A device and method for preparing melamine phase change microcapsules based on microfluidic technology

Abstract

The present application relates to the technical field of melamine phase change microcapsule preparation, and particularly relates to a melamine phase change microcapsule preparation device and method based on microfluidic technology; the technical scheme: a melamine phase change microcapsule preparation device and method based on microfluidic technology, comprising an aqueous solution tank, an aqueous phase liquid inlet pump, a first valve, a pressure regulator, an oil phase liquid inlet assembly, a liquid mixing assembly, a reaction assembly and a collection assembly; compared with the traditional melamine phase change microcapsule preparation method, the melamine phase change microcapsule prepared by the intermittent method has the problems of poor quality stability, low performance reproducibility, low production efficiency and low cost, etc.; the melamine phase change microcapsule preparation method adopts a microfluidic device integrating temperature control, liquid mixing and chemical reaction, etc., and by connecting the liquid inlet pump at different places, various components can be introduced and polymerization reaction can be carried out in the process of preparing the melamine phase change microcapsule.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of melamine phase change microcapsule preparation, and particularly relates to a melamine phase change microcapsule preparation device and method based on microfluidic technology. BACKGROUND

[0002] The phase change microcapsule is a material with a core-shell structure, the core material is a substance with phase change characteristics, which can absorb or release a large amount of latent heat at a specific temperature, and the wall material plays a protective role. When the temperature changes, the phase change material changes phase in the microcapsule, absorbs or releases heat, thereby realizing the storage and release of heat energy. This material is widely used in the fields of building, textile, electronics, etc. for temperature adjustment, energy efficiency improvement and comfort enhancement. The phase change microcapsule with melamine as the wall material is a high-performance energy storage material, which is usually prepared by in-situ polymerization method with melamine formaldehyde resin (MF) or melamine modified urea-formaldehyde resin (MUF) as the wall material and paraffin, fatty alcohol and other organic substances as the core material, and has good thermal stability and phase change energy storage effect.

[0003] The existing melamine phase change microcapsule preparation method generally adopts an intermittent preparation method. The phase change microcapsule prepared by the intermittent method with melamine as the wall material often has problems of poor quality stability, low performance reproducibility, low production efficiency and low cost.

[0004] Compared with the existing melamine phase change microcapsule preparation method, the intermittent method is generally used for preparation. The phase change microcapsule prepared by the intermittent method with melamine as the wall material often has problems of poor quality stability, low performance reproducibility, low production efficiency and low cost. The microfluidic device used in the present melamine phase change microcapsule preparation method integrates temperature control, liquid mixing and chemical reaction and other functions. By connecting the liquid inlet pump at different places, it is convenient to introduce various components and perform polymerization reaction during the preparation of melamine phase change microcapsule, realize the continuous and high-throughput of phase change microcapsule, and improve the production efficiency. SUMMARY

[0005] In order to overcome the problems of poor quality stability, low performance reproducibility, low production efficiency and low cost of the phase change microcapsule prepared by the intermittent method with melamine as the wall material in the existing melamine phase change microcapsule preparation method.

[0006] The technical scheme of the present application is: a melamine phase change microcapsule preparation device and method based on microfluidic technology, comprising an aqueous solution tank, an aqueous phase liquid inlet pump, a first valve, a pressure regulator, an oil phase liquid inlet assembly, a liquid mixing assembly, a reaction assembly and a collection assembly, one side of the aqueous solution tank is provided with the liquid mixing assembly, the aqueous solution tank is connected with the liquid mixing assembly through a pipeline, the outer side of the pipeline is provided with the aqueous phase liquid inlet pump, one side of the aqueous phase liquid inlet pump is provided with the first valve, one side of the first valve is provided with the pressure regulator, the other side of the aqueous solution tank is provided with the oil phase liquid inlet assembly, one side of the liquid mixing assembly is provided with the reaction assembly, one side of the reaction assembly is provided with the collection assembly.

