Thermosetting resin hollow microspheres, method of making and use thereof

Abstract

The application discloses a thermosetting resin hollow microsphere and a preparation method and application thereof. The preparation method comprises the following steps: (1) dissolving the thermosetting resin in a solvent to obtain a middle-layer dispersed phase; meanwhile, taking air as an inner-layer dispersed phase and taking an oil-phase substance as an outer-layer continuous phase; (2) providing a microfluidic chip with an inner-layer dispersed phase channel, a middle-layer dispersed phase channel and an outer-layer continuous phase channel; (3) loading the inner-layer dispersed phase, the middle-layer dispersed phase and the outer-layer continuous phase into the inner-layer dispersed phase channel, the middle-layer dispersed phase channel and the outer-layer continuous phase channel respectively and driving the phases to flow; at a first intersection, the middle-layer dispersed phase shears the inner-layer dispersed phase to form air microspheres; at a second intersection, the outer-layer continuous phase shears the middle-layer dispersed phase containing the air microspheres to obtain the hollow microspheres with a concentric structure; and (4) solidifying to obtain the thermosetting resin hollow microspheres. The method is simple in process and high in efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of thermosetting resin hollow microspheres and preparation method and application. BACKGROUND

[0002] Thermosetting resin hollow microspheres are a kind of spherical material with special cavity structure, relative to other general structure block material, hollow structure spherical material has smaller density, larger specific surface area and good heat insulation etc.Advantages, therefore, thermosetting resin hollow microspheres have extensive application value.At present, the preparation method of thermosetting resin hollow microspheres generally has self-assembly method, emulsion polymerization method, foaming method and other methods.

[0003] Patent CN106939073A discloses a kind of preparation method of epoxy resin type polymer microsphere, which utilizes the principle of traditional polymer induced phase separation, adopts new liquid crystal / polymer composite material system, and prepares a series of epoxy resin type polymer microspheres with uniform size distribution.

[0004] Patent CN108794721A discloses a kind of preparation method of polyurethane hollow microsphere, which adopts fine emulsion process, and prepares size-adjustable, wall-thickness-controllable polyurethane hollow microsphere.

[0005] But these preparation processes are complex or production efficiency is low or spherical degree is poor etc.Reasons, limit the large-scale production and application of thermosetting resin hollow microspheres. SUMMARY

[0006] Therefore, one purpose of the present application is to provide a kind of preparation method of thermosetting resin hollow microspheres, the method of the present application is simple, and efficiency is high, can realize batch production.Another purpose of the present application is to provide a kind of thermosetting resin hollow microspheres.A further purpose of the present application is to provide a kind of application in the preparation of thermosetting resin hollow microspheres with air as inner dispersed phase.

[0007] The present application achieves the above-mentioned purposes by the following technical solutions.

[0008] In one aspect, the present application provides a kind of preparation method of thermosetting resin hollow microspheres, comprising the following steps:

[0009] (1) dissolve thermosetting resin in solvent, obtain middle dispersed phase;With air as inner dispersed phase, oil phase material as outer continuous phase;

[0010] (2) providing a microfluidic chip with an inner layer dispersed phase channel, a middle layer dispersed phase channel and an outer layer continuous phase channel; the inner layer dispersed phase channel is a single line channel, which has a first inlet and a first outlet; the middle layer dispersed phase channel is a branch line channel, which intersects with the inner layer dispersed phase channel to form a first intersection; the outer layer continuous phase channel is a branch line channel, which intersects with the inner layer dispersed phase channel to form a second intersection; the first intersection is located between the first inlet and the second intersection; the inlet of the middle layer dispersed phase channel and the inlet of the outer layer continuous phase channel are close to the first inlet and far away from the first outlet;

[0011] (3) loading the inner layer dispersed phase, the middle layer dispersed phase and the outer layer continuous phase into the inner layer dispersed phase channel, the middle layer dispersed phase channel and the outer layer continuous phase channel respectively and driving the flow of each phase; at the first intersection, the middle layer dispersed phase shears the inner layer dispersed phase to form air microspheres; at the second intersection, the outer layer continuous phase shears the middle layer dispersed phase containing the air microspheres to obtain hollow microspheres with a concentric structure;

[0012] (4) discharging the obtained hollow microspheres with a concentric structure at the first outlet, solidifying to obtain thermosetting resin hollow microspheres.

