Temperature-resistant insulating coating for new energy battery cell and preparation method of temperature-resistant insulating coating

Abstract

The invention discloses a new energy battery cell temperature-resistant insulating coating which is prepared from a component A, a component B and a component C. The component A is prepared from, by weight, 20-60 parts of film forming matter, 15-50 parts of temperature-resistant filler, 15-25 parts of flame retardant, 10-15 parts of carrier powder, 1-2 parts of organic silicon additive and 3-5 parts of diluent, the component B is a catalyst, and the component C is a curing agent. The composition of the methyl polysiloxane resin, the epoxy modified polysiloxane resin and the silazane resin is used as a film forming substance, and the battery cell coating with high flame retardant grade and shear resistance can be obtained. The low-melting-point glass powder with the initial melting temperature of 500 DEG C is introduced into a film forming substance, so that the voltage resistance of the coating before high temperature resistance can be improved, the insulation effect of the coating is optimized, and the salt mist resistance, acid and alkali resistance, electrolyte resistance and water resistance are improved.

Description

Technical Field

[0001] The present invention relates to the field of coating compositions, and specifically to a high-temperature resistant insulating coating for new energy battery cells and a preparation method thereof. Background Art

[0002] With the progress of technology, new energy electric vehicles are increasingly widely used in life. However, the popularization of electric vehicles is accompanied by battery safety problems. After an electric vehicle accident, the impact may cause the battery to short-circuit and catch fire. After the battery box catches fire and leaks electricity, it will pose a huge electric shock safety hazard to the people on the vehicle and the rescue personnel. Therefore, it is necessary to use insulating, high-temperature resistant, and flame-retardant coatings to reduce the combustion and leakage problems of the battery. Existing insulating and flame-retardant materials include PET blue film and powder coatings. The thickness of the PET blue film is small, and appearance defects are likely to occur. The cost of powder coatings is high, and they need to be painted and baked after filling with electrolyte, and the process is complex. Therefore, it is crucial to develop a new type of flame-retardant and insulating coating for application in new energy battery cells.

[0003] Chinese invention patent CN117659811A discloses a fireproof insulating powder coating, its preparation method and application. The modified dicyandiamide curing agent used has excellent flame-retardant and high-temperature resistant properties, and has good curing reaction activity with epoxy resin, which is beneficial to improving the fireproof and high-temperature resistant properties of the coating, and has a wide application in battery protection. However, its baking temperature is high, and the baking process after loading the electrolyte is complex. Chinese invention patent CN117363165A discloses a coating for a new energy vehicle battery box, its preparation method and application. Epoxy resin and silicone resin are respectively melt-wrapped with glass powder, and then melt-extruded with glass powder, flame retardant, etc. Finally, a hierarchical network structure in which a double-layer glass powder protects the main resin framework is formed inside the coating, greatly improving the high-temperature resistant level compared with conventional high-temperature resistant powders, thereby greatly improving the insulation of the coating after high temperature, but the processing technology is complex and time-consuming. Summary of the Invention

[0004] In order to develop a new type of flame-retardant and insulating coating for application in new energy battery cells, the first aspect of the present invention provides a high-temperature resistant insulating coating for new energy battery cells. The preparation raw materials include component A, component B, and component C. Component A includes, by weight parts: film-forming substance 20 - 60 parts, high-temperature resistant filler 15 - 50 parts, flame retardant 15 - 25 parts, carrier powder 10 - 15 parts, silicone-based auxiliary agent 1 - 2 parts, and diluent 3 - 5 parts. Component B is a catalyst, and component C is a curing agent.

[0005] As an implementation manner, the weight ratio of component A, component B, and component C is 110:(3 - 8):(3 - 8).

[0006] As an implementation mode, the weight ratio of the A component, B component and C component is 110:5:5.

[0007] As an implementation mode, the film-forming substance includes at least one of methyl polysiloxane resin, epoxy-modified polysiloxane resin or silicon nitride resin.

[0008] As an implementation mode, the weight ratio of the methyl polysiloxane resin, epoxy-modified polysiloxane resin and silicon nitride resin is (10-25):(10-25):(1-5).

