Dispersion process for the preparation of micrometric particles

Abstract

The application discloses a dispersion method for preparing micron-sized particles, which comprises the step of dispersing by using a shearing machine, wherein the shearing machine comprises a tank body, a tank cover, a material injection port, a material discharge port and a shearing module, and the method comprises the following steps: (1) injecting a dispersion medium into the shearing machine tank body through the material injection port firstly, and starting shearing; (2) injecting a dispersed phase and the dispersion medium in proportion; (3) making the dispersed phase circulate and shear in the shearing machine for more than three times; and (4) discharging small-particle-size particles or emulsion drops from the upper material discharge port under the action of fluid injection power, and sinking large-particle-size particles or emulsion drops back to the tank bottom under the action of gravity to be sheared by the shearing machine again. The application solves the problems of uneven shearing, poor particle morphology and excessive heat generation, meets the demand of any required scale from small test to scale-up production, solves the limitations of batch-type shearing machines and pipeline-type shearing machines, reduces scale-up effect and reduces research and development cost.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to application number 2023118648249, filed on December 29, 2023, entitled “Dispersion method for preparing micron-sized particles”, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] This invention relates to the field of particle dispersion technology, and more specifically to a dispersion method for preparing micron-sized particles. Background Technology

[0004] Shear emulsification equipment is widely used in the pharmaceutical, food, cosmetic, and chemical industries. Materials are sheared and dispersed by a high-speed rotating rotor to prepare products with different particle sizes, such as dairy products, emulsions, suspensions, and nano- and micron-sized particles. The particle size is usually around 0.1 μm to 100 μm, and the particle size and particle size distribution have a direct impact on the quality of the product.

[0005] Common preparation equipment includes batch high-shear dispersers and inline high-shear dispersers. Batch high-shear dispersers are suitable for particle dispersion in laboratories or small-batch production workshops, and typically include top-mounted and bottom-mounted types. The size of the shear head and the effective shear volume of batch high-shear dispersers limit their effectiveness. After obtaining a small-scale sample that meets expectations in the early stages of research and development, it is necessary to further scale up the production, i.e., increase the reaction volume. However, increasing the reaction volume makes it difficult to ensure uniform shearing, usually requiring changes to the appropriate shear head. This involves alterations to various process parameters and a scale-up effect. Continuous process parameter adjustments require more time and cost, and there is even a risk of not being able to reproduce the small-scale results. On the other hand, it must also be considered that batch high-shear dispersers may not meet the requirements of large-scale mass production.

[0006] Inline high-shear dispersers enable continuous production, solving most problems in the transition from small-scale to large-scale product manufacturing. However, for materials with significant viscosity differences between the dispersed phase and the dispersion medium, inline high-shear dispersers often result in large clumps of material forming before it reaches the shear head, hindering uniform dispersion. Furthermore, the relatively small mixing chamber means the material is not fully homogenized before being discharged, leading to large particle sizes and non-spherical shapes in the final product, failing to meet quality standards. Increasing the speed of the inline high-shear disperser from 15,000 rpm to 18,000 rpm further exacerbates the problem. The powerful suction of the equipment results in a large amount of material being discharged before being uniformly dispersed, leading to larger particle sizes and irregular product morphology.

[0007] The micrometer-sized particles are prepared by using a pipeline high-shear dispersion machine, and the rotation speed is set to 11000 rpm, 15000 rpm and 18000 rpm respectively, the prepared microparticles have a large particle size, a wide particle size span (Span) and uneven particle size distribution, and the particle size is not effectively reduced with the increase of the rotation speed, and the prepared microparticles have poor morphology. Moreover, the temperature of the material rises rapidly when the micrometer-sized particles are prepared by using the pipeline high-shear dispersion machine, and the temperature of the material rises by 6 ℃ after shearing for 5 min at 15000 rpm, which is not conducive to the preparation of heat-sensitive materials. SUMMARY

[0008] The present application proposes a dispersion method for preparing micrometer-sized particles to solve the problems in the prior art, and specifically, the present application mainly includes the following contents.

