Phase-change temperature-regulating microcapsule as well as preparation method and application thereof

Abstract

The invention provides a phase-change temperature-regulating microcapsule as well as a preparation method and application thereof. The preparation method of the phase-change temperature-regulating microcapsule comprises the following steps: (1) melting and mixing heat-conducting particles and an organic polymer material to obtain a molten liquid; (2) adding the molten liquid into a preheated solid-liquid phase change solution, and emulsifying to obtain a Pickering emulsion; and (3) centrifuging the Pickering emulsion, collecting an upper-layer substance, and drying to obtain the phase-change temperature-regulating microcapsule. The heat-conducting particles and the organic polymer material are melted and mixed and then form the Pickering emulsion with high stability and low pollution with the solid-liquid phase-change solution, the phase-change temperature-adjusting microcapsule with a core-shell structure is formed through self-assembly, and the phase-change temperature-adjusting microcapsule has the advantages of high heat conductivity and high heat storage efficiency, can release heat within a specified temperature range and solves the problem of phase separation. In addition, the heat storage and release performance is stable, melting and solidification are within the temperature range comfortable for the human body, particle size distribution is uniform, and the textile is still soft by being fixed to the textile through coating.

Description

Technical Field

[0001] The invention relates to the technical field of phase change energy storage materials, in particular to a phase change temperature regulating microcapsule and a preparation method and application thereof. Background Art

[0002] As global energy demand continues to grow, energy consumption will increase significantly in the coming decades, especially for developing countries. The per capita energy consumption in developing countries is still very low, and the energy consumption potential is huge. Therefore, improving energy efficiency and developing renewable energy have become urgent issues that need to be addressed in the energy field.

[0003] Thermal storage technology can improve energy efficiency by reasonably allocating the time and space distribution of energy. Phase change material (PCM) is an effective thermal storage material that uses phase change characteristics to achieve heat storage or release. Moreover, it has the characteristics of large phase change latent heat, large volume change, and stable chemical properties. However, there are still some problems in directly using PCM as a thermal storage material, such as phase separation after multiple cycles of heat absorption and heat release, low thermal conductivity, and inability to release heat within the specified temperature range, which affects the thermal storage efficiency. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the deficiencies in the prior art, the present invention provides a phase-change temperature-regulating microcapsule and a preparation method and application thereof. The microcapsule is prepared by a Pickering emulsion template method, which solves the problems raised in the above background technology.

[0006] (II) Technical solution

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] According to a first aspect of the present invention, a method for preparing a phase-change temperature-regulating microcapsule is provided, comprising the following steps:

[0009] (1) melting and mixing the thermally conductive particles and the organic polymer material to obtain a molten liquid;

[0010] (2) adding the molten liquid to the preheated solid-liquid phase change solution and emulsifying to obtain a Pickering emulsion;

[0011] (3) Centrifuging the Pickering emulsion, collecting the upper layer and drying it to obtain phase change temperature regulating microcapsules.

[0012] The present invention obtains a composite material with high thermal conductivity by melt-mixing heat-conducting particles with organic polymer materials, which can effectively improve the heat transfer efficiency of phase change materials and improve heat storage and heat release performance. The composite material is then added to a solid-liquid phase change solution to form a Pickering emulsion, and a phase change temperature-regulating microcapsule with a core-shell structure is formed through self-assembly. The microcapsule has high thermal conductivity, high heat storage efficiency, can release heat within a specified temperature range, and solves the problem of phase separation.

[0013] Preferably, in step (1), the thermally conductive particles are selected from at least one of nano-alumina, nano-diamond, carbon nanotube, graphene nanosheet, boron nitride nanosheet, nano-silver and nano-aluminum;

[0014] The organic polymer material is selected from at least one of cellulose or aramid nanofibers;

[0015] The mass ratio of the thermally conductive particles to the organic polymer material is 1:2-4.

[0016] Further preferably, the thermally conductive particles are selected from carbon nanotubes or graphene nanosheets;

[0017] The organic polymer material is selected from aramid nanofibers;

[0018] The mass ratio of the thermally conductive particles to the organic polymer material is 1:2.

