Electrophoretic paint based on phase change material, composite coating, preparation method and application

Abstract

The invention relates to the technical field of electrophoretic paint, and particularly discloses electrophoretic paint based on a phase change material, a composite coating, a preparation method and application. The electrophoretic paint based on the phase-change material is prepared from the following raw materials in parts by weight: 10-15 parts of phase-change material microcapsules MicroPCM, 35-70 parts of epoxy resin, 15-25 parts of TPU resin, 1-3 parts of an anti-settling agent and 0.5-2 parts of other auxiliaries, the phase change material microcapsule MicroPCM is subjected to surface spraying treatment by using a functional additive before application, and the functional additive comprises the following components in parts by weight: 2-5 parts of graphene oxide, 0.8-1.2 parts of lauryl sodium sulfate, 5-10 parts of propylene glycol monomethyl ether and 80-90 parts of a polyvinyl alcohol solution. According to the application, the dispersity and compatibility of the phase-change material microcapsule MicroPCM in the electrophoretic paint can be improved through the application of the functional additive, so that the formed electrophoretic paint layer structure can show excellent temperature control stability, and further the stable exertion of the corrosion resistance of the outer composite layer structure of the battery shell is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrophoretic paint, more particularly, it relates to an electrophoretic paint based on phase change material, a composite coating, a preparation method and application. BACKGROUND

[0002] With the rapid development of global economy, the demand for traditional fossil energy such as oil is increasing, while oil resources are becoming exhausted, and its price is greatly affected by international politics, economy and other factors. The development of new energy vehicles helps to reduce dependence on oil and promote the adjustment of energy structure to diversification and cleanization. For example, electric vehicles can use renewable energy such as wind and solar power to charge, realizing sustainable use of energy. In addition, continuous innovation in key technologies such as battery technology, motor technology and electronic control technology provides strong support for the development of new energy vehicles.

[0003] And the battery as the core component of new energy vehicles, its safety is directly related to the safe operation of the vehicle and the safety of passengers' life and property. Once the battery thermal runaway, fire, explosion and other safety accidents occur, not only the vehicle will be damaged, but also the safety of surrounding personnel and facilities will be endangered. Therefore, the design of the battery shell is particularly important. At present, special heat insulation materials are generally used to design the battery shell, or heat dissipation fins, heat dissipation channels and other structures are designed on the surface of the battery shell. However, this is generally customized, and needs to be designed and manufactured separately according to different vehicle models and different battery specifications, which increases the use cost of new energy vehicles and reduces the market competitiveness of products, and does not have universality.

[0004] Electrophoretic paint is a coating technology that uses electrophoresis principle to deposit paint on the surface of metal. Its application on the battery shell mainly reflects in corrosion protection and structural reinforcement, and the application of electrophoretic paint also has high economy, and makes the production process more efficient and energy-saving. Therefore, by using electrophoretic paint technology, a "electrophoretic paint + PCM" composite layer is coated on the outside of the battery shell to absorb heat fluctuations at extreme temperatures, which can extend the battery life by 20%, reduce the risk of thermal runaway by 30%, and has lower cost and higher universality.

[0005] For the related technologies in the above, the inventors believe that phase change material (PCM) is a functional material that stores and releases energy through state change, which can absorb or release latent heat at a specific temperature to maintain a relatively constant temperature. Its dispersion and compatibility in electrophoretic paint are often poor, and the temperature control stability is poor, which will affect the stable performance of the corrosion resistance of the composite layer structure on the outside of the battery shell.

[0006] Therefore, there is an urgent need to propose a scheme to solve the above technical problems. SUMMARY

[0007] In order to improve the dispersibility and compatibility of the phase change material in the electrophoretic paint, make the formed electrophoretic paint layer structure exhibit excellent temperature control stability, and further ensure the stable performance of the anticorrosion performance of the composite layer structure of the battery shell, the application provides an electrophoretic paint based on a phase change material, a composite coating and a preparation method and application.