[0007] Preferably, the aqueous solution required for preparing the microcapsule is stored in the aqueous solution tank, the aqueous solution is pumped out from the aqueous solution tank by the aqueous phase liquid inlet pump and sent into the liquid mixing assembly through the pipeline to form O / W droplets, the first valve is convenient to check when blocked, the pressure in the aqueous phase liquid inlet pipeline is adjusted by the pressure regulator, which is helpful to form uniform droplets, the oil phase solution is transported by the oil phase liquid inlet assembly, the formation and mixing of the droplets are promoted by the liquid mixing assembly, the liquid is subjected to polymerization reaction by the reaction assembly, and the microcapsule aqueous solution is collected by the collection assembly.

[0008] Preferably, the oil phase liquid inlet assembly comprises an oil phase solution tank, an oil phase liquid inlet pump, a second valve and a heating wire, one side of the aqueous solution tank is provided with the oil phase solution tank, the oil phase solution tank is connected with the liquid mixing assembly through a pipeline, the outer side of the oil phase liquid inlet pipeline is provided with the heating wire, one side of the oil phase liquid inlet pipeline is provided with the oil phase liquid inlet pump, one side of the oil phase liquid inlet pump is provided with the second valve.

[0009] Preferably, the liquid mixing assembly comprises a constant temperature circulating water pump, a microreactor and a heat exchange jacket, the other side of the aqueous solution tank is provided with the microreactor, the outer side of the microreactor is provided with the heat exchange jacket, one side of the microreactor is provided with the constant temperature circulating water pump.

[0010] Preferably, the reaction assembly comprises a MUF prepolymer solution tank, a MUF prepolymer liquid inlet pump, a third valve and a three-way valve, one side of the microreactor is provided with a heat exchange pipeline, one end of the heat exchange pipeline is provided with the three-way valve, one side of the three-way valve is provided with the third valve, one side of the third valve is provided with the MUF prepolymer liquid inlet pump, and the top end of the MUF prepolymer liquid inlet pump is provided with the MUF prepolymer solution tank.

[0011] Preferably, the collection assembly comprises a detachable coil pipe, an ultrasonic heating field and a sample collection tank, one side of the three-way valve is provided with a collection pipeline, one end of the collection pipeline is provided with the detachable coil pipe, the outer side of the detachable coil pipe is provided with the ultrasonic heating field, and one end of the detachable coil pipe is provided with the sample collection tank.

[0012] A preparation method of melamine phase change microcapsules based on microfluidic technology, comprising the following steps:

[0013] S101: First, the MUF prepolymer solution, oil phase and water phase are prepared;

[0014] S102: The prepared multiple solutions are mixed to prepare phase change microcapsules.

[0015] As preferred, when the multiple solutions are prepared, the following steps are included:

[0016] S201: The formaldehyde solution is added to water, then a certain amount of triethanolamine is added to adjust the pH to 8-9, then melamine and urea are added, and the solution is stirred at 70 DEG C until it is clear, and then cooled and used.

[0017] S202: A certain amount of phase change material and cyclohexane solution are weighed and uniformly mixed;

[0018] S203: A certain amount of emulsifier is weighed and added to water, and the pH is adjusted to 3-4 with citric acid, and then stirred uniformly to obtain the water phase solution.

[0019] As preferred, when the phase change microcapsules are prepared, the following steps are included:

[0020] S301: The water phase solution and the oil phase solution are pumped into the microreactor respectively to form O / W droplets in the microreactor;

[0021] S302: The temperature of the microreactor 10 is kept at 70 DEG C, the MUF prepolymer solution is pumped into the outlet of the microreactor 10, and the droplets and the MUF prepolymer solution are connected at the outlet of the microreactor and then enter the coil, and the temperature of the coil is kept at 70 DEG C;

[0022] S303: After collection, centrifugal washing is performed to obtain phase change microcapsules.