[0009] The dispersion method for preparing micrometer-sized particles provided by the present application comprises the step of dispersing by using a shear machine, wherein the shear machine comprises a tank body, a tank cover, a material injection port, a material discharge port and a shearing module, and the step comprises:

[0010] (1) The dispersion medium is first injected into the shear machine tank body through the material injection port, and the shearing is started;

[0011] (2) The dispersed phase and the dispersion medium are injected in proportion, the injection speed of the dispersed phase is 5 mL / min to 100 mL / min, and the injection speed of the dispersion medium is 1000 mL / min to 10000 mL / min;

[0012] (3) The dispersed phase and the dispersion medium are subjected to more than three cycles of shearing in the shear machine, so as to obtain small-particle-size particles or emulsion droplets with a volume average diameter of 0.5-30 μm; and

[0013] (4) The small-particle-size particles or emulsion droplets are discharged from the upper material discharge port under the action of fluid injection, and the large-particle-size particles or emulsion droplets sink back to the tank bottom under the action of gravity and are sheared again by the shear machine.

[0014] In some embodiments, the dispersion method for preparing micrometer-sized particles according to the present application, wherein the rotation speed of the shear machine is controlled to be 4800-7700 rpm, so as to obtain particles or emulsion droplets with a volume average diameter of 22.51-27.26 μm.

[0015] In some embodiments, the dispersion method for preparing micrometer-sized particles according to the present application, wherein the material is continuously injected into the shear machine tank body from the material injection port, and the flow rate of the material discharge port is consistent with the flow rate of the material injection port.

[0016] In some embodiments, the dispersion method for preparing micron-sized particles according to the present application, wherein the volume of the continuous injection of the material is 2 L-200 L.

[0017] In some embodiments, the dispersion method for preparing micron-sized particles according to the present application, wherein the bottom of the tank is connected with a support frame, and the stability of the tank is maintained by the support frame.

[0018] In some embodiments, the dispersion method for preparing micron-sized particles according to the present application, wherein the viscosity ratio of the dispersed phase to the dispersion medium is in the range of 300-7500:1.

[0019] In some embodiments, the dispersion method for preparing micron-sized particles according to the present application, wherein the shear machine comprises a driving motor arranged at the upper part of the tank, a stator assembly arranged inside the tank, and a rotor assembly, the rotor assembly comprising a rotor connecting rod and rotor blades radially arranged at the end of the rotor connecting rod, the stator assembly comprising a stator and a stator connecting cover arranged on the upper surface of the stator, the rotor assembly being inside the stator assembly, the upper part of the rotor connecting rod being connected with the driving motor through the center of the tank cover, and the rotor blades being rotated by the driving motor for cyclic shearing.

[0020] In some embodiments, the dispersion method for preparing micron-sized particles according to the present application, wherein the tank and the tank cover are sealed by an O-ring, and the tank cover and the rotor connecting rod are sealed by a double-end mechanical seal.

[0021] In some embodiments, the dispersion method for preparing micron-sized particles according to the present application, wherein the shear machine further comprises a material injection pipe, the material injection pipe comprising an outer injection pipe and an inner injection pipe for the injection of the dispersion medium and the dispersed phase, respectively.

[0022] In some embodiments, the dispersion method for preparing micron-sized particles according to the present application, wherein a lifting machine is arranged at one side of the tank, the lifting machine being connected with the tank cover and being arranged to enable the lifting of the shear machine.

[0023] The dispersion method for preparing micrometer-sized particles of the present application is suitable for preparing products with different particle size ranges and more uniform particle size distribution. In particular, the increased tank volume and bottom feeding method can obtain small particle size particles with a volume average particle size of less than 30 μm without requiring extreme rotational speed, and can meet the needs of any desired scale from small test to large-scale production without the need to replace equipment, thereby solving the limitations of batch high-shear dispersion machines and pipeline high-shear dispersion machines and reducing the scale-up effect. It is suitable for mixing two immiscible media, and especially suitable for use at different temperatures, where the viscosity difference between the two phases is extremely large, resulting in uneven shear and poor particle morphology.