[0013] In step (1) of the present application, the middle layer dispersed phase and the outer layer continuous phase are prepared respectively. The thermosetting resin is dissolved in a solvent to obtain the middle layer dispersed phase, and the solvent can be a good solvent of the thermosetting resin.

[0014] The inventors surprisingly found that thermosetting resin hollow microspheres can be prepared directly by taking air as the inner layer dispersed phase, and such a preparation process is simpler and more efficient. For example, compared with the prior art which takes polydimethylsiloxane as the inner layer dispersed phase, the replacement step can be omitted, the efficiency is improved, and the introduction of impurities is reduced.

[0015] According to the preparation method of the present application, preferably, the thermosetting resin is selected from at least one of epoxy resin, phenolic resin, polyurethane, vinyl ester, bismaleimide and polyimide. More preferably, the thermosetting resin is selected from one of epoxy resin, phenolic resin and polyurethane.

[0016] According to the preparation method of the present application, preferably, in step (1), the solvent is selected from one or more of ethanol, acetone, N,N-dimethylformamide and ethyl acetate. More preferably, the solvent is selected from one or more of ethanol, acetone and N,N-dimethylformamide.

[0017] According to the preparation method of the present application, preferably, in step (1), the oil phase material is selected from one or more of liquid paraffin and a mixture of C5-C8 alkane, polydimethylsiloxane, petroleum ether. In the mixture of liquid paraffin and C5-C8 alkane, the volume ratio of C5-C8 alkane to liquid paraffin can be 0.5-1.5:1, preferably 0.8-1.2:1. The C5-C8 alkane can be an alkane, preferably a straight-chain alkane, which can be n-pentane, n-hexane, n-heptane, n-octane, preferably n-hexane or n-heptane. More preferably, the oil phase material is selected from one of a mixture of liquid paraffin and C5-C8 alkane or polydimethylsiloxane. According to a specific embodiment of the present application, the oil phase material is a mixture of liquid paraffin and n-hexane.

[0018] According to the preparation method of the present application, preferably, in step (1), the viscosity of the middle-layer dispersed phase is 5-50 mPa.s, and the viscosity of the outer-layer continuous phase is 5-50 mPa.s. More preferably, the viscosity of the middle-layer dispersed phase is 5-15 mPa.s, and the viscosity of the outer-layer continuous phase is 5-15 mPa.s.

[0019] In step (2) of the present application, the inner-layer dispersed phase channel, the middle-layer dispersed phase channel and the outer-layer continuous phase channel are located on a microfluidic chip. The microfluidic chip is a chip of micron scale, which can integrate the basic operation units of sample preparation, reaction, separation and detection onto it. The inner-layer dispersed phase, the middle-layer dispersed phase and the outer-layer continuous phase are respectively loaded into different channels and driven to flow. In the present application, the inner-layer dispersed phase channel is a single-line channel, which is also the main channel for reaction, and it is not only used for containing the inner-layer dispersed phase, but also produces different substances at different intersections. The middle-layer dispersed phase channel is used for containing the middle-layer dispersed phase, which is a branch channel, and it intersects with the inner-layer dispersed phase channel to form a first intersection (corresponding to the formation of air microspheres); the outer-layer continuous phase channel is used for containing the outer-layer continuous phase, which is a branch channel, and it intersects with the inner-layer dispersed phase channel to form a second intersection (corresponding to the formation of hollow microspheres with a concentric structure). This facilitates the embedding of the middle-layer dispersed phase to the inner-layer dispersed phase supported by air and the embedding of the outer-layer continuous phase to the middle-layer dispersed phase containing air microspheres.

[0020] In step (3) of the present application, the device for driving the flow of each phase is not particularly specified, and can be a propulsion system. Each phase can be loaded into a different driveable device, such as a syringe or a pressure container. In some embodiments, the driveable device is a syringe. The head of the syringe is respectively connected to the corresponding channel on the microfluidic chip through a pipeline, and the driving force of the driving device is used to push each dispersed phase or flow phase in the syringe into the corresponding channel on the microfluidic chip.

