Continuous flow shear emulsification device and application thereof in preparation of polymer microspheres and polymer microcapsules

Abstract

The invention provides a continuous flow shear emulsification device and application thereof, and relates to the technical field of polymer microspheres and polymer microcapsules. The continuous flow shear emulsification device comprises a raw material storage tank, a plunger pump, a gas steel cylinder, a thermometer, a reaction kettle gas inlet, a micro-channel, a jacket water outlet, a reaction kettle, a motor, a feed port, a stirring paddle, a condensation pipe, a condensation pipe gas outlet, a condensation pipe water outlet, a condensation pipe water inlet, a condensation pipe gas inlet, a jacket, a jacket water inlet, a tank body, a discharge valve and a discharge port, the system comprises a gas switching valve, a vacuum pump, a water storage tank, a submersible pump, a high-low temperature circulation integrated machine water outlet, a high-low temperature circulation integrated machine water inlet and a high-low temperature circulation integrated machine. The continuous flow shear emulsification device provided by the invention can enable the particle size of a product to be distributed in a narrower range. In addition, the device conveys the dispersed phase only through the micro-channel, the equipment complexity and the operation cost are reduced, the production efficiency is improved, and the device is suitable for industrial large-scale production and has a good application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer microspheres and polymer microcapsules, and particularly relates to a continuous flow shear emulsification device and its application. Background Art

[0002] Polymer microspheres and microcapsules have wide applications in many fields such as coatings, biomedicine, catalysis, and optics. With the continuous in-depth application research, the particle size distribution requirements of polymer microspheres and microcapsules in various application fields are getting higher and higher. Polymer microspheres and microcapsules with non-uniform particle size distributions are difficult to meet the requirements of fine compounding and processing. For example, polymer microspheres with a wide particle size distribution have poor optical transparency, weather resistance, and chemical stability, and non-uniformly distributed polymer microcapsule particles are difficult to achieve uniform heat transfer, which is not conducive to giving full play to the temperature control and heat storage performance of phase change materials.

[0003] The particle size distribution of the polymer emulsion formed by the emulsification technology determines the uniformity of the polymer product. In order to obtain polymer microspheres and microcapsules with a narrow particle size distribution, researchers have adopted various emulsification technologies, such as mechanical stirring emulsification method, high-speed shear emulsification method, membrane emulsification method, and microfluidic emulsification method, etc.

[0004] The mechanical stirring emulsification method is to mix the dispersed phase and the continuous phase through mechanical stirring to form fine droplets. The high-speed shear emulsification method is that a high-speed shear emulsifier uses the precise cooperation of the rotor and the stator to emulsify the material with the powerful shear force generated by high-speed rotation. Both of them have the difference in shear force at different positions, which will make the particle size of the emulsified droplets non-uniform, resulting in a wide particle size distribution of the product. After scaling up the reaction kettle, the mass transfer and heat transfer processes of the reaction are quite different from those in small-scale experiments, and finally, the scale-up effect of this process is obvious. The membrane emulsification method can be divided into two types: direct membrane emulsification method and rapid membrane emulsification method. The direct membrane emulsification method is to press the dispersed phase through the small holes on the solid membrane under a certain pressure to form dispersed phase droplets, and the shear force of the flowing continuous phase is used to make them break away from the membrane holes. The difference in the flow velocity of the fluid at different positions causes different shear forces on the dispersed phase, resulting in inconsistent particle sizes of the emulsified droplets. The rapid membrane emulsification method is to first prepare the primary emulsion by the traditional emulsification method, and then press the primary emulsion through the membrane tube, and the large droplets are broken by increasing the operating pressure to form smaller droplets. Compared with the direct membrane emulsification method, the rapid membrane emulsification method has higher emulsification efficiency and is suitable for large-scale production. However, the particle size of the primary emulsion prepared by the traditional emulsification method is non-uniform, and the droplet size of the primary emulsion may not match the membrane pore size, which will lead to a wide particle size distribution of the produced polymer product. The microfluidic emulsification method is to generate droplets by the controlled rupture of the two-phase flow interface in the micro-scale channel. The blockage or uneven wear of the micro-channel will lead to the instability of droplet generation. When multiple channels are connected in parallel, the liquid pressure distribution in each channel is uneven, resulting in a wide particle size distribution of the product. Summary of the Invention

[0005] The object of the present invention is to overcome the deficiencies of the prior art, and provides a continuous flow shear emulsification device and a process for preparing polymer microspheres and microcapsules by using the same. The device and the process can simultaneously prepare polymer microspheres and microcapsule products with a narrow particle size distribution on a large scale, and can also meet the requirements of low-cost, high-efficiency and safe industrial production.

