Preparation method of polyurethane acrylate double-layer shell phase change microcapsule

Abstract

The invention provides a preparation method of a polyurethane acrylate double-layer shell phase change microcapsule. The preparation method comprises the following steps: S1, water phase preparation: weighing 30 g of a 5% SMA solution, and mixing with 70 mL of deionized water to obtain a water phase; s2, preparing an oil phase: weighing 1g of MMA, 4g of styrene, 15g of butyl stearate, 2.5 g of IPDI and 5g of Mn1000 organic silicon, and uniformly mixing to obtain the oil phase; according to the preparation method of the polyurethane acrylate double-layer shell phase change microcapsule, on the basis that a single polyurethane shell is prepared through an interfacial polymerization method, acrylate is introduced through a free radical polymerization method, the polyurethane acrylate double-layer shell microcapsule is formed, and the polyurethane acrylate double-layer shell phase change microcapsule is prepared by accurately controlling the polymerization condition and the material ratio. The uniformity and the stability of the double-layer shell are ensured; the organic silicon is added into the core material, and the main chain of the organic silicon is composed of silicon-oxygen bonds, so that the organic silicon has high bond energy and good thermal stability, and the microcapsule can be kept stable in a wider temperature range.

Description

Technical Field

[0001] The invention relates to the technical field of material chemistry, and in particular to a method for preparing polyurethane acrylate double-layer shell phase-change microcapsules. Background Art

[0002] At present, thermal energy storage technologies are mainly divided into three types: thermochemical energy storage, sensible heat storage and latent heat storage. Among them, thermochemical heat storage technology achieves the storage and release of thermal energy by utilizing the destruction and recombination of molecular bonds in reversible thermochemical reactions. This technology has the advantages of higher heat storage density and long-term storage and long-distance transportation. However, due to its complex chemical reaction process and high requirements for equipment safety, it is still in the small-scale research and experimental stage, and it is difficult to achieve industrial and large-scale application. Sensible heat storage technology is based on the heat capacity characteristics of materials and realizes energy storage through temperature changes. Although it has low cost and relatively simple technology, it has low energy storage density, large equipment volume, and it is difficult to maintain a constant temperature when thermal energy is released.

[0003] In contrast, phase change thermal storage technology uses phase change materials (PCM) to absorb or release a large amount of heat during the phase change process to achieve energy storage. The temperature of PCM is approximately constant during the phase change process, and it has the advantages of high heat storage density, small temperature fluctuation range and good chemical stability. The material used for variable energy storage is called phase change material (PCM). It has been widely studied because of its low cost, high energy storage density, good chemical stability and non-corrosiveness. However, in actual use, phase change materials also have many problems, such as supercooling, phase separation, stability and other problems.

[0004] To solve the above problems, people use microcapsule technology to encapsulate PCM. The embedded phase change material is called phase change microcapsule (MicPCM, Microencapsulated Phase Change Material). MicPCM consists of a core material (PCM) and a shell. The core material is wrapped by the shell to place it in a relatively closed space, which can effectively reduce the leakage of PCM during use. At the same time, it also increases the heat transfer area of ​​PCM and thus increases the heat transfer efficiency. However, the traditional microcapsule shell is relatively simple, and during use, it will have poor density and thermal stability, which is easy to cause damage to the microcapsule, which will cause the core material to be inactivated or leaked to a certain extent, reducing the utilization rate.

[0005] Therefore, it is necessary to provide a method for preparing polyurethane acrylate double-layer shell phase change microcapsules to solve the above technical problems. Summary of the invention

[0006] The present invention provides a method for preparing a polyurethane acrylate double-layer shell phase change microcapsule, which solves the problem that the microcapsule shell is relatively single, has poor density and thermal stability during use, is easily damaged, and to a certain extent causes the core material to be inactivated or leaked, thereby reducing the utilization rate.