[0023] The beneficial effects of the present application are:

[0024] 1. Compared with the traditional preparation method of melamine phase change microcapsules, the intermittent method is generally used for preparation, and the phase change microcapsules prepared by the intermittent method using melamine as the wall material often have the problems of poor quality stability, low performance reproducibility, low production efficiency and low cost, etc., the microfluidic device used in the present melamine phase change microcapsule preparation method integrates temperature control, liquid mixing and chemical reaction, etc., by connecting the liquid pumps at different places, it is convenient to introduce various components and perform polymerization reaction during the preparation of melamine phase change microcapsules, realize the continuous and high-throughput of phase change microcapsules, and improve the production efficiency;

[0025] 2. By using three liquid inlet pumps to achieve mixing of the raw liquids, adding a heat exchange jacket to the microreactor to avoid solidification of the core material, and placing the coil in a heated ultrasonic field to achieve heating and generate a sufficiently strong ultrasonic field, while controlling the polymerization reaction time and temperature while avoiding precipitation in the coil channel during the polymerization process, the agglomerated particles are dispersed, and to a certain extent, the temperature and pressure in the microfluidic device are guaranteed not to fluctuate significantly, avoiding affecting the stability and repeatability of the experiment. Ultimately, controllable melamine phase change microcapsules are prepared, the device is simple to operate, and continuous production is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Shown is a schematic diagram of the first three-dimensional structure of a melamine phase change microcapsule preparation device based on microfluidic technology of the present invention;

[0027] Figure 2 Shown is a schematic diagram of the second three-dimensional structure of a melamine phase change microcapsule preparation device based on microfluidic technology of the present invention;

[0028] Figure 3 Shown is a schematic plan view of a melamine phase change microcapsule preparation device based on microfluidic technology of the present invention;

[0029] Figure 4 Shown is a schematic diagram of the first partial three-dimensional structure of a melamine phase change microcapsule preparation device based on microfluidic technology of the present invention;

[0030] Figure 5 Shown is a schematic diagram of the second partial three-dimensional structure of a melamine phase change microcapsule preparation device based on microfluidic technology of the present invention;

[0031] Explanation of the accompanying symbols: 1. aqueous solution tank; 2. aqueous liquid inlet pump; 3. first valve; 4. pressure regulator; 5. oil solution tank; 6. oil liquid inlet pump; 7. second valve; 8. heating wire; 9. constant temperature circulating water pump; 10. microreactor; 11. heat exchange jacket; 12. MUF prepolymer solution tank; 13. MUF prepolymer liquid inlet pump; 14. third valve; 15. three-way valve; 16. detachable coil; 17. ultrasonic heating field; 18. sample collection tank. DETAILED DESCRIPTION

[0032] The present invention will be further described below with reference to the accompanying drawings and examples.

[0033] See also Figure 1-5The present invention provides an embodiment: a melamine phase change microcapsule preparation device and method based on microfluidic technology, comprising an aqueous solution tank 1, an aqueous liquid inlet pump 2, a first valve 3, a pressure regulator 4 [leaf 4], an oil phase liquid inlet component, a liquid mixing component, a reaction component and a collection component, a liquid mixing component is provided on one side of the aqueous solution tank 1, the aqueous solution tank 1 is connected to the liquid mixing component through a pipeline, an aqueous liquid inlet pump 2 is provided on the outside of the pipeline, a first valve 3 is provided on one side of the aqueous liquid inlet pump 2, a pressure regulator 4 is provided on one side of the first valve 3, an oil phase liquid inlet component is provided on the other side of the aqueous solution tank 1, a reaction component is provided on one side of the liquid mixing component, and a collection component is provided on one side of the reaction component.