[0006] The first aspect of the present invention is to provide a continuous flow shear emulsification device, which includes a raw material storage tank, a plunger pump, a gas cylinder, a thermometer, an inlet of a reaction kettle, a microchannel, an outlet of a jacket, a reaction kettle, a motor, a feed inlet, a stirring paddle, a condenser, an outlet of the condenser, an outlet of the condenser water, an inlet of the condenser water, an inlet of the condenser gas, a jacket, an inlet of the jacket, a tank body, a discharge valve, a discharge outlet, a vacuum pump, a water storage tank, a submersible pump, an outlet of a high and low temperature circulation integrated machine, an inlet of the high and low temperature circulation integrated machine, and a high and low temperature circulation integrated machine.

[0007] Further, the number of the plunger pumps is equal to that of the microchannels.

[0008] Further, the diameter of the microchannel is 0.2 - 0.8 mm.

[0009] The second aspect of the present invention is to provide an application of the continuous flow shear emulsification device in the preparation of polymer microspheres or polymer microcapsules.

[0010] The method for preparing polymer microspheres by the continuous flow shear emulsification device is as follows:

[0011] S1-1, preparing an oil phase and a water phase and respectively pouring them into the raw material storage tank and the reaction kettle;

[0012] The oil phase is composed of a monomer and an initiator; the monomer is at least one of styrene, methyl methacrylate, butyl acrylate and divinylbenzene combination, the initiator is at least one of benzoyl peroxide, dimethyl azobisisobutyrate or azobisisobutyronitrile, and the mass ratio of styrene, methyl methacrylate or butyl acrylate to divinylbenzene is (4 - 8):1, preferably 4:1, 6:1 or 8:1; the dosage of the initiator is 2 wt.% - 5 wt.% of the mass of the monomer;

[0013] The water phase is an aqueous solution of an emulsifier with a concentration of 2 wt.% - 6 wt.%; the emulsifier is at least one of sodium dodecyl sulfate (SDS), sodium p-vinylbenzenesulfonate (NaSS), alkenyl sulfonate, hydroxyethyl cellulose (HEC) or polyvinyl alcohol (PVA), preferably at least one of alkenyl sulfonate, NaSS, PVA;

[0014] The mass ratio of the oil phase to the water phase is 1:(2 - 5);

[0015] S1-2. Turn on the vacuum pump to evacuate the air in the reaction kettle, then open the gas cylinder and introduce the protective gas; turn on the submersible pump to circulate tap water through the condenser; turn on the high and low temperature circulating unit and the stirrer, and set the circulating temperature and the mechanical shear rate of the stirring paddle;

[0016] The mechanical shear rate of the stirring paddle is 200 - 750 r·min -1 , preferably 300 - 750 r·min -1 ; The circulating temperature range of the high and low temperature circulating unit is 10°C - 95°C; The protective gas is nitrogen or argon;

[0017] S1-3. Turn on the plunger pump and adjust the flow rate, transport the oil phase to the microchannel to form a continuous flow and inject it into the water phase, and carry out the emulsification reaction under the action of mechanical shear;

[0018] The diameter of the microchannel is preferably 0.3 - 0.8 mm, the temperature of the water phase is 15°C - 25°C, and the flow rate is 70 - 120 mL·min -1 , preferably 80 - 110 mL·min -1 ; The emulsification temperature is 15°C - 25°C, the emulsification time is 15 - 30 min, and the temperature of the water phase is the same as the emulsification temperature;

[0019] S1-4. After the emulsification reaction is completed, adjust the circulating temperature of the high and low temperature circulating unit and then carry out the free radical polymerization reaction. After the reaction is completed, open the discharge valve to separate the product and dry it to obtain polymer microspheres.

[0020] The free radical polymerization reaction is carried out in two stages. The reaction temperature in the first stage is 60°C - 70°C, and the reaction time is 4 - 6 h. The reaction temperature in the second stage is 80°C - 90°C, and the reaction time is 2 - 6 h, preferably 2 - 4 h; The drying temperature is 40°C - 90°C, preferably 70°C - 90°C.