[0008] In a first aspect, the application provides an electrophoretic paint based on a phase change material, which adopts the following technical scheme: An electrophoretic paint based on a phase change material is made of raw materials containing the following weight parts: Phase change material microcapsule MicroPCM 10-15 parts; Epoxy resin 35-70 parts; TPU resin 15-25 parts; Anti-settling agent 1-3 parts; Other auxiliary agents 0.5-2 parts; The phase change material microcapsule MicroPCM is surface sprayed with a functional auxiliary agent before application, and the functional auxiliary agent contains the following components by weight: Graphene oxide 2-5 parts; Sodium dodecyl sulfate 0.8-1.2 parts; Propylene glycol methyl ether 5-10 parts; Polyvinyl alcohol solution 80-90 parts.

[0009] By adopting the above technical scheme, the phase change material microcapsule MicroPCM serves as a phase change energy storage core to provide temperature regulation function. The inner core material absorbs / releases heat to stabilize the coating temperature during the phase change process, the outer wall material prevents leakage and provides excellent flame retardance and thermal conductivity, improving the safety of batteries or other application scenarios. The epoxy resin is the main film-forming matrix, which realizes high-strength crosslinking and curing through epoxy groups, and provides the coating with excellent adhesion, corrosion resistance and mechanical rigidity. The TPU resin introduces a soft block structure to improve the flexibility, impact resistance and elasticity of the coating, complementing the epoxy resin to overcome brittleness and enhance overall mechanical properties and environmental adaptability. The anti-settling agent inhibits the settling of the phase change material microcapsule MicroPCM, maintains the dispersion stability of the coating, optimizes the uniformity and flowability during the electrophoretic coating process, and avoids delamination or caking defects. When the electrophoretic paint based on the phase change material is applied, the epoxy resin forms a rigid skeleton, the TPU resin provides flexible cushioning, the phase change material microcapsule MicroPCM is uniformly dispersed to achieve dynamic thermal management, the anti-settling agent ensures stable suspension of the microcapsule, and the auxiliary agent optimizes the electrophoretic process parameters, which can form a multifunctional coating system with intelligent temperature control, flame retardance and high toughness.

[0010] The surface of the phase change material microcapsule MicroPCM is sprayed with a functional aid before application, and the sodium dodecyl sulfate in the functional aid can reduce the surface tension of the phase change material microcapsule MicroPCM, promote its infiltration with the resin matrix, and use the two-dimensional sheet structure of graphene oxide to construct an efficient heat conduction network, reduce the interfacial thermal resistance between the microcapsule and the resin matrix, and improve the heat transfer efficiency, so that the response speed of the phase change material is improved. At the same time, the graphene oxide can be embedded on the surface of the phase change material microcapsule MicroPCM to form a micro-convex spherical structure, thereby improving the uniform distribution and interfacial bonding force in the resin matrix; at the same time, the polyvinyl alcohol solution forms a protective layer on the surface of the microcapsule due to its film-forming property, which not only further prevents the leakage of the phase change material during the electrophoresis process, but also relieves the debonding problem between the microcapsule and the matrix caused by temperature cycling, and uses propylene glycol methyl ether as a film-forming aid to ensure that the functional aid uniformly coats the surface of the phase change material microcapsule MicroPCM. In this way, through the application of the functional aid, the synergistic cooperation between graphene oxide, sodium dodecyl sulfate, propylene glycol methyl ether and polyvinyl alcohol solution can improve the dispersibility and compatibility of the phase change material microcapsule MicroPCM in the electrophoretic paint, so that the structure of the formed electrophoretic paint layer can exhibit excellent temperature control stability, thereby ensuring the stable performance of the anticorrosion performance of the composite layer structure of the battery shell.

[0011] Preferably, the functional aid contains the following components by weight: Graphene oxide 3.5 parts; Sodium dodecyl sulfate 1 part; Propylene glycol methyl ether 7.5 parts; Polyvinyl alcohol solution 85 parts.

