Water repellent emulsions, methods of making and using the same

Abstract

The present application relates to waterproof agent emulsion production technical field, specifically waterproof agent emulsion and its preparation method and application, including the following mass fraction of raw materials: PDMS-epoxy modified emulsion: 30-40 parts; PTFE nano dispersion emulsion: 8-12 parts; Polysiloxane modified elastomer: 5-10 parts; Silicon carbide nanowire (SiC): 3-8 parts; Cyclotriphosphazene (PZN): 5-8 parts; Expanded graphite (EG): 3-6 parts; Boron nitride nanosheet (BNNS): 10-15 parts; CeO2@MXene hybrid material: 5-8 parts; Carboxylated CNT: 2-5 parts; Polyurethane / epoxy IPN microcapsule: 2-5 parts; Aramid nanofiber (ANF): 1-3 parts; Water: 10-30 parts. The present application greatly improves the performance of waterproof agent emulsion through functional gradient design and multi-scale interface regulation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waterproof agent emulsion production, in particular to a waterproof agent emulsion, a preparation method and application thereof. BACKGROUND

[0002] In terms of power batteries, the sealing of the shell needs to meet multiple performance requirements under complex working conditions. With the development of new energy vehicles towards high energy density and high power output, power batteries are facing challenges such as internal temperature gradient >10℃ caused by high-rate charging and discharging (such as 3C or more), high-frequency electromagnetic radiation (shielding effectiveness needs to be >40dB) when high-voltage battery systems (800V platform) are running, and fatigue cracking of the sealing interface caused by random vibration (5-2000Hz) during vehicle driving. Traditional shell materials have significant shortcomings in terms of thermal management, electromagnetic interference (EMI) suppression and mechanical reliability, for example: the thermal conductivity is only 0.2-1.5W / m·K, which cannot effectively uniform temperature; the shielding effectiveness is <25dB, which affects vehicle-mounted electronic devices; the fatigue life is <1×10 6 , which cannot meet the 10-year warranty requirement.

[0003] The existing waterproof agent emulsion on the market provides a basic solution to the above problems. The waterproof agent emulsion mainly based on silicone rubber (PDMS) or fluorocarbon resin (PTFE) has excellent hydrophobicity (contact angle >120°), but its functional characteristics still have a significant gap with the extreme working condition requirements of power battery shells.

[0004] Specifically, it is characterized by: single function: only focusing on waterproofing, lacking composite functions such as flame retardation, thermal conduction, EMC shielding, etc. For example, a certain brand of PDMS emulsion (SYLGARD184) has a contact angle of 130°, but the thermal conductivity is only 0.2W / m·K, and the UL94 flame retardation level is only HB, which cannot meet the thermal safety, insulation and electromagnetic compatibility requirements of battery shells.

[0005] Insufficient environmental adaptability: brittle cracking at low temperature (-40℃), softening deformation at high temperature (>150℃). Traditional waterproof agent emulsion is easy to fail under extreme environments (such as low temperature in northern winter or high temperature during fast charging) of power batteries, resulting in a decrease in sealing performance or even leakage.

[0006] Comprehensive performance defects: the thermal conductivity, mechanics, shielding, etc. of traditional materials cannot be synergistically improved. For example, simple compounding of thermal conductive fillers (such as BNNS) and flame retardants (such as APP) will cause performance degradation due to interface incompatibility, and the migration of flame retardants may reduce insulation.

[0007] Therefore, developing a multifunctional waterproof agent emulsion with high thermal conductivity, flame retardation, vibration resistance, wide temperature adaptability and strong shielding effectiveness has become the key to breaking through the technical bottleneck of power battery shell sealing. SUMMARY

[0008] According to the deficiencies in the prior art above, the purpose of the present application is to provide a waterproof agent emulsion, which breaks through the performance bottleneck and greatly improves the performance of the waterproof agent emulsion through functional gradient design and multi-scale interface regulation.

[0009] Another purpose of the present application is to provide a preparation method of the waterproof agent emulsion, which adapts the existing production line in terms of spraying viscosity and significantly improves the efficiency compared with the traditional high-temperature process in terms of step curing time.

[0010] The third purpose of the present application is to provide an application of the waterproof agent emulsion, which is used for sealing the power battery shell.

[0011] The present application is implemented by using the following technical solutions:

[0012] The waterproof agent emulsion comprises the following raw materials in mass fraction: PDMS-epoxy modified emulsion: 30-40 parts; PTFE nano-dispersed emulsion: 8-12 parts; polysiloxane modified elastomer: 5-10 parts; silicon carbide nanowire (SiC): 3-8 parts; cyclotriphosphazene (PZN): 5-8 parts; expanded graphite (EG): 3-6 parts; boron nitride nanosheet (BNNS): 10-15 parts; CeO2@MXene hybrid material: 5-8 parts; carboxylated CNT: 2-5 parts; polyurethane / epoxy IPN microcapsule: 2-5 parts; aramid nanofiber (ANF): 1-3 parts; and water: 10-30 parts.