[0021] The method for preparing polymer microcapsules by the continuous flow shear emulsification device is as follows:

[0022] S2-1. Prepare the oil phase and the water phase and pour them into the raw material storage tank and the reaction kettle respectively;

[0023] The oil phase is composed of monomers, core materials, co-solvents and initiators; the monomers are at least one of styrene, methyl methacrylate, butyl acrylate and divinylbenzene in combination, the co-solvents are at least one of dichloromethane, dichloroethane, ethyl acetate, the core materials are at least one of tetradecane, octadecane, decanol, dodecanol, tetradecanol, hexadecanol, the initiators are at least one of benzoyl peroxide, dimethyl 2,2'-azobis(2-methylpropionate), azobisisobutyronitrile, and the mass ratio of styrene or methyl methacrylate or butyl acrylate to divinylbenzene is (4-8):1, the mass ratio of the co-solvent to the monomer is 1:(1.2-2.4), the mass ratio of the core material to the monomer is 1:(0.5-1.4); the dosage of the initiator is 2wt.% - 7wt.% of the mass of the monomer;

[0024] The aqueous phase is an aqueous solution of an emulsifier with a concentration of 0.5wt.% - 5wt.%; the emulsifier is at least one of SDS, NaSS, alkenyl sulfonate, HEC, PVA, preferably at least one of SDS, NaSS, alkenyl sulfonate, HEC;

[0025] The mass ratio of the oil phase to the aqueous phase is 1:(2-5);

[0026] S2-2. Turn on the vacuum pump to evacuate the air in the reaction kettle, then open the gas cylinder and introduce the protective gas; turn on the submersible pump to circulate tap water through the condenser; turn on the high and low temperature circulation unit and the stirrer, and set the circulation temperature and the mechanical shear rate of the stirring paddle;

[0027] The mechanical shear rate of the stirring paddle is 200-700r·min -1 , preferably 400-700r·min -1 ; the circulation temperature range of the high and low temperature circulation unit is 10°C - 95°C; the protective gas is nitrogen or argon;

[0028] S2-3. Turn on the plunger pump and adjust the flow rate, transport the oil phase to the microchannel to form a continuous flow and inject it into the aqueous phase, and carry out an emulsification reaction under the action of mechanical shear;

[0029] The diameter of the microchannel is preferably 0.5-0.6mm, and the flow rate is 70-120mL·min -1 , preferably 80-110mL·min -1 ; the emulsification temperature is 15°C - 25°C; the emulsification time is 15-30min, preferably 20-25min;

[0030] S2-4. After the emulsification reaction is completed, adjust the circulation temperature of the high and low temperature circulation unit and then carry out a free radical polymerization reaction. After the reaction is completed, open the discharge valve to separate the product and dry it to obtain polymer microcapsules.

[0031] The free radical polymerization reaction is carried out in two stages. The reaction temperature in the first stage is 60°C - 70°C, the reaction time is 3 - 6 h, preferably 5 h. The reaction temperature in the second stage is 80°C - 90°C, preferably 90°C, and the reaction time is 2 - 6 h. The drying temperature is 40°C - 60°C.

[0032] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0033] (1) In the present invention, a continuous flow shear emulsification device is used to inject the dispersed phase into the continuous phase in the form of a continuous flow through a microchannel, and at the same time, mechanical shearing is used for emulsification to form emulsified liquid droplets with uniform particle size, solving the problem of wide particle size distribution of products caused by the difference in shear force at each position in the reaction vessel during the large-scale preparation of polymer microspheres and microcapsules in the prior art.

[0034] (2) In the process of the present invention, only the dispersed phase is transported through the microchannel, and other processes such as mechanical shearing and polymerization can be carried out in a traditional reaction kettle, reducing the equipment complexity and operation cost, improving the production efficiency, being suitable for large-scale industrial production, and having good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be further described below in conjunction with the drawings.

[0036] Figure 1 It is a schematic diagram of the continuous flow shear emulsification device of the present invention;

[0037] Figure 2 It is a comparison diagram of the process principles of mechanical stirring emulsification and continuous flow shear emulsification. Among them, a) is the process principle of mechanical stirring emulsification; b) is the process principle of continuous flow shear emulsification;

[0038] Figure 3 It is an OM diagram of the polymer microspheres prepared in Examples 2 - 4 and Comparative Examples 1 - 2 of the present invention; among them, A) is the 500 mL scale of poly(butyl acrylate) microspheres by continuous flow shear method; B) is the 500 mL scale of poly(methyl methacrylate) microspheres by continuous flow shear method; C) is the 500 mL scale of polystyrene microspheres by continuous flow shear method; D) is the 5 L scale of polystyrene microspheres by continuous flow shear method; E) is the 500 mL scale of polystyrene microspheres by emulsifier method; F) is the 5 L scale of polystyrene microspheres by emulsifier method; G) is the 500 mL scale of polystyrene microspheres by mechanical stirring method; H) is the 5 L scale of polystyrene microspheres by mechanical stirring method;

