Melamine phase change microcapsule preparation device and method based on microfluidic technology

Abstract

The invention relates to the technical field of preparation of melamine phase change microcapsules, in particular to a device and a method for preparing melamine phase change microcapsules based on a microfluidic technology. According to the technical scheme, the melamine phase change microcapsule preparation device based on the microfluidic technology comprises a water phase solution tank, a water 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 which is prepared by taking melamine as a wall material and is prepared by an intermittent method, the preparation method has the problems of poor quality stability, low performance reproducibility, low production efficiency, low cost and the like; according to the preparation method of the melamine phase change microcapsule, the adopted microfluidic device integrates multiple functions of temperature control, liquid mixing, chemical reaction and the like, and liquid inlet pumps are connected into different places, so that various components can be conveniently introduced and polymerization reaction can be conveniently carried out in the preparation process of the melamine phase change microcapsule.

Description

Technical Field

[0001] The invention relates to the technical field of melamine phase-change microcapsule preparation, and in particular to a melamine phase-change microcapsule preparation device and method based on microfluidic technology. Background Art

[0002] Phase change microcapsules are a material with a core-shell structure. The core material is a substance with phase change properties that can absorb and release a large amount of latent heat at a specific temperature. The wall material plays a protective role. When the temperature changes, the phase change material undergoes a phase change in the microcapsule, absorbing or releasing heat, thereby realizing the storage and release of thermal energy. This material is widely used in construction, textiles, electronics and other fields to regulate temperature, improve energy efficiency and enhance comfort. Phase change microcapsules with melamine as the wall material are a high-performance energy storage material. They usually use 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. They are prepared by in-situ polymerization and have good thermal stability and phase change energy storage effect.

[0003] The existing method for preparing melamine phase change microcapsules generally adopts a batch method. The phase change microcapsules prepared by the batch method using melamine as the wall material often have problems such as poor quality stability, low performance reproducibility, low production efficiency and low cost.

[0004] Compared with the existing preparation method of melamine phase change microcapsules, which are generally prepared by an intermittent preparation method, the phase change microcapsules prepared by the intermittent method with melamine as the wall material often have problems such as poor quality stability, low performance reproducibility, low production efficiency and low cost. The microfluidic device used in the preparation method of melamine phase change microcapsules integrates multiple functions such as temperature control, liquid mixing and chemical reaction. By connecting liquid inlet pumps at different places, it is convenient to introduce various components and perform polymerization reactions in the process of preparing melamine phase change microcapsules, thereby realizing continuous and high-throughput quantification of phase change microcapsules and improving production efficiency. Summary of the invention

[0005] In order to overcome the existing preparation method of melamine phase change microcapsules, an intermittent preparation method is generally used for preparation. The phase change microcapsules prepared by the intermittent method using melamine as the wall material often have problems such as poor quality stability, low performance reproducibility, low production efficiency and low cost.

[0006] The technical solution of the present invention is as follows: A device and method for preparing melamine phase change microcapsules based on microfluidic technology, including an aqueous solution tank, an aqueous phase inlet pump, a first valve, a pressure regulator,

[0007] an oil phase inlet assembly, a liquid mixing assembly, a reaction assembly and a collection assembly. A liquid mixing assembly is arranged on one side of the aqueous solution tank. The aqueous solution tank is connected to the liquid mixing assembly through a pipeline. An aqueous phase inlet pump is arranged on the outer side of the pipeline. A first valve is arranged on one side of the aqueous phase inlet pump. A pressure regulator is arranged on one side of the first valve. An oil phase inlet assembly is arranged on the other side of the aqueous solution tank. A reaction assembly is arranged on one side of the liquid mixing assembly. A collection assembly is arranged on one side of the reaction assembly. Preferably, the aqueous solution tank stores the aqueous solution required for preparing the microcapsules. The aqueous phase inlet pump pumps the aqueous solution out of the aqueous solution tank and sends it into the liquid mixing assembly through a pipeline to form O / W droplets.

[0008] The first valve is convenient for troubleshooting when blocked. The pressure regulator adjusts the pressure in the aqueous phase inlet pipeline, which helps to form uniform droplets. The oil phase inlet assembly transports the oil phase solution. The liquid mixing assembly promotes the formation and mixing of droplets. The reaction assembly performs a polymerization reaction on the liquid. The collection assembly collects the microcapsule aqueous solution. As a preference, the oil phase inlet assembly includes an oil phase solution tank, an oil phase inlet pump, a second valve and a heating wire. An oil phase solution tank is arranged on one side of the aqueous solution tank. The oil phase solution tank is connected to the liquid mixing assembly through a pipeline. A heating wire is arranged on the outer side of the oil phase inlet pipeline. An oil phase inlet pump is arranged on one side of the oil phase inlet pipeline. A second valve is arranged on one side of the oil phase inlet pump.