[0024] The emulsification effect is greatly enhanced in the exemplary method of the present application, and the viscosity ratio of the dispersed phase to the dispersion medium is in the range of 300-7500:1. At the same time, the high-speed shear machine must generate heat during use, although a jacketed temperature control method is often used in actual operation to avoid excessive heating of the material. However, for batch high-shear dispersion machines, the temperature control jacket cannot effectively reduce the material temperature during long-term operation, which is not conducive to the preparation of heat-sensitive materials. In addition to jacketed temperature control, the enlarged tank volume in the present application allows continuous injection of the dispersion medium and the dispersed phase during preparation, which can continuously update the liquid in the tank and timely remove the heat generated by the high-shear dispersion machine, thereby avoiding the problem of excessive heat generation and poor heat dissipation due to small tank volume and long-term operation of the machine. The present application has good applicability for the preparation of heat-sensitive materials and non-heat-sensitive materials.

[0025] In the exemplary method of the present application, the scale-up effect of batch high-shear dispersion machines can be avoided, and the problem of uneven dispersion of two-phase materials with large property differences can be solved by using pipeline high-shear dispersion machines. Without extreme rotational speed, extremely small particle size or droplets can be stably prepared, greatly improving the uniformity of the product. The product can maintain uniform characteristics from small-scale test to large-scale production, meet different batch production requirements, and reduce research and development costs. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 Overall structure schematic diagram of the embodiment of the shear machine with the discharge port arranged at the top of the tank body.

[0027] Figure 2 Overall structure schematic diagram of the embodiment of the shear machine with the discharge port arranged at the top of the tank body.

[0028] Figure 3 Particle morphology prepared by using a pipeline high-shear dispersion machine with a rotational speed of 11000 rpm.

[0029] Figure 4 Particle morphology prepared by using a pipeline high-shear dispersion machine with a rotational speed of 15000 rpm.

[0030] Figure 5 Particle morphology prepared using a top-entry high shear disperser, 50 L scale.

[0031] Figure 6 Particle morphology prepared using a top-entry high shear disperser, 50 L scale.

[0032] Figure 7 Particle morphology prepared using a top-entry high shear disperser, 50 L scale.

[0033] Figure 8 Particle morphology prepared using a top-entry high shear disperser, 50 L scale.

[0034] Figure 9 Particle morphology prepared using a top-entry high shear disperser, 50 L scale.

[0035] Reference sign list:

[0036] 100. tank body; 200. tank cover; 310. stator; 320. stator connecting cover; 410. rotor connecting rod; 420. rotor blade; 500. motor; 600. support frame; 710. outer injection pipe; 711. outer injection pipe outlet; 712. outer injection pipe inlet; 720. inner injection pipe; 721. inner injection pipe outlet; 722. inner injection pipe inlet; 810. top discharge outlet; 820. side upper discharge outlet; 900. temperature control jacket; 910. cooling inlet; 920. cooling outlet; 930. deflector; 1000. elevator. DETAILED DESCRIPTION

[0037] Various exemplary embodiments of the present application will now be described in detail, with reference to the figures. Such description, however, is to be considered in all respects only as illustrative, and not restrictive.

[0038] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. Additionally, it is to be understood that where the application is herein described as comprising or having particular elements and / or features, such a description is taken to mean that such elements and / or features are in addition to legible components of the present application that are explicitly stated or otherwise apparent from context. Further, it is to be understood that the description and drawings included herein relate to only one or more exemplary embodiments of the present application and are not intended to be limiting of the present application, for the present application can have additional embodiments and / or can be used in additional variations.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, exemplary methods and materials are described herein.

[0040] The terms first, second, third, etc. as used in the specification and claims are used for distinguishing between like elements and do not necessarily have an ordinal or chronological significance. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the application described herein are capable of operating in other sequences than described or illustrated herein.