[0013] The preparation method of the PDMS-epoxy modified emulsion is as follows: NH2-PDMS with a molecular weight of 8000-12000 is mixed with bisphenol A type epoxy resin at a mass ratio of 5-7:1, 0.5% stannous octoate catalyst is added, and the mixture is reacted at 75-80°C for 3-4 hours under nitrogen protection to generate a prepolymer; then the prepolymer is mixed with deionized water and 2% Tween-80 emulsifier, and processed in a high-speed shearing emulsifier at 8000-10000 rpm for 30 minutes to form a PDMS-epoxy modified emulsion; and the solid content of the emulsion is 40-50%.

[0014] The pretreatment method of the polysiloxane modified elastomer is as follows: hydroxyl-terminated polydimethylsiloxane with a molecular weight of 20000-30000 is mixed with polyurethane prepolymer with an NCO content of 6-8% at a mass ratio of 3-5:1, 0.1% dibutyltin dilaurate catalyst is added, and the mixture is reacted at 60°C for 2 hours to generate a polysiloxane-polyurethane block copolymer; then the copolymer is dissolved in ethyl acetate, the solid content is adjusted to 30-40%, and ultrasonic dispersion is performed, and the polysiloxane modified elastomer is obtained.

[0015] The pretreatment method of the silicon carbide nanowire is as follows: surface modification: the SiC nanowire is dispersed in anhydrous ethanol, 3% KH-560 silane coupling agent is added, stirring is carried out at 60 DEG C for 3 hours, and then centrifugal washing and drying are carried out; the modified SiC dispersion liquid is placed in parallel plate electrodes with a spacing of 10 mm, and a 10 kV / mm direct current electric field is applied for 30-35 minutes.

[0016] The preparation method of the polyurethane / epoxy IPN microcapsule is as follows: dimethyl silicone oil and nano-SiO2 are used as core materials in a mass ratio of 9:1, and polyurethane prepolymer and epoxy resin are used as shell materials in a mass ratio of 3:1; the core material and the shell material are respectively injected into a coaxial microfluidic chip, the flow rate ratio is 1:3, UV curing is carried out for 5-8 minutes, the polyurethane / epoxy IPN microcapsule is formed, and the microcapsule is washed and dried with ethanol; wherein the viscosity of the dimethyl silicone oil is 50 cSt, the NCO content in the polyurethane prepolymer is 6%, the inner diameter of the coaxial microfluidic chip is 200-210 mu m, the outer diameter is 500-510 mu m, and the UV curing condition is 365 nm, 10 mW / cm2.

[0017] The preparation method of the aramid nanofiber is as follows: para-aramid fiber is mixed with [BMIM][BF4] ionic liquid at a mass ratio of 1:20, stirring is carried out at 80-90 DEG C for 10-12 hours, an ANF dispersion liquid is obtained, then 0.5% KH-550 silane coupling agent is added, and reaction is carried out at 55-60 DEG C for 2-2.5 hours, and the aramid nanofiber is obtained.

[0018] The preparation method of the waterproof agent emulsion comprises the following steps:

[0019] (1) Pretreatment of the CeO2@MXene hybrid material:

[0020] ① MXene preparation: etching Ti3AlC2 by molten salt method, and intercalating and exfoliating single-layer MXene by TMAOH;

[0021] ② CeO2 loading: mixing the MXene dispersion liquid with 0.1M Ce(NO3)3 solution, UV irradiation for 2 hours, and photochemical oxidation into CeO2 nanoparticles; 3+

[0022] ③ Antioxidant treatment: mixing the hybrid material obtained in step ② with 0.1% propyl gallate, and drying under nitrogen protection;

[0023] (2) BNNS-CNT composite

[0024] ​The BN bulk was exfoliated by NMP solvent under 500W ultrasonic for 4h, and the supernatant was obtained by centrifugation;

[0025] The carboxylated CNT was mixed with BNNS at a mass ratio of 1:3, and EDC / NHS activator was added, and the mixture was reacted at 60℃ for 6h;

[0026] (3) Premixing of the matrix

[0027] The PDMS-epoxy modified emulsion, PTFE nano-dispersed emulsion, polysiloxane modified elastomer and polyurethane / epoxy IPN microcapsule were premixed at 35-40℃ for 10min at 600-800rpm; then 1-2% KH-550 silane coupling agent was added, and stirred at 800rpm for 20-30min;

[0028] (4) Layered blending under nitrogen protection

[0029] Bottom layer: BNNS, carboxylated CNT and SDBS (0.3-0.8% of the total mass of raw materials) were added in turn under 1:1 ethanol and water, and dispersed under 500W ultrasonic for 30-35min;

[0030] Middle layer: cyclotriphosphazene and expanded graphite were added under 300-500rpm, and stirred for 15-30min;

[0031] Surface layer: SiC nanowires and CeO2@MXene were dispersed under 10kV / mm electric field, and aramid nanofibers were added.

[0032] SDBS is sodium dodecyl benzene sulfonate. EDC is 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide; NHS is N-hydroxysuccinimide; BNNS and carboxylated CNT form a stable heterostructure (reaction formula as follows):

[0033] .

[0034] In the molten salt method, ZnCl2 / KCl was treated at 800℃ for 6h; in step ②, the UV irradiation conditions were 365nm, 100W, and the particle size of CeO2 nanoparticles was 20-50nm.