[0034] The oil phase liquid inlet component includes an oil phase solution tank 5, an oil phase liquid inlet pump 6, a second valve 7 and a heating wire 8. The oil phase solution tank 5 is provided on one side of the aqueous phase solution tank 1. The oil phase solution tank 5 is connected to the liquid mixing component pipeline. A heating wire 8 is provided on the outside of the oil phase liquid inlet pipeline. The oil phase liquid inlet pump 6 is provided on one side of the oil phase liquid inlet pipeline. The second valve 7 is provided on one side of the oil phase liquid inlet pump 6. When in use, the oil phase solution required for preparing microcapsules is stored in the oil phase solution tank 5, and the oil phase solution is pumped out from the oil phase solution tank 5 by the oil phase liquid inlet pump 6 and sent into the liquid mixing component through the pipeline to mix with the aqueous phase solution to form O / W droplets. The oil phase liquid inlet pipeline is controlled by the oil phase liquid inlet pump 6 [leaf 5] to ensure that the flow of the oil phase solution can be accurately opened or closed when needed. The oil phase solution is heated by the heating wire 8 to prevent it from solidifying during the pumping process, ensuring that it enters the liquid mixing component smoothly.

[0035] Preferably, the liquid mixing assembly includes a constant temperature circulating water pump 9, a microreactor 10 and a heat exchange jacket 11. The microreactor 10 is provided on the other side of the aqueous solution tank 1, and the heat exchange jacket 11 is provided on the outside of the microreactor 10. A constant temperature circulating water pump 9 is provided on one side of the microreactor 10. When in use, the microreactor 10 is used as an O / W droplet formation to promote the formation and mixing of droplets. The heat exchange jacket 11 is used to ensure that the temperature in the microreactor 10 is constant. The constant temperature circulating water pump 9 is connected to the heat exchange jacket 11 to provide constant temperature circulating water, control the temperature in the microreactor 10, and ensure that the polymerization reaction is carried out at a constant temperature.

[0036] Preferably, the reaction assembly includes a MUF prepolymer solution tank 12, a MUF prepolymer liquid feed pump 13, a third valve 14 and a three-way valve 15. A heat exchange pipe is provided on one side of the microreactor 10, and a three-way valve 15 is provided at one end of the heat exchange pipe [leaf 6]. A third valve 14 is provided on one side of the three-way valve 15, and a MUF prepolymer liquid feed pump 13 is provided on one side of the third valve 14. The top of the MUF prepolymer liquid feed pump 13 is provided with a MUF prepolymer solution tank 12. When in use, the MUF prepolymer liquid feed pipe and the microreactor are connected by the three-way valve 15. The outlet of the reactor 10 and the collecting assembly ensure that the MUF prepolymer solution can be mixed with the O / W droplets at the correct position. The switch of the MUF prepolymer inlet pipeline is controlled by the MUF prepolymer inlet pump 13 to ensure that the flow of the MUF prepolymer solution can be accurately opened or closed when needed. The MUF prepolymer inlet pump 13 pumps the MUF prepolymer solution out of the tank and sends it to the outlet of the microreactor 10 through the pipeline to mix with the O / W droplets for polymerization reaction. The prepared MUF prepolymer solution is stored in the MUF prepolymer solution tank 12.

[0037] Preferably, the collection assembly includes a detachable coil 16, an ultrasonic heating field 17 and a sample collection tank 18. A collection pipe is provided on one side of the three-way valve 15, and a detachable coil 16 is provided at one end of the collection pipe. The ultrasonic heating field 17 is provided on the outside of the detachable coil 16, and a sample collection tank 18 is provided at one end of the detachable coil 16. When in use, the detachable coil 16 provides sufficient residence time for the MUF prepolymer and the O / W droplets to fully react to form microcapsules. The ultrasonic heating field 17 heats the detachable coil 16 and provides an ultrasonic field, which helps to disperse the agglomerated particles and ensure the uniformity and stability of the polymerization reaction. The microcapsule aqueous solution formed after the polymerization reaction is collected by the sample collection tank 18 to facilitate subsequent centrifugal washing and drying treatment.

[0038] A method for preparing melamine phase-change microcapsules based on microfluidic technology comprises the following steps:

[0039] S101: First, the MUF prepolymer solution, oil phase and water phase are prepared;

[0040] S102: Mixing the prepared multiple groups of solutions to prepare phase change microcapsules.