[0012] By adopting the above technical solution, the components in the above weight parts have good corresponding effects when they are used in the composition of the functional aid, and the dispersibility and compatibility of the phase change material microcapsule MicroPCM in the electrophoretic paint are improved after the application of the functional aid, thereby ensuring the stable performance of the temperature control stability of the electrophoretic paint layer and the anticorrosion performance of the battery shell.

[0013] Preferably, the amount of the functional aid on the surface of the phase change material microcapsule MicroPCM is 8-12wt%.

[0014] By adopting the above technical solution, when the amount of the functional aid is less than the above range, it is difficult to form a uniform coating on the surface of the phase change material microcapsule MicroPCM; when the amount of the functional aid is greater than the above range, the viscosity will increase sharply, and the phase change material microcapsule MicroPCM is prone to agglomeration, making it difficult to achieve excellent and stable effects; and the amount of the functional aid in the above range can ensure that the functional aid has excellent and stable effects.

[0015] Preferably, the particle size of the phase change material microcapsule MicroPCM is 5-10 pm, and the phase change temperature is 25-35℃.

[0016] By adopting the above technical solution, the particle size of 5-10 pm is close to the size of the electrophoretic paint resin molecular chain, and is combined with the resin by Van der Waals force, and the settling rate in the electrophoresis process is moderate, and the coating layer is not easy to delaminate; and the narrow range of the phase change temperature of 25-35℃ can reduce the volume change rate, effectively reduce the resin cross-linking stress cracks when absorbing the charge and discharge heat shock, and avoid the rupture of the microcapsule; in this way, the phase change material microcapsule MicroPCM can play an excellent and stable role in the application process.

[0017] Preferably, the other auxiliary agent is a combination of one or more of dispersants, leveling agents and defoaming agents.

[0018] By adopting the above technical solution, the dispersant can inhibit agglomeration and sedimentation; the leveling agent can eliminate shrinkage holes and orange peel caused by uneven electrophoretic wetting; and the defoaming agent can break the foam structure to ensure the continuity of the coating structure; and the selection and combination of the above-mentioned other auxiliary agents are suitable for the application of the electrophoretic paint and ensure the excellent role of the phase change material microcapsule MicroPCM.

[0019] In a second aspect, the application provides a composite coating based on phase change material, which adopts the following technical solution: A composite coating based on phase change material, comprising a three-layer structure, in order: a bottom layer, an intermediate layer and a surface layer, wherein the intermediate layer is prepared by using the electrophoretic paint based on phase change material according to any one of claims 1-5.

[0020] By adopting the above technical solution, the bottom layer is a corrosion protection layer, and the surface layer is a protective layer, which is combined with the intermediate layer prepared by using the electrophoretic paint based on phase change material, to form a three-layer composite structure of "corrosion protection + temperature control + protection", and through gradient function distribution (bottom layer anchoring-intermediate layer regulation-surface layer protection), the needs of heat runaway protection and corrosion inhibition of high-heat components such as lithium battery shells are simultaneously solved, and the composite coating based on phase change material shows better application on the battery shell.

[0021] Preferably, the thickness of the bottom layer is 10-15 pm, the thickness of the intermediate layer is 10-20 pm, and the thickness of the surface layer is 5-10 pm.

[0022] By adopting the technical scheme, the bottom layer has a thickness of 10-15 μm, can form a continuous and dense structure, block the penetration of corrosion medium, has reliable corrosion prevention effect, has strong compatibility with the base material, can adapt to the ups and downs of the surface of the base material, and is prone to incomplete coverage when too thin and reduces flexibility when too thick; the middle layer has a thickness of 10-20 μm, can realize the balance of phase change performance and structure, reduces the heat capacity when too thin, and prolongs the heat response time when too thick; the surface layer has a thickness of 5-10 μm, can meet the application requirements, brings better protection effect, reduces the wear resistance when too thin, and increases the brittleness when too thick; therefore, the thicknesses of the layers are selected and matched to bring better synergistic effect, and thus the stable application of the composite coating based on the phase change material on the battery shell is ensured.