[0035] The application of the waterproof agent emulsion is used for sealing the power battery shell; the application method comprises the following steps:

[0036] Ⅰ. Transfer the waterproof agent emulsion three-layer slurry to the substrate under vacuum, and spray 0.1% KH-550 ethanol solution between the layers;

[0037] Ⅱ. UV pre-curing at 365nm, 10mW / cm² for 3-5min;

[0038] III. After adding the pretreated bismaleimide, ladder heat curing under nitrogen protection: 80℃ / 20min→120℃ / 40min→150℃ / 10min.

[0039] The pretreatment method of the bismaleimide is that the bismaleimide powder is dissolved in 50% acetone at 40-42℃, 0.1% zinc acetylacetone is added, then the solution is bubbled with nitrogen for 30 minutes to remove dissolved oxygen, and the bismaleimide is added in an amount of 0.8-1.2% of the dry weight of the waterproof agent emulsion.

[0040] The working principle of the present application is that:

[0041] Thermal conductivity enhancement: the in-plane thermal conductivity of boron nitride nanosheet (BNNS), the axial thermal conductivity of silicon carbide nanowire (SiC), and the bridging effect of carboxylated carbon nanotube (CNT) form a "face-line" complementary three-dimensional thermal conductivity network, the thermal conductivity is improved by 150%, and the high insulation property (>10 15 Ω·cm) is maintained.

[0042] Flame retardant synergy: cyclotriphosphazene (PZN) catalyzes the formation of a dense carbon layer, and expanded graphite (EG) expands to insulate heat, and the two synergistically improve the flame retardant efficiency (LOI) from 24% to 34%, and the material passes UL94V-0. PZN generates phosphoric acid substances by catalytic decomposition, promoting the carbonization of polymers; EG expands to form a porous carbon layer, which cooperates with the dense carbon layer generated by PZN to insulate oxygen and heat, significantly improving the flame retardant efficiency.

[0043] Mechanical and environmental adaptability: polysiloxane modified elastomer provides low temperature flexibility, and polyurethane / epoxy IPN microcapsules dissipate vibration energy through the viscoelastic flow of the core material silicone oil; aramid nanofiber (ANF) bridges cracks to improve fracture energy, and bismaleimide (BMI) high temperature crosslinking improves the glass transition temperature and reduces the high temperature deformation.

[0044] Corrosion protection and shielding integration: in the Ce 3+ CeO2@MXene hybrid material realizes chemical passivation corrosion protection, and the conductive network of MXene realizes reflection-absorption synergy, so that the EMC shielding effectiveness is >45dB, and there is no corrosion after salt spray for 1500h.

[0045] Compared with the prior art, the present application has the following advantages:

[0046] (1) The waterproof agent emulsion prepared by the present application integrates high thermal conductivity, flame retardation, vibration resistance, wide temperature adaptability and strong shielding performance, solves the problem of single function of traditional materials, improves the extreme environmental adaptability and fatigue life by nearly 3 times through elastomer toughening and microcapsule energy dissipation design, and enhances the compatibility through interface modification and ordered dispersion process to avoid filler separation.

[0047] (2) The present application is adapted to the production line through a premixing-layering blending process, the spraying viscosity is shortened by 30% working hours, and the step curing is shortened; the high dispersion and orientation of nanofillers are realized through the melting salt stripping, ultrasonic dispersion and electric field induction technology; the water / ethanol solvent system reduces VOCs emission, which meets the environmental protection requirements.

[0048] (3) When applied to the sealing of power battery shells, the three-layer paste vacuum transfer is combined with the coupling agent spraying to enhance the interlayer adhesion, the step curing reduces the internal stress; the high thermal conductivity uniform temperature, strong shielding anti-interference and long fatigue life ensure safety; it is adapted to the existing production line, without the need for large-scale modification, and reduces the industrial application cost. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical scheme of the present application more clear and explicit, the present application will be further described in detail below.

[0050] Manufacturer:

[0051] PTFE nanodispersion emulsion: DuPont DISP35, commercially available product of Dongguan Baida Plastic Raw Material Co., Ltd.;

[0052] Cyclotriphosphazene: purity ≥ 99%, commercially available product of Zhangjiagang Xinyi Chemical Co., Ltd.;

[0053] Expanded graphite: LG-3001, fixed carbon ≥ 99.996%, commercially available product of Henan Liugong Graphite Co., Ltd.;

[0054] Boron nitride nanosheet: commercially available product of Guangdong Shengpeng Technology Co., Ltd.;

[0055] CeO2@MXene hybrid material: commercially available product of Suzhou Beikuo Nanometer Technology Co., Ltd.;

[0056] Carboxylated CNT: purity ≥ 95%, commercially available product of Xi'an Haoran Biological Technology Co., Ltd.