[0041] Preferably, when preparing multiple groups of solutions, the following steps are included:

[0042] S201: Add formaldehyde solution to water, then add a certain amount of triethanolamine to adjust the pH to 8-9, then add melamine and urea, stir at 70°C until the solution becomes clear to obtain MUF prepolymer, and let it stand and cool for use;

[0043] S202: A certain amount of phase change material and cyclohexane solution are weighed and uniformly mixed;

[0044] S203: A certain amount of emulsifier is weighed and added to water, and the pH is adjusted to 3-4 with citric acid, and then stirred uniformly to obtain an aqueous phase solution.

[0045] As preferred, in the preparation of phase change microcapsules, the following steps are included:

[0046] S301: The aqueous phase solution and the oil phase solution are respectively pumped into the microreactor 10 to form O / W droplets in the microreactor 10;

[0047] S302: The temperature of the microreactor 10 is kept at 70℃, the MUF prepolymer solution is pumped into the outlet of the microreactor 10, and the droplets and the MUF prepolymer solution are connected at the outlet of the microreactor 10 and then enter the coil, and the temperature of the coil is kept at 70℃;

[0048] S303: After collection, centrifugal washing is performed to obtain phase change microcapsules.

[0049] The molar mass ratio of melamine to (formaldehyde / urea) is 1:0.5-4; the molar mass ratio of formaldehyde to urea is 3-12:1; the stirring time is 0.5-1h; the mass ratio of melamine urea formaldehyde resin to water is 1:3-5;

[0050] The mass ratio of phase change material to melamine urea formaldehyde resin is 1:0.5-3; the mass ratio of core material to cyclohexane is 1:0.1-1;

[0051] The phase change core material is a single normal alkane or a mixture of C10, C11, C12, C13, C14 and C18;

[0052] The mass ratio of emulsifier to water is 0.5-5:100;

[0053] The emulsifier is sodium dodecyl sulfate.

[0054] Example 1:

[0055] Preparation of MUF prepolymer solution: 2.4g of formaldehyde solution is added to 40mL of water, 1.2mL of triethanolamine is added to adjust the pH to 8-9, then 0.26g of melamine and 0.5g of urea are added, and the solution is stirred at 70℃ for 40min until it is clear to obtain MUF prepolymer, which is cooled and used.

[0056] Preparation of oil phase: 10g of octadecane and 5g of cyclohexane solution are weighed and uniformly mixed.

[0057] Preparation of aqueous phase: 1g of sodium dodecyl sulfate is weighed and added to 100mL of water, the pH is adjusted to 3-4 with citric acid, and then stirred uniformly to obtain an aqueous phase solution.

[0058] Preparation of phase-change microcapsules: The aqueous phase solution and the oil phase solution were pumped into the microreactor at a rate of 1 mL / min and 0.4 mL / min, respectively. The pressure was adjusted to 1 MPa and the microreactor temperature was maintained at 35°C. O / W droplets formed within the microreactor and then flowed out of the microreactor. Simultaneously, the MUF prepolymer solution was pumped into the microreactor outlet at a rate of 1.2 mL / min. The droplets and MUF prepolymer solution merged at the microreactor outlet and entered a coil. The coil temperature was maintained at 70°C and the coil was selected to be 1.5 m. After collection, the phase-change microcapsules were centrifuged, washed, and dried to obtain phase-change microcapsules.

[0059] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge of those skilled in the art without departing from the spirit of the present invention.