[0023] In a third aspect, the application provides a preparation method of a composite coating based on a phase change material, which adopts the following technical scheme: A preparation method of a composite coating based on a phase change material, comprising the following steps: (1) preparing raw materials of electrophoretic paint for preparing a bottom layer, a middle layer and a surface layer according to a proportion; (2) bottom layer electrophoresis, immersing a workpiece into an electrophoresis tank, the workpiece being an anode and the tank body being a cathode, then connecting a power supply, performing ultrafiltration water washing after deposition, and high-temperature baking to form a bottom layer on the surface of the workpiece; (3) middle layer electrophoresis, immersing the workpiece obtained in step (2) into an electrophoresis tank, the workpiece being an anode and the tank body being a cathode, then connecting a power supply, performing ultrafiltration water washing after deposition, and high-temperature baking to form a middle layer on the surface of the workpiece; (4) surface layer electrophoresis, immersing the workpiece obtained in step (3) into an electrophoresis tank, the workpiece being an anode and the tank body being a cathode, then connecting a power supply, performing ultrafiltration water washing after deposition, and high-temperature baking to form a surface layer on the surface of the workpiece, and finally obtaining a composite coating based on a phase change material with a three-layer structure of a bottom layer, a middle layer and a surface layer.

[0024] By adopting the technical scheme, a segmented electrophoresis process is adopted to deposit different functional layers in stages, and thus the combination between the bottom layer, the middle layer and the surface layer is realized, which is beneficial to the quality control of the layers during the operation process and makes the bottom layer, the middle layer and the surface layer form excellent combination, and thus a composite coating based on a phase change material with better quality is ensured.

[0025] Preferably, in step (3), the voltage of the electrophoresis process is 235-245 V, the time is 3-4 min, the temperature is 25-30℃, and the solid content of the tank liquid is 20-25%.

[0026] By adopting the above technical scheme, the voltage of the electrophoresis process is 235-245V, which can drive the phase change material microcapsule MicroPCM to overcome the Brownian motion, and at the same time, avoid the breakdown of the phase change material microcapsule MicroPCM, ensure better deposition efficiency, and realize dense accumulation; and within 3-4min, the deposition behavior is different, wherein within 0-2min, the phase change material microcapsule MicroPCM impacts the substrate at high speed to form a vertically arranged bottom skeleton, and within 2-4min, the resin phase slowly coats and fills the gap to smooth the surface; and the temperature of 25-30℃ can maintain the size stability of the phase change material microcapsule MicroPCM and prevent the phase change material microcapsule MicroPCM from falling off due to the impact of high-speed electrophoretic flow; at the same time, the solid content of the bath liquid is 20-25%, which can avoid stress cracking caused by the dense accumulation of the phase change material microcapsule MicroPCM; in this way, a middle layer with uniform, stable and complete structure can be obtained.

[0027] In a fourth aspect, the application provides an application of the composite coating based on the phase change material in the preparation of a battery shell.

[0028] In summary, the application has the following beneficial effects: In the application, the phase change material microcapsule MicroPCM is treated by surface spraying with a functional aid before application, and the synergistic cooperation among graphene oxide, sodium dodecyl sulfate, propylene glycol methyl ether and polyvinyl alcohol solution in the functional aid can improve the dispersibility and compatibility of the phase change material microcapsule MicroPCM in the electrophoretic paint, so that the structure of the formed electrophoretic paint layer can exhibit excellent temperature control stability, and further ensure the stable performance of the anticorrosion performance of the composite layer structure of the battery shell. DETAILED DESCRIPTION

[0029] The application will be further described in detail below in combination with examples and comparative examples.

[0030] The raw materials used in the examples and comparative examples of the application are commercially available, except for special instructions.