[0039] Figure 4OM images of the polymer microcapsules prepared in Examples 5-7 and Comparative Examples 3-4 of the present invention; wherein, A) is a 500 mL scale of poly(butyl acrylate) microcapsules by continuous flow shearing method; B) is a 500 mL scale of poly(methyl methacrylate) microcapsules by continuous flow shearing method; C) is a 500 mL scale of polystyrene microcapsules by continuous flow shearing method; D) is a 5 L scale of polystyrene microcapsules by continuous flow shearing method; E) is a 500 mL scale of polystyrene microcapsules by emulsifier method; F) is a 5 L scale of polystyrene microcapsules by emulsifier method; G) is a 500 mL scale of polystyrene microcapsules by mechanical stirring method; H) is a 5 L scale of polystyrene microcapsules by mechanical stirring method;

[0040] Description of reference numerals: 1, raw material storage tank; 2, plunger pump; 3, gas cylinder; 4, thermometer; 5, reaction kettle inlet; 6, microchannel; 7, jacket water outlet; 8, reaction kettle; 9, motor; 10, feed inlet; 11, stirring paddle; 12, condenser; 13, condenser gas outlet; 14, condenser water outlet; 15, condenser water inlet; 16, condenser gas inlet; 17, jacket; 18, jacket water inlet; 19, tank body; 20, discharge valve; 21, discharge outlet; 22, gas switching valve; 23, vacuum pump; 24, water storage tank; 25, submersible pump; 26, high and low temperature circulation integrated machine water outlet; 27, high and low temperature circulation integrated machine water inlet; 28, high and low temperature circulation integrated machine. Detailed implementation manners

[0041] The technical solutions of the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0042] To further illustrate the present invention, the following examples are provided for detailed description. All raw materials used in the following examples of the present invention are commercially available. Unless otherwise specified, each experiment is repeated three times, and the results are expressed as averages.

[0043] Example 1 A continuous flow shearing emulsification device, comprising a raw material storage tank 1, a plunger pump 2, a gas cylinder 3, a thermometer 4, a reaction kettle inlet 5, a microchannel 6, a jacket water outlet 7, a reaction kettle 8, a motor 9, a feed inlet 10, a stirring paddle 11, a condenser 12, a condenser gas outlet 13, a condenser water outlet 14, a condenser water inlet 15, a condenser gas inlet 16, a jacket 17, a jacket water inlet 18, a tank body 19, a discharge valve 20, a discharge outlet 21, a gas switching valve 22, a vacuum pump 23, a water storage tank 24, a submersible pump 25, a high and low temperature circulation integrated machine water outlet 26, a high and low temperature circulation integrated machine water inlet 27, and a high and low temperature circulation integrated machine 28.

[0044] Example 2 A process for preparing poly(butyl acrylate) microspheres using a continuous flow shear emulsification device is as follows:

[0045] (1) Mix 56 g of butyl acrylate and 14 g of divinylbenzene as monomers. Dissolve 1.1 g of benzoyl peroxide and 1.0 g of dimethyl 2,2'-azobis(2-methylpropionate) in 70 g of the monomers, mix well as the oil phase, and pour it into the raw material storage tank. Add 3.5 g of HEC and 2.8 g of SDS to 203.7 g of aqueous solution, mix well as the water phase, and pour it into the reaction kettle through the feed port.

[0046] (2) Turn on the vacuum pump to remove the air in the reaction kettle, then open the gas cylinder and introduce the protective gas. Turn on the submersible pump to circulate tap water through the condenser. Turn on the high and low temperature circulating machine and adjust the circulating temperature to make the temperature of the water phase 15 °C. Turn on the motor and adjust the mechanical shear rate of the stirring paddle to 300 r·min -1 ;

[0047] (3) Inject the oil phase into the water phase through a 0.3 mm microchannel at a flow rate of 110 mL·min -1 to form a continuous flow. After emulsifying at 15 °C for 30 min, raise the temperature to 60 °C and react for 6 h, then raise the temperature to 85 °C and continue to react for 4 h. The whole reaction process is protected by nitrogen.

[0048] (4) After the reaction is completed, open the discharge valve to separate the product. Wash the product with hot distilled water, centrifuge it, and then dry the product at 50 °C to obtain poly(butyl acrylate) microspheres.

[0049] Example 3 A process for preparing poly(methyl methacrylate) microspheres using a continuous flow shear emulsification device is as follows:

[0050] (1) Mix 62.22 g of methyl methacrylate and 7.78 g of divinylbenzene as monomers. Dissolve 2.8 g of dimethyl 2,2'-azobis(2-methylpropionate) in 70 g of the monomers, mix well as the oil phase, and pour it into the raw material storage tank. Add 7.5 g of alkenyl sulfonate and 10 g of NaSS to 332.5 g of aqueous solution, mix well as the water phase, and pour it into the reaction kettle through the feed port.