Claims

1. A device for preparing melamine phase-change microcapsules based on microfluidics technology; characterized by: The invention comprises an aqueous solution tank (1), an aqueous liquid inlet pump (2), a first valve (3), a pressure regulator (4), an oil phase liquid inlet assembly, a liquid mixing assembly, a reaction assembly and a collection assembly. The aqueous solution tank (1) is provided with a liquid mixing assembly on one side. The aqueous solution tank (1) is connected to the liquid mixing assembly pipeline. The aqueous solution tank (2) is provided on the outside of the pipeline. The aqueous solution tank (2) is provided with a first valve (3). The pressure regulator (4) is provided on one side of the first valve (3). The aqueous solution tank (1) is provided with an oil phase liquid inlet assembly on the other side. The liquid mixing assembly is provided with a reaction assembly on one side. The reaction assembly is provided with a collection assembly on one side. The oil phase liquid inlet assembly comprises an oil phase solution tank (5), an oil phase liquid inlet pump (6), a second valve (7) and a heating wire (8). The aqueous solution tank (1) is provided with an oil phase solution tank (5). The oil phase solution tank (5) is connected to the liquid mixing assembly pipeline. The oil phase liquid inlet pipeline is provided with a heating wire (8). An oil phase inlet pump (6) is provided on one side of the phase inlet pipeline, a second valve (7) is provided on one side of the oil phase inlet pump (6), a liquid mixing component includes a constant temperature circulating water pump (9), a microreactor (10) and a heat exchange jacket (11), a microreactor (10) is provided on the other side of the aqueous solution tank (1), a heat exchange jacket (11) is provided on the outside of the microreactor (10), a constant temperature circulating water pump (9) is provided on one side of the microreactor (10), and a reaction component includes a MUF prepolymer. A solution tank (12), a MUF prepolymer liquid inlet pump (13), a third valve (14) and a three-way valve (15); a heat exchange pipe is provided on one side of the microreactor (10); a three-way valve (15) is provided at one end of the heat exchange pipe; a third valve (14) is provided on one side of the three-way valve (15); a MUF prepolymer liquid inlet pump (13) is provided on one side of the third valve (14); and a MUF prepolymer solution tank (12) is provided at the top of the MUF prepolymer liquid inlet pump (13).

2. The device for preparing melamine phase-change microcapsules based on microfluidic technology according to claim 1, characterized in that: The collection component comprises a detachable coil (16), an ultrasonic heating field (17) and a sample collection tank (18); a collection pipe is provided on one side of a three-way valve (15); a detachable coil (16) is provided at one end of the collection pipe; an ultrasonic heating field (17) is provided on the outer side of the detachable coil (16); and a sample collection tank (18) is provided at one end of the detachable coil (16).

3. A device for preparing melamine phase-change microcapsules based on microfluidic technology according to any one of claims 1 to 2, characterized in that: A method for preparing melamine phase-change microcapsules based on microfluidic technology comprises the following steps: S101: First, prepare a MUF prepolymer solution, an oil phase, and an aqueous phase; S102: Mixing the prepared multiple groups of solutions to prepare phase change microcapsules.

4. The device for preparing melamine phase-change microcapsules based on microfluidic technology according to claim 3, characterized in that: When preparing multiple groups of solutions, the following steps are included: S201: adding formaldehyde solution to water, adding a certain amount of triethanolamine to adjust the pH to 8-9, then adding melamine and urea, stirring at 70° C. until the solution becomes clear to obtain MUF prepolymer, and standing to cool for use; S202: Weigh a certain amount of phase change material and cyclohexane solution and mix them evenly; S203: Weigh a certain amount of emulsifier and add it to water, adjust the pH to 3-4 with citric acid, and stir evenly to obtain an aqueous phase solution.

5. The device for preparing melamine phase-change microcapsules based on microfluidic technology according to claim 3, characterized in that: The preparation of phase change microcapsules includes the following steps: S301: Pumping the aqueous phase solution and the oil phase solution into the microreactor (10) respectively to form O / W droplets in the microreactor (10); S302: The temperature of the microreactor (10) is maintained at 70° C., and the MUF prepolymer solution is pumped into the outlet of the microreactor (10). The droplets and the MUF prepolymer solution are connected at the outlet of the microreactor (10) and then enter the coil. The coil temperature is maintained at 70° C. S303: After collection, centrifugation and washing are performed to obtain phase change microcapsules.

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