[0041] In addition, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like as used in the specification and claims indicate directions or positional relationships in accordance with the orientations shown in the drawings and are used for convenience in describing the present application and simplifying the description, and are not intended to indicate or imply that a referred part must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the application. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the application described herein are capable of operating in other orientations than described or illustrated herein.

[0042] The term "fixed connection" of the present application includes detachable fixed connection or non-detachable fixed connection. The detachable fixed connection includes bolt connection and the like. The non-detachable fixed connection includes welding and the like.

[0043] Embodiment

[0044] The structure of an exemplary shear machine used in the dispersion method of the present embodiment is as follows:

[0045] As shown in Figure 1 , it is a tank type high-speed shear machine, which includes a tank body 100, a tank cover 200, a stator assembly, a rotor assembly, a driving motor 500, a material injection sleeve, and a material discharge port.

[0046] A seal is provided between the tank body 100 and the tank cover 200, which can be an O-ring seal or a packing seal. The tank cover 200 and the driving part of the shear machine use a mechanical seal, which effectively maintains the sealing of the shear machine and can achieve sterile production.

[0047] The ratio of the diameter to the height of the tank body 100 is 0.6-0.9, and the volume of the tank body 100 is 1.5L-3L. Further, a support frame 600 is provided at the lower part of the tank body 100 to maintain the stability of the tank body 100.

[0048] Further, a lift 1000 is provided beside the shear machine, which can realize the lifting function through the lift 1000, facilitating operation and disassembly.

[0049] Further, the tank body 100 is externally provided with a temperature control jacket 900, the lower part of which is provided with a cooling inlet 910, and the upper part is provided with a cooling outlet 920. By passing in cold or hot fluid, the temperature of the material in the tank body 100 is raised or lowered to meet the expected temperature. Preferably, the temperature control jacket 900 is externally provided with a thermal insulation layer, which can be made of high-efficiency thermal insulation materials such as polyurethane foam and phenolic foam, which can provide good insulation and heat insulation effect while ensuring thermal insulation performance.

[0050] Further, a plurality of guide plates 930 are arranged in the temperature control jacket 900 to prevent dead zones in the flow and make the heat transfer uniform and improve the heat transfer efficiency. The number and shape of the guide plates 930 are set as needed, and they are preferably arranged at the flow direction changing positions in the temperature control jacket 900.

[0051] The tank body 100 is provided with a sleeve at the bottom center position for material injection, and is provided with a material discharge port at the top or side upper part for material discharge. The top discharge port 810 is located at the top of the tank body 100 and is connected with the tank cover 200; the side upper discharge port 820 is located on the side wall above the side upper part of the tank body 100 and is connected with the tank body 100. The position of the material discharge port can be set as needed.

[0052] The material injection sleeve arranged at the bottom center position of the tank body 100 is divided into an outer injection pipe 710 and an inner injection pipe 720, which are respectively used for the injection of two-phase medium. The two ends of the inner injection pipe 720 and the outer injection pipe 710 are respectively liquid inlet and liquid outlet, and the liquid inlet and liquid outlet of the inner injection pipe 720 and the outer injection pipe 710 are not communicated with each other. The inner injection pipe 720 is located at the bottom center of the tank body 100, and the diameter is preferably 3-6 mm. The liquid inlet 722 of the inner injection pipe is arranged at the lower part of the tank body 100, and the liquid outlet 721 of the inner injection pipe is arranged inside the tank body 100 and is close to the inner side of the bottom wall of the tank body 100, and the vertical distance is preferably 1-5 cm, and further preferably 3 cm. The liquid outlet 721 of the inner injection pipe is very close to the bottom surface of the stator 310 of the stator assembly, and the vertical distance is preferably 0.5-1 cm, so that the material can be dispersed more uniformly. The outer injection pipe 710 is sleeved outside the inner injection pipe 720, and the two are vertically arranged and consistent with the center line of the tank body. The liquid outlet 711 of the outer injection pipe is flush with the inner side of the bottom wall of the tank body. Preferably, in order to make the feeding and discharging speeds consistent, the diameter of the material discharge port is the same as the diameter of the outer injection pipe 710.