[0057] Test method:

[0058] UL94 flame retardant grade: GB / T 2408-2021 "Determination of Combustion Behavior of Plastics Horizontal and Vertical Methods";

[0059] Salt spray test: GB / T 10125-2021 "Artificial Atmosphere Corrosion Test Salt Spray Test";

[0060] Working temperature range (℃): GB / T 2423.1-2008 "Electrical and Electronic Products Environmental Test Part 2: Test Method Test A: Low Temperature", GB / T 2423.2-2008 "Electrical and Electronic Products Environmental Test Part 2: Test Method Test B: High Temperature";

[0061] Vibration fatigue life: GB / T 4857.23-2012 “Packaging and Transport - Packaging Goods - Part 23: Random Vibration Test Methods”;

[0062] Thermal conductivity: GB / T 10297-2015 “Determination of thermal conductivity of non-metallic solid materials - Hot-wire method”;

[0063] Volume resistivity: GB / T 1410-2006 “Test methods for volume and surface resistivity of solid insulating materials”;

[0064] EMC shielding effectiveness: GB / T 17626.3-2016 “Techniques of measurement and test for electromagnetic compatibility - Radiated disturbance tests on R.F. communications equipment subjected to spurious emissions”;

[0065] Spraying viscosity: GB / T 1723-1993 “Determination of viscosity of paints”;

[0066] The following is the pretreatment process of some raw materials in the examples and comparative examples:

[0067] The preparation method of the PDMS-epoxy modified emulsion is as follows: 10000 molecular weight NH2-PDMS is mixed with bisphenol A type epoxy resin at a mass ratio of 6:1, 0.5% stannous octoate catalyst is added, and the mixture is reacted at 80°C for 4 hours under nitrogen protection to form a prepolymer; then the prepolymer is mixed with deionized water and 2% Tween-80 emulsifier, and processed in a high-speed shearing emulsifier at 10000 rpm for 30 minutes to form a PDMS-epoxy modified emulsion; the solid content of which is 45%.

[0068] The pretreatment method of the polysiloxane modified elastomer is as follows: 25000 molecular weight hydroxyl-terminated polydimethylsiloxane is mixed with a polyurethane prepolymer with a NCO content of 7% at a mass ratio of 4:1, 0.1% dibutyltin dilaurate catalyst is added, and the mixture is reacted at 60°C for 2 hours to form a polysiloxane-polyurethane block copolymer; then it is dissolved in ethyl acetate, the solid content is adjusted to 35%, and ultrasonic dispersion is performed to obtain the product.

[0069] The pretreatment method of the silicon carbide nanowire is as follows: surface modification: disperse the SiC nanowire in anhydrous ethanol, add 3% KH-560 silane coupling agent, stir at 60°C for 3 hours, centrifuge and wash, and then dry; place the modified SiC dispersion liquid in parallel plate electrodes with a spacing of 10 mm, apply a direct current electric field of 10 kV / mm for 35 minutes.

[0070] The preparation method of the polyurethane / epoxy IPN microcapsule is as follows: dimethyl silicone oil and nano-SiO2 are used as core materials in a mass ratio of 9:1, and polyurethane prepolymer and epoxy resin are used as shell materials in a mass ratio of 3:1; the core material and the shell material are respectively injected into a coaxial microfluidic chip, the flow rate ratio is 1:3, UV curing is performed for 6 minutes, and the polyurethane / epoxy IPN microcapsule is formed, and the microcapsule is washed and dried with ethanol; wherein the viscosity of the dimethyl silicone oil is 50 cSt, the NCO content in the polyurethane prepolymer is 6%, the inner diameter of the coaxial microfluidic chip is 200 μm, the outer diameter is 500 μm, and the UV curing condition is 365 nm, 10 mW / cm².

[0071] The preparation method of the aramid nanofiber is as follows: para-aramid fiber is mixed with [BMIM][BF4] ionic liquid at a mass ratio of 1:20, stirring at 85°C for 12 hours to obtain an ANF dispersion liquid, and then 0.5% KH-550 silane coupling agent is added and reacted at 60°C for 2 hours to obtain the aramid nanofiber.

[0072] Example 1

[0073] The waterproof agent emulsion comprises the following raw materials in mass fractions: PDMS-epoxy modified emulsion: 30 parts; PTFE nano-dispersed emulsion: 8 parts; polysiloxane modified elastomer: 5 parts; silicon carbide nanowire: 3 parts; cyclotriphosphazene: 5 parts; expanded graphite: 3 parts; boron nitride nanosheet: 10 parts; CeO2@MXene hybrid material: 5 parts; carboxylated CNT: 2 parts; polyurethane / epoxy IPN microcapsule: 2 parts; aramid nanofiber: 1 part; and water: 10 parts.