[0021] The present application discloses a method for preparing thermosetting resin hollow microspheres with high purity, controllable particle size and wall thickness, and batch production.

[0022] According to the preparation method of the present application, preferably, in step (3), the driving rate of the inner layer dispersion phase is 1-60 μL / min, the driving rate of the middle layer dispersion phase is 10-70 μL / min, and the driving rate of the outer layer continuous phase is 10-90 μL / min. More preferably, the driving rate of the inner layer dispersion phase is 5-30 μL / min, the driving rate of the middle layer dispersion phase is 10-50 μL / min, and the driving rate of the outer layer continuous phase is 15-70 μL / min. Still more preferably, the driving rate of the inner layer dispersion phase is 10-20 μL / min, the driving rate of the middle layer dispersion phase is 25-40 μL / min, and the driving rate of the outer layer continuous phase is 40-50 μL / min.

[0023] In step (4) of the present application, the thermosetting resin hollow microspheres obtained in step (3) are cured to obtain cured thermosetting resin hollow microspheres. Such thermosetting resin hollow microspheres have higher purity and are more complete and less likely to be broken. The curing temperature can be 50-200°C, preferably 100-150°C. The thermosetting resin hollow microspheres obtained in this way have high purity. The curing equipment is not particularly specified and any commonly used equipment in the art can be used. In the present application, the particle size of the obtained thermosetting resin hollow microspheres is 100-200 μm.

[0024] According to the preparation method of the present application, preferably, the hollow microspheres with concentric structure are cured in a mixture of the outer layer continuous phase and a thermosetting resin curing agent at 50-200°C. The present application discloses that the thermosetting resin curing agent has a great influence on the yield of the thermosetting resin hollow microspheres. If not added, some of the thermosetting resin hollow microspheres will be broken before curing, thereby affecting the yield. However, the use of a mixture of the outer layer continuous phase and a corresponding thermosetting resin curing agent for curing the thermosetting resin hollow microspheres has a better effect and higher yield.

[0025] According to the preparation method of the present application, preferably, the concentration of the thermosetting resin curing agent is 1-20 wt%. More preferably, the concentration of the thermosetting resin curing agent is 1-10 wt%. The curing time can be 1-120 s, more preferably 10-50 s.

[0026] In another aspect, the present application provides a thermosetting resin hollow microsphere prepared by the above method.

[0027] In still another aspect, the present application provides a use of air as an inner layer dispersed phase in preparing a thermosetting resin hollow microsphere, comprising the following steps:

[0028] (1) dissolving the thermosetting resin in a solvent to obtain a middle layer dispersed phase; taking air as an inner layer dispersed phase and taking an oil phase substance as an outer layer continuous phase;

[0029] (2) providing a microfluidic chip having an inner layer dispersed phase channel, a middle layer dispersed phase channel and an outer layer continuous phase channel; the inner layer dispersed phase channel is a single line channel having a first inlet and a first outlet; the middle layer dispersed phase channel is a branch line channel which intersects with the inner layer dispersed phase channel to form a first intersection; the outer layer continuous phase channel is a branch line channel which intersects with the inner layer dispersed phase channel to form a second intersection; the first intersection is located between the first inlet and the second intersection; the inlet of the middle layer dispersed phase channel and the inlet of the outer layer continuous phase channel are both close to the first inlet and far away from the first outlet;

[0030] (3) loading the inner layer dispersed phase, the middle layer dispersed phase and the outer layer continuous phase into the inner layer dispersed phase channel, the middle layer dispersed phase channel and the outer layer continuous phase channel respectively and driving the flow of each phase; at the first intersection, the middle layer dispersed phase shears the inner layer dispersed phase to form air microspheres; at the second intersection, the outer layer continuous phase shears the middle layer dispersed phase containing the air microspheres to obtain hollow microspheres with a concentric structure;

[0031] (4) discharging the obtained hollow microspheres with a concentric structure at the first outlet and performing solidification to obtain thermosetting resin hollow microspheres. The detailed content is described above and will not be repeated here.

[0032] The present application takes air as an inner layer dispersed phase as a support skeleton, can directly prepare thermosetting resin microspheres with a hollow structure, avoids the complex operation caused by continuously replacing the inner layer substance of the microspheres, and has the advantages of short solidification time, controllable particle size and wall thickness of the hollow microspheres, simple operation and batch production. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 It is a schematic diagram of each channel of the microfluidic chip in Example 1.