[0009] As a preference, the liquid mixing assembly includes a constant temperature circulating water pump, a microreactor and a heat exchange jacket. A microreactor is arranged on the other side of the aqueous solution tank. A heat exchange jacket is arranged on the outer side of the microreactor. A constant temperature circulating water pump is arranged on one side of the microreactor.

[0010] As a preference, the reaction assembly includes a MUF prepolymer solution tank, a MUF prepolymer inlet pump, a third valve and a three-way valve. A heat exchange pipeline is arranged on one side of the microreactor. One end of the heat exchange pipeline

[0011] is provided with a three-way valve. A third valve is arranged on one side of the three-way valve. A MUF prepolymer inlet pump is arranged on one side of the third valve. A MUF prepolymer solution tank is arranged at the top of the MUF prepolymer inlet pump. As a preference, the collection assembly includes a detachable coiled pipe, an ultrasonic heating field and a sample collection tank. A collection pipeline is arranged on one side of the three-way valve. One end of the collection pipeline is provided with a detachable coiled pipe. An ultrasonic heating field is arranged on the outer side of the detachable coiled pipe. A sample collection tank is arranged at one end of the detachable coiled pipe.

[0012] A method for preparing melamine phase change microcapsules based on microfluidic technology comprises the following steps: S101: First, a MUF prepolymer solution, an oil phase and an aqueous phase are prepared; S102: Mixing the prepared multiple groups of solutions to prepare phase change microcapsules.

[0013] Preferably, when preparing multiple groups of solutions, the following steps are included: S201: Add the formaldehyde solution to water, 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 is clear to obtain MUF prepolymer, and let it stand and 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.

[0014] Preferably, the preparation of phase change microcapsules includes the following steps: S301: The aqueous solution and the oil phase solution are pumped into the microreactor to form O / W droplets in the microreactor; S302: The temperature of the microreactor 10 is maintained 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 and then enter the coil, and the coil temperature is maintained at 70 ℃; S303: After collection, centrifugation and washing are performed to obtain phase change microcapsules.

[0015] Beneficial effects of the present invention: 1. Compared with the traditional preparation method of melamine phase change microcapsules, which are generally prepared by an intermittent method, the phase change microcapsules prepared by the intermittent method with melamine as the wall material often have problems such as poor quality stability, low performance reproducibility, low production efficiency and low cost. The microfluidic device used in the preparation method of melamine phase change microcapsules integrates multiple functions such as temperature control, liquid mixing and chemical reaction. By connecting the liquid inlet pump at different places, it is convenient to introduce various components and perform polymerization reaction in the process of preparing melamine phase change microcapsules, so as to achieve continuous and high-throughput quantification of phase change microcapsules and improve production efficiency. 2. The raw liquids are mixed by using three liquid inlet pumps, the core material is prevented from solidifying by adding a heat exchange jacket in the microreactor, and the coil is placed in a heated ultrasonic field to achieve heating and generate a sufficiently strong ultrasonic field. While controlling the polymerization reaction time and temperature, precipitation in the coil channel during the polymerization process is avoided, and the agglomerated particles are dispersed. To a certain extent, the temperature and pressure in the microfluidic device are guaranteed not to fluctuate greatly, avoiding affecting the stability and repeatability of the experiment. Finally, controllable melamine phase change microcapsules are prepared. The device is simple to operate and realizes continuous production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 What is 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; Figure 2 Shown is a second three-dimensional structural schematic diagram of a melamine phase change microcapsule preparation device based on microfluidic technology of the present invention; Figure 3 Shown is a schematic plan view of a melamine phase change microcapsule preparation device based on microfluidics technology of the present invention; Figure 4 What is 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; 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; Explanation of the reference numerals: 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

[0017] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0018] See also Figure 1-5The present invention provides an embodiment: a device and method for preparing melamine phase change microcapsules 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 arranged on one side of the aqueous solution tank 1, the aqueous solution tank 1 is connected to the liquid mixing component by a pipeline, an aqueous liquid inlet pump 2 is arranged on the outside of the pipeline, a first valve 3 is arranged on one side of the aqueous liquid inlet pump 2, a pressure regulator 4 is arranged on one side of the first valve 3, an oil phase liquid inlet component is arranged on the other side of the aqueous solution tank 1, a reaction component is arranged on one side of the liquid mixing component, and a collection component is arranged on one side of the reaction component.