[0074] The preparation method of the waterproof agent emulsion comprises the following steps:

[0075] (1) Pretreatment of the CeO2@MXene hybrid material:

[0076] ① MXene preparation: etching Ti3AlC2 by a molten salt method, and intercalating and exfoliating single-layer MXene by TMAOH;

[0077] ② CeO2 loading: mixing the MXene dispersion liquid with 0.1M Ce(NO3)3 solution, and irradiating with UV for 2 hours to obtain CeO2 nanoparticles; 3+ photochemical oxidation;

[0078] ③ Antioxidant treatment: mixing the hybrid material obtained in step ② with 0.1% propyl gallate, and drying under nitrogen protection;

[0079] (2) BNNS-CNT compounding

[0080] The BN bulk is exfoliated by NMP solvent under ultrasonic waves at 500W for 4 hours, and the supernatant is obtained by centrifugation;

[0081] Carboxylated CNT mixed with boron nitride nanosheet at a mass ratio of 1:3, EDC / NHS activator was added, and reacted at 60°C for 6h;

[0082] (3) Premixing of the matrix

[0083] PDMS-epoxy modified emulsion, PTFE nano-dispersed emulsion, polysiloxane modified elastomer, and polyurethane / epoxy IPN microcapsule, and 1-2% polyether modified silicone BYK-349 were premixed at 35-40°C for 10 min at 600-800 rpm; then 1% KH-550 silane coupling agent was added and stirred at 800 rpm for 20 min;

[0084] (4) Layered blending under nitrogen protection

[0085] Bottom layer: boron nitride nanosheet, carboxylated CNT, and SDBS were added successively under a mass ratio of 1:1 ethanol and water, and ultrasonically dispersed at 500W for 30-35 min;

[0086] Middle layer: 0.5% non-ionic emulsifier OP-10 was added first, then cyclotriphosphazene and expanded graphite were added at 300 rpm and stirred for 15 min;

[0087] Surface layer: 10kV / mm electric field was used to induce dispersion of silicon carbide nanowires and CeO2@MXene, and aramid nanofibers were added.

[0088] In the molten salt method, ZnCl2 / KCl was treated at 800°C for 6h; in step ②, the UV irradiation conditions were 365nm, 100W, and the particle size of CeO2 nanoparticles was 20nm.

[0089] For power battery shell sealing; including the following steps:

[0090] Ⅰ. Vacuum transfer the three-layer slurry of waterproof agent emulsion to the substrate, and spray 0.1% KH-550 ethanol solution between layers;

[0091] Ⅱ. UV pre-curing at 365nm, 10mW / cm² for 3min;

[0092] Ⅲ. After adding pretreated bismaleimide, ladder heat curing under nitrogen protection: 80°C / 20min→120°C / 40min→150°C / 10min.

[0093] The pretreatment method of bismaleimide is: dissolve bismaleimide powder in 50% concentrated acetone at 40°C, add 0.1% zinc acetylacetone, then bubble nitrogen through the solution for 30 minutes to remove dissolved oxygen; the addition amount of bismaleimide is 0.8% of the dry weight of the waterproof agent emulsion.

[0094] Example 2

[0095] The waterproof agent emulsion comprises the following raw materials in mass fraction: PDMS-epoxy modified emulsion: 35 parts; PTFE nano-dispersed emulsion: 10 parts; polysiloxane modified elastomer: 8 parts; silicon carbide nanowire: 5 parts; cyclotriphosphazene: 6 parts; expanded graphite: 4 parts; boron nitride nanosheet: 12 parts; CeO2@MXene hybrid material: 6 parts; carboxylated CNT: 3 parts; polyurethane / epoxy IPN microcapsule: 3 parts; aramid nanofiber: 2 parts; and water: 15 parts.

[0096] The preparation method of the waterproof agent emulsion comprises the following steps:

[0097] (1) Pretreatment of the CeO2@MXene hybrid material:

[0098] ① MXene preparation: etching Ti3AlC2 by a molten salt method, and obtaining single-layer MXene by TMAOH intercalation and exfoliation;

[0099] ② CeO2 loading: mixing the MXene dispersion liquid with a 0.1M Ce(NO3)3 solution, and irradiating under UV for 2 hours to obtain CeO2 nanoparticles by photochemical oxidation; 3+

[0100] ③ Antioxidant treatment: mixing the hybrid material obtained in step ② with 0.1% propyl gallate, and drying under nitrogen protection;

[0101] (2) BNNS-CNT compounding

[0102] The BN bulk is exfoliated by NMP solvent under ultrasonic waves at 500W for 4 hours, and the supernatant is obtained by centrifugation;

[0103] The carboxylated CNT and the boron nitride nanosheet are mixed in a mass ratio of 1:3, and an EDC / NHS activator is added, and the mixture is reacted at 60°C for 6 hours;

[0104] (3) Matrix premixing

[0105] The PDMS-epoxy modified emulsion, the PTFE nano-dispersed emulsion, the polysiloxane modified elastomer, the polyurethane / epoxy IPN microcapsule, and 1-2% polyether modified silicone BYK-349 are premixed at 38°C and 700rpm for 10 minutes; then 1-2% KH-550 silane coupling agent is added, and the mixture is stirred at 800rpm for 25 minutes;

[0106] (4) Layered blending under nitrogen protection

[0107] Bottom layer: the boron nitride nanosheet, the carboxylated CNT, and SDBS are added in sequence, and the mixture is dispersed under ultrasonic waves at 500W for 32 minutes in ethanol and water in a mass ratio of 1:1;​

[0108] Middle layer: first add 0.5% nonionic emulsifier OP-10, then add cyclotriphosphazene, expanded graphite at 400 rpm, stir for 18 min;

[0109] Surface layer: 10 kV / mm electric field induces dispersion of silicon carbide nanowires and CeO2@MXene, add aramid nanofiber, and it is ready.