[0034] Figure 2 It is a flow condition diagram of each dispersed phase and flow phase in the channel.

[0035] Figure 3 It is a scanning electron microscope diagram of the thermosetting resin hollow microspheres obtained in Example 1.

[0036] Figure 4 It is a transmission electron microscope diagram of the thermosetting resin hollow microspheres obtained in Example 1.

[0037] Figure 5 The infrared spectrum of the thermosetting resin hollow microspheres obtained in Example 1.

[0038] Figure 6 The infrared spectrum of the thermosetting resin hollow microspheres obtained in Example 1.

[0039] Figure 7 The scanning electron microscope image of the thermosetting resin hollow microspheres obtained in Example 2.

[0040] Figure 8 The transmission electron microscope image of the thermosetting resin hollow microspheres obtained in Example 2.

[0041] Figure 9 The scanning electron microscope of the thermosetting resin hollow microspheres obtained in Comparative Example 2.

[0042] BRIEF DESCRIPTION OF DRAWINGS

[0043] 1 - inner layer dispersed phase channel; 11 - first inlet; 12 - first intersection; 13 - second intersection; 14 - first outlet; 2 - middle layer dispersed phase channel; 21 - middle layer dispersed phase channel inlet; 3 - outer layer continuous phase channel; 31 - outer layer continuous phase channel inlet. DETAILED DESCRIPTION

[0044] The application will be further described in conjunction with the specific embodiments, but the scope of protection of the application is not limited thereto.

[0045] The test methods are described below:

[0046] (1) Scanning electron microscope image: measured by a cold field emission scanning electron microscope of Japan Hitachi S-4800 type.

[0047] (2) Transmission electron microscope image: measured by a transmission electron microscope of Japan Hitachi H-800 type.

[0048] (3) Infrared spectrum: measured by a Fourier transform infrared spectrometer of America Thermo Scientific Nicolet iS20 type.

[0049] Example 1

[0050] Figure 1 is a schematic diagram of each channel of the microfluidic chip. Figure 2 is a flow diagram of each dispersed phase and flow phase in the channel.

[0051] As shown in Figure 1 and Figure 2 , the microfluidic chip comprises an inner layer dispersed phase channel 1, a middle layer dispersed phase channel 2 and an outer layer continuous phase channel 3.

[0052] The inner layer dispersed phase channel 1 is a single line channel having a first inlet 11 and a first outlet 14. The first inlet 11 of the inner layer dispersed phase channel 1 is connected to the device containing the inner layer dispersed phase by a pipe.

[0053] The middle layer dispersed phase channel 2 is a branch line channel which intersects with the inner layer dispersed phase channel 1 to form a first intersection 12. The middle layer dispersed phase channel inlet 21 is connected to the device containing the middle layer dispersed phase by a pipe.

[0054] The outer layer continuous phase channel 3 is a branch line channel which intersects with the inner layer dispersed phase channel 1 to form a second intersection 13. The first intersection 12 is located between the first inlet 11 and the second intersection 13. The outer layer continuous phase channel inlet 31 is connected to the device containing the outer layer continuous phase by a pipe.

[0055] The middle layer dispersed phase channel inlet 21 and the outer layer continuous phase channel inlet 31 are both close to the first inlet 11 and far away from the first outlet 14.

[0056] In this embodiment, the devices containing the dispersed phases and the continuous phase are syringes.

[0057] The preparation method of the thermosetting hollow microspheres is described as follows:

[0058] The phenolic resin is dissolved in anhydrous ethanol to prepare the middle layer dispersed phase with a viscosity of 11 mPa.s. Air is used as the inner layer dispersed phase. The polydimethylsiloxane is prepared into the outer layer continuous phase with a viscosity of 11 mPa.s.