[0053] The structure of the downward and upward movement utilizes the medium gravity to make the small particle size particles or emulsion droplets be discharged from the upper material discharge port under the action of power, and the larger particle size particles or emulsion droplets sink to the bottom of the tank under the action of gravity, and are sucked into the rotor blades rotating at the shaft center under the action of the strong centrifugal force of the shearing machine to be sheared again, so that the shearing is more sufficient and uniform, and the emulsification effect is enhanced. At the same time, due to the continuous injection of the dispersion medium and the dispersed phase, the liquid in the tank is constantly updated, and the problems of a large amount of heat generation due to the long-time operation of the high-speed shearing machine and poor heat dissipation are avoided.

[0054] The stator assembly and the rotor assembly are arranged on the vertical central axis inside the tank body, the rotor assembly is arranged inside the stator assembly, the rotor assembly includes a rotor connecting rod 410 and rotor blades 420, the rotor blades 420 are arranged at the bottom end of the rotor connecting rod 410 and are uniformly distributed in the radial direction along the circumference of the rotor connecting rod 410, the upper part of the rotor connecting rod 410 is connected with the driving motor 500, and the rotor blades 420 rotate under the driving of the driving motor 500 to perform shearing. The stator assembly includes a stator 310 and a stator connecting cover 320, the stator connecting cover 320 is fixed to the upper end surface of the stator 310, the stator 310 is connected with the rotor connecting rod 410 through the stator connecting cover 320, the stator 310 is in a hollow cylindrical shape, and a plurality of dispersion groove holes are arranged on the stator 310 and used for medium dispersion.

[0055] When working, the motor 500 drives the rotor assembly to rotate at high speed, when the rotor assembly in the shearing machine rotates at high speed, a very strong negative pressure will be formed in the area around the rotor blades 420, and the material is continuously sucked in under the action of the strong centrifugal force, so that the material is diffused from the center to the periphery, and the negative pressure generated in the shearing machine helps the suction and conveying of the material, and when the rotating speed of the motor increases, the negative pressure gradually increases, so that the material can be more easily sucked from the liquid outlet of the inner injection pipe.

[0056] The dispersion method of the embodiment is as follows:

[0057] (1) First, the dispersion medium is injected into the shearing machine tank 100 through the liquid outlet 711 of the outer injection pipe, after the tank 100 is filled with the dispersion medium, the shearing is started;

[0058] (2) Then, the dispersed phase and the dispersion medium are injected in proportion, the injection speed of the dispersed phase can be 5 mL / min to 100 mL / min, and the injection speed of the dispersion medium can be 1000 mL / min to 10000 mL / min;

[0059] (3) The dispersed phase and the dispersion medium are subjected to more than three times of circulation shearing in the shearing machine, so that small particle size particles or emulsion droplets with a volume average diameter of 0.5-30 μm are obtained; and

[0060] (4) Small particle size particles or emulsion droplets are discharged from the upper material outlet under the fluid injection power, and large particle size particles or emulsion droplets sink back to the tank bottom under the action of gravity and are sheared again by the shearing machine.

[0061] In the third step:

[0062] The shearing and dispersion process of the material in the tank body mainly includes three shearing processes, and the three shearing processes are repeated until the particle size is sufficiently dispersed and refined and discharged out of the tank.

[0063] The first shearing process: when the dispersion starts, the material enters the tank body from the feed inlet, and under the action of strong centrifugal force, a very strong vortex is formed in the rotor blade 420 area, which enhances the collision and friction between the dispersed phase and the dispersion medium in the material, which is beneficial to the further mixing and dispersion of the material, and diffuses from the rotor blade 420 area to the gap between the stator and the rotor.