[0110] In the molten salt method, ZnCl2 / KCl is treated at 800℃ for 6h; in step ②, the UV irradiation condition is 365nm, 100W, and the particle size of CeO2 nanoparticles is 30nm.

[0111] For power battery shell sealing; comprising the following steps:

[0112] I. Vacuum transfer the three-layer slurry of waterproof agent emulsion to the substrate, and spray 0.1% KH-550 ethanol solution between the layers;

[0113] II. UV pre-curing at 365nm, 10mW / cm² for 4min;

[0114] III. After adding pretreated bismaleimide, ladder heat curing under nitrogen protection: 80℃ / 20min→120℃ / 40min→150℃ / 10min.

[0115] The pretreatment method of bismaleimide is: dissolve bismaleimide powder in 50% acetone at 42℃, add 0.1% zinc acetylacetone, then bubble nitrogen gas through the solution for 30 minutes to remove dissolved oxygen; the addition amount of bismaleimide is 1% of the dry weight of the waterproof agent emulsion.

[0116] Example 3

[0117] Waterproof agent emulsion, including the following mass fractions of raw materials: PDMS-epoxy modified emulsion: 40 parts; PTFE nano-dispersed emulsion: 12 parts; polysiloxane modified elastomer: 10 parts; silicon carbide nanowire: 8 parts; cyclotriphosphazene: 8 parts; expanded graphite: 6 parts; boron nitride nanosheet: 15 parts; CeO2@MXene hybrid material: 8 parts; carboxylated CNT: 5 parts; polyurethane / epoxy IPN microcapsule: 5 parts; aramid nanofiber: 3 parts; water: 30 parts.

[0118] (1) Pretreatment of CeO2@MXene hybrid material:

[0119] ① MXene preparation: etching Ti3AlC2 by molten salt method, and single-layer MXene is obtained by TMAOH intercalation and exfoliation;

[0120] ②CeO2 loading: MXene dispersion liquid mixed with 0.1M Ce(NO3)3 solution, UV irradiation for 2 hours, Ce 3+ Photochemical oxidation into CeO2 nanoparticles;

[0121] ③Antioxidant treatment: the hybrid material obtained in step ② is mixed with 0.1% propyl gallate, and dried under nitrogen protection;

[0122] (2) BNNS-CNT composite

[0123] The BN bulk is exfoliated by NMP solvent under 500W ultrasonic for 4h, and the supernatant is taken by centrifugation;

[0124] Carboxylated CNT is mixed with boron nitride nanosheet at a mass ratio of 1:3, and EDC / NHS activator is added, and the reaction is carried out at 60℃ for 6h;

[0125] (3) Matrix premixing

[0126] PDMS-epoxy modified emulsion, PTFE nano dispersed emulsion, polysiloxane modified elastomer and polyurethane / epoxy IPN microcapsule and 1-2% polyether modified silicone BYK-349 are premixed at 40℃ for 10min at 800rpm; Then add 2% KH-550 silane coupling agent, stir at 800rpm for 30min;

[0127] (4) Layered blending under nitrogen protection

[0128] Bottom layer: boron nitride nanosheet, carboxylated CNT, SDBS are added in turn, and ultrasonic dispersion is carried out at 500W for 35min;

[0129] Middle layer: first add 0.5% nonionic emulsifier OP-10, then add cyclotriphosphazene and expanded graphite at 500rpm, stir for 30min;

[0130] Surface layer: 10kV / mm electric field induces dispersion of silicon carbide nanowire and CeO2@MXene, and aramid nanofiber is added.

[0131] In the molten salt method, ZnCl2 / KCl is treated at 800℃ for 6h; In step ②, the UV irradiation condition is 365nm, 100W, and the particle size of CeO2 nanoparticles is 40nm.

[0132] For power battery shell sealing; comprising the following steps:

[0133] Ⅰ. Vacuum transfer the three-layer slurry of waterproof agent emulsion to the substrate, and spray 0.1% KH-550 ethanol solution between the layers;

[0134] Ⅱ. UV pre-curing at 365nm, 10mW / cm² for 5min;

[0135] III. After adding the pretreated bismaleimide, ladder heat curing under nitrogen protection: 80°C / 20min→120°C / 40min→150°C / 10min.

[0136] The pretreatment method of bismaleimide is to dissolve the bismaleimide powder in 50% concentration acetone at 42°C, add 0.1% zinc acetylacetone, then bubble nitrogen to the solution for 30 minutes to remove dissolved oxygen, and it is ready; the addition amount of bismaleimide is 1.2% of the dry weight of the waterproof agent emulsion.

[0137] Comparative Example 1

[0138] Compared with Example 2, the difference is that boron nitride nanosheets are not added.

[0139] Comparative Example 2

[0140] Compared with Example 2, the difference is that silicon carbide nanowires are not added.

[0141] Comparative Example 3

[0142] Compared with Example 2, the difference is that carboxylated CNTs are not added.

[0143] Comparative Example 4

[0144] Compared with Example 2, the difference is that cyclotriphosphazene is not added.