[0059] The inner layer dispersed phase, the middle layer dispersed phase and the outer layer continuous phase are respectively filled into three different syringes. The propelling system is used to drive the dispersed phases and the continuous phase in the syringes to enter the respective channels. The driving rate of the inner layer dispersed phase is 10 μL / min, the driving rate of the middle layer dispersed phase is 29 μL / min, and the driving rate of the outer layer continuous phase is 47 μL / min. At the first intersection 12 of the inner layer dispersed phase channel 1 and the middle layer dispersed phase channel 2, the middle layer dispersed phase shears the inner layer dispersed phase into air microspheres. At the second intersection 13 of the inner layer dispersed phase channel 1 and the outer layer continuous phase channel 3, the outer layer continuous phase further shears the middle layer dispersed phase containing the air microspheres to obtain the hollow microspheres.

[0060] The polydimethylsiloxane and the phenolic resin curing agent are mixed to prepare the collection phase with a viscosity of 11 mPa.s. The collection phase is placed in the curing device. The obtained hollow microspheres are cured and formed in the curing device at 130°C to obtain the cured thermosetting resin hollow microspheres (which can also be referred to as phenolic resin hollow microspheres). The scanning electron microscope image, the transmission electron microscope image, the actual object image and the infrared spectrum of the obtained thermosetting resin hollow microspheres are shown in FIGS. 1-4. Figures 3-6 The obtained thermosetting resin hollow microspheres are cured and formed in the curing device at 130°C to obtain the cured thermosetting resin hollow microspheres (which can also be referred to as phenolic resin hollow microspheres). The scanning electron microscope image, the transmission electron microscope image, the actual object image and the infrared spectrum of the obtained thermosetting resin hollow microspheres are shown in FIGS. 1-4.

[0061] Example 2

[0062] The microfluidic chip used was the same as in Example 1.

[0063] The epoxy resin was dissolved in N,N-dimethylformamide to prepare a middle layer dispersion phase with a viscosity of 13 mPa.s. Air was used as the inner layer dispersion phase. N-hexane and liquid paraffin (volume ratio of 0.8:1) were mixed to prepare an outer layer continuous phase with a viscosity of 13 mPa.s.

[0064] The inner layer dispersion phase, the middle layer dispersion phase and the outer layer continuous phase were respectively filled into three different syringes, and the dispersion phase and the continuous phase in the syringes were driven into the respective channels by using a push system, wherein the driving rate of the inner layer dispersion phase was 10 μL / min, the driving rate of the middle layer dispersion phase was 35 μL / min, and the driving rate of the outer layer continuous phase was 43 μL / min. At the first intersection 12 of the inner layer dispersion phase channel 1 and the middle layer dispersion phase channel 2, the middle layer dispersion phase sheared the inner layer dispersion phase into air microspheres. At the second intersection 13 of the inner layer dispersion phase channel 1 and the outer layer continuous phase channel 3, the outer layer continuous phase further sheared the middle layer dispersion phase containing the air microspheres to obtain the hollow microspheres.

[0065] N-hexane, liquid paraffin and an epoxy resin curing agent were mixed to prepare a collection phase with a viscosity of 13 mPa.s, and the collection phase was placed in a curing device. The obtained hollow microspheres were cured and formed in the curing device at 100°C to obtain cured thermosetting resin hollow microspheres (which can also be referred to as epoxy resin hollow microspheres). The scanning electron microscope image and the transmission electron microscope image of the obtained epoxy resin hollow microspheres are shown in FIGS. 2A and 2B, respectively. Figures 7-8

[0066] Example 3

[0067] The microfluidic chip used was the same as in Example 1.

[0068] The polyurethane was dissolved in an appropriate amount of N,N-dimethylformamide to prepare a middle layer dispersion phase with a viscosity of 8 mPa.s. Air was used as the inner layer dispersion phase. N-hexane and liquid paraffin (volume ratio of 1.2:1) were mixed to prepare an outer layer continuous phase with a viscosity of 8 mPa.s.

[0069] ​The inner layer dispersed phase, the middle layer dispersed phase and the outer layer continuous phase are respectively filled in three different syringes, and the dispersed phase and the continuous phase in the syringes are driven into the respective channels by a propulsion system, wherein the driving rate of the inner layer dispersed phase is 13 μL / min, the driving rate of the middle layer dispersed phase is 33 μL / min, and the driving rate of the outer layer continuous phase is 45 μL / min; at the first intersection 12 of the inner layer dispersed phase channel 1 and the middle layer dispersed phase channel 2, the middle layer dispersed phase shears the inner layer dispersed phase into air microspheres; at the second intersection 13 of the inner layer dispersed phase channel 1 and the outer layer continuous phase channel 3, the outer layer continuous phase further shears the middle layer dispersed phase containing the air microspheres, and the hollow microspheres are obtained.