[0007] In order to solve the above technical problems, the present invention provides a method for preparing a polyurethane acrylate double-layer shell phase change microcapsule, comprising the following steps:

[0008] S1. Preparation of aqueous phase: weigh 30 g of 5% SMA solution and mix with 70 mL of deionized water to obtain an aqueous phase;

[0009] S2. Preparation of oil phase: weigh 1 g MMA, 4 g styrene, 15 g butyl stearate, 2.5 g IPDI, and 5 g Mn1000 silicone and mix them evenly to obtain an oil phase;

[0010] S3, experimental reaction process: slowly add the oil phase to the water phase at room temperature, add a small amount multiple times, emulsify the oil phase and water phase mixture on a high-speed shear emulsifier at a mechanical stirring rate of 10000rpm for 20min, and then obtain an O / W emulsion, then transfer the O / W emulsion into a three-necked flask for reaction, add 2.5g of triethanolamine at 40°C for reaction for 1 hour, heat to 60°C for reaction for 2 hours, heat to 75°C, add potassium persulfate (0.2g / 10ml deionized water) for reaction for 4 hours, and obtain a microcapsule suspension;

[0011] S4. Processing and collection: The microcapsule suspension after the reaction is completed is centrifuged, and the obtained product is dried to obtain microcapsule solid.

[0012] Preferably, the centrifugal speed of the centrifuge in S4 is 8000 r / min, and the centrifugal time is 5 min.

[0013] Preferably, the centrifuge used in S4 comprises a body, a rotating groove is provided on the top of the body, a turntable is arranged on the inner side of the rotating groove, a plurality of limit frames are fixedly installed at the edge of the top of the turntable, a slide groove is provided at the bottom of the inner side of the plurality of limit frames, a bidirectional threaded rod is rotatably connected to one end of the inner side of the slide groove, moving blocks are threadedly connected to both ends of the outer side of the bidirectional threaded rod, a clamping plate is fixedly installed on the top of the two moving blocks, and a rubber pad is fixedly installed on one side of the clamping plate.

[0014] Preferably, a slide bar is fixedly mounted on the other side of the clamping plate, and a spring is sleeved on the outer side of the slide bar.

[0015] Preferably, two sides of the moving block are respectively attached to two sides of the inner side of the sliding groove.

[0016] Preferably, a rotating handle is fixedly mounted on one end of the bidirectional threaded rod, and the rotating handle is arranged on the side of the rotating disk.

[0017] Preferably, a limiting plate is fixedly mounted on one end of the sliding rod, and the spring is arranged between the clamping plate and the limiting frame.

[0018] Preferably, a rotating seat is fixedly installed on the top of the body, a rotating rod is fixedly installed on the inner side of the rotating seat, a rotating block is rotatably connected to the outer side of the rotating rod, a protective cover is fixedly installed on one side of the rotating block, and a handle is fixedly installed on one side of the protective cover.

[0019] Preferably, support feet are fixedly installed around the bottom of the body.

[0020] Preferably, the outer side surface of the supporting foot is threadedly connected with a thread ring, and the bottom of the thread ring is fixedly installed with an anti-slip pad.

[0021] Compared with the related art, the preparation method of the polyurethane acrylate double-layer shell phase change microcapsule provided by the present invention has the following beneficial effects:

[0022] The present invention provides a method for preparing a polyurethane acrylate double-layer shell phase change microcapsule. On the basis of preparing a single polyurethane shell by an interfacial polymerization method, acrylate is introduced by a free radical polymerization method to form a polyurethane acrylate double-layer shell microcapsule. The uniformity and stability of the double-layer shell are ensured by precisely controlling the polymerization conditions and material ratio.

[0023] Adding silicone to the core material, because the main chain of silicone is composed of silicon-oxygen bonds, it has high bond energy and good thermal stability, so that the microcapsules can remain stable in a wider temperature range;

[0024] Adding silicone to the core material has good chemical stability, which can protect the core material from corrosion by external chemicals to a certain extent, reduce the possibility of chemical reaction between the core material and other substances, and thus improve the stability of the microcapsules. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A flowchart of a preferred embodiment of a method for preparing a polyurethane acrylate double-layer shell phase change microcapsule provided by the present invention;

[0026] Figure 2 A schematic structural diagram of a first embodiment of a centrifuge for use in a method for preparing polyurethane acrylate double-layer shell phase-change microcapsules provided by the present invention;