[0145] Comparative Example 5

[0146] Compared with Example 2, the difference is that expanded graphite is not added.

[0147] Comparative Example 6

[0148] Compared with Example 2, the difference is that polysiloxane elastomer is not added.

[0149] Comparative Example 7

[0150] Compared with Example 2, the difference is that polyurethane / epoxy IPN microcapsules are not added.

[0151] Comparative Example 8

[0152] Compared with Example 2, the difference is that aramid nanofibers are not added.

[0153] Comparative Example 9

[0154] Compared with Example 2, the difference is that bismaleimide is not added.

[0155] Comparative Example 10

[0156] The difference compared with Example 2 is that CeO2@MXene is not added.

[0157] The test data of Examples 1-3 are shown in Table 1.

[0158] The test data of Comparative Examples 1-5 are shown in Table 2.

[0159] The test data of Comparative Examples 6-10 are shown in Table 3.

[0160] Table 1: Test data of Examples 1-3

[0161]

[0162] Table 2: Test data of Comparative Examples 1-5

[0163]

[0164] Table 3: Test data of Comparative Examples 6-10

[0165]

[0166] Comparative Example 1: The thermal conductivity decreases from 3.7 W / m·K to 2.1 W / m·K. BNNS acts as the main in-plane thermal conduction material, and its absence leads to the inability of heat to diffuse along the plane, and only relying on the axial thermal conduction path of SiC is inefficient, and heat accumulation at high temperature is intensified. Comparative Example 2: The thermal conductivity decreases to 2.8 W / m·K. The axial thermal conduction effect of SiC nanowires cannot be replaced, and its absence leads to a decrease in heat dissipation ability in the vertical direction, but BNNS can still maintain part of the in-plane thermal conduction. Comparative Example 3: The thermal conductivity is 2.5 W / m·K. CNT acts as a “bridge” to connect BNNS and SiC, and its absence leads to an increase in interfacial thermal resistance, a collapse of the three-dimensional thermal conduction network, and a decrease in heat transfer efficiency by 32%. Comparative Example 4: The flame retardant level decreases to V-2. PZN forms a dense carbon layer by catalyzing carbonization, and its absence makes EG only physically expand to insulate heat, and cannot effectively interrupt the free radical chain reaction, and the amount of smoke generated during combustion increases significantly. Comparative Example 5: The flame retardant level is V-1. The expanded carbon layer of EG can insulate oxygen and heat, and its absence leads to the easy breaking of the thin carbon layer generated by PZN, and a decrease in flame retardant efficiency. Comparative Example 7: The vibration life decreases from 5.2×10 6 to 1.2×10 6 seconds. IPN microcapsules dissipate energy through the viscoelastic flow of the core material silicone oil, and its absence leads to the inability of vibration energy to be effectively attenuated, and the rapid expansion of cracks. Comparative Example 8: The vibration life decreases from 5.2×10 6 to 2.0×10 6Second, ANF suppresses crack propagation by bridging, and its absence increases the crack propagation rate by 2 times. Comparative Example 9: BMI crosslinked network can increase the glass transition temperature, and its absence leads to the increase of molecular chain segment movement at high temperature and the decrease of rigidity. Comparative Example 10: The EMC shielding effectiveness decreases from 46 dB to 25 dB, and pitting corrosion occurs in the salt spray test. The conductive network of MXene shields electromagnetic waves by reflection-absorption synergy, and its absence makes the shielding effectiveness decrease by 35%.

Claims

1. A water repellent emulsion characterized by, Raw materials including the following mass fractions: PDMS-epoxy modified emulsion: 30-40 parts; PTFE nano-dispersed emulsion: 8-12 parts; polysiloxane modified elastomer: 5-10 parts; silicon carbide nanowire: 3-8 parts; cyclotriphosphazene: 5-8 parts; expanded graphite: 3-6 parts; boron nitride nanosheet: 10-15 parts; CeO2@MXene hybrid material: 5-8 parts; carboxylated CNT: 2-5 parts; polyurethane / epoxy IPN microcapsule: 2-5 parts; aramid nanofiber: 1-3 parts; Water: 10-30 parts; The preparation method of the polyurethane / epoxy IPN microcapsule is as follows: taking dimethyl silicone oil and nano-SiO2 as core materials in a mass ratio of 9:1, and taking polyurethane prepolymer and epoxy resin as shell materials in a mass ratio of 3:1; the core material and the shell material are respectively injected into a coaxial microfluidic chip, the flow rate ratio is 1:3, and UV curing is performed for 5-8 minutes to form the polyurethane / epoxy IPN microcapsule, which is washed and dried with ethanol; wherein the viscosity of the dimethyl silicone oil is 50 cSt, the NCO content in the polyurethane prepolymer is 6%, the inner diameter of the coaxial microfluidic chip is 200-210 μm, the outer diameter is 500-510 μm, and the UV curing condition is 365 nm, 10 mW / cm².