[0070] The n-hexane, the liquid paraffin and the polyurethane curing agent are mixed to prepare a collection phase with a viscosity of 8 mPa.s, and the collection phase is placed in a curing device. The obtained hollow microspheres are cured and formed in the curing device at 100 ℃, and the cured thermosetting resin hollow microspheres (which can also be referred to as polyurethane hollow microspheres) are obtained.

[0071] Comparative Example 1

[0072] The difference from Example 1 is that the inner layer dispersed phase is different. The polydimethylsiloxane is prepared into an inner layer dispersed phase with a viscosity of 8 mPa.s.

[0073] The inner layer dispersed phase, the middle layer dispersed phase and the outer layer continuous phase are respectively filled in three different syringes, and the dispersed phase and the continuous phase in the syringes are driven into the respective channels by a propulsion system, wherein the driving rate of the inner layer dispersed phase is 10 μL / min, the driving rate of the middle layer dispersed phase is 29 μL / min, and the driving rate of the outer layer continuous phase is 47 μL / min; at the first intersection 12 of the inner layer dispersed phase channel 1 and the middle layer dispersed phase channel 2, the middle layer dispersed phase shears the inner layer dispersed phase into polydimethylsiloxane microspheres; at the second intersection 13 of the inner layer dispersed phase channel 1 and the outer layer continuous phase channel 3, the outer layer continuous phase further shears the middle layer dispersed phase containing the polydimethylsiloxane microspheres, and the phenolic resin core-shell structure microspheres are obtained.

[0074] The petroleum ether is added to the curing device every 6 h, and after 42 h, the phenolic resin core-shell structure microspheres are placed in the petroleum ether to displace the polydimethylsiloxane in the phenolic resin core-shell structure microspheres. Then the acetone is added every 6 h, and after 42 h, the phenolic resin core-shell structure microspheres are placed in the acetone containing the phenolic resin curing agent, and finally the curing is completed after 16 h in an oven, and the phenolic resin hollow microspheres are prepared.

[0075] It can be seen from the comparative example 1 that the polydimethylsiloxane is used as the inner layer dispersion phase, and the hollow microspheres are obtained by continuously replacing the polydimethylsiloxane in the inner layer of the microspheres in the subsequent preparation process. The operation is very cumbersome, time-consuming, and the obtained phenolic resin hollow microspheres have more impurities.

[0076] Comparative Example 2

[0077] The difference from example 2 is that the collection phase is liquid paraffin and n-hexane, and there is no epoxy resin curing agent. The scanning electron microscope image of the obtained epoxy resin hollow microspheres is shown in Figure 9 .

[0078] It can be seen from Figure 9 that the prepared epoxy resin hollow microspheres are not cured in time, and part of the epoxy resin hollow microspheres are broken before curing, which reduces the room temperature yield of the epoxy resin hollow microspheres.

[0079] The present application is not limited to the above-mentioned embodiments, and any modification, improvement, and replacement that can be conceived by those skilled in the art without departing from the essential content of the present application falls within the scope of the present application.