[0027] Figure 3 for Figure 1 The schematic diagram of the body structure shown;

[0028] Figure 4 for Figure 1 The schematic diagram of the turntable structure shown;

[0029] Figure 5 for Figure 2 An enlarged schematic diagram of part A is shown;

[0030] Figure 6 for Figure 4 An enlarged schematic diagram of part B is shown;

[0031] Figure 7 for Figure 4 An enlarged schematic diagram of part C is shown;

[0032] Figure 8 The present invention provides a schematic structural diagram of a second embodiment of a centrifuge for use in a method for preparing polyurethane acrylate double-layer shell phase-change microcapsules.

[0033] Numbers in the figure: 1. machine body, 11. supporting foot, 12. rotating groove, 2. rotating seat, 21. rotating rod, 22. rotating block, 23. protective cover, 24. handle, 3. turntable, 31. limit frame, 32. slide groove, 33. two-way threaded rod, 34. rotating handle, 35. moving block, 36. clamping plate, 37. rubber pad, 4. sliding rod, 41. spring, 42. limit plate, 5. threaded ring, 51. anti-slip pad. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with the accompanying drawings and implementation modes.

[0035] First embodiment

[0036] Please refer to Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 ,in, Figure 1 A flowchart of a preferred embodiment of a method for preparing a polyurethane acrylate double-layer shell phase change microcapsule provided by the present invention; Figure 2 A schematic structural diagram of a first embodiment of a centrifuge for use in a method for preparing polyurethane acrylate double-layer shell phase-change microcapsules provided by the present invention; Figure 3 for Figure 1 The schematic diagram of the body structure shown; Figure 4 for Figure 1 The schematic diagram of the turntable structure shown; Figure 5 for Figure 2 An enlarged schematic diagram of part A is shown; Figure 6 for Figure 4 An enlarged schematic diagram of part B is shown; Figure 7 for Figure 4 The enlarged schematic diagram of part C is shown. A method for preparing a polyurethane acrylate double-layer shell phase change microcapsule comprises the following steps:

[0037] S1. Preparation of aqueous phase: weigh 30 g of 5% SMA solution and mix with 70 mL of deionized water to obtain an aqueous phase;

[0038] S2. Preparation of oil phase: weigh 1 g MMA, 4 g styrene, 15 g butyl stearate, 2.5 g IPDI, and 5 g Mn1000 silicone and mix them evenly to obtain an oil phase;

[0039] S3, experimental reaction process: slowly add the oil phase to the water phase at room temperature, add a small amount multiple times, emulsify the oil phase and water phase mixture on a high-speed shear emulsifier at a mechanical stirring rate of 10000rpm for 20min, and then obtain an O / W emulsion, then transfer the O / W emulsion into a three-necked flask for reaction, add 2.5g of triethanolamine at 40°C for reaction for 1 hour, heat to 60°C for reaction for 2 hours, heat to 75°C, add potassium persulfate (0.2g / 10ml deionized water) for reaction for 4 hours, and obtain a microcapsule suspension;

[0040] S4. Processing and collection: The microcapsule suspension after the reaction is completed is centrifuged, and the obtained product is dried to obtain microcapsule solid.

[0041] The centrifugal speed of the centrifuge in S4 is 8000 r / min, and the centrifugal time is 5 min.

[0042] The microcapsule suspension obtained by the reaction was subjected to a thermogravimetric test. The test showed that the initial decomposition temperature (T5%) of the shell microcapsule was increased by 31.5°C compared with the simple core material butyl stearate, and the heat resistance temperature (T50%) when the mass loss was 50% was increased by 57.9°C. When the core material was completely lost at 279.6°C, the mass retention rate was 64.67%, and the shell microcapsule had good thermal stability. The obtained microcapsule solid was placed at 130°C for 60 minutes, and its mass loss rate was 5.15%, and the shell microcapsule had good compactness.