[0064] The second shearing process: under the action of strong centrifugal force, the material is thrown into the gap between the stator and the rotor along the radial direction from the rotor blade 420 area, and the gap between the stator and the rotor is the main area where shearing occurs. A large number of vortices exist therein, and at the same time, the material is subjected to forces such as centrifugal extrusion and impact, so that the material is further dispersed and mixed. In the gap between the stator and the rotor, the medium is subjected to the shearing action of the high-speed rotating rotor blade, and the particle medium is rapidly collided and broken. In the entire gap between the stator and the rotor, the material can be quickly mixed and dispersed uniformly under the combined action of strong shearing stress and turbulent stress, achieving better mixing and dispersion effect.

[0065] The third shearing process: the material is continuously ejected from the rotor blade 420 at high speed, part of which is ejected outside the stator 310, and the particle size of the particles or emulsion droplets is smaller. Under the action of the continuous fluid injection power, the larger particle size particles or emulsion droplets sink back to the tank bottom under the action of gravity and are continuously rolled into the rotor blade at the shaft center under the action of the strong centrifugal force of the shearing machine. Because a certain velocity gradient is generated in the radial direction, according to Bernoulli's theorem, the pressure and velocity in the fluid are related, that is, the faster the velocity, the smaller the pressure, and the slower the velocity, the greater the pressure. At this time, because the speed in the stator 310 is fast, the pressure is small, and the speed outside the stator 310 is slow, so the pressure is large. The pressure difference will push the material to flow from the outside to the inside of the stator 310, and the backflow and suction phenomenon occurs. The medium backflowing and suctioning into the stator 310 from the tank body 100 and the medium continuously sucked by the negative pressure source in the rotor blade 420 area converge in the gap between the stator and the rotor, forming multiple strong turbulent flows, which are continuously sheared. After several cycles of shearing, the dispersion and homogenization process is completed.

[0066] After several cycles of shearing process, the medium is fully sheared, and the particle size distribution is more uniform. In particular, the increased tank volume and bottom feeding method make the shearing more sufficient, and small particle size particles with a volume average diameter range of 0.5-30 μm can be obtained without extreme speed, and the need for equipment replacement can meet the needs from small test to large production scale, solving the limitations of batch high shear dispersion machines and pipeline high shear dispersion machines.

[0067] Test Example

[0068] 1. Relationship between motor speed and particle size when preparing extremely small particle size particles by tank type high speed shear machine

[0069] First, fill the tank with the dispersion medium, and inject the dispersed phase and the dispersion medium through the inner injection pipe and the outer injection pipe in a certain proportion. Under the condition that other conditions remain unchanged, the target product is prepared by changing the speed of the tank type high speed shear machine. The particle size of the product is measured by a laser particle size analyzer.

[0070] Table 1

[0071]

[0072] According to the research data of Test Example 1, it can be known that the size of the particles can be adjusted by adjusting the speed, and the particle size decreases as the speed increases. The span is smaller than that of the pipeline online homogenizer and the top-mounted high speed shear machine, and the particle size is more uniform.

[0073] 2. Relationship between material injection speed and particle size when preparing extremely small particle size particles by tank type high speed shear machine

[0074] First, fill the tank with the dispersion medium, and inject the dispersed phase and the dispersion medium through the inner injection pipe and the outer injection pipe in a certain proportion. Under the condition that other conditions remain unchanged, the target product is prepared by changing the speed of the tank type high speed shear machine. The particle size of the product is measured by a laser particle size analyzer.

[0075] Table 2

[0076]

[0077] According to the results of Test Example 2, increasing the flow rate of the two phases has no significant effect on the particle size of the prepared product, and the particle size of the product under different flow rates is basically the same

[0078] 3. Relationship between medium injection time and particle size when preparing extremely small particle size particles by tank type high speed shear machine

[0079] Preparation stability of the device at different scales. First, fill the tank with the dispersion medium, and inject the dispersion phase and the dispersion medium through the inner injection pipe and the outer injection pipe in a certain proportion. Different scales correspond to different material quantities, and other process conditions remain unchanged. Prolong the injection time of the two phases to obtain products prepared at different scales. The particle size of the product is measured using a laser particle size analyzer.