2. The waterproofing agent emulsion according to claim 1, characterized by, The preparation method of the PDMS-epoxy modified emulsion is as follows: NH2-PDMS with a molecular weight of 8000-12000 is mixed with bisphenol A type epoxy resin in a mass ratio of 5-7:1, 0.5% stannous octoate catalyst is added, and reaction is performed at 75-80°C for 3-4 hours under nitrogen protection to form a prepolymer; then the prepolymer is mixed with deionized water and 2% Tween-80 emulsifier, and treated in a high-speed shearing emulsifier at 8000-10000 rpm for 30 minutes to form the PDMS-epoxy modified emulsion; and the solid content thereof is 40-50%.

3. The water repellent emulsion according to claim 1, characterized in that, The pretreatment method of the polysiloxane modified elastomer is as follows: hydroxyl-terminated polydimethylsiloxane with a molecular weight of 20000-30000 is mixed with polyurethane prepolymer with an NCO content of 6-8% in a mass ratio of 3-5:1, 0.1% dibutyltin dilaurate catalyst is added, and reaction is performed at 60°C for 2 hours to form a polysiloxane-polyurethane block copolymer; then the copolymer is dissolved in ethyl acetate, the solid content is adjusted to 30-40%, and ultrasonic dispersion is performed to obtain the polysiloxane modified elastomer.

4. The water repellent emulsion according to claim 1, characterized by, The pretreatment method of the silicon carbide nanowire is as follows: surface modification: SiC nanowires are dispersed in anhydrous ethanol, 3% KH-560 silane coupling agent is added, and stirring is performed at 60°C for 3 hours; after centrifugal washing and drying, the modified SiC dispersion liquid is placed in parallel plate electrodes with a spacing of 10 mm, and a direct current electric field of 10 kV / mm is applied for 30-35 minutes.

5. The water repellent emulsion of claim 1, wherein The preparation method of the aramid nanofiber is as follows: para-aramid fiber is mixed with [BMIM][BF4] ionic liquid in a mass ratio of 1:20, stirring is performed at 80-90°C for 10-12 hours to obtain an ANF dispersion liquid, then 0.5% KH-550 silane coupling agent is added, and reaction is performed at 55-60°C for 2-2.5 hours to obtain the aramid nanofiber.

6. A method for producing the emulsion of the water repellent agent according to any one of claims 1 to 5, characterized by, Comprising the following steps: (1) Pretreatment of CeO2@MXene hybrid material: ① MXene preparation: etching Ti3AlC2 by molten salt method, and intercalating and exfoliating single-layer MXene by TMAOH; CeO2 loading: MXene dispersion liquid was mixed with 0.1 M Ce(NO3)3 solution, UV irradiation for 2 hours, Ce 3+ photochemical oxidation into CeO2 nanoparticles; ③ Antioxidant treatment: mixing the hybrid material obtained in step ② with 0.1% propyl gallate, and drying under nitrogen protection; (2) BNNS-CNT composite BN bulk was exfoliated by NMP solvent under 500W ultrasonic for 4h, and the supernatant was obtained by centrifugation; Carboxylated CNT was mixed with boron nitride nanosheet at a mass ratio of 1:3, and EDC / NHS activator was added, and the mixture was reacted at 60°C for 6h; (3) Matrix premixing PDMS-epoxy modified emulsion, PTFE nano-dispersed emulsion, polysiloxane modified elastomer and polyurethane / epoxy IPN microcapsule were premixed at 35-40°C and 600-800rpm for 10min; then 1-2% KH-550 silane coupling agent was added, and stirred at 800rpm for 20-30min; (4) Layered blending under nitrogen protection Bottom layer: boron nitride nanosheet, carboxylated CNT and SDBS were added in turn, and ultrasonic dispersion was carried out in ethanol and water at 500W and a mass ratio of 1:1 for 30-35min; Middle layer: cyclotriphosphazene and expanded graphite were added under stirring at 300-500rpm for 15-30min; Surface layer: silicon carbide nanowire and CeO2@MXene were dispersed under 10kV / mm electric field, and aramid nanofiber was added.

7. The method for producing a water repellent emulsion according to claim 6, characterized by, In the molten salt method, ZnCl2 / KCl was treated at 800°C for 6h; in step ②, the UV irradiation conditions were 365nm and 100W, and the particle size of CeO2 nanoparticles was 20-50nm.

8. Use of an emulsion of a water repellent agent according to any one of claims 1 to 5, characterized in that, For power battery shell sealing; the application method comprises the following steps: Ⅰ. Vacuum transfer the three-layer slurry of waterproof agent emulsion to the substrate, and spray 0.1% KH-550 ethanol solution between the layers; Ⅱ. UV pre-curing at 365nm and 10mW / cm² for 3-5min; Ⅲ. After adding pretreated bismaleimide, stepwise heat curing under nitrogen protection: 80°C / 20min→120°C / 40min→150°C / 10min.

9. The use of a water repellent emulsion according to claim 8, characterized in that The pretreatment method of the bismaleimide is as follows: dissolve the bismaleimide powder in 40-42°C concentrated acetone with a concentration of 50%, add 0.1% zinc acetylacetonate, then bubble nitrogen through the solution for 30min to remove dissolved oxygen; the addition amount of bismaleimide is 0.8-1.2% of the dry weight of the waterproof agent emulsion.

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