[0009] During the experiment, the inventors found that using a combination of methyl polysiloxane resin, epoxy-modified polysiloxane resin, and silicon nitride resin as the film-forming substance can obtain a battery cell coating with a high flame retardancy rating and shear resistance. It is speculated that the possible reason is that the content of methyl in the self-made methyl silicone resin is relatively high. When combined with the epoxy-modified polysiloxane resin, the reactivity of the resin combination is increased, and the relatively large number of methyl substituents makes the film-forming substance have a large viscosity and high shear resistance, resulting in good adhesion when applied to the battery cell and being not easily damaged. And introducing silicon nitride containing nitrogen elements increases the high-temperature resistance temperature of the film-forming substance, thereby improving the flame retardant performance of the film-forming substance.

[0010] As an implementation mode, the temperature-resistant filler includes at least one of high-silica glass fiber, cobalt black, alumina, mica powder, bentonite.

[0011] As an implementation mode, in parts by weight, the temperature-resistant filler includes 5-10 parts of silica glass fiber, 3-8 parts of cobalt black, 5-15 parts of alumina, 5-15 parts of mica powder, and 1-2 parts of bentonite.

[0012] As an implementation mode, the mesh number of the silica glass fiber is 750-850 mesh.

[0013] As an implementation mode, the mesh number of the silica glass fiber is 800 mesh.

[0014] As an implementation mode, the carrier powder is low-melting-point glass powder, and the initial melting temperature of the low-melting-point glass powder is 460-540 °C.

[0015] As an implementation mode, the initial melting temperature of the low-melting-point glass powder is 500 °C.

[0016] During the experiment, the inventors further found that introducing low-melting glass powder with an initial melting temperature of 500 °C into the film-forming substance can improve the withstand voltage performance before high-temperature resistance and optimize the insulation effect of the coating. The possible reason is speculated as follows: The low-melting glass powder used can increase the temperature-resistant bonding strength of the battery cell coating, making the battery cell coating have a suitable viscosity before the temperature-resistant test and good withstand voltage performance. However, when the usage amount of the low-melting glass powder is higher than the preferred range, the bonding strength of the battery cell coating further increases, but it will instead reduce the voltage before temperature resistance and affect the withstand voltage performance.

[0017] As an implementation manner, the silicone auxiliary agent is a silicone oligomer.

[0018] As an implementation manner, the flame retardant is a combination of aluminum hydroxide and a silicon-based flame retardant.

[0019] As an implementation manner, the weight ratio of the aluminum hydroxide to the silicon-based flame retardant is (5 - 10):(10 - 15).

[0020] As an implementation manner, the diluent is ethylene glycol monobutyl ether.

[0021] As an implementation manner, the raw materials for preparing the methyl polysiloxane resin include methyl orthosilicate, methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane and water; the preparation method of the methyl polysiloxane resin includes the following steps: Mix methyl orthosilicate, methyltrimethoxysilane, dimethyldimethoxysilane, and trimethylmethoxysilane evenly, add water, raise the temperature and then keep it warm for reaction, and obtain the methyl polysiloxane resin after distillation.

[0022] As an implementation manner, by weight, the raw materials for preparing the methyl polysiloxane resin include 40 - 60 parts of methyl orthosilicate, 5 - 15 parts of methyltrimethoxysilane, 5 - 15 parts of dimethyldimethoxysilane, 20 - 40 parts of trimethylmethoxysilane and 20 - 30 parts of water.

[0023] As an implementation manner, by weight, the raw materials for preparing the methyl polysiloxane resin include 50 parts of methyl orthosilicate, 10 parts of methyltrimethoxysilane, 10 parts of dimethyldimethoxysilane, 30 parts of trimethylmethoxysilane and 25 parts of water.

[0024] As an implementation manner, in the preparation method of the methyl polysiloxane resin, the heat preservation temperature is 60 - 70 °C and the heat preservation time is 7 - 9 h.

[0025] As an implementation manner, in the preparation method of the methyl polysiloxane resin, the heat preservation temperature is 65 °C and the heat preservation time is 8 h.