[0080] Table 3

[0081]

[0082] From the particle size results of Test Example 3, it can be seen that the particle size of the product prepared using the tank-type high-speed shearing machine is almost consistent, Figure 9 The scanning electron microscope image of the product prepared at a scale of 50 L shows that the prepared particles have high roundness and good morphology. The tank-type high-speed shearing machine used in this application uses the initial volume as a template (2 L in the test example), and by running for different lengths of time, different scales of materials can be continuously prepared, meeting the production batch of 2 L-200 L and larger scales. Economically and efficiently scale up from small-scale tests to production scale, consistent material properties can be obtained, reducing the scale-up effect and reducing research and development costs.

[0083] Comparative Example 1

[0084] This comparative example is to prepare micron-sized particles using a single shearing of a pipeline-type high-shear dispersing machine. The pipeline-type high-shear dispersing machine is used to prepare micron-sized particles, and the rotational speed is set to 11000 rpm, 15000 rpm, and 18000 rpm, respectively. The particle size and morphology of the particles prepared at different rotational speeds are investigated.

[0085] Table 4

[0086]

[0087] From the research data of Comparative Example 1, it can be seen that as the shear speed increases from 11000 rpm to 18000 rpm, the particle size of the prepared particles does not effectively decrease, the particle size span (Span) is wide, and the particle size distribution is not uniform. From Figures 3-5 It can be seen that the morphology of the particles does not become closer to spherical with increasing shear speed, which does not meet the preparation target. On the other hand, 18000 rpm is close to the upper limit of the rotational speed of the pipeline-type high-shear dispersing machine used in this experiment, and long-term operation is not conducive to the service life and maintenance of the equipment.

[0088] Comparative Example 2

[0089] The present comparative example is to prepare micron-sized particles using a top-mounted high shear dispersion machine. The top-mounted high shear dispersion machine equipment is used, and the bottom injection material is used at the same time. By changing the volume of the tank, particles of different scales are prepared to investigate the feasibility of proportional scaling. The top-mounted high shear dispersion machine equipment (rotor diameter 38 mm).

[0090] Table 5

[0091]

[0092] According to the particle size data of Comparative Example 2, the volume average diameter of the particles prepared at the scale of 2 L-10 L is less than 20 μm. When the scale is increased to 50 L, the D50 and D90 particle sizes increase significantly, indicating that the shear machine is not suitable for the current scale, and the equipment needs to be replaced and the process parameters need to be adjusted. On the other hand, from the particle size data of Comparative Example 3, the D50 and D90 particle sizes of the particles prepared at the scale of 2 L-10 L are larger than those of Comparative Example 2, and the D90 particle size of the particles prepared at the scale of 50 L is smaller than that of Comparative Example 2. It can be seen that the particle size of the particles prepared at the scale of 2 L-10 L is smaller than that of Comparative Example 2, and the particle size of the particles prepared at the scale of 50 L is smaller than that of Comparative Example 2. It can be seen that the particle size of the particles prepared at the scale of 2 L-10 L is smaller than that of Comparative Example 2, and the particle size of the particles prepared at the scale of 50 L is smaller than that of Comparative Example 2. Figures 6-8 It can be seen that the particles prepared at the scale of 2 L have high roundness and good morphology, and a large number of strips appear at the scale of 10 L-50 L. The process has a scaling effect, and different morphologies of particles may have an impact on product quality. Therefore, the use of top-mounted high-speed shear machines has limitations in scaling.

[0093] In summary, the dispersion method for preparing micron-sized particles proposed in the present application can avoid the scaling effect of batch high shear dispersion machines and improve the problem that the pipeline high shear dispersion machine cannot disperse uniformly when the properties of the two phases are significantly different. Without extreme speed, it can stably prepare particles or emulsion droplets with extremely small particle size, greatly improve the uniformity of the product, and can maintain the uniformity of the product from small-scale to large-scale production, meet different batch production, and reduce research and development costs.