[0019] 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 arranged on one side of the water phase solution tank 1, and the oil phase solution tank 5 is connected to the liquid mixing component pipeline. The outer side of the oil phase liquid inlet pipeline is provided with a heating wire 8, and the oil phase liquid inlet pump 6 is arranged on one side of the oil phase liquid inlet pipeline. The second valve 7 is arranged 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 water phase solution to form O / W droplets. The switch of 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 to ensure that it enters the liquid mixing component smoothly.

[0020] Preferably, the liquid mixing component includes a constant temperature circulating water pump 9, a microreactor 10 and a heat exchange jacket 11. The microreactor 10 is arranged on the other side of the aqueous solution tank 1, and the heat exchange jacket 11 is arranged on the outside of the microreactor 10. The constant temperature circulating water pump 9 is arranged 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.

[0021] Preferably, the reaction assembly includes a MUF prepolymer 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, 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 inlet pump 13 is provided on one side of the third valve 14. A MUF prepolymer liquid inlet pump 13 is provided on the top of the MUF prepolymer liquid inlet pump 13. When in use, the MUF prepolymer liquid inlet pipe and the microreactor 10 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 is used to pump the MUF prepolymer solution out of the tank and send it to the outlet of the microreactor 10 through a 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.

[0022] Preferably, the collecting assembly includes a detachable coil 16, an ultrasonic heating field 17 and a sample collecting tank 18. A collecting pipe is provided on one side of the three-way valve 15, a detachable coil 16 is provided on one end of the collecting pipe, an ultrasonic heating field 17 is provided on the outer side of the detachable coil 16, and a sample collecting tank 18 is provided on one end of the detachable coil 16. When in use, the detachable coil 16 provides sufficient residence time for the MUF prepolymer to fully react with the O / W droplets to form microcapsules. The detachable coil 16 is heated by the ultrasonic heating field 17, and an ultrasonic field is provided, 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 collecting tank 18, which is convenient for subsequent centrifugal washing and drying treatment.

[0023] A method for preparing melamine phase change microcapsules based on microfluidic technology comprises the following steps: S101: First, a MUF prepolymer solution, an oil phase and an aqueous phase are prepared; S102: Mixing the prepared multiple groups of solutions to prepare phase change microcapsules.

[0024] Preferably, when preparing multiple groups of solutions, the following steps are included: S201: Add the formaldehyde solution to water, 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 is clear to obtain MUF prepolymer, and let it stand and 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.

[0025] Preferably, the preparation of phase change microcapsules includes the following steps: S301: The aqueous solution and the oil phase solution are pumped into the microreactor 10 to form O / W droplets in the microreactor 10; S302: The temperature of the microreactor 10 is maintained at 70 ° 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 10 and then enter the coil, and the coil temperature is maintained at 70 ° C; S303: After collection, centrifugation and washing are performed to obtain phase change microcapsules.

[0026] 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, and the mass ratio of melamine urea-formaldehyde resin to water is 1:3~5; 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; The phase change core material is a single normal alkane or a mixture such as C10, C11, C12, C13, C14 and C18; The mass ratio of emulsifier to water is 0.5~5:100; The emulsifier is sodium lauryl sulfate.

[0027] Embodiment 1: Preparation of MUF prepolymer solution: Add 2.4 g of formaldehyde solution to 40 mL of water, then add 1.2 mL of triethanolamine to adjust the pH to 8-9, then add 0.26 g of melamine and 0.5 g of urea, stir at 70 ° C for 40 min until the solution is clear to obtain MUF prepolymer, and let it stand and cool for use.

[0028] Preparation of oil phase: Weigh 10 g of octadecane and 5 g of cyclohexane solution and mix them evenly.

[0029] Preparation of aqueous phase: Weigh 1 g of sodium dodecyl sulfate and add it to 100 mL of water, adjust the pH to 3-4 with citric acid, and stir evenly to obtain an aqueous phase solution.

[0030] Preparation of phase change microcapsules: The aqueous phase solution was pumped into the microreactor at a rate of 1 mL / min and the oil phase solution was pumped into the microreactor at a rate of 0.4 mL / min, respectively. The pressure was adjusted to 1 MPa, and the temperature of the microreactor was maintained at 35°C. After the O / W droplets were formed in the microreactor, they flowed out of the microreactor. At the same time, the MUF prepolymer solution was pumped into the outlet of the microreactor at 1.2 mL / min. The droplets and the MUF prepolymer solution were connected at the outlet of the microreactor and then entered the coil. The coil temperature was maintained at 70°C, and the coil was selected to be 1.5 m. After collection, centrifugation, washing and drying were performed to obtain phase change microcapsules.