[0051] (2) Turn on the vacuum pump to remove the air in the reaction kettle, then open the gas cylinder and introduce the protective gas. Turn on the submersible pump to circulate tap water through the condenser. Turn on the high and low temperature circulating machine and adjust the circulating temperature to make the temperature of the water phase 25 °C. Turn on the motor and adjust the mechanical shear rate of the stirring paddle to 750 r·min -1 ;

[0052] (3) Inject the oil phase into the water phase through a 0.3 mm microchannel at a flow rate of 80 mL·min -1The flow rate of was passed through a 0.4 mm microchannel to form a continuous flow and injected into the aqueous phase. After emulsification at 25 °C for 20 min, the temperature was raised to 65 °C and the reaction was carried out for 5 h, and then the temperature was raised to 90 °C and the reaction was continued for 3 h. The whole reaction process was protected by nitrogen;

[0053] (4) After the reaction was completed, the discharge valve was opened to separate the product. The product was washed with hot distilled water, centrifuged, and then dried at 70 °C to obtain polymethyl methacrylate microspheres.

[0054] Example 4 A process for preparing polystyrene microspheres by a continuous flow shear emulsification device, the specific steps are as follows:

[0055] (1) 60 g of styrene and 10 g of divinylbenzene were mixed as monomers. 1.4 g of azobisisobutyronitrile was dissolved in 70 g of monomers and mixed evenly as the oil phase and poured into the raw material storage tank; 4.2 g of PVA was added to 135.8 g of aqueous solution and mixed evenly as the aqueous phase and poured into the reaction kettle through the feed port;

[0056] (2) The vacuum pump was started to remove the air in the reaction kettle, and then the gas cylinder was opened to introduce the protective gas; the submersible pump was turned on to circulate the tap water through the condenser; the high and low temperature circulating machine was turned on and the circulating temperature was adjusted so that the temperature of the aqueous phase was 20 °C, and the motor was turned on and the mechanical shear rate of the stirring paddle was adjusted to 650 r·min -1 ;

[0057] (3) The oil phase was passed through a 0.8 mm microchannel at a flow rate of 90 mL·min -1 to form a continuous flow and injected into the aqueous phase. After emulsification at 20 °C for 15 min, the temperature was raised to 70 °C and the reaction was carried out for 4 h, and then the temperature was raised to 80 °C and the reaction was continued for 2 h. The whole reaction process was protected by nitrogen;

[0058] (4) After the reaction was completed, the discharge valve was opened to separate the product. The product was washed with hot distilled water, centrifuged, and then dried at 90 °C to obtain polystyrene microspheres.

[0059] Example 5 A process for preparing polybutyl acrylate microcapsules by using a continuous flow shear emulsification device, the specific steps are as follows:

[0060] (1) 28 g of butyl acrylate and 7 g of divinylbenzene were mixed as monomers. 35 g of monomers, 30 g of tetradecane, 20 g of octadecane and 20 g of dichloromethane were magnetically stirred until the liquid was clear, and 1.4 g of dimethyl azobisisobutyrate was added and stirred until completely dissolved to obtain the oil phase and poured into the raw material storage tank; 1.65 g of HEC and 7.15 g of alkenyl sulfonate were added to 405 g of aqueous solution and mixed evenly as the aqueous phase and poured into the reaction kettle through the feed port;

[0061] (2) Turn on the vacuum pump to remove the air in the reaction kettle, then open the gas cylinder and introduce the protective gas; turn on the submersible pump to circulate tap water through the condenser; turn on the high and low temperature circulating machine and adjust the circulating temperature so that the temperature of the aqueous phase is 25 °C; turn on the motor and adjust the mechanical shear rate of the stirring paddle to 400 r·min -1 ; turn on the submersible pump to circulate tap water through the condenser;

[0062] (3) Inject the oil phase into the aqueous phase as a continuous flow at a flow rate of 100 mL·min -1 through a 0.5 mm microchannel, emulsify at 25 °C for 25 min, then raise the temperature to 60 °C and react for 5 h, and then raise the temperature to 90 °C and continue to react for 3 h. The whole reaction process is protected by nitrogen;

[0063] (4) After the reaction is completed, open the discharge valve to separate the product, wash it with hot distilled water, centrifuge it, and then dry the product at 50 °C to obtain polybutyl acrylate microcapsules.