[0019] The organic polymer material selected by the present invention has the characteristics of high fiber strength, high modulus, acid and alkali resistance, high temperature resistance, flame retardancy and good moldability, and can be constructed into the outer wall of the phase change temperature regulating microcapsule; the thermal conductive particles themselves have low density and high thermal conductivity. By introducing thermal conductive particles, conductive pathways and thermal conductive pathways can be constructed, thereby enhancing the photothermal and electrothermal characteristics of the phase change temperature regulating microcapsule, increasing the heat transfer channel, and improving the heat storage and heat release efficiency of thermal energy.

[0020] Preferably, in step (2), the solid-liquid phase change solution is selected from at least one of paraffin, n-docosane, n-octadecane, stearic acid and polyethylene glycol.

[0021] Further preferably, the solid-liquid phase change solution is selected from n-docosane.

[0022] Preferably, in step (2), the mass fraction of the solid-liquid phase change solution in the Pickering emulsion is 10 to 70 wt %.

[0023] Optionally, the mass fraction of the solid-liquid phase change solution in the Pickering emulsion is selected from any value of 10wt%, 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, 70wt% or a range between any two values.

[0024] Preferably, in step (2), the temperature of the preheated solid-liquid phase change solution is 40-50°C.

[0025] Preferably, in step (2), the stirring speed of the emulsification is 3000-6000 r / min, the temperature of the emulsification is 40-50° C., and the time of the emulsification is 5-20 min.

[0026] Preferably, in step (3), the centrifugal speed is 3000-5000 rpm, and the centrifugal time is 5-8 min.

[0027] According to a second aspect of the present invention, a phase change temperature regulating microcapsule obtained according to the above-mentioned preparation method is provided, comprising a core material, a wall material and thermally conductive particles, wherein the wall material is coated on the surface of the core material, the thermally conductive particles are dispersed in the wall material, the core material is a solid-liquid phase change material, and the wall material is an organic phase change material.

[0028] Preferably, the particle size of the phase-change temperature-regulating microcapsules is 3 to 10 μm, and the thickness of the wall material is 300 to 500 nm.

[0029] According to a third aspect of the present invention, there is provided an application of phase change temperature regulating microcapsules in temperature regulating textiles.

[0030] (III) Beneficial effects

[0031] The present invention provides a phase-change temperature-regulating microcapsule and a preparation method and application thereof, which has the following beneficial effects:

[0032] (1) The present invention provides a method for preparing phase-change thermostatic microcapsules, which comprises melt-mixing heat-conducting particles and organic polymer materials and then forming a Pickering emulsion with a solid-liquid phase change solution to form a phase-change thermostatic microcapsule with a core-shell structure through self-assembly. The microcapsules have high thermal conductivity, high heat storage efficiency, and can release heat within a specified temperature range, thereby solving the problem of phase separation.

[0033] (2) The present invention provides a phase-change temperature-regulating microcapsule with stable heat storage and release performance, which melts and solidifies within a temperature range comfortable for the human body, has a uniform particle size distribution, and can be fixed on textiles by coating, while the textiles remain soft. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a SEM image of the phase change temperature regulating microcapsule prepared in Example 1 of the present invention at 5 μm. DETAILED DESCRIPTION

[0035] In order to better illustrate the content of the present invention, a detailed description is given below in conjunction with specific embodiments.

[0036] Example 1

[0037] 50 g of carbon nanotubes and 100 g of aramid nanofibers are weighed and placed in a sealed container, heated to 570° C. in an inert atmosphere for melt mixing to obtain a molten liquid, and then the molten liquid is added to a n-docosane solution preheated to 40° C., and emulsified at 40° C. for 10 min at a stirring speed of 3000 r / min to obtain a Pickering emulsion, wherein the mass of n-docosane accounts for 30 wt% of the Pickering emulsion; finally, the Pickering emulsion is placed in a centrifuge and centrifuged at a speed of 3000 rpm for 5 min, the upper layer of the material is collected and dried to obtain a phase change temperature regulating microcapsule with a particle size of 3 to 10 μm, such as Figure 1 As shown, the wall thickness of the phase change temperature regulating microcapsule is 360nm.

