2-1.4 μm were discharged from the wide channel of 40-60 μm; target particles of 0.8-1.2 μm were collected from the middle channel of 25-35 μm; ultrafine particles of 0.4-0.6 μm were recovered from the narrow channel of 8-12 μm; and a narrow distribution slurry with a particle size of 0.6-0.8 μm ± 0.1-0.2 μm and a span of 0.4-0.5 was obtained. S3: Low-temperature plasma grafting: spray-dry the narrow-distribution slurry into microparticles with a water content of 2-4%, and place them in a radio frequency plasma reaction chamber. Then, introduce argon gas and treat it at a vacuum of 80-120 Pa and a power of 150-250 W for 3-7 minutes. The collision of high-energy plasma electrons with argon gas achieves argon ionization, water vapor cracking, and isolation surface activation. Azobisisobutyronitrile is prepared into a 5% by mass solution with anhydrous ethanol, and the solution is introduced into the reaction chamber at a volume ratio of 1:8 to 1:12 with gaseous acrylic acid monomer at a rate of 1 to 3% by mass of the acrylic acid monomer. Liquid acrylic acid is vaporized in a stainless steel vaporizer, and its jacket is heated to 80-90°C. The pressure difference between the vaporizer unit and the reaction chamber is controlled by a buffer tank + back pressure valve to be ≤20Pa; the temperature is raised to 50-70°C and the reaction is carried out for 1-3 hours; Heat to 100-120℃, add 0.1-0.5% p-toluenesulfonic acid, react for 20-40min, and obtain a grafting rate of 10%-15% and a specific area of ​​22-26m 2 / g of calcium carbonate filler particles.

2. The calcium carbonate filler particles according to claim 1, characterized in that: The pulsed high-frequency ultrasonic reactor in S1 has a frequency of 1.0-1.5 MHz and a power density of 400-600 W / L. The treatment is carried out in a 4-6 s on / 1-3 s off pulse mode for 1.5-2.5 hours, and the temperature is controlled at 35-45°C.

3. The calcium carbonate filler particles according to claim 1, characterized in that: The frequency of the radio frequency plasma reaction chamber in S3 is 13.56 MHz, and the flow rate of the argon gas is 40-60 sccm.

4. The calcium carbonate filler particles according to claim 1, characterized in that: The equipment for spray drying in S3 is equipped with a hot air filter assembly and uses a polytetrafluoroethylene filter element with a pore size of ≤1 μm.

5. The use of the calcium carbonate filler particles according to claim 1 in the plastics industry, characterized in that: The calcium carbonate filler particles are used as reinforcing fillers for polyethylene, polypropylene or polyvinyl chloride.

6. The use of the calcium carbonate filler particles according to claim 1 in the coating industry, characterized in that: The calcium carbonate filler particles are used as functional fillers in water-based paints or solvent-based paints, and the added amount is 15-40% of the total mass of the paint.

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