[0026] As an implementation manner, the catalyst is a titanate catalyst, and the curing agent is an organosilicon amine curing agent.

[0027] As an implementation manner, the raw materials for preparing the organosilicon amine curing agent include methyltrimethoxysilane, dimethyldimethoxysilane, aminopropyltrimethoxysilane and water. The preparation method of the organosilicon amine curing agent includes the following steps: Mix methyltrimethoxysilane, dimethyldimethoxysilane and aminopropyltrimethoxysilane evenly, add water, raise the temperature, keep the temperature for reaction, and distill to obtain the organosilicon amine curing agent.

[0028] As an implementation manner, based on parts by weight, the raw materials for preparing the organosilicon amine curing agent include 50 - 70 parts of methyltrimethoxysilane, 10 - 30 parts of dimethyldimethoxysilane, 10 - 30 parts of aminopropyltrimethoxysilane and 10 - 30 parts of water.

[0029] As an implementation manner, based on parts by weight, the raw materials for preparing the organosilicon amine curing agent include 60 parts of methyltrimethoxysilane, 20 parts of dimethyldimethoxysilane, 20 parts of aminopropyltrimethoxysilane and 20 parts of water.

[0030] As an implementation manner, in the preparation method of the organosilicon amine curing agent, the heat preservation temperature is 60 - 80 °C, and the heat preservation time is 5 - 8 h.

[0031] As an implementation manner, in the preparation method of the organosilicon amine curing agent, the heat preservation temperature is 70 °C, and the heat preservation time is 6 h.

[0032] The second aspect of the present invention provides a preparation method of a temperature-resistant insulating coating for a new energy battery cell, including the following steps:

[0033] S1: Mix methyl polysiloxane resin and epoxy-modified polysiloxane resin, add temperature-resistant filler, flame retardant, carrier powder and diluent, mix evenly, grind to a fineness < 40 μm, and then add silazane resin and organosilicon additive, mix evenly to obtain component A;

[0034] S2: Mix component B and component C evenly;

[0035] S3: Add the mixed component B and component C in step S2 to component A, mix evenly to obtain the temperature-resistant insulating coating for a new energy battery cell.

[0036] As an implementation manner, the construction method of the temperature-resistant insulating coating for a new energy battery cell includes the following steps:

[0037] S1 Filter the prepared temperature-resistant insulating coating for a new energy battery cell through a 60-mesh screen;

[0038] After being filtered by S2, it is loaded into a spray gun, and the spraying pressure is 0.2 - 0.3 MPa (2 - 3 kgf / cm 2 ), and the distance between the nozzle and the substrate during spraying is 15 - 30 cm;

[0039] For the first pass of spraying, the film thickness is 70 - 90 μm. After spraying, it is flash dried at room temperature for 5 min, then placed in an oven at 50 - 80°C for drying for 10 - 20 min. After cooling, for the second pass of spraying, the film thickness is 70 - 90 μm. After spraying, it is flash dried at room temperature for 5 - 10 min, then placed in an oven at 50 - 80°C for drying for 10 - 15 min, and then baked at 150°C for 1 h to obtain a temperature-resistant insulating coating film for new energy battery cells.

[0040] As an implementation method, the total thickness of the temperature-resistant insulating coating film for new energy battery cells is 150 - 180 μm.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) For the temperature-resistant insulating coating for new energy battery cells of the present invention, a combination of methyl polysiloxane resin, epoxy-modified polysiloxane resin, and silicon nitride resin is used as the film-forming substance, and a battery cell coating with a high flame retardancy grade and shear resistance can be obtained.

[0043] (2) For the temperature-resistant insulating coating for new energy battery cells of the present invention, the methyl polysiloxane resin, epoxy-modified polysiloxane resin, and silicon nitride resin are in a weight ratio of (10 - 25):(10 - 25):(1 - 5), which can improve the adhesion between the coating and the substrate and optimize the insulation, flame retardancy, and electrolyte resistance before and after heat resistance.

[0044] (3) For the temperature-resistant insulating coating for new energy battery cells of the present invention, low-melting glass powder with an initial melting temperature of 500°C is introduced into the film-forming substance, which can improve the bonding force of the coating to the substrate during the high-temperature process and enhance the performance of the coating against air flow erosion after the battery cell catches fire.