[0094] Although the present application has been described with reference to exemplary embodiments, it is to be understood that the application is not limited to the disclosed exemplary embodiments. Various adjustments or changes can be made to the exemplary embodiments of the present application without departing from the scope or spirit of the present application. The scope of the claims should be based on the broadest interpretation to encompass all modifications and equivalent structures and functions.

Claims

1. A dispersion method for preparing micron-sized particles, characterized in that, The process includes a dispersing step using a shearing machine, wherein the shearing machine includes a tank body (100), a tank cover (200), a material inlet, a material outlet, a drive motor (500), and a shearing module. The shearing machine includes a drive motor (500) disposed on the upper part of the tank body (100), a stator assembly and a rotor assembly disposed inside the tank body. The rotor assembly includes a rotor connecting rod (410) and rotor blades (420), the rotor blades (420) being radially evenly distributed at the end of the rotor connecting rod (410). The stator assembly includes a stator (310) and stator blades disposed on the upper surface of the stator. The connecting cover (320) is located inside the stator assembly. The upper part of the rotor connecting rod (410) passes through the center of the tank cover (200) and is connected to the drive motor (500). The drive motor (500) drives the rotor blades (420) to rotate and perform cyclic shearing. A sleeve is provided at the center of the bottom of the tank body (100) for material injection. A top discharge port (810) or a side discharge port (820) is provided at the top for material discharge. The sleeve includes an outer injection pipe (710) and an inner injection pipe (720), which are used for the injection of the dispersion medium and the dispersion phase, respectively. The steps include: (1) The dispersion medium is first injected into the shearing machine tank (100) through the material injection port, and the shearing is started; (2) Inject the dispersed phase and the dispersion medium in proportion, wherein the injection rate of the dispersed phase is 5 mL / min to 100 mL / min and the injection rate of the dispersion medium is 1000 mL / min to 10000 mL / min; (3) The dispersed phase and the dispersion medium are subjected to more than three cyclic shearing cycles in a shear mill to obtain small-diameter particles or droplets with a volume average diameter of 0.5-30 μm; and (4) Small-diameter particles or droplets are discharged from the upper material outlet under the power of fluid injection, while large-diameter particles or droplets sink back to the bottom of the tank under the action of gravity and are sheared again by the shearing machine.

2. The dispersion method for preparing micron-sized particles according to claim 1, characterized in that, The rotational speed of the shearing machine is controlled between 4800-7700 rpm, thereby obtaining particles or droplets with a volume average diameter of 22.51-27.26 μm.

3. The dispersion method for preparing micron-sized particles according to claim 1, characterized in that, The material is continuously injected into the shearing machine tank (100) from the material inlet, and the flow rate of the material outlet is controlled to be consistent with the flow rate of the material inlet.

4. The dispersion method for preparing micron-sized particles according to claim 1, characterized in that, The volume of material continuously injected is 2 L-200 L.

5. The dispersion method for preparing micron-sized particles according to claim 1, characterized in that, The bottom of the tank (100) is connected to the support frame (600), and the support frame (600) keeps the tank (100) stable.

6. The dispersion method for preparing micron-sized particles according to claim 1, characterized in that, The viscosity ratio of the dispersed phase to the dispersion medium is in the range of 300-7500:

1.

7. The dispersion method for preparing micron-sized particles according to claim 1, characterized in that, The tank body (100) and the tank cover (200) are sealed by an O-ring, and the tank cover (200) and the rotor connecting rod (410) are sealed by a double-end mechanical seal.

8. The dispersion method for preparing micron-sized particles according to claim 1, characterized in that, A lift (1000) is provided on one side of the tank body (100), the lift (1000) is connected to the tank cover (200), and is configured to enable the shearing machine to move up and down.

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