[0031] The phase change material microcapsule MicroPCM is purchased from Dongguan Shengbang High Polymer Material Co., Ltd.; The epoxy resin is a bisphenol A type E-44 epoxy resin; The TPU resin is LB-1532 from Shenzhen Lanbo Environmental Protection Technology Co., Ltd.; The anti-settling agent is fumed silica, and is AEROSIL 380 from Wincat; The graphene oxide is nano graphene oxide from Shanghai Maoguo Nanotechnology Co., Ltd., with a single-layer sheet diameter of 100nm; The polyvinyl alcohol solution is purchased from Guangzhou Qihua Chemical Co., Ltd., with a solid content of 20%. The electrophoretic paint used for the preparation of the bottom layer and the surface layer is of the same brand, which is PPG ED-5000. Examples

[0032] Examples 1-3 An electrophoretic paint based on phase change material, the raw materials used for the preparation and their corresponding weight parts are shown in Table 1, and each raw material is mixed to obtain.

[0033] Table 1 Raw materials used for the preparation of Examples 1-3 and their corresponding weight parts (parts / kg) The above-mentioned phase change material microcapsule MicroPCM is surface sprayed with a functional aid before application, the raw materials used for the functional aid and their corresponding weight parts are shown in Table 2, and each raw material is mixed to obtain. Other aids are defoamers, which are DVK-1700 defoamers for electrophoretic paint purchased from Guangzhou Huidi Chemical Co., Ltd. The amount of phase change material microcapsule MicroPCM surface functional aid is 10wt%. The particle size of the phase change material microcapsule MicroPCM is 7.5μm, and the phase change temperature is 30℃.

[0034] Examples 4-5 An electrophoretic paint based on phase change material, which is different from Example 1, the raw materials used for the functional aid and their corresponding weight parts are shown in Table 2.

[0035] Table 2 Raw materials used for the preparation of functional aids of Examples 1, 4-5 and their corresponding weight parts (parts / kg) Raw materials Example 1 Example 4 Example 5 Graphene oxide 3.5 2 5 Sodium dodecyl sulfate 1 0.8 1.2 Propylene glycol methyl ether 7.5 5 10 Polyvinyl alcohol solution 85 80 90 Example 6 An electrophoretic paint based on phase change material, which is different from Example 1, the amount of phase change material microcapsule MicroPCM surface functional aid is 8wt%.

[0036] Example 7 An electrophoretic paint based on phase change material, which is different from Example 1, the amount of phase change material microcapsule MicroPCM surface functional aid is 12wt%.

[0037] Example 8 An electrophoretic paint based on phase change material, which is different from Example 1, the particle size of the phase change material microcapsule MicroPCM is 5μm, and the phase change temperature is 25℃.

[0038] Example 9 An electrophoretic paint based on phase change material, which is different from Example 1, the particle size of the phase change material microcapsule MicroPCM is 10μm, and the phase change temperature is 35℃.

[0039] Comparative Example 1 Comparative Example 1 A phase change material-based electrophoretic paint, different from Example 1 in that the phase change material microcapsules MicroPCM are not subjected to surface spraying treatment with functional additives before application.

[0040] Comparative Example 2 A phase change material-based electrophoretic paint, different from Example 1 in that no graphene oxide, sodium dodecyl sulfate is used in the functional additives.

[0041] Comparative Example 3 A phase change material-based electrophoretic paint, different from Example 1 in that no graphene oxide, propylene glycol methyl ether is used in the functional additives.

[0042] Comparative Example 4 A phase change material-based electrophoretic paint, different from Example 1 in that no sodium dodecyl sulfate, propylene glycol methyl ether is used in the functional additives.

[0043] Comparative Example 5 A phase change material-based electrophoretic paint, different from Example 1 in that no graphene oxide, sodium dodecyl sulfate, propylene glycol methyl ether is used in the functional additives.