[0031] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of those skilled in the art without departing from the spirit of the present invention.

Claims

1. A device for preparing melamine [Ziye1] phase change microcapsules based on microfluidic technology; characterized in that: It includes an aqueous solution tank (1), an aqueous phase inlet pump (2), a first valve (3), a pressure regulator (4) [cotyledon 2][3], an oil phase inlet assembly, a liquid mixing assembly, a reaction assembly and a collection assembly. A liquid mixing assembly is arranged on one side of the aqueous solution tank (1). The aqueous solution tank (1) is connected to the liquid mixing assembly through a pipeline. The aqueous phase inlet pump (2) is arranged on the outer side of the pipeline. The first valve (3) is arranged on one side of the aqueous phase inlet pump (2). The pressure regulator (4) is arranged on one side of the first valve (3). An oil phase inlet assembly is arranged on the other side of the aqueous solution tank (1). A reaction assembly is arranged on one side of the liquid mixing assembly. A collection assembly is arranged on one side of the reaction assembly.

2. The device for preparing melamine phase-change microcapsules based on microfluidics technology according to claim 1, characterized in that: The oil phase inlet assembly includes an oil phase solution tank (5), an oil phase inlet pump (6), a second valve (7) and a heating wire (8). The oil phase solution tank (5) is arranged on one side of the aqueous solution tank (1). The oil phase solution tank (5) is connected to the liquid mixing assembly through a pipeline. The heating wire (8) is arranged on the outer side of the oil phase inlet pipeline. The oil phase inlet pump (6) is arranged on one side of the oil phase inlet pipeline. The second valve (7) is arranged on one side of the oil phase inlet pump (6).

3. The device for preparing melamine phase-change microcapsules based on microfluidics technology according to claim 2, characterized in that: 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 arranged on the other side of the aqueous solution tank (1). The heat exchange jacket (11) is arranged on the outer side of the microreactor (10). The constant temperature circulating water pump (9) is arranged on one side of the microreactor (10).

4. The device for preparing melamine phase-change microcapsules based on microfluidics technology according to claim 3, characterized in that: The reaction assembly includes a MUF prepolymer solution tank (12), a MUF prepolymer inlet pump (13), a third valve (14) and a three-way valve (15). A heat exchange pipeline is arranged on one side of the microreactor (10). One end of the heat exchange pipeline [cotyledon 4] is provided with the three-way valve (15). The third valve (14) is arranged on one side of the three-way valve (15). The MUF prepolymer inlet pump (13) is arranged on one side of the third valve (14). The MUF prepolymer solution tank (12) is arranged at the top of the MUF prepolymer inlet pump (13).

5. The device for preparing melamine phase-change microcapsules based on microfluidics technology according to claim 4, characterized in that: The collection assembly includes a detachable coiled pipe (16), an ultrasonic heating field (17) and a sample collection tank (18). A collection pipeline is arranged on one side of the three-way valve (15). One end of the collection pipeline is provided with the detachable coiled pipe (16). The ultrasonic heating field (17) is arranged on the outer side of the detachable coiled pipe (16). One end of the detachable coiled pipe (16) is provided with the sample collection tank (18).

6. A device for preparing melamine phase-change microcapsules based on microfluidic technology according to claims 1-5, characterized in that: A preparation method of melamine phase change microcapsules based on microfluidic technology includes the following steps: S101: First, prepare the MUF prepolymer solution, the oil phase and the aqueous phase; S102: Mix the prepared multiple groups of solutions to prepare phase change microcapsules.

7. The method for preparing melamine phase change microcapsules based on microfluidic technology according to claim 6, characterized in that: When preparing multiple groups of solutions, it includes the following steps: S201: Add formaldehyde solution to water, then add a certain amount of triethanolamine to adjust the pH to 8-9, and then add melamine and urea. Stir at 70 °C until the solution is clear to obtain the MUF prepolymer, and let it stand and cool for later use; S202: Weigh a certain amount of phase change material and mix it evenly with cyclohexane solution; 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.

8. The method for preparing melamine phase change microcapsules based on microfluidic technology according to claim 7, characterized in that: When preparing phase change microcapsules, the following steps are included: S301: The aqueous solution and the oil phase solution are pumped into the microreactor (10), forming O / W droplets in the microreactor 10; S302: The temperature of the microreactor (10) is maintained at 70°C, 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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