[0038] The melting temperature, solidification temperature, melting heat and solidification heat of the phase change temperature regulating microcapsules prepared in Example 1 were measured, and the melting temperature was 28.8°C, the solidification temperature was 5.6°C, the melting heat was 194J / g, and the solidification heat was 188.5J / g. It can be seen that the melting temperature and solidification temperature of the phase change temperature regulating microcapsules prepared in this example are within the comfortable range for the human body, and have a high energy storage effect, and are suitable for clothing temperature regulation.

[0039] Example 2

[0040] 50g of graphene nanosheets and 150g of aramid nanofibers are weighed and placed in a closed container, and the temperature is raised to 570°C in an inert atmosphere for melt mixing to obtain a molten liquid; the molten liquid is then added to an n-octadecane solution preheated to 40°C, and emulsified at 40°C for 10 minutes at a stirring speed of 3200r / min to obtain a Pickering emulsion, wherein the mass of n-octadecane accounts for 50wt% of the Pickering emulsion; finally, the Pickering emulsion is placed in a centrifuge, centrifuged at a speed of 3500rpm for 5 minutes, the upper layer of material is collected and dried to obtain phase change temperature regulating microcapsules with a particle size of 3-8μm, wherein the wall thickness of the phase change temperature regulating microcapsules is 370nm.

[0041] Example 3

[0042] 50 g of nano-alumina and 200 g of aramid nanofiber are weighed and placed in a closed container, and the temperature is raised to 570° C. in an inert atmosphere for melt mixing to obtain a molten liquid; the molten liquid is then added to a paraffin solution preheated to 50° C., and emulsified at 45° C. for 10 min at a stirring speed of 5000 r / min to obtain a Pickering emulsion, wherein the mass of the paraffin accounts for 20 wt% of the Pickering emulsion; finally, the Pickering emulsion is placed in a centrifuge, and centrifuged at a speed of 5000 rpm for 8 min, and the upper layer of material is collected and dried to obtain phase change temperature regulating microcapsules with a particle size of 6 to 10 μm, wherein the wall thickness of the phase change temperature regulating microcapsules is 450 nm.

[0043] Example 4

[0044] 50 g of nano-diamond and 100 g of aramid nanofiber are weighed and placed in a closed container, and the temperature is raised to 570° C. in an inert atmosphere for fusion and mixing to obtain a molten liquid; the molten liquid is then added to a stearic acid solution preheated to 50° C., and emulsified at 45° C. for 10 min at a stirring speed of 6000 r / min to obtain a Pickering emulsion, wherein the mass of the stearic acid solution accounts for 70wt% of the Pickering emulsion; finally, the Pickering emulsion is placed in a centrifuge, and centrifuged at a speed of 4500 rpm for 6 min, the upper layer of material is collected and dried, and a phase-change temperature-regulating microcapsule with a particle size of 6 to 8 μm is obtained, wherein the wall thickness of the phase-change temperature-regulating microcapsule is 400 nm.

[0045] Comparative Example 1

[0046] The preparation method of this comparative example is the same as that of Example 1, except that the mass of n-docosane accounts for 5 wt % of the Pickering emulsion.

[0047] Comparative Example 2

[0048] The preparation method of this comparative example is the same as that of Example 1, except that the mass of n-docosane accounts for 80 wt % of the Pickering emulsion.

[0049] In Comparative Example 1, the mass of n-docosane accounts for only 5wt% of the Pickering emulsion. Due to the small proportion, the overall thermal performance of the phase change microcapsule may be affected, and the supercooling phenomenon may be more serious, because there are not enough atomic nuclei in the tiny space, resulting in a significant decrease in the crystallization temperature. At the same time, its heat storage capacity may be reduced, affecting its application effect; in Comparative Example 2, the mass proportion of n-docosane is too high, which will cause phase separation of the phase change microcapsule during the phase change process, affecting the structure and performance, such as reduced thermal conductivity, weakened heat storage capacity, etc. In addition, too much docosane will also cause supercooling.