[0064] Example 6 A process for preparing polymethyl methacrylate microcapsules using a continuous flow shear emulsification device, the specific steps are as follows:

[0065] (1) Mix 30.62 g of methyl methacrylate and 4.38 g of divinylbenzene as monomers; magnetically stir 35 g of monomers, 16.9 g of decanol, 10 g of myristyl alcohol and 15.2 g of ethyl acetate until the liquid is clear, add 0.75 g of benzoyl peroxide and 1 g of dimethyl azobisisobutyrate and stir until completely dissolved to obtain the oil phase and pour it into the raw material storage tank; add 3.75 g of NaSS and 5.5 g of SDS to 222 g of aqueous solution, mix evenly as the aqueous phase, and pour it into the reaction kettle through the feed port;

[0066] (2) Turn on the vacuum pump to remove the air in the reaction kettle, then open the gas cylinder and introduce the protective gas; turn on the submersible pump to circulate tap water through the condenser; turn on the high and low temperature circulating machine and adjust the circulating temperature so that the temperature of the aqueous phase is 15 °C, turn on the motor and adjust the mechanical shear rate of the stirring paddle to 700 r·min -1 ;

[0067] (3) Inject the oil phase into the aqueous phase as a continuous flow at a flow rate of 80 mL·min -1 through a 0.6 mm microchannel, emulsify at 15 °C for 20 min, then raise the temperature to 80 °C and react for 5 h, and then raise the temperature to 90 °C and continue to react for 2 h. The whole reaction process is protected by nitrogen;

[0068] (4) After the reaction is completed, open the discharge valve to separate the product, wash it with hot distilled water, centrifuge it, and then dry the product at 60 °C to obtain polymethyl methacrylate microcapsules.

[0069] Example 7 A process for preparing polystyrene microcapsules using a continuous flow shearing emulsification device, the specific steps are as follows:

[0070] (1) Mix 28 g of styrene and 7 g of divinylbenzene as monomers; magnetically stir 35 g of monomers, 30 g of tetradecane, 20 g of octadecane, and 25 g of dichloroethane until the liquid is clear, add 1.4 g of azobisisobutyronitrile and stir until completely dissolved to obtain an oil phase, and pour it into the raw material storage tank; add 8.8 g of alkenyl sulfonate to 431.2 g of aqueous solution, mix evenly as the aqueous phase, and pour it into the reaction kettle through the feed port;

[0071] (2) Turn on the vacuum pump to remove the air in the reaction kettle, then open the gas cylinder and introduce the protective gas; turn on the submersible pump to circulate tap water through the condenser; turn on the high and low temperature circulator and adjust the circulation temperature to make the temperature of the aqueous phase 20 °C, turn on the motor and adjust the mechanical shearing rate of the stirring paddle to 400 r·min -1 ; Turn on the submersible pump to circulate tap water through the condenser;

[0072] (3) Inject the oil phase into the aqueous phase through a 0.6 mm microchannel at a flow rate of 110 mL·min -1 to form a continuous flow, emulsify at 20 °C for 20 min, then raise the temperature to 60 °C and react for 5 h, and then raise the temperature to 90 °C and continue to react for 6 h, with nitrogen protection throughout the reaction;

[0073] (4) After the reaction is completed, open the discharge valve to separate the product, wash it with hot distilled water, centrifuge it, and then dry the product at 40 °C to obtain polystyrene microcapsules.

[0074] Comparative Example 1 A process for preparing polystyrene microspheres using an emulsifier emulsification method, the specific steps are as follows:

[0075] (1) Mix 60 g of styrene and 10 g of divinylbenzene as monomers, and dissolve 1.4 g of azobisisobutyronitrile in 70 g of monomers as the oil phase; add 4.2 g of PVA to 135.8 g of aqueous solution as the aqueous phase;

[0076] (2) Add the oil phase to the aqueous phase and emulsify it with an emulsifier in a 20 °C water bath at 1500 r·min -1 for 30 min, pour the obtained emulsion into a three-necked flask, and raise the temperature to 70 °C and react for 4 h under mechanical stirring at 650 r·min -1 , then raise the temperature to 80 °C and react for 2 h, with nitrogen protection throughout the reaction, and introduce tap water to reflux the solvent;

[0077] (3) After the reaction is completed, pour the reaction solution into a beaker and let it stand overnight, wash it with hot distilled water, centrifuge it, and then dry the product at 40 °C to obtain polystyrene microspheres.