[0043] The centrifuge used in S4 comprises a body 1, a rotating groove 12 is provided on the top of the body 1, a turntable 3 is provided on the inner side of the rotating groove 12, a plurality of limit frames 31 are fixedly installed at the edge of the top of the turntable 3, a slide groove 32 is provided at the bottom of the inner side of the plurality of limit frames 31, a bidirectional threaded rod 33 is rotatably connected to one end of the inner side of the slide groove 32, a moving block 35 is threadedly connected to both ends of the outer side of the bidirectional threaded rod 33, a clamping plate 36 is fixedly installed on the top of the two moving blocks 35, and a rubber pad 37 is fixedly installed on one side of the clamping plate 36.

[0044] A slide bar 4 is fixedly mounted on the other side of the clamping plate 36 , and a spring 41 is sleeved on the outer side of the slide bar 4 .

[0045] Two sides of the moving block 35 are respectively attached to two sides of the inner side surface of the sliding groove 32 .

[0046] A rotating handle 34 is fixedly mounted on one end of the bidirectional threaded rod 33 , and the rotating handle 34 is disposed on the side of the rotating disk 3 .

[0047] A limiting plate 42 is fixedly mounted on one end of the slide rod 4 , and the spring 41 is disposed between the clamping plate 36 and the limiting frame 31 .

[0048] A rotating seat 2 is fixedly installed on the top of the body 1, a rotating rod 21 is fixedly installed on the inner side of the rotating seat 2, a rotating block 22 is rotatably connected to the outer side of the rotating rod 21, a protective cover 23 is fixedly installed on one side of the rotating block 22, and a handle 24 is fixedly installed on one side of the protective cover 23.

[0049] Support legs 11 are fixedly installed around the bottom of the body 1.

[0050] When in use, a vessel containing a microcapsule suspension is placed into the inner side of the limiting frame 31, and then the rotating handle 34 is rotated to drive the bidirectional threaded rod 33 to rotate, so that the bidirectional threaded rod 33 is threadedly connected inside the two moving blocks 35, and then the two moving blocks 35 drive the two clamping plates 36 to move toward the middle, so that the two rubber pads 37 clamp and limit the vessel, and then the machine body 1 is started to drive the turntable 3 to rotate, so as to centrifuge the microcapsule suspension inside the vessel;

[0051] When the clamping plate 36 moves, it can drive the slide bar 4 to slide inside the side of the fixed frame 31, so as to limit the clamping plate 36 and increase the stability of the clamping plate 36 when moving;

[0052] By setting a protective cover 23 on the top of the body 1, it can play a protective role when in use to prevent impurities from falling onto the inner side of the rotating groove 12, and the setting of the handle 24 makes it convenient for the user to rotate the protective cover 23.

[0053] Compared with the related art, the preparation method of the polyurethane acrylate double-layer shell phase change microcapsule provided by the present invention has the following beneficial effects:

[0054] Based on the preparation of a single polyurethane shell by interfacial polymerization, acrylate is introduced by free radical polymerization to form polyurethane acrylate double-layer shell microcapsules. The uniformity and stability of the double-layer shell are ensured by precisely controlling the polymerization conditions and material ratio.

[0055] Adding silicone to the core material, because the main chain of silicone is composed of silicon-oxygen bonds, it has high bond energy and good thermal stability, so that the microcapsules can remain stable in a wider temperature range;

[0056] Adding silicone to the core material has good chemical stability, which can protect the core material from corrosion by external chemicals to a certain extent, reduce the possibility of chemical reaction between the core material and other substances, and thus improve the stability of the microcapsules.

[0057] Second embodiment

[0058] Please refer to Figure 8 Based on the preparation method of a polyurethane acrylate double-layer shell phase-change microcapsule provided in the first embodiment of the present application, the second embodiment of the present application proposes another preparation method of a polyurethane acrylate double-layer shell phase-change microcapsule. The second embodiment is only a preferred embodiment of the first embodiment, and the implementation of the second embodiment will not affect the independent implementation of the first embodiment.

[0059] Specifically, the difference of the preparation method of a polyurethane acrylate double-layer shell phase change microcapsule provided in the second embodiment of the present application is that, in a preparation method of a polyurethane acrylate double-layer shell phase change microcapsule, the outer side surface of the support foot 11 is threadedly connected with a thread ring 5, and the bottom of the thread ring 5 is fixedly installed with an anti-slip pad 51.