[0050] Application Examples

[0051] The phase change thermoregulating microcapsules of Examples 1 to 4 and Comparative Examples 1 and 2 were coated on textile fabrics, respectively, and air-dried to obtain thermoregulating textiles. The thermoregulating performance of the thermoregulating textiles was tested, and the test results are shown in Table 1.

[0052] Table 1

[0053]

[0054] It can be seen from Table 1 that the phase change thermoregulating fabric prepared by spraying was cooled to 0°C in a refrigerator and then placed on a heating plate at 45°C. Table 1 shows the temperature change of the phase change thermoregulating fabric over time. After heating for 60 seconds, the temperature of the phase change thermoregulating fabric in Example 1 was about 31.1°C, while the temperature of Comparative Examples 1 and 2 was close to 45°C. As shown in Table 1, the heating rate of the phase change thermoregulating fabrics of Examples 1 to 4 is much slower than that of the thermoregulating fabrics of Comparative Examples 1 and 2. This shows that the microcapsules prepared in Examples 1 to 4 have significant temperature regulation capabilities.

[0055] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing phase-change temperature-regulating microcapsules, characterized in that: The following steps are involved: (1) melting and mixing the thermally conductive particles and the organic polymer material to obtain a molten liquid; (2) adding the molten liquid to the preheated solid-liquid phase change solution and emulsifying to obtain a Pickering emulsion; (3) Centrifuging the Pickering emulsion, collecting the upper layer and drying it to obtain phase change temperature regulating microcapsules.

2. The method for preparing a phase-change temperature-regulating microcapsule according to claim 1, characterized in that: In step (1), the thermally conductive particles are selected from at least one of nano-alumina, nano-diamond, carbon nanotube, graphene nanosheet, boron nitride nanosheet, nano-silver and nano-aluminum; The organic polymer material is selected from at least one of cellulose or aramid nanofibers; The mass ratio of the thermally conductive particles to the organic polymer material is 1:2-4.

3. The method for preparing a phase-change temperature-regulating microcapsule according to claim 1, characterized in that: In step (2), the solid-liquid phase change solution is selected from at least one of paraffin, n-docosane, n-octadecane, stearic acid and polyethylene glycol.

4. The method for preparing a phase-change temperature-regulating microcapsule according to claim 1, characterized in that: In step (2), the mass fraction of the solid-liquid phase change solution in the Pickering emulsion is 10 to 70 wt %.

5. The method for preparing a phase-change temperature-regulating microcapsule according to claim 1, characterized in that: In step (2), the temperature of the preheated solid-liquid phase change solution is 40-50°C.

6. The method for preparing a phase-change temperature-regulating microcapsule according to claim 1, characterized in that: In step (2), the stirring speed of the emulsification is 3000-6000 r / min, the temperature of the emulsification is 40-50° C., and the time of the emulsification is 5-20 min.

7. The method for preparing a phase-change temperature-regulating microcapsule according to claim 1, characterized in that: In step (3), the centrifugal speed is 3000-5000 rpm, and the centrifugal time is 5-8 min.

8. A phase-change temperature-regulating microcapsule obtained by the preparation method according to any one of claims 1 to 7, characterized in that: The invention comprises a core material, a wall material and heat-conducting particles. The wall material is coated on the surface of the core material, the heat-conducting particles are dispersed in the wall material, the core material is a solid-liquid phase change material, and the wall material is an organic phase change material.

9. The phase-change temperature-regulating microcapsule according to claim 8, characterized in that: The particle size of the phase-change temperature-regulating microcapsule is 3-10 μm, and the thickness of the wall material is 300-500 nm.

10. Use of the phase-change temperature-regulating microcapsule according to claim 8 or 9 in temperature-regulating textiles.

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