[0044] Application Example Application Example 1 A phase change material-based composite coating, comprising a three-layer structure, in order, a bottom layer, an intermediate layer, and a surface layer, the intermediate layer being prepared from the phase change material-based electrophoretic paint obtained in Example 1, and being prepared by the following steps: (1) Prepare the raw materials for preparing the electrophoretic paint of the bottom layer, the intermediate layer, and the surface layer according to the proportions; (2) Bottom layer electrophoresis, immerse the workpiece in the electrophoresis tank, the workpiece being the anode and the electrophoresis tank body being the cathode, then connect the power supply, after deposition is complete, perform ultrafiltration water washing, and after high-temperature baking, form the bottom layer on the surface of the workpiece; the voltage during the electrophoresis process is 280V, the time is 2.5min, the temperature is 25℃, and the solid content of the tank liquid is 20%; (3) Intermediate layer electrophoresis, immerse the workpiece obtained in step (2) in the electrophoresis tank, the workpiece being the anode and the electrophoresis tank body being the cathode, then connect the power supply, after deposition is complete, perform ultrafiltration water washing, and after high-temperature baking, form the intermediate layer on the surface of the workpiece; (4) surface layer electrophoresis, the workpiece obtained in step (3) is immersed in an electrophoresis tank, the workpiece is an anode and the electrophoresis tank body is a cathode, then a power supply is connected, after deposition, ultrafiltration water washing is performed, and high-temperature baking is performed to form a surface layer on the surface of the workpiece, the voltage in the electrophoresis process is 280 V, the time is 2.5 min, the temperature is 25 °C, and the solid content proportion of the tank solution is 20%; finally, a composite coating based on a phase change material with a three-layer structure of a bottom layer, an intermediate layer and a surface layer is obtained.

[0045] Note: in the obtained composite coating, the thickness of the bottom layer is 12.5 μm, the thickness of the intermediate layer is 15 μm, and the thickness of the surface layer is 7.5 μm. In step (3), the voltage in the electrophoresis process is 240 V, the time is 3.5 min, the temperature is 27.5 °C, and the solid content proportion of the tank solution is 22.5%.

[0046] Application Example 2 A composite coating based on a phase change material, which is different from application example 1 in that, in the obtained composite coating, the thickness of the bottom layer is 10 μm, the thickness of the intermediate layer is 10 μm, and the thickness of the surface layer is 5 μm.

[0047] Application Example 3 A composite coating based on a phase change material, which is different from application example 1 in that, in the obtained composite coating, the thickness of the bottom layer is 15 μm, the thickness of the intermediate layer is 20 μm, and the thickness of the surface layer is 10 μm.

[0048] Application Example 4 A composite coating based on a phase change material, which is different from application example 1 in that, in step (3), the voltage in the electrophoresis process is 235 V, the time is 4 min, the temperature is 30 °C, and the solid content proportion of the tank solution is 20%.

[0049] Application Example 5 A composite coating based on a phase change material, which is different from application example 1 in that, in step (3), the voltage in the electrophoresis process is 245 V, the time is 3 min, the temperature is 25 °C, and the solid content proportion of the tank solution is 25%.

[0050] Application Example 6 A composite coating based on a phase change material, which is different from application example 1 in that, the intermediate layer is made of the electrophoretic paint based on a phase change material obtained in example 2.

[0051] Application Example 7 A composite coating based on a phase change material, which is different from application example 1 in that, the intermediate layer is made of the electrophoretic paint based on a phase change material obtained in example 3.

[0052] Application Example 8 A composite coating based on a phase change material, which differs from the application example 1 in that the intermediate layer is made of the phase change material based electrophoretic paint obtained in example 4.

[0053] Application example 9 A composite coating based on a phase change material, which differs from the application example 1 in that the intermediate layer is made of the phase change material based electrophoretic paint obtained in example 5.

[0054] Application example 10 A composite coating based on a phase change material, which differs from the application example 1 in that the intermediate layer is made of the phase change material based electrophoretic paint obtained in example 6.

[0055] Application example 11 A composite coating based on a phase change material, which differs from the application example 1 in that the intermediate layer is made of the phase change material based electrophoretic paint obtained in example 7.

[0056] Application example 12 A composite coating based on a phase change material, which differs from the application example 1 in that the intermediate layer is made of the phase change material based electrophoretic paint obtained in example 8.