[0045] (4) For the temperature-resistant insulating coating for new energy battery cells of the present invention, a dual-curing mechanism is adopted. A titanate catalyst is used to make the resin curable by moisture, and an organosilicon amine curing agent can cure the epoxy groups in the resin and organosilicon oligomers, improving the denseness of the coating film after film formation and enhancing the salt spray resistance, acid and alkali resistance, electrolyte resistance, and water resistance.

[0046] (5) For the temperature-resistant insulating coating for new energy battery cells of the present invention, an organosilicon oligomer additive is introduced, which can improve the drawability and electrolyte resistance of the coating.

[0047] (6) For the temperature-resistant insulating coating for new energy battery cells of the present invention, a combination of flame retardants of aluminum hydroxide and silicon-based flame retardants is used, which can significantly improve the flame retardancy grade and meet the UL94V-0 standard. Detailed implementation mode

[0048] Example

[0049] A temperature-resistant insulating coating for new energy battery cells, the preparation raw materials include component A, component B and component C, and the specific weight parts are shown in Table 1 below:

[0050] Table 1

[0051]

[0052]

[0053] Calculated by weight parts, the preparation raw materials of the methyl polysiloxane resin include 50 parts of tetramethoxysilane, 10 parts of methyltrimethoxysilane, 10 parts of dimethyldimethoxysilane, 30 parts of trimethylmethoxysilane and 25 parts of water.

[0054] The preparation method of the methyl polysiloxane resin includes the following steps: Mix tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane and trimethylmethoxysilane evenly, add water, heat up to 65°C and keep the temperature for reaction for 8 hours, and obtain the methyl polysiloxane resin after distillation.

[0055] Calculated by weight parts, the preparation raw materials of the organosilicon amine curing agent include 60 parts of methyltrimethoxysilane, 20 parts of dimethyldimethoxysilane, 20 parts of aminopropyltrimethoxysilane and 20 parts of water.

[0056] The preparation method of the organosilicon amine curing agent includes the following steps: Mix methyltrimethoxysilane, dimethyldimethoxysilane and aminopropyltrimethoxysilane evenly, add water, heat up to 70°C, keep the temperature for reaction for 6 hours, and obtain the organosilicon amine curing agent after distillation.

[0057] The sources of the preparation raw materials are specifically shown in Table 2.

[0058] Table 2

[0059]

[0060]

[0061] The initial melting temperature of the low-melting glass powder is 500°C.

[0062] The weight ratio of component A, component B and component C is 110:5:5.

[0063] A preparation method of a temperature-resistant insulating coating for new energy battery cells, including the following steps:

[0064] S1: Mix methyl polysiloxane resin and epoxy-modified polysiloxane resin, add heat-resistant filler, flame retardant, carrier powder and diluent, mix them evenly, grind to a fineness of <40 μm, then add silazane resin and silicone auxiliary agent and mix evenly to obtain Component A;

[0065] S2: Mix Component B and Component C evenly;

[0066] S3: Add the mixed Component B and Component C in Step S2 to Component A and mix evenly to obtain a heat-resistant insulating coating for new energy battery cells.

[0067] The construction method of the heat-resistant insulating coating for new energy battery cells includes the following steps:

[0068] S1 Filter the prepared heat-resistant insulating coating for new energy battery cells with a 60-mesh sieve;

[0069] S2 After filtration, load it into a spray gun, and the spraying pressure is 0.2 - 0.3 MPa (2 - 3 kgf / cm 2 ), and the distance between the nozzle and the substrate during spraying is 15 - 30 cm;

[0070] S3 The thickness of the first-pass spray film is 80 μm. After spraying, flash dry at room temperature for 5 min, then put it into an oven at 65 °C and dry for 15 min. After cooling, the thickness of the second-pass spray film is 80 μm. After spraying, flash dry at room temperature for 8 min, then put it into an oven at 65 °C and dry for 13 min, and then bake at 150 °C for 1 h to obtain a heat-resistant insulating coating film for new energy battery cells.