[0078] Comparative Example 2 A process for preparing polystyrene microspheres by mechanical stirring emulsification method, the specific steps are as follows:

[0079] (1) Mix 60 g of styrene and 10 g of divinylbenzene as monomers, and dissolve 1.4 g of azobisisobutyronitrile in 70 g of monomers as the oil phase; add 4.2 g of PVA to 135.8 g of aqueous solution as the water phase;

[0080] (2) Under a 20 °C water bath and 650 r·min -1 With mechanical stirring, directly add the oil phase to the water phase, mechanically stir and emulsify for 15 min, then raise the temperature to 70 °C and react for 4 h, then raise the temperature to 80 °C and react for 2 h. The whole reaction process is protected by nitrogen, and tap water is introduced to reflux the solvent;

[0081] (3) After the reaction is completed, pour the reaction solution into a beaker and let it stand overnight, wash with hot distilled water, centrifuge, and then dry the product at 90 °C to obtain polystyrene microspheres.

[0082] Comparative Example 3 A process for preparing polystyrene microcapsules by emulsifier emulsification method, the specific steps are as follows:

[0083] (1) Mix 28 g of styrene and 7 g of divinylbenzene as monomers, stir 35 g of monomers, 30 g of tetradecane, 20 g of octadecane and 25 g of dichloroethane with a magnetic stirrer to make the solution clear, add 1.4 g of azobisisobutyronitrile and stir until completely dissolved to obtain the oil phase; add 8.8 g of alkenyl sulfonate to 432.1 g of aqueous solution and mix evenly as the water phase;

[0084] (2) Add the oil phase to the water phase and emulsify with an emulsifier in a 20 °C water bath at 1500 r·min -1 for 30 min, pour the obtained emulsion into a three-necked flask, and raise the temperature to 60 °C and react for 5 h under mechanical stirring at 400 r·min -1 Then raise the temperature to 90 °C and react for 6 h. The whole reaction process is protected by argon, and tap water is introduced to reflux the solvent;

[0085] (3) After the reaction is completed, pour the reaction solution into a beaker and let it stand overnight, wash with hot distilled water, centrifuge, and then dry the product at 40 °C to obtain polystyrene microcapsules.

[0086] Comparative Example 4 A process for preparing polystyrene microcapsules by mechanical stirring emulsification method, the specific steps are as follows:

[0087] (1) 28 g of styrene and 7 g of divinylbenzene were mixed as monomers. 35 g of the monomers, 30 g of tetradecane, 20 g of octadecane, and 25 g of dichloroethane were magnetically stirred to clarify the solution. 1.4 g of azobisisobutyronitrile was added and stirred until completely dissolved to obtain the oil phase. 8.8 g of sodium vinylsulfonate was added to 432.1 g of an aqueous solution as the water phase;

[0088] (2) Under a 20 °C water bath and mechanical stirring at 400 r·min -1 , the oil phase was directly added to the water phase. After mechanical stirring and emulsification for 25 min, the temperature was raised to 60 °C and the reaction was carried out for 5 h, then the temperature was raised to 90 °C and the reaction was carried out for 6 h. The whole reaction process was protected by argon, and tap water was introduced to reflux the solvent;

[0089] (3) After the reaction was completed, the reaction solution was poured into a beaker and left to stand overnight. It was washed with hot distilled water, centrifuged, and the product was dried at 40 °C to obtain polystyrene microcapsules.

[0090] The particle size distribution indices of the polymer microspheres and microcapsules obtained in the examples and comparative examples were analyzed. The specific method was as follows:

[0091] The reaction solution was aspirated and dropped on a glass slide. Photos of the polymer microspheres and microcapsules were taken under an optical microscope (OM). The diameters of the polymer microspheres and microcapsules in the photos were measured using Nano Measure software, and then the particle size distribution indices of the polymer microspheres and microcapsules were statistically analyzed by Origin software. The calculation of the particle size distribution index (U) referred to equations (1)-(3)

[0092]

[0093] In equations (1)-(3), d i is the particle size, μm; n i is the number of polymer microspheres and microcapsules with a particle size of d i . Theoretically, U ≥ 1, and U = 1 when and only when the particle sizes of all polymer microspheres and microcapsules are equal. The closer the U value is to 1, the narrower the particle size distribution of the polymer microspheres and microcapsules.

[0094] The OM images of the polymer microspheres and microcapsule products are shown in Figure 3 and Figure 4 respectively, and the particle size distribution indices are shown in Table 1 and Table 2 respectively:

[0095] Table 1 Detection results of the particle size distribution index of polymer microspheres

[0096]

[0097]

[0098] Table 2 Detection results of the particle size distribution index of polymer microcapsules

[0099]

[0100] As can be seen from Table 1 and Table 2, at the 500 mL level, compared with the mechanical stirring emulsification method and the emulsifier emulsification method, the polymer microspheres and microcapsules prepared by the continuous flow shear emulsification method of the present invention have a smaller particle size distribution index, that is, the narrowest particle size distribution. After scaling up to the 5 L level, the particle size distribution index of the polymer microcapsules prepared by the continuous flow shear emulsification method is still significantly smaller than that of the other two methods. These results indicate that the continuous flow shear emulsification method of the present invention has a relatively small scale-up effect in the scale-up experiment, and has good stability, controllability and adaptability.