[0057] Application example 13 A composite coating based on a phase change material, which differs from the application example 1 in that the intermediate layer is made of the phase change material based electrophoretic paint obtained in example 9.

[0058] Application comparative example Application comparative example 1 A composite coating based on a phase change material, which differs from the application example 1 in that the intermediate layer is made of the phase change material based electrophoretic paint obtained in comparative example 1.

[0059] Application comparative example 2 A composite coating based on a phase change material, which differs from the application example 1 in that the intermediate layer is made of the phase change material based electrophoretic paint obtained in comparative example 2.

[0060] Application comparative example 3 A composite coating based on a phase change material, which differs from the application example 1 in that the intermediate layer is made of the phase change material based electrophoretic paint obtained in comparative example 3.

[0061] Application comparative example 4 A composite coating based on a phase change material, which differs from the application example 1 in that the intermediate layer is made of the phase change material based electrophoretic paint obtained in comparative example 4.

[0062] Application comparative example 5 A composite coating based on phase change material, which is different from application example 1 in that the intermediate layer is prepared from the electrophoretic paint based on phase change material obtained in comparative example 5.

[0063] Performance test test samples: the composite coatings based on phase change material obtained in application examples 1-13 are selected as test samples 1-13, and the composite coatings based on phase change material obtained in application comparative examples 1-3 are selected as control samples 1-5.

[0064] Test method: the composite coating based on phase change material is placed in a salt spray test chamber for salt spray resistance test; then a 5% sodium chloride solution is prepared, 50 g of analytical pure NaCl is dissolved in 950 mL of pure distilled water, stirred until completely dissolved, and the pH value is adjusted to the range of 6.5-7.2; the test chamber temperature is set to 35±1℃, the spray pressure is 0.1 MPa, the relative humidity is 85%, and the test period is set to ≥800 hours; the sample corrosion conditions (such as pitting, cracking, bubbles, etc.) are checked regularly every 24 hours, and the time until corrosion occurs through the composite coating is recorded as A; Then the composite coating of the same phase change material is placed in a high-low temperature alternating test chamber, the initial temperature is 25℃, first heated to 35℃ at a rate of 2℃ / min, maintained for 30 min, then cooled to 5℃ at a rate of 1℃ / min for 15 min, and then heated to 25℃ at a rate of 2℃ / min, recorded as 1 cycle; after 50 cycles, the above salt spray resistance test is performed again, and the time until corrosion occurs is recorded as B; Finally, the deviation rate is calculated, deviation rate = (A-B) / A, and the smaller the deviation rate, the better the temperature control stability exhibited by the intermediate layer, and thus the more stable the overall corrosion protection performance of the composite coating based on phase change material.

[0065] After the above tests are performed on test samples 1-13 and control samples 1-5, the test results are recorded in Table 3.

[0066] Table 3 Test results of test samples 1-13 and control samples 1-5 It can be seen from the combination of the test sample 1 and the control sample 1 and Table 3 that the excellent effect of the phase change material microcapsule MicroPCM in the electrophoretic paint can be significantly improved by using the functional aid to perform surface spraying treatment on the phase change material microcapsule MicroPCM before application, so that the electrophoretic paint based on the phase change material exhibits better temperature control stability when forming the intermediate layer structure in application, and then the overall corrosion resistance of the composite coating also exhibits better stability, and the deviation rate obtained by the above test is significantly reduced. In combination with the control samples 2-5 and Table 3, it can be seen that if only polyvinyl alcohol solution is used as a functional aid after being sprayed on the surface of the phase change material microcapsule MicroPCM, although it can bring limited improvement in the corresponding effect, if any one of graphene oxide, sodium dodecyl sulfate and propylene glycol methyl ether is used in combination with polyvinyl alcohol solution on this basis, although it can bring further improvement in the corresponding effect, but the sum of the improvement effects brought by the addition of the three is far less than the excellent improvement effect brought by the combination of the three, thus it can be seen that the functional aids of graphene oxide, sodium dodecyl sulfate, propylene glycol methyl ether and polyvinyl alcohol solution can bring excellent synergistic effect, which can significantly improve the dispersibility and compatibility of the phase change material microcapsule MicroPCM in the electrophoretic paint, so as to ensure that the composite coating based on the phase change material on the outside of the battery shell can stably exert the corrosion resistance.