Claims

1. A method for producing a thermosetting resin hollow microsphere, characterized by, The method comprises the following steps: (1) dissolving a thermosetting resin in a solvent to obtain a middle-layer dispersed phase; taking air as an inner-layer dispersed phase and taking an oil-phase substance as an outer-layer continuous phase; the solvent is selected from one or more of ethanol, acetone, N,N-dimethylformamide and ethyl acetate; the oil-phase substance is selected from one or more of a mixture of liquid paraffin and C5-C8 alkane, polydimethylsiloxane and petroleum ether; (2) providing a microfluidic chip having an inner-layer dispersed phase channel, a middle-layer dispersed phase channel and an outer-layer continuous phase channel; the inner-layer dispersed phase channel is a single-line channel having a first inlet and a first outlet; the middle-layer dispersed phase channel is a branch-line channel intersecting with the inner-layer dispersed phase channel to form a first intersection; the outer-layer continuous phase channel is a branch-line channel intersecting with the inner-layer dispersed phase channel to form a second intersection; the first intersection is located between the first inlet and the second intersection; the inlet of the middle-layer dispersed phase channel and the inlet of the outer-layer continuous phase channel are both close to the first inlet and far away from the first outlet; (3) loading the inner-layer dispersed phase, the middle-layer dispersed phase and the outer-layer continuous phase into the inner-layer dispersed phase channel, the middle-layer dispersed phase channel and the outer-layer continuous phase channel respectively and driving the phases to flow; at the first intersection, the middle-layer dispersed phase shears the inner-layer dispersed phase to form air microspheres; at the second intersection, the outer-layer continuous phase shears the middle-layer dispersed phase containing the air microspheres to obtain hollow microspheres with a concentric structure; the driving rate of the inner-layer dispersed phase is 10-20 μL / min, the driving rate of the middle-layer dispersed phase is 25-40 μL / min, and the driving rate of the outer-layer continuous phase is 40-70 μL / min; (4) discharging the obtained hollow microspheres with a concentric structure at the first outlet, placing them in a mixture of the outer-layer continuous phase and a thermosetting resin curing agent and curing them at 50-200 ℃ for 1-120 s to obtain thermosetting resin hollow microspheres; the concentration of the thermosetting resin curing agent is 1-20 wt%.

2. The production method according to claim 1, characterized by, In step (1), the thermosetting resin is selected from at least one of epoxy resin, phenolic resin, polyurethane, vinyl ester, bismaleimide and polyimide.

3. The preparation method according to claim 1, characterized in that, In step (1), in the mixture of liquid paraffin and C5-C8 alkane, the volume ratio of C5-C8 alkane to liquid paraffin is 0.5-1.5:1; the C5-C8 alkane is n-hexane or n-heptane.

4. The method of claim 1, wherein, In step (1), the viscosity of the middle-layer dispersed phase is 5-50 mPa.s, and the viscosity of the outer-layer continuous phase is 5-50 mPa.s.

5. A thermosetting resin hollow microsphere, characterized by, The thermosetting resin hollow microspheres are prepared by the preparation method in any one of claims 1-4.

6. Use of air as an internal phase dispersing agent in the preparation of thermoset resin microspheres, characterized in that, The method comprises the following steps: (1) dissolving a thermosetting resin in a solvent to obtain a middle-layer dispersed phase; taking air as an inner-layer dispersed phase and taking an oil-phase substance as an outer-layer continuous phase; the solvent is selected from one or more of ethanol, acetone, N,N-dimethylformamide and ethyl acetate; the oil-phase substance is selected from one or more of a mixture of liquid paraffin and C5-C8 alkane, polydimethylsiloxane and petroleum ether; (2) providing a microfluidic chip with an inner dispersed phase channel, a middle dispersed phase channel and an outer continuous phase channel; the inner dispersed phase channel is a single-line channel with a first inlet and a first outlet; the middle dispersed phase channel is a branch-line channel intersecting with the inner dispersed phase channel to form a first intersection; the outer continuous phase channel is a branch-line channel intersecting with the inner dispersed phase channel to form a second intersection; the first intersection is located between the first inlet and the second intersection; the inlet of the middle dispersed phase channel and the inlet of the outer continuous phase channel are both close to the first inlet and far from the first outlet; the driving rate of the inner dispersed phase is 10-20 μL / min, the driving rate of the middle dispersed phase is 25-40 μL / min, and the driving rate of the outer continuous phase is 40-70 μL / min; (3) loading the inner dispersed phase, the middle dispersed phase and the outer continuous phase into the inner dispersed phase channel, the middle dispersed phase channel and the outer continuous phase channel respectively and driving the phases to flow; at the first intersection, the middle dispersed phase shears the inner dispersed phase to form air microspheres; at the second intersection, the outer continuous phase shears the middle dispersed phase containing the air microspheres to obtain hollow microspheres with a concentric structure; (4) discharging the obtained hollow microspheres with a concentric structure at the first outlet, placing them in a mixture of the outer continuous phase and a thermosetting resin curing agent and curing at 50-200 ℃ for 1-120 s to obtain thermosetting resin hollow microspheres; the concentration of the thermosetting resin curing agent is 1-20 wt%.

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