[0071] Performance Test

[0072] Place the heat-resistant insulating coating film for new energy battery cells after construction in Examples 1 - 5 for 96 h and then conduct performance tests.

[0073] The test results are shown in Table 3.

[0074] Table 3

[0075]

[0076]

[0077]

[0078] Result analysis: Example 1 meets the requirements. The addition amount of the low-melting glass powder in Example 2 exceeds the preferred range, and the voltage before heat resistance < 2700V, which does not meet the test requirements, and subsequent projects will no longer be tested; in Example 3, no silazane resin is added, the voltage resistance after heat resistance < 1000V, and the shear performance decreases, which does not meet the test requirements, and subsequent projects will no longer be tested; the flame retardancy of Example 4 does not meet the test requirements, and subsequent projects will no longer be tested; in Example 5, bubbling occurs after heat resistance, and the voltage cannot be tested normally, which does not meet the test requirements, and subsequent projects will no longer be tested.

Claims

1. A temperature-resistant insulating coating for new energy battery cells, characterized in that, The preparation raw materials include component A, component B and component C. Component A includes, by weight parts: 20-60 parts of film-forming substance, 15-50 parts of temperature-resistant filler, 15-25 parts of flame retardant, 10-15 parts of carrier powder, 1-2 parts of silicone auxiliary and 3-5 parts of diluent. Component B is a catalyst, and component C is a curing agent.

2. The temperature-resistant insulating coating for new energy battery cells according to claim 1, wherein The weight ratio of component A, component B and component C is 110:(3-8):(3-8).

3. The temperature-resistant insulating coating for new energy battery cells according to claim 1, wherein The film-forming substance includes at least one of methyl polysiloxane resin, epoxy-modified polysiloxane resin or silicon nitride resin.

4. The new energy cell temperature-resistant insulation coating according to claim 3, characterized in that The weight ratio of the methyl polysiloxane resin, epoxy-modified polysiloxane resin and silicon nitride resin is (10-25):(10-25):(1-5).

5. The temperature-resistant insulating coating for new energy battery cells according to claim 1, wherein The temperature-resistant filler includes at least one of high-silica glass fiber, cobalt black, alumina, mica powder, bentonite.

6. The temperature-resistant insulating coating for new energy battery cells according to claim 1, wherein The carrier powder is low-melting-point glass powder, and the initial melting temperature of the low-melting-point glass powder is 460-540°C.

7. The new energy cell heat-resistant insulating coating according to claim 3, characterized in that, The preparation raw materials of the methyl polysiloxane resin include methyl orthosilicate, methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane and water. The preparation method of the methyl polysiloxane resin includes the following steps: Mix methyl orthosilicate, methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane evenly, add water, raise the temperature and then keep the temperature for reaction, and obtain methyl polysiloxane resin after distillation.

8. The temperature-resistant insulating coating for new energy battery cells according to claim 1, wherein The catalyst is a titanate catalyst, and the curing agent is an organosilicon amine curing agent.

9. The new energy cell heat-resistant insulating paint according to claim 8, wherein The preparation raw materials of the organosilicon amine curing agent include methyltrimethoxysilane, dimethyldimethoxysilane, aminopropyltrimethoxysilane and water. The preparation method of the organosilicon amine curing agent includes the following steps: Mix methyltrimethoxysilane, dimethyldimethoxysilane and aminopropyltrimethoxysilane evenly, add water, raise the temperature, keep the temperature for reaction, and obtain the organosilicon amine curing agent after distillation.

10. A method for preparing a temperature-resistant insulating coating for a new energy battery cell according to any one of claims 3-9, characterized in that, Including the following steps: S1: Mix the methyl polysiloxane resin and epoxy-modified polysiloxane resin, add the temperature-resistant filler, flame retardant, carrier powder and diluent and mix evenly, grind to a fineness <40μm, and then add the silicon nitride resin and silicone auxiliary and mix evenly to obtain component A; S2: Mix component B and component C evenly; S3: Add the mixture of component B and component C obtained in step S2 to component A and mix evenly to obtain the temperature-resistant insulating coating for new energy battery cells.

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