[0067] The specific embodiments are only an explanation of the present application, and are not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, and the modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. An electrophoretic paint based on a phase change material, characterized in that, The raw materials are prepared by the following weight parts: Phase change material microcapsule MicroPCM 10-15 parts; Epoxy resin 35-70 parts; TPU resin 15-25 parts; Anti-settling agent 1-3 parts; Other auxiliary agent 0.5-2 parts; The phase change material microcapsule MicroPCM is surface sprayed with a functional auxiliary agent before application, and the functional auxiliary agent comprises the following components by weight parts: Graphene oxide 2-5 parts; Sodium dodecyl sulfate 0.8-1.2 parts; Propylene glycol methyl ether 5-10 parts; Polyvinyl alcohol solution 80-90 parts.

2. The electrophoretic paint based on phase change material according to claim 1, characterized in that: The functional auxiliary agent comprises the following components by weight parts: Graphene oxide 3.5 parts; Sodium dodecyl sulfate 1 part; Propylene glycol methyl ether 7.5 parts; Polyvinyl alcohol solution 85 parts.

3. The electrophoretic paint based on phase change material according to claim 1, characterized in that: The amount of the phase change material microcapsule MicroPCM surface functional auxiliary agent is 8-12wt%.

4. The electrophoretic paint based on phase change material according to claim 1, characterized in that: The particle size of the phase change material microcapsule MicroPCM is 5-10μm, and the phase change temperature is 25-35℃.

5. The electrophoretic paint based on phase change material according to claim 1, characterized in that: The other auxiliary agent is a combination of one or more of dispersants, leveling agents, and defoaming agents.

6. A composite coating based on a phase change material, characterized by: It comprises a three-layer structure, in order of bottom layer, middle layer, and surface layer, and the middle layer is prepared using the phase change material-based electrophoretic paint according to any one of claims 1-5.

7. The composite coating based on phase change material according to claim 6, characterized in that: The thickness of the bottom layer is 10-15μm, the thickness of the middle layer is 10-20μm, and the thickness of the surface layer is 5-10μm.

8. The method of claim 6, wherein the method of producing a composite coating based on a phase change material is characterized by: It comprises the following steps: (1) Prepare the electrophoretic paint raw materials for preparing the bottom layer, middle layer, and surface layer according to the ratio; (2) Bottom layer electrophoresis, immerse the workpiece in the electrophoresis tank, the workpiece is the anode and the electrophoresis tank body is the cathode, then connect the power supply, after deposition, perform ultrafiltration water washing, and high-temperature baking to form a bottom layer on the surface of the workpiece; (3) Middle layer electrophoresis, immerse the workpiece obtained in step (2) in the electrophoresis tank, the workpiece is the anode and the electrophoresis tank body is the cathode, then connect the power supply, after deposition, perform ultrafiltration water washing, and high-temperature baking to form a middle layer on the surface of the workpiece; (4) Surface layer electrophoresis, immerse the workpiece obtained in step (3) in the electrophoresis tank, the workpiece is the anode and the electrophoresis tank body is the cathode, then connect the power supply, after deposition, perform ultrafiltration water washing, and high-temperature baking to form a surface layer on the surface of the workpiece, and finally obtain a three-layer structure of bottom layer, middle layer, and surface layer based on phase change material composite coating.

9. The method of claim 8, wherein: In step (3), the voltage during the electrophoresis process is 235-245 V, the time is 3-4 min, the temperature is 25-30℃, and the solid content of the tank solution is 20-25%.

10. Use of the phase change material-based composite coating according to any one of claims 6-7 in the preparation of a battery shell.

Images