[0060] The working principle of the preparation method of the polyurethane acrylate double-layer shell phase change microcapsule provided by the present invention is as follows:

[0061] When in use, the user can thread the threaded ring 5 onto the bottom of the support foot 11 , and then place the machine body 1 on a tabletop, so that the bottom of the anti-slip pad 51 is in contact with the tabletop, thereby achieving an anti-slip effect.

[0062] Compared with the related art, the preparation method of the polyurethane acrylate double-layer shell phase change microcapsule provided by the present invention has the following beneficial effects:

[0063] By cooperating with each other, the threaded ring 5 and the anti-skid pad 51 can be threadedly connected to the outer side of the support foot 11 during use, so that the anti-skid pad 51 can be installed on the bottom of the support foot 11 to prevent slipping.

[0064] Comparative experiment 1:

[0065] The difference from Example 1 is that the microcapsules prepared in Comparative Experiment 1 are single polyurethane shell microcapsules.

[0066] (1) Preparation of aqueous phase: 30 g of 5% SMA solution was mixed with 70 mL of deionized water to obtain an aqueous phase;

[0067] (2) Preparation of oil phase: 4 g IPDI, 15 g butyl stearate, and 6 g triethanolamine were weighed and uniformly mixed to obtain an oil phase;

[0068] (3) Experimental reaction process: Slowly add the oil phase to the water phase at room temperature in small amounts and multiple times. Emulsify the oil-water phase mixture on a high-speed shear emulsifier at a mechanical stirring rate of 10,000 rpm for 20 minutes to obtain an O / W emulsion. Subsequently, the O / W emulsion was transferred to a three-necked flask for reaction, and the reaction monomer was added at 40°C for 1 hour, the temperature was raised to 60°C for 4 hours, and then the temperature was raised to 70°C for 1 hour to obtain a microcapsule suspension;

[0069] (4) Treatment and collection: The microcapsule suspension after the reaction is completed is centrifuged at a rate of 8000 r / min for 5 min, and the obtained product is dried to obtain a microcapsule solid.

[0070] The single polyurethane microcapsule suspension obtained by the reaction was subjected to thermogravimetric testing. The initial decomposition temperature (T5%) of the shell microcapsule was increased by 8.7°C compared with the simple core material butyl stearate, and the heat resistance temperature (T50%) was increased by 8.9°C when the mass loss was 50%. When the core material was completely lost at 279.6°C, the mass retention rate was 44.16%. The obtained microcapsule solid was placed at 130°C for 60 minutes, and its mass loss rate was 7.23%. The comparison shows that the microcapsule shell component has a significant effect on the thermal stability and density of the microcapsule. The polyurethane / acrylate double-layer shell microcapsule has better thermal stability and density than the single polyurethane shell microcapsule.

[0071] Comparative experiment 2:

[0072] The same experimental method as in Example 1 was used, except that the core material ratio in the microcapsules was changed (as shown in the table):

[0073]

[0074]

[0075] After testing, when the core material is completely lost at 279.6℃, the mass retention rates of microcapsules with core material ratios of 30%, 45%, 60%, and 75% are 39.03%, 65.68%, 58.04%, and 39.07%, respectively. Among them, the effect is best when the core material ratio is 45%, which is significantly better than other ratios. When the core material ratio is higher than 45%, the thermal stability of the capsule decreases. This may be because as the core material ratio increases, the protective effect of the shell on the core material gradually weakens. The protective effect of the shell is limited, and after exceeding a certain limit, the core material is prone to leakage. Therefore, the microcapsule core material ratio of 45% exhibits better thermal stability.

[0076] Under the same placement time, when the core material ratio is 30%, 45%, 60%, and 75%, the final mass loss rate of the microcapsule is 6.04%, 5.28%, 6.66%, and 7.69%, respectively. In general, the larger the core material ratio, the more the mass of the microcapsule decreases. This is because the higher the amount of core material butyl stearate, the lower the mass fraction of the shell in the microcapsule, which in turn weakens the strength of the shell. The decrease in shell strength weakens the microcapsule's ability to coat the core material butyl stearate and increases the leakage rate. Therefore, the greater the amount of core material used, the greater the mass loss rate of the microcapsule.