[0101] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A continuous flow shearing emulsification device, characterized in that, Including: Raw material storage tank (1); Plunger pump (2); Gas cylinder (3); Thermometer (4); Reactor air inlet (5); Microchannel (6); Jacket water outlet (7); Reactor (8); Motor (9); Feed inlet (10); Stirring paddle (11); Condenser (12); Condenser gas outlet (13); Condenser water outlet (14); Condenser water inlet (15); Condenser air inlet (16); Jacket (17); Jacket water inlet (18); Tank body (19); Discharge valve (20); Discharge outlet (21); Gas switching valve (22); Vacuum pump (23); Water storage tank (24); Submersible pump (25); High and low temperature circulation integrated machine water outlet (26); High and low temperature circulation integrated machine water inlet (27); High and low temperature circulation integrated machine (28).

2. The continuous flow shearing emulsifying device according to claim 1, characterized in that, The number of the plunger pumps is equal to that of the microchannels.

3. A continuous flow shearing emulsification device according to claim 1, characterized in that, The diameter of the microchannel is 0.2 - 0.8 mm.

4. Application of the continuous flow shearing emulsification device according to any one of claims 1 - 3 in the preparation of polymer microspheres or polymer microcapsules.

5. The application according to claim 4, wherein The method for preparing polymer microspheres by the continuous flow shearing emulsification device is as follows: S1-1. Prepare an oil phase and a water phase and pour them into the raw material storage tank and the reactor respectively. The oil phase consists of a monomer and an initiator. S1-2. Turn on the vacuum pump to remove the air in the reactor, then open the gas cylinder to introduce a protective gas; Turn on the submersible pump to circulate tap water through the condenser; Turn on the high and low temperature circulation integrated machine and the stirrer, and set the circulation temperature and the mechanical shearing rate of the stirring paddle. S1-3. Turn on the plunger pump and adjust the flow rate to transport the oil phase to the microchannel to form a continuous flow and inject it into the water phase, and carry out an emulsification reaction under the action of mechanical shearing. S1-4. After the emulsification reaction is completed, adjust the circulation temperature of the high and low temperature circulation integrated machine and then carry out a free radical polymerization reaction. After the reaction is completed, open the discharge valve to separate the product and dry it to obtain polymer microspheres.

6. The application according to claim 5, wherein In the step S1-2, the mechanical shear rate of the stirring paddle is 200-750 r·min -1 ; the circulating temperature range of the high and low temperature circulation all-in-one machine is 10°C-95°C.

7. The application according to claim 5, wherein In the steps S1-3, the flow rate is 70-120 mL·min -1 ; the emulsification temperature is 15°C-25°C, and the emulsification time is 15-30 min.

8. The application according to claim 4, characterized in that The method for preparing polymer microcapsules by the continuous flow shearing emulsification device is as follows: S2-1. Prepare an oil phase and a water phase and pour them into the raw material storage tank and the reactor respectively. The oil phase consists of a monomer, a core material, a co-solvent and an initiator. S2-2. Turn on the vacuum pump to remove the air in the reactor, then open the gas cylinder to introduce a protective gas; Turn on the submersible pump to circulate tap water through the condenser; Turn on the high and low temperature circulation integrated machine and the stirrer, and set the circulation temperature and the mechanical shearing rate of the stirring paddle. S2-3. Turn on the plunger pump and adjust the flow rate to transport the oil phase to the microchannel to form a continuous flow and inject it into the water phase, and carry out an emulsification reaction under the action of mechanical shearing. S2-4. After the emulsification reaction is completed, adjust the circulation temperature of the high and low temperature circulation integrated machine and then carry out a free radical polymerization reaction. After the reaction is completed, open the discharge valve to separate the product and dry it to obtain polymer microcapsules.

9. The application according to claim 8, wherein In the step S2-2, the mechanical shear rate of the stirring paddle is 200-700 r·min -1 ; the circulating temperature range of the high and low temperature circulation all-in-one machine is 10°C-95°C; the protective gas is nitrogen or argon.

10. The application according to claim 8, wherein In the step S2-3, the flow rate is 70-120 mL·min -1 ; the emulsification temperature is 15℃-25℃, and the emulsification time is 15-30 min.

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