[0077] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing polyurethane acrylate double-layer shell phase change microcapsules, characterized in that: The following steps are involved: S1. Preparation of aqueous phase: weigh 30 g of 5% SMA solution and mix with 70 mL of deionized water to obtain an aqueous phase; S2. Preparation of oil phase: weigh 1 g MMA, 4 g styrene, 15 g butyl stearate, 2.5 g IPDI, and 5 g Mn1000 silicone and mix them evenly to obtain an oil phase; S3, experimental reaction process: slowly add the oil phase to the water phase at room temperature, add a small amount multiple times, emulsify the oil phase and water phase mixture on a high-speed shear emulsifier at a mechanical stirring rate of 10000rpm for 20min, and then obtain an O / W emulsion, then transfer the O / W emulsion into a three-necked flask for reaction, add 2.5g of triethanolamine at 40°C for reaction for 1 hour, heat to 60°C for reaction for 2 hours, heat to 75°C, add potassium persulfate (0.2g / 10ml deionized water) for reaction for 4 hours, and obtain a microcapsule suspension; S4. Processing and collection: The microcapsule suspension after the reaction is completed is centrifuged, and the obtained product is dried to obtain microcapsule solid.

2. The method for preparing a polyurethane acrylate double-layer shell phase change microcapsule according to claim 1, characterized in that: The centrifugal speed of the centrifuge in S4 is 8000 r / min, and the centrifugal time is 5 min.

3. The method for preparing a polyurethane acrylate double-layer shell phase change microcapsule according to claim 1, characterized in that: The centrifuge used in S4 comprises a body, a rotating groove is provided on the top of the body, a turntable is provided on the inner side of the rotating groove, a plurality of limit frames are fixedly installed at the edge of the top of the turntable, a slide groove is provided at the bottom of the inner side of the plurality of limit frames, a bidirectional threaded rod is rotatably connected to one end of the inner side of the slide groove, moving blocks are threadedly connected to both ends of the outer side of the bidirectional threaded rod, a clamping plate is fixedly installed on the top of two moving blocks, and a rubber pad is fixedly installed on one side of the clamping plate.

4. The method for preparing a polyurethane acrylate double-layer shell phase change microcapsule according to claim 3, characterized in that: A slide bar is fixedly mounted on the other side of the clamping plate, and a spring is sleeved on the outer side of the slide bar.

5. The method for preparing a polyurethane acrylate double-layer shell phase change microcapsule according to claim 3, characterized in that: The two sides of the moving block are respectively attached to the two sides of the inner side surface of the sliding groove.

6. The method for preparing a polyurethane acrylate double-layer shell phase change microcapsule according to claim 3, characterized in that: A rotating handle is fixedly mounted on one end of the bidirectional threaded rod, and the rotating handle is arranged on the side of the rotating disk.

7. The method for preparing a polyurethane acrylate double-layer shell phase change microcapsule according to claim 4, characterized in that: A limiting plate is fixedly mounted on one end of the slide rod, and the spring is arranged between the clamping plate and the limiting frame.

8. The method for preparing a polyurethane acrylate double-layer shell phase change microcapsule according to claim 3, characterized in that: A rotating seat is fixedly installed on the top of the body, a rotating rod is fixedly installed on the inner side of the rotating seat, a rotating block is rotatably connected to the outer side of the rotating rod, a protective cover is fixedly installed on one side of the rotating block, and a handle is fixedly installed on one side of the protective cover.

9. The method for preparing a polyurethane acrylate double-layer shell phase change microcapsule according to claim 3, characterized in that: Support feet are fixedly installed around the bottom of the machine body.

10. The method for preparing a polyurethane acrylate double-layer shell phase change microcapsule according to claim 9, characterized in that: The outer side surface of the support foot is threadedly connected with a thread ring, and the bottom of the thread ring is fixedly installed with an